THESIS Ground Source Heat Pumps Feasibility Analysis

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ABSTRACT

RAY, SAURABH ASOKKUMAR. Feasibility Analysis of Implementing Ground SourceHeat Pump Systems for Commercial and Residential Buildings in the United States. (Under the direction of Dr. Soolyeon Cho and Dr. Stephen D Terry).

Ground Source Heat Pump (GSHP) systems are one of the most efficient and reliable

systems for providing heating and cooling in buildings. Today, there is an enormous potential

for GSHP systems in continental United States, but high capital cost of GSHP systems

(without Federal tax credits) has limited the growth rate of this technology. The objective of

this study was to develop a methodology for conducting feasibility analysis of GSHP systems

in residential homes and commercial buildings. A user interactive tool was also developed

based on the methodology. This study analyzes the feasibility of GSHP systems across seven

climate zones and three climate regions in the United States, represented by fifteen cities.

The methodology involves collection and analysis of data for energy use, energy cost and

design parameters in the fifteen locations. Using the analyzed data, four different feasibility



sites in the VERY HIGH category, 3 sites in HIGH, 8 sites in GOOD, 4 sites in

MODERATE, and no sites in FAIR. For commercial buildings there are no sites in the

VERY HIGH category, 1 site in HIGH, 7 sites in GOOD, 7 sites in MODERATE, and no

sites in FAIR.



Feasibility Analysis of Implementing Ground Source Heat Pump Systems for Commercialand Residential Buildings in the United States

bySaurabh Asokkumar Ray

A thesis submitted to the Graduate Faculty of North Carolina State University

in partial fulfillment of therequirements for the degree of

Master of Science

Mechanical Engineering

Raleigh, North Carolina

2012



DEDICATION

This thesis is dedicated to my parents for their unconditional love and support. I also dedicate

this thesis to my teachers, who have taught me so much.



BIOGRAPHY

Saurabh Ray was born to Mr. Ashok Kumar Ray and Mrs. Supriya Ray in Asansol, India. His

parents soon moved to Mumbai, the biggest city in India, where he spent most of his

childhood. During his school years, Saurabh was always fascinated by science and

technology. As a result of this keen interest he decided to pursue engineering, and completed

his Bachelor’s degree in Mechanical Engineering from the University of Mumbai. After

completing his Baccalaureate he decided to pursue his Master’s in Mechanical Engineering

and got enrolled in North Carolina State University. There he joined the Industrial

Assessment Center (IAC) in the summer of 2011 and developed a keen interest in energy

systems and energy conservation. Upon graduation, Saurabh plans to stay in the USA to

pursue a career in the field of Energy engineering.



ACKNOWLEDGMENTS

I would like to thank my committee co-chair Dr. Stephen Terry for giving me the opportunity

to work with the IAC and being my mentor during that time. It has been a wonderful

experience to learn so much from the numerous industrial visits and solving so many

practical problems. I also thank him for serving as my committee co-chair.

I would like to thank Dr. Soolyeon Cho who is also my committee co-chair. I am grateful for

all the time and effort he has taken to help me with my thesis, and answer the numerous

questions that I had.

I want to thank Dr. Herbert Eckerlin who readily accepted my request for being a member of

my graduate committee. I want to thank Dr. Piljae Im at Oak Ridge National Laboratory for

letting me work on a pilot project, the result of which is part of this thesis.

I want to thank all the wonderful people I met in the IAC during my time there It was great



TABLE OF CONTENTS

LIST OF TABLES ............................................................................................................ viii

LIST OF FIGURES ...............................................................................................................x

ABBREVIATIONS ........................................................................................................... xiii

CHAPTER 1: INTRODUCTION ..........................................................................................1

1.1 Energy and the United States ........................................................................................2

1.2 Initiatives and Challenges.............................................................................................8

1.3 Energy Conservation Measures and Standards for Buildings ...................................... 10

1.3.1 ASHRAE Standards ............................................................................................ 10

1.3.2 Energy Star .......................................................................................................... 11

1.3.3 LEED Ratings ..................................................................................................... 12

CHAPTER 2: GOALS AND OBJECTIVES........................................................................ 14

2.1 Goals ......................................................................................................................... 14

2.2 Objectives .................................................................................................................. 15

CHAPTER 3: OVERVIEW OF HEAT PUMPS 16



3.4.2 Types of GSHP systems ...................................................................................... 34

3.4.3 Ground-Coupled Heat Pumps .............................................................................. 34

3.4.4 Surface Water Heat Pumps .................................................................................. 37

3.4.5 Ground Water Heat Pumps .................................................................................. 39

CHAPTER 4: METHODOLOGY ....................................................................................... 40

4.1 Data and Resources .................................................................................................... 40

4.1.1 Heating and Cooling Degree Days ....................................................................... 40

4.1.2 Climate Zones and Regions ................................................................................. 43

4.1.3 Selected Cities for Representing Climate Zones in the United States.................... 47

4.1.4 Summer and Winter Design Temperatures ........................................................... 49

4.1.5 Annual Average Ground Temperature ................................................................. 50

4.1.6 Commercial Buildings Energy Consumption Survey Data ................................... 53

4.1.7 Residential Energy Consumption Survey Data ..................................................... 57

4.2 Procedures for GSHP Application Feasibility Screening ................................ ............ 60

4.2.1 Process Flow Chart .............................................................................................. 61



CHAPTER 5: RESULTS AND ANALYSIS ....................................................................... 96

5.1 Results ....................................................................................................................... 96

5.1.1 Prescreening Analysis - 1 Results ........................................................................ 96

5.1.2 Prescreening Analysis - 2 Results ........................................................................ 99

5.1.3 Prescreening Analysis - 3 Results ...................................................................... 102

5.1.4 Prescreening Analysis - 4 Results ...................................................................... 106

5.1.5 Integrated Feasibility Results ............................................................................. 110

5.2 Analysis ................................................................................................................... 115

CHAPTER 6: CONCLUSION .......................................................................................... 121

CHAPTER 7: FUTURE STUDIES.................................................................................... 123

REFERENCES.................................................................................................................. 124

APPENDICES .................................................................................................................. 128

APPENDIX A: 2003 CBECS Report Data ........................................................................ 129

APPENDIX B: 2009 RECS Report Data ........................................................................... 143

APPENDIX C: Analysis of RECS and CBECS Data for Prescreening Analysis – 3 & 4 .... 147



LIST OF TABLES

Table 1: Energy Star efficiency requirements for Tier 1 GSHP systems (Energy Star, 2012)12

Table 2: Efficiency requirements for GSHP systems for LEED homes (LEED, 2008) ......... 13

Table 3: Annual HDD and CDD for 16 selected cities (ASHRAE, 2009) ............................. 42

Table 4: International Climate Zone Definitions (IECC®, 2009) .......................................... 43

Table 5: Climate Zone Definitions (ASHRAE, 2007) .......................................................... 44

Table 6: 16 Cities Representing 8 Climate Zones in the United States (PNNL, 2009) .......... 48

Table 7: Heating and Cooling Design Temperatures for 16 cities (ASHRAE, 2009) ............ 50

Table 8: Annual Average Ground Temperature across the United States .............................. 52

Table 9: Summary of data from Appendix A obtained from 2003 CBECS report ................. 55

Table 10: Summary of data from Appendix B obtained from 2009 RECS report ................. 59

Table 11: EUI for 5 climate zones based on RECS data ....................................................... 73

Table 12: 5 Group classifications for 15 cities ..................................................................... 74

Table 13: Maximum, Minimum and Range values for 5 groups ........................................... 75

Table 14: Adjusted EUI per residential housing unit in 15 locations 77



Table 21: Normalized Total Energy Cost saving per commercial office building ................. 91

Table 22: Weighting Factors for 4 prescreening analysis ..................................................... 93

Table 23: Scores, Feasibility Levels and Rankings for Prescreening Analysis - 1 ................. 97

Table 24: Scores, Feasibility Levels and Rankings for Prescreening Analysis - 2 ............... 100

Table 25: Prescreening Analysis -3 Scores, Feasibility Levels and Rankings for residential

homes ................................................................................................................................ 103

Table 26: Prescreening Analysis -3 Scores, Feasibility Levels and Rankings for commercial

buildings ................................................................ ........................................................... 105

Table 27: Prescreening Analysis -4 Scores, Feasibility Levels and Rankings for residential

homes ................................................................................................................................ 107

Table 28: Prescreening Analysis -4 Scores, Feasibility Levels and Rankings for commercial

buildings ................................................................ ........................................................... 109

Table 29: Integrated Feasibility Scores, Feasibility Levels and Rankings for residential

homes ................................................................................................................................ 112

Table 30: Integrated Feasibility Scores, Feasibility Levels and Rankings for commercial



LIST OF FIGURES

Figure 1.1: Total World and US Primary Energy Production 1980 – 2006 .............................3

Figure 1.2: Total World and US Primary Energy Consumption 1980 – 2008 .........................3

Figure 1.3: Distribution of energy usage in the United States by various sectors in 2009

(Number in Quads) (LLNL, 2010) .........................................................................................5

Figure 1.4: The United States Energy Use by Sector in 2009 (Quads; %)...............................6

Figure 1.5: Corrected United States Energy Use by Sector in 2009 (Quads; %) .....................7

Figure 1.6: Effectiveness of energy usage in the United States in 2009 (Quads; %) ...............8

Figure 2.1: Area suitable for GSHP systems in the United States (NREL, 2006) .................. 14

Figure 3.1: The Carnot Heat Engine .................................................................................... 16

Figure 3.2: P-V diagram of the Carnot Cycle ....................................................................... 17

Figure 3.3: T-s Diagram of the reversed Carnot Cycle (Cengel and Boles, 2011) ................. 21

Figure 3.4: The Vapor Compression Cycle (Dincer and Kanoglu, 2010) .............................. 23

Figure 3.5: T-s diagram (left) and P-h diagram for an ideal Vapor Compression Cycle

(Cengel and Boles 2011) 24



Figure 3.11: Vertical Ground Coupled Heat Pump (Kavanaugh and Rafferty, 1997) ............ 35

Figure 3.12: Horizontal Ground Coupled Heat Pump (Kavanaugh and Rafferty, 1997) ........ 36

Figure 3.13: Slinky type Horizontal Ground Coupled Heat Pump (Kavanaugh and Rafferty,

1997) ................................................................................................................................... 37

Figure 3.14: Closed loop (left) and Open loop SWHP systems (KGS, 2011)........................ 38

Figure 4.1: Climate Zones and Regions in the United States (PNNL and ORNL, 2010) ....... 46

Figure 4.2: Average Annual ground temperature across the United States (Geo4VA, 2006). 51

Figure 4.3: Census divisions for 2003 CBECS report (EIA, 2009) ....................................... 54

Figure 4.4: Climate Zones for 2009 RECS report (PPNL and ORNL, 2010) ........................ 58

Figure 4.5: Process Flow Diagram of Pre-Screening Processes ............................................ 62

Figure 5.1: Distribution of Scores of Combined HDDs and CDDs for 7 climate zones......... 96

Figure 5.2: Five Level Environmental Feasibility and number of sites appeared in each

category .............................................................................................................................. 98

Figure 5.3: Distribution of Scores of the Ground Conditions in Relation to the Design and

Degree Days for 7 climate zones ......................................................................................... 99



.......................................................................................................................................... 105

Figure 5.8: Five Level Energy Savings Feasibility and number of sites appeared in each

category for commercial buildings ..................................................................................... 106

Figure 5.9: Distribution of Scores for Normalized Cost Savings in residential homes ........ 107

Figure 5.10: Five Level Cost Savings Feasibility and number of sites appeared in each

category for residential homes ........................................................................................... 108

Figure 5.11: Distribution of Scores for Normalized Cost Savings in commercial buildings 109

Figure 5.12: Five Level Cost Savings Feasibility and number of sites appeared in each

category for commercial buildings ..................................................................................... 110

Figure 5.13: Distribution of the Integrated Scores for residential homes in 7 climate zones 111

Figure 5.14: Five Level Integrated Feasibility and number of sites appeared in each category

for residential homes ......................................................................................................... 112

Figure 5.15: Distribution of the Integrated Scores for commercial buildings in 7 climate

zones ................................................................................................................................. 113

Figure 5.16: Five Level Integrated Feasibility and number of sites appeared in each category



(t) GSF: Gross Square Feet

(u) Btu: British Thermal Unit

(v) EUI: Energy Use Intensity

(w) EIA: U.S. Energy Information Administration



CHAPTER 1: INTRODUCTION

Our quest for finding better and more optimum solutions to engineering problems is one of

the most pressing issues of our time. One such problem which engulfs our community is the

issue of “Energy”. While the term energy is by itself very diverse in nature, for this study we

will limit ourselves to Ground Source Heat Pump (GSHP) systems, which are energy

efficient systems for providing thermal energy for various purposes.

Currently, buildings (commercial and residential) these days are being retrofitted with GSHP

systems because their existing Heating, Ventilation and Air Conditioning (HVAC) systems

are nearing the end of their life cycle. Also newly constructed buildings are often provided

with GSHP systems for meeting thermal loads in more energy efficient ways. These projects

are typically cost intensive and require some level of prescreening analysis prior to detailed,

and investment grade analysis. This study serves as the first step for the project planning

process, for understanding the feasibility of ground source heat pump systems for residential

and commercial buildings across continental the United States The tool created for this study



1.1 Energy and the United States

Energy is the prime mover of economic growth and is vital to the sustenance of a modern

economy (Siemens, 2010). We live in a time when global energy issues have reached

unprecedented levels of significance both for nations and the consuming public. Our

existence by and large depends in our ability to understand, and utilize this limited resource

in the most optimum manner, and also educate future generations regarding the need to be

conscientious in the use of energy.

There has been a constant increase in energy production to keep up with ever increasing

demand over the last few decades, and given the advancements in science and technology,

coupled with economic developments and an increasing rate of population growth, the

demand for energy is destined to grow higher. Figure 1.1 depicts the Total Primary Energy 1

production in the World and the United States between 1980 and 2006 (EIA, 2012). Figure

1.2 depicts the Total Primary Energy consumption by the World and the United States

between 1980 and 2008 (EIA, 2012).



E n e r g y ( Q u a d r i l l i o n B t u )

g y ( Q u a d r i l l i o n B t u )

Figure 1.1: Total World and US Primary Energy Production 1980 – 2006



It is observed that the total world’s annual primary energy production grew from 287.6

quadrillion2

Btu to 469.4 quadrillion Btu, from 1980 to 2006 (EIA, 2012). This is an increase

of 63% over 26 years. At the same time the primary energy production in the United States

grew from 67.2 quadrillion Btu to 71 quadrillion Btu (EIA, 2012), which is just a 6%

increase in production within the same time frame.

Similarly it is observed that the total world’s primary energy consumption grew from 283.2

quadrillion Btu to 493 quadrillion Btu, from 1980 to 2008 (EIA, 2012). This is an increase of

74% over 28 years. At the same time the primary energy consumption in the United States

grew from 78.1 quadrillion Btu to 100.6 quadrillion Btu (EIA, 2012), which is a 29%

increase in demand for energy.

The energy production and consumption data highlights the fact that, there has not been a

significant increase in energy production within the United States over last few decades. On

the other hand energy consumed by the United States has been drastically increasing, and is



5

Figure 1.3: Distribution of energy usage in the United States by various sectors in 2009 (Number in Quads) (LLNL, 2010)



While the end use of energy can be by various means, there are four major energy consuming

sectors in which all energy consumption is categorized in the United States. They are

Residential, Industrial, Commercial and Transportation. Figure 1.4 shows the distribution of

energy use based on values from Figure 1.3, by all the four sectors.

Transportation appears to be the most energy intensive sector, while Residential and

Commercial facilities together use about 29% of the total energy, if we consider the end use

energy demand in each sector. In reality however, various losses due to inefficiencies

contribute towards more energy being used up, to meet the demand for all sectors. For

example, primary energy sources like coal, hydro, nuclear and natural gas is used to generate

electricity (the highest quality of energy) with a maximum process efficiency of about 40%

(Eurelectric and VGB, 2003).



Figure 1.5 depicts an integrated version of the energy use distribution for various sectors of

the United States economy by considering the effects of losses due to inefficiencies. We

notice that in this case the industrial sector is the highest consumer of energy followed by

transportation, residential and commercial sectors respectively.

Figure 1.5: Corrected United States Energy Use by Sector in 2009 (Quads; %)

It is also to be noted that about 58% of the total energy used in 2009 was lost due to



Figure 1.6: Effectiveness of energy usage in the United States in 2009 (Quads; %)

The savings from energy lost can be in the form of various energy efficiency optimizations

starting from production to delivery. In case of used energy, we have to consider alternatives,

and methods which reduce the energy requirement of all four sectors of the United States

energy economy. Since this research is related to GSHP systems, we shall only consider

residential and commercial sectors where it has the most applications.



The US Department of Energy (DOE) has come up with the Net-Zero Commercial Building

Initiative (CBI) which will strive for building Net-Zero Energy Buildings (NZEBs) for

commercial facilities by the year 2025 (DOE, 2010). A NZEB is a building which can

generate an equivalent amount of energy as it consumes in a year period. The CBI was

launched in the year 2008 and DOE is collaborating with National Laboratory Collaborative

on Building Technologies (NLCBT), architectural and engineering companies, and building

owners to meet the goals of the project.

Another interesting challenge for the future is “The 2030 Challenge”, which is an initiative of

architect Edward Mazria and his organization known as Architecture 2030. The targets of

this initiative are (2030 Inc., 2011):

1. All new buildings, developments and major renovations shall be designed to meet a

fossil fuel, Greenhouse Gas (GHG)-emitting, energy consumption performance

standard of 60% below the regional (or national) average for that building type.

2. At a minimum, an equal amount of existing building area shall be renovated annually



90% in 2025

Carbon-neutral in 2030 (using no fossil fuel GHG emitting energy to operate)

1.3 Energy Conservation Measures and Standards for Buildings

The strategies discussed in the previous section need various supporting standards and

measures that ascertain energy savings and curtails GHG emissions. Some of the prevailing

standards and measures include: the American Society of Heating, Refrigerating and Air

Conditioning Engineers (ASHRAE) Standards, Energy Star, Leadership in Energy and

Environmental Design (LEED) rating system, and various other technology upgrades

(Energy Conservation Measures) done on existing systems for commercial and industrial

facilities, and residential houses.

1.3.1 ASHRAE Standards

ASHRAE is one of the major international technical societies dedicated to the HVAC and



& maintenance, and utilization of on-site renewable energy sources (ASHRAE, 2010).

Established in 1989, the current version is Standard 90.1-2010 and ASHRAE is currently

developing Standard 90.1-2013 version.

ASHRAE Standard 90.2: This is the standard for Energy-Efficient Design of Low-Rise

Residential Buildings. The latest update for this standard is 2007, and has similar objectives

to standard 90.1.

ASHRAE Standard 189.1: This is the Standard for the Design of High-Performance Green

Buildings except low-rise residential buildings. Introduced in 2009, the standard currently

has one update in 2011. The objectives of this standard are similar to that of standard 90.1 as

applied to green-buildings and at the same time ensuring sustainable living (ASHRAE,

2009).

1.3.2 Energy Star



they can be certified as Energy Star compatible systems. Table 1 below show the minimum

EER and COP values for different GSHP systems for Tier 1 systems (Energy Star, 2012).

Table 1: Energy Star efficiency requirements for Tier 1 GSHP systems (Energy Star, 2012)

In order to be certified as an Energy Star compliant GSHP system3, the EER and COP values

need to be equal to or greater than the values mentioned in Table 1. These requirements are

in effect from the year 2009.

1 3 3 LEED Ratings



LEED is a point-based rating system. This means that a building is assigned points based on

certain sustainability performance areas, as measured by LEED. The ratings are awarded on a

110 point scale, and based on the LEED score, a building could be rated as LEED Certified

(40-49 points), LEED Silver (50-59 points), LEED Gold (60-79 points) or LEED Platinum

(80+ points).

Table 2 below shows the minimum efficiency requirements for GSHP systems in LEED

Homes (LEED, 2008). High efficiency GSHPs are entitled to earn 2 points and very high

efficiency GSHP systems can earn 4 points (the maximum possible points) under the Space

Heating and Cooling Equipment category.

Table 2: Efficiency requirements for GSHP systems for LEED homes (LEED, 2008)

End Use Open Loop Closed Loop Direct expansion

Cooling ≥ 16.2 EER ≥ 14.1 EER ≥ 15 EER

Heating ≥ 3.6 COP ≥ 3.3 COP ≥ 3.5 COP

Cooling ≥ 17 8 EER ≥ 15 5 EER ≥ 16 5 EER

Ground Source Heat Pump Type

Good HVAC Design and Installation (prerequisite)

HVAC Equipment



CHAPTER 2: GOALS AND OBJECTIVES

2.1 Goals

The goal of this research is to help building practitioners understand their standings as far as

building energy use and performance. This will enable them to make decisions that can

change the energy consumption by the buildings, which in turn has a greater impact on

society.

Today, GSHPs have enormous potential in the United States. Figure 2.1 below shows the

areas that have the potential for electric power generation, direct use and GSHP systems in

the United States (NREL, 2006). As shown, all the areas in the United States are suitable for

the application of GSHP systems.



GSHPs are a great way to reduce a building’s energy consumption and GHG emissions by

improving the system efficiency of heating and cooling systems, which in turn the systems

use less energy to meet the thermal demand. Even though the prospect of installing such

energy efficient systems seems very exciting, significant analysis and study is required

before installing such systems. The feasibility tool created for this research serves as the

starting point for carrying out major GSHP projects.

2.2 Objectives

The objectives of this study are:

1. To analyze the GSHP application feasibility for different climates and ground

conditions for residential homes and commercial buildings in the United States.

2. To identify energy and cost savings potential for different regions in the United States

based on the Commercial Buildings Energy Consumption Survey (CBECS) and

Residential Energy Consumption Survey (RECS) data respectively.



CHAPTER 3: OVERVIEW OF HEAT PUMPS

3.1 Background

Nicolas Carnot, the French scientist was the first to establish a precise relationship between

heat and work (Zogg, 2008). In 1894, Carnot proposed a theoretical thermodynamic cycle,

known today as the “Carnot Cycle” which consists of four completely reversible 4 processes

and forms the basis of a “Carnot Heat Engine”. Figure 3.1 and Figure 3.2 below show the

Carnot Heat Engine and the corresponding P-V diagram for the Carnot Cycle.

Figure 3.1: The Carnot Heat Engine



Figure 3.2: P-V diagram of the Carnot Cycle

The four reversible processes in the Carnot Cycle are:

1. Reversible Isothermal Expansion (process 1-2): This process occurs at the higher

temperature (T1). The expansion of the gas in the cylinder causes the temperature to



no heat transfer taking place as the gas expands in the cylinder, causing the

temperature to drop from T1 to T2 and doing work on the surrounding.

3. Reversible Isothermal Compression (process 3-4): This process is similar to the first

one, with the only difference being that the gas is compressed at constant

temperature. The compression of the gas in the cylinder causes the temperature to

increase by dT and an equivalent amount of heat is transferred out of the system to the

surrounding, which lowers the temperature back to T2. This continues until the piston

reaches point 4, and by that time the system transfers Q2 amount of heat to the

surrounding sink.

4. Reversible Adiabatic (Isentropic) Compression (process 4-1): As a final step in the

cycle, the system is again assumed to be completely insulated from the surrounding.

The gas is compressed, while the surrounding does work on the system. The

temperature rises from T2 to T1, and the gas returns to the initial state (point 1), thus

completing the cycle.

Based on the above processes, the work done by a Carnot Engine is given by the expression:



The efficiency of a Carnot heat engine operating between two reservoirs is the maximum

theoretical efficiency that can be achieved at those temperatures. The efficiency is defined by

the expression:

Where,

= the Carnot efficiency of the system.

T1 = the temperature of the source reservoir.

T2 = the temperature of the sink reservoir.

Prior to Carnot, William Thompson (later known as Lord Kelvin) in 1852 had the idea about

a “reverse heat engine” which could be used for both cooling and heating. He described an

open system in great detail with individual components like compressor, expansion valves,

evaporator and air as the refrigerant (Heap, 1979). His ideas are a precursor to the commonly

used and known closed vapor compression cycle system.



Post 1900, with industrialization bringing about various inventions, refrigeration systems

were commercially applied in various industries. Between 1919 - 1950 heat pumps for

residential space heating had become reliable and commercially viable. As of today, heat

pumps and other HVAC units have become an essential part of most commercial, residential

and certain industrial facilities, both in terms of providing thermal comfort and sharing a

large part of the energy consumption footprint.

3.2 The Vapor Compression Cycle

As mentioned in the previous section, the Carnot heat engine operates on a completely

reversible cycle shown in Figure 3.2. Reversing the Carnot cycle results in heat getting

extracted from a low temperature source and released into a high temperature sink. This

phenomenon occurs when some external work is done on the system, thus staying consistent

with the second law of thermodynamics5.



Figure 3.3: T-s Diagram of the reversed Carnot Cycle (Cengel and Boles, 2011)

Process 1-2 occurs in the evaporator (a heat exchanger). Here the working fluid, known as a

refrigerant, absorbs heat (QL) form the source at lower temperature (TL) during isothermal

expansion



Process 3-4 occurs in the condenser (also a heat exchanger). The saturated vapor rejects heat

(QH) isothermally to the sink at higher temperature (TH). The refrigerant now becomes a

saturated liquid at the end of this process.

Process 4-1 is the final stage in the cycle. It is assumed to occur in a turbine (a work

producing device). The liquid refrigerant is isentropically expanded so that it reaches its

initial state (point 1) as a two-phase mixture.

In practice however, the reversed Carnot cycle has not been implemented on actual devices.

For example, compressors and turbines are not designed to handle two-phase mixtures. Due

to the limitations faced by practical devices, a modification to the reversed Carnot cycle,

known as the vapor compression cycle is applied to refrigerators and heat pumps7. Figure 3.4

below shows the components of a simple vapor compression cycle (Dincer and Kanoglu,

2010).



Figure 3.4: The Vapor Compression Cycle (Dincer and Kanoglu, 2010)

The vapor compression cycle operates similarly to the reversed Carnot cycle discussed

previously in this section. The evaporator absorbs heat (QL) from the low temperature source



3.2.1 Ideal Vapor Compression Cycle

The schematic discussed above serves as the backbone for the vapor compression cycle.

Figure 3.5 below represents the temperature vs. entropy (T-s) and pressure vs. enthalpy (P-h)

diagrams for an ideal vapor compression cycle (Cengel and Boles, 2011). These diagrams are

essential for understanding certain performance parameters of a vapor compression cycle for

an ideal case. The ideal conditions become the benchmark, and basis for practical

considerations.



Just like we use the term “efficiency” to understand the performance of a Carnot engine, the

term “Coefficient of Performance” (COP) is used for describing the efficiency of refrigerators and heat pumps. The COP is given by the expression:

The refrigeration effect depends on whether the system is a refrigerator or a heat pump. In

case of a refrigerator the refrigeration effect is the cooling effect produced, and for a heat

pump it is the heating effect produced. The work input for the system is the total work done

on the cycle.

Thus, work done on the cycle:

Where,

h2 = specific enthalpy of the refrigerant leaving the compressor

h1 = specific enthalpy of the refrigerant entering the compressor



For a heat pump the COP is expressed as:

Where,

h3 = specific enthalpy of the refrigerant leaving the evaporator

The difference comes about because in heating mode, the compressor work is available for

heating. The following relation is true for a unit operating between the same temperatures:

3.3 Air Source Heat Pumps

An air source heat pump (ASHP) is a mechanical device used for providing thermal

conditioning. ASHPs use the outside air as the heat source in winter or heat sink in summer,

depending on which cycle it is being run. During the cooling cycle, the outside air acts as the



Figure 3.6: ASHP heating cycle (USDOE, 2001)



In the heating cycle, the evaporator is in contact with the outside air, and absorbs heat from

the air. The gaseous refrigerant is compressed and sent into the conditioning space, where it

loses the heat to the space, thus providing heat. For the cooling cycle, the system is reversed

using a reversing valve. The evaporator is now inside the conditioning space, where the

refrigerant picks up the heat to be removed from the space. The condenser rejects this heat to

the outside air, as the refrigerant is condensed.

Conventional ASHPs are rated based on a number of parameters8, besides the COP. They are

as follows:

1. Energy Efficiency Ratio (EER): The EER is the measure of an ASHP’s cooling

capacity. It is the ratio of the output (cooling provided) measured in Btu/hr. to the

input energy measured in Watts. EER is related to COP by the equation:

2. Heating Seasonal Performance Factor (HSPF): This is the measure of an ASHP’s

performance for the heating cycle over an entire heating season. It is considered to be



EER, as SEER is the ratio of the total cooling provided in Btu/hr. for the entire season

divided by the power consumption during the same time frame, measured in Watts.

SEER and EER are related by the following equation (Hendron and Engebrecht,

2010):

4. kW/Ton: this is a direct measure of the power consumption of a heat pump for

producing one ton of cooling. A ton of cooling is equal to 12,000 Btu/hr. This ratio is

also called the Performance Factor (PF).

3.4 Ground Source Heat Pumps

3.4.1 Introduction

In the previous chapter we looked into how heat pumps work. GSHPs operate using same

principles as an ASHP. The difference between the two is that ASHPs use the outside air as

the source or sink whereas GSHPs use the more stable ground or surface water as a source



and the air delivery system. Figure 3.8 depicts the working components that make up a

GSHP system (digtheheat.com, 2011).

Figure 3.8: Components of a typical GSHP system using a hydronic heat delivery system



with an anti-freeze solution for circulating the thermal energy. In GSHP design, the

construction of the ground loop is the most critical factor for all types of GSHP systems. We

shall look at various construction parameters and GSHP types in the following sections. The

third component of a GSHP system is the ductwork that delivers the conditioned air to the

space.

Figure 3.9 below shows the operation of a GSHP during the cooling cycle (Geo4VA, 2006).



During the cooling cycle the anti-freeze solution in the ground loop absorbs the heat from the

superheated refrigerant coming out of the compressor. The ground (which remains at a lower

temperature than the outside air condition at all times during the cooling cycle) absorbs the

heat from the pipes in the ground loop. The refrigerant leaving the condenser in the heat

pump now becomes saturated liquid at high pressure. This liquid passes through an

expansion valve where the pressure and temperature is significantly lowered. The cold liquid

refrigerant is circulated across the evaporator (the heat exchanger between the heat pump and

the conditioned space) where it gains the heat due to the cooling load from the conditioned

space. This saturated vapor gets compressed in the compressor and the cycle gets repeated. It

is to be noted that part of heat from the superheated refrigerant can be utilized for domestic

hot water heating. This is achieved by using a de-superheater as shown in Figure 3.9.

In the heating cycle, the system is reversed using a reversing valve. Figure 3.10 below shows

the working of a GSHP system for the heating cycle (Geo4VA, 2006).



Figure 3.10: Operation of a GSHP during the heating cycle (Geo4VA, 2006)

When the system is reversed, the direction of flow of the refrigerant changes in the heat

pump. The cold liquid refrigerant comes out of the expansion valve and fills the evaporator.



pressure. Just like in case of the cooling cycle, a de-superheater may be used to extract some

of the heat from the superheated vapor for domestic hot water heating. The hot vapor

refrigerant is circulated across the condenser (the heat exchanger between the heat pump and

the conditioned space now acts as a condenser) where it loses the heat to provide heating to

the conditioned space. The hot vapor comes out of the condenser as saturated hot liquid and

enters the expansion valve and the cycle gets repeated.

3.4.2 Types of GSHP systems

GSHP systems are categorized into three basic types, which are: Ground-Coupled Heat

Pumps (GCHPs), Surface Water Heat Pumps (SWHPs) and Ground Water Heat Pumps

(GWHPs). The following sections describe them in detail.

3.4.3 Ground-Coupled Heat Pumps

GCHPs are closed loop systems which run a network of loops into the ground. The loops are

made of High Density Polyethylene (HDPE) pipes which circulate an anti-freeze solution



Figure 3.11: Vertical Ground Coupled Heat Pump (Kavanaugh and Rafferty, 1997)

Vertical GCHPs consist of an array of supply and return HDPE piping loops. These loops are

placed vertically in the ground and spaced 15 – 25 feet apart between loops The loops have a



The second type of the GCHPs is the Horizontal Ground Coupled Heat Pump System. Figure

3.12 shows the layout for a Horizontal GCHP system (Kavanaugh and Rafferty, 1997).

Figure 3.12: Horizontal Ground Coupled Heat Pump (Kavanaugh and Rafferty, 1997)

Horizontal GCHPs are closed loop systems which are constructed by placing the piping loops



Figure 3.13: Slinky type Horizontal Ground Coupled Heat Pump (Kavanaugh and Rafferty, 1997)

In this system the pipes are placed in a coiled format. This reduces the land requirement but

may increase the pipe length for avoiding thermal interference. Slinky systems are more

expensive to install than conventional horizontal GCHP systems.



requirements of the system. An area of major concern is the effects of thermal pollution

caused by SWHP systems. Care must be taken and proper analysis should be done to

understand the impact of SWHP systems, before such projects are undertaken.

Figure 3.14 depicts the layout of closed loop and open loop SWHP systems (KGS, 2011).

Figure 3.14: Closed loop (left) and Open loop SWHP systems (KGS, 2011)

Closed loop SWHP systems consist of a heat pump which is located in the building and a



Open loop systems use water from the water body directly by pumping water into the heat

pump. A water-to-air or water-to-water heat exchanger extracts or rejects heat and provides

heating or cooling as needed. Due to the direct pumping of water from the water body, a

good filtration mechanism is essential to prevent damage to piping and equipment. One

disadvantage of open loop systems is that they cannot be used for heating in colder climates

(Kavanaugh and Rafferty, 1997).

3.4.5 Ground Water Heat Pumps

GWHPs are open loop systems where the energy in the ground water is used for heating,

cooling and domestic hot water preparation. Ground water (which remains at fairly constant

temperature) is pumped via a well, which then circulates between a water-to-water heat

exchanger. The closed loop side of the water-to-water heat exchanger is connected to the

water-to-air heat exchanger in the heat pump. Ground water can also be directly circulated

across the heat pump, but care has to be taken for possible fouling problems.



CHAPTER 4: METHODOLOGY

4.1 Data and Resources

4.1.1 Heating and Cooling Degree Days

Heating Degree Days (HDD) and Cooling Degree Days (CDD) are the measure of heating

and cooling requirements for a location or any specific building respectively. The HDD and

CDD are calculated based on a certain reference temperature.

HDD is the difference between the base temperature at which the HDD is to be determined

and the average temperature for a given day. The difference if positive means that the HDD

for that particular day is the difference in degrees Fahrenheit temperature between the base

temperature and the average temperature for that day. If the difference between the two is

negative, then the HDD is considered to be zero. The annual HDD for a certain location is

the sum of all HDD for the location over one calendar year. The following equations show

the relationship between HDD and outside temperature.



Tmin = Minimum temperature for that particular day (°F)

Tavg = Average of maximum and minimum temperatures for that particular day (°F)

Annual HDD is given by:

Where,

n = Number of days in the calendar year.

Similarly, CDD is the difference between the average temperature for a given day, and the

base temperature at which the CDD is to be determined. The difference if positive means that

the CDD for that particular day is the difference in degrees Fahrenheit temperature between

the average temperature and the base temperature for that day. If the difference between the

two is negative, then the CDD is considered to be zero. The annual CDD for a certain

location is the sum of all CDD for the location over one calendar year. The following



Tmax = Maximum temperature for that particular day (°F)

Tmin = Minimum temperature for that particular day (°F)

Tavg = Average of maximum and minimum temperatures for that particular day (°F)

Annual CDD is given by:

For this study, the annual HDD and CDD for the 16 cities representing the 8 climate zones in

USA were considered. The values for annual HDD and CDD were taken from the 2009

ASHRAE Handbook, with T b as 65°F. Table 3 below lists the HDD65, and CDD65 data for

the 16 locations in the United States, and their sum (ASHRAE, 2009):

Table 3: Annual HDD and CDD for 16 selected cities (ASHRAE, 2009)

NO. CITY STATECLIMATE

ZONEHDD65 CDD65 SUM

1 Miami Florida 1A 130 4,458 4,588

2 Houston Texas 2A 1,204 3,103 4,3073 Phoenix Arizona 2B 941 4,557 5,498

4 Atlanta Georgia 3A 2,694 1,841 4,535



4.1.2 Climate Zones and Regions

The International Code Council (ICC) is an organization which publishes codes and

standards for building design, construction and safety for existing and new buildings. One

such set of codes is known as the International Energy Conservation Code (IECC ®). The

IECC® divides the world into eight different climate zones. These zones are classified based

on the prevailing climate conditions and thermal criteria (Heating and Cooling Degree Days).

Table 4 shows the different climate zones based on IECC® classification (IECC®, 2009):

Table 4: International Climate Zone Definitions (IECC®, 2009)

NO. ZONE NUMBER THERMAL CRITERIA

1 1 9,000 < CDD50°F

2 2 6,300 < CDD50°F ≤ 9,000

3 3A and 3B4,500 < CDD50°F ≤ 6,300

AND HDD65°F ≤ 5,400

4 4A and 4BCDD50°F ≤ 4,500 AND

HDD65°F ≤ 5,400

5 3C HDD65°F ≤ 3,6006 4C 3,600 < HDD65°F ≤ 5,400

7 5 5,400 < HDD65°F ≤ 7,200



ORNL, 2010). The 3 climate regions are defined based on the moisture regimes at those

locations.

ASHRAE adopted the IECC® climate zone definition and published it in its ASHRAE 90.1,

2004 edition. This study adopts the values specified by ASHRAE for the different climate

zones and regions across the United States. Table 5 below shows ASHRAE’s design criteriafor different zones depicted in Figure 4.1 (ASHRAE, 2007).

Table 5: Climate Zone Definitions (ASHRAE, 2007)

NO. ZONE NUMBER ZONE NAME THERMAL CRITERIA

1 1A and 1BVery Hot – Humid (1A)

Dry (1B)9,000 < CDD50°F

2 2A and 2BHot – Humid (2A)

Dry (2B)6,300 < CDD50°F ≤ 9,000

3 3A and 3B

Warm – Humid (3A)

Dry (3B) 4,500 < CDD50°F ≤ 6,300

4 3C Warm – Marine (3C)CDD50°F ≤ 4,500 AND

HDD65°F ≤ 3 600



The three climate regions are defined by ASHRAE as (ASHRAE, 2007):

Marine (C) definition – Locations meeting all four of the following criteria:

1. Mean temperature of coldest month between 27°F and 65°F

2. Warmest month mean < 72°F

3. At least four months with mean temperatures over 50°F

4.

Dry season in summer. The month with the heaviest precipitation in the cold season

has at least three times as much precipitation as the month with the least precipitation in the

rest of the year. The cold season is October through March in the Northern Hemisphere and

April through September in the Southern Hemisphere.

Dry (B) definition – Locations meeting the following criteria:

Not Marine (C) and

Where,

P = annual precipitation in inches



46

Figure 4.1: Climate Zones and Regions in the United States (PNNL and ORNL, 2010)



4.1.3 Selected Cities for Representing Climate Zones in the United States

As mentioned in the previous section, there are 8 climate zones that cover all of continental

United States. Out of these, zones 1 (Very Hot), 2 (Hot), 3 (Warm), 4 (Mixed), 5 (Cool), 6

(Cold), 7 (Very Cold), and 8 (Subarctic) are further classified as A (Humid), B (Dry) or C

(Marine) depending on the region. Due to the diverse nature of climatic conditions in these

zones, along with the variation in RECS and CBECS data, it becomes essential to select

specific locations that represent the physical conditions of every specific zone.

Based on the research done by Pacific Northwest National Laboratory (PNNL) for analyzing

energy savings design in medium sized office buildings, 16 cities across the United States

were selected to represent the different climate zones that cover the United States. This

research adopts the same 16 cities for understanding the feasibility of GSHP systems over

conventional ASHP systems. Table 6 below shows the list of 16 cities along with certain

specific information related to their location (PNNL, 2009).



Table 6: 16 Cities Representing 8 Climate Zones in the United States (PNNL, 2009)

Climate zone 3B (3B-CA and 3B-other, both falling under zone name hot – dry) is represented

by two different cities, Los Angeles, CA and Las Vegas, NV. This was done because the two

cities experience very different climate conditions even though they are in the same climate

zone (PNNL, 2009).

NO. CLIMATE ZONE CITY STATE ZONE NAME COORDINATES

1 1A Miami Florida hot - humid 25°47′16″N 80°13′27″W2 2A Houston Texas hot - humid 29°45′46″N 95°22′59″W

3 2B Phoenix Arizona hot - dry 33°27′N 112°04′W

4 3A Atlanta Georgia hot - humid 33°45′18″N 84°23′24″W

5 3B-CA Los Angeles California hot - dry 34°03′N 118°15′W

6 3B-other Las Vegas Nevada hot - dry 36°10′30″N 115°08′11″W

7 3C San Francisco California marine 37°46′45.48″N 122°25′9.12″W

8 4A Baltimore Maryland mild - humid 39°17′N 76°37′W

9 4B Albuquerque New Mexico mild - dry 35°06′39″N 106°36′36″W

10 4C Seattle Washington marine 47°36′35″N 122°19′59″W

11 5A Chicago Illinois cold - humid 41°52′55″N 87°37′40″W

12 5B Denver Colorado cold - dry 39°44′21″N 104°59′5″W

13 6A Minneapolis Minnesota cold - humid 44°59′N 93°16′W

14 6B Helena Montana cold - dry 46°35′44.9″N 112°1′37.31″W

15 7 Duluth Minnesota very - cold 46°47′12.98″N 92°5′53.5″W

16 8 Fairbanks Alaska extreme - cold 64°50′37″N 147°43′23″W



4.1.4 Summer and Winter Design Temperatures

The summer and winter design temperatures are important factors that indicate the peak

heating and cooling load requirements for any given location. These temperatures help

designers understand equipment design and sizing to meet the peak thermal loads. The design

temperatures are based on a percentile value for the calendar year.

For this study, the winter design heating temperature (dry bulb temperature) is the 99.6

percentile value. This means that the heating design temperature is the lowest temperature

experienced for 99.6% of the total hours annually. The summer cooling design temperature

(dry bulb temperature) is the 0.4 percentile value. This means that the cooling design

temperature is the highest temperature experienced in all but 0.4% of the hours annually. In

this study, the wet-bulb coincident design temperature was not combined as a factor. Table 7

below shows the values for heating (99.6%) and cooling (0.4%) design temperatures for the

16 selected cities representing the 8 climate zones in the United States (ASHRAE, 2009).



Table 7: Heating and Cooling Design Temperatures for 16 cities (ASHRAE, 2009)

4.1.5 Annual Average Ground Temperature

The soil has a better heat capacity than air. Due to this property of soil, it serves as a better

h t d i k Th il t t i t bl di t b d t d th f

NO. CITY STATECLIMATE

ZONE

Heating Design

Temp. (°F )(99.6%)

Cooling Design

Temp. (°F )(0.4%)

1 Miami Florida 1A 47.7 91.8

2 Houston Texas 2A 31.3 95.1

3 Phoenix Arizona 2B 38.6 110.2

4 Atlanta Georgia 3A 20.7 93.8

5 Los Angeles California 3B-CA 44.4 83.7

6 Las Vegas Nevada 3B-other 30.5 108.37 San Francisco California 3C 38.8 83.0

8 Baltimore Maryland 4A 12.9 93.9

9 Albuquerque New Mexico 4B 17.7 95.2

10 Seattle Washington 4C 24.0 86.1

11 Chicago Illinois 5A -4.0 91.9

12 Denver Colorado 5B 0.7 94.3

13 Minneapolis Minnesota 6A -13.4 91.0

14 Helena Montana 6B -15.4 92.7

15 Duluth Minnesota 7 -19.5 84.5

16 Fairbanks Alaska 8 -43.3 81.2



As changes in soil temperature at lower depths depends mostly on the soil characteristics, it a

very site specific analysis is needed to understand the design and construction of horizontal

GCHP systems. Due to the lack of data for individual locations, a more general case has been

considered for this research which is more suitable for vertical GCHP systems. The average

annual ground temperature for various locations across the United States is used for

analyzing feasibility of GSHP systems in the 8 climate zones within continental United

States. Figure 4.2 shows the average annual ground temperature across the United States

(Geo4VA, 2006).



Based on Figure 4.2, values for annual average ground temperature for the 16 cities

representing 8 climate zones in continental United States were determined. Table 8 below

shows the values for the ground temperature observed from Figure 4.2.

Table 8: Annual Average Ground Temperature across the United States

NO. CITY STATE CLIMATEZONE

Annual Avg. GroundTemp. (°F)

1 Miami Florida 1A 77

2 Houston Texas 2A 71

3 Phoenix Arizona 2B 67

4 Atlanta Georgia 3A 62

5 Los Angeles California 3B-CA 676 Las Vegas Nevada 3B-other 62

7 San Francisco California 3C 62

8 Baltimore Maryland 4A 57

9 Albuquerque New Mexico 4B 52

10 Seattle Washington 4C 53

11 Chicago Illinois 5A 50

12 Denver Colorado 5B 52

13 Minneapolis Minnesota 6A 42

14 Helena Montana 6B 44



4.1.6 Commercial Buildings Energy Consumption Survey Data

Introduced in 1979, CBECS is a national survey for commercial buildings10 in the United

States. The CBECS database is the largest available statistical resource for energy

consumption, and energy expenditures in commercial buildings across the United States. EIA

has been publishing CBECS results on a quadrennial basis from 1979 – 2003. However data

from the 2007 survey was not released by EIA because of poor quality standard of acquired

data (EIA, 2008). Subsequently the CBECS for 2011 was not conducted due to financial

constraints. EIA however has resumed work for publishing a new CBECS report, with a

target date of 2014 (EIA, 2008).

The 2003 CBECS report was based on a sample size of 5,215 buildings, which were selected

across nine census divisions and five climate zones as defined by the EIA. This sample size

is weighted to represent 4,859,000 commercial buildings, which is an estimate for the total

number of commercial buildings in the United States back in 2003 (EIA, 2008). Figure 4.3

shows the census divisions from which the census data was gathered for the 2003 CBECS



Figure 4.3: Census divisions for 2003 CBECS report (EIA, 2009)



55

Table 9 below lists a summary of data compiled from Appendix A which is used for this research.

Table 9: Summary of data from Appendix A obtained from 2003 CBECS report

OFFICE BUILDING DATA (CBECS 2003)

New

England

Middle

Atlantic

East

North

Central

West

North

Central

South

Atlantic

East

South

Central

West

South

Central

M ount ain Pacific

NO. OF BUILDINGS 47,000 108,000 134,000 97,000 125,000 41,000 84,000 62,000 125,000

TOTAL GSF (Million sq.ft) 578 2,434 2,190 799 1,958 481 1,343 629 1,796

Electricity Consumption (Billion Btu) 30,717 136,520 143,346 40,956 119,455 30,717 92,151 34,130 88,738

Natural Gas Consumption (Billion Btu) 0 73,944 86,268 19,513 12,324 0 12,324 19,513 17,459

Others (Fuel Oil + District Heat) (Billion Btu) 35,283 28,536 33,386 1,531 23,221 19,283 19,525 4,357 10,803

TOTAL ENERGY USE (Billion Btu) 66,000 239,000 263,000 62,000 155,000 50,000 124,000 58,000 117,000

EUI (kBtu/sq.ft-yr.) 114.60 98.00 120.10 77.60 79.30 103.20 92.30 91.90 65.10

Elect. Expenditure (Million $) 900 4,000 2,940 840 2,450 630 1,890 1,000 2,600

Nat. Gas Expenditure (Million $) 0 667 669 151 105 0 105 139 125

Others (Million $) 75 316 285 104 255 63 175 82 233

TOTAL EXPENDITURE (Million $) 975 4,984 3,894 1,095 2,809 693 2,169 1,221 2,958

Avg. Size/Office Bldg.(sq.ft) 12, 298 22, 537 16, 343 8, 237 15, 664 11, 732 15, 988 10, 145 14, 368

Census Region and Division

Northeast Midwest South West



For commercial buildings, the best available data in the 2003 CBECS report was for office

buildings. This is based on the fact that office buildings show the least number of “Q” values

in the 2003 CBECS report. A “Q” value indicates that data for a particular field was not

released due to statistical inaccuracies. Thus for this research, the feasibility of GSHP

systems for commercial buildings across all climate zones in the United States pertains only

to office buildings in the respective climate zones.

Table 9 lists the data for number of office buildings and the total gross square feet area for

the different census divisions. The energy consumption and energy cost data comprises of

electricity, natural gas, and other fuel types (fuel oil and district heat) all expressed in kBtu

and US$ respectively. The 2003 CBECS report has data for electricity, natural gas and total

energy consumption and expenditure respectively, for office buildings in all census regions.

The energy consumption and expenditure by other fuel types was determined by subtracting

the consumption and expenditure values for electricity and natural gas from the total energy

consumption and expenditure respectively.



The average size for office buildings in respective census division was determined by

dividing the total square feet area by the total number of office buildings in the census

division. The values for the same are shown in Table 9 above.

4.1.7 Residential Energy Consumption Survey Data

Similar to CBECS, RECS is a national survey for residential housing units. The RECS

database is the largest available statistical resource for energy consumption, and energy

expenditures in residential housing units across the country. EIA has been publishing RECS

results on a quadrennial basis from 1978 – 2009. Figure 4.4 shows the climate zones from

which the census data was gathered for the 2009 RECS report (PPNL and ORNL, 2010).

Appendix B shows data used from the 2009 RECS report.



58

Figure 4.4: Climate Zones for 2009 RECS report (PPNL and ORNL, 2010)



The climate zone map used for the 2009 RECS report covers 7 of the 8 climate zones in the

United States, with the exception being climate zone 8 (the subarctic zone represented by

Fairbanks in the list of 16 cities). Figure 4.4 also depicts the location of 15 cities which

represent the 7 climate zones in continental United States. Table 10 below lists a summary of

data compiled from Appendix A which was used for this research.

Table 10: Summary of data from Appendix B obtained from 2009 RECS report

Very Cold/Cold Mixed-HumidMixed-Dry/Hot-

DryHot-Hum id Marine

TOTAL GSF (Million sq.ft) 85,300 73,000 23,000 32,200 10,500

Electricity Consumption (Billion Btu) 1,250,000 1,540,000 440,000 960,000 200,000

Natural Gas Consumption (Billion Btu) 2,440,000 1,320,000 470,000 270,000 200,000

Propane/ LPG (Billion Btu) 230,000 180,000 30,000 40,000 10,000

Fuel Oil (Billion Btu) 380,000 190,000 0 0 0

Kerosene (Billion Btu) 20,000 10,000 0 0 0

TOTAL ENERGY USE (Billion Btu) 4,320,000 3,240,000 940,000 1,270,000 410,000

EUI (kBtu/sq.ft-yr.) 50.64 44.38 40.87 39.44 39.05

Climate Region



For residential housing units, the major fuel types that are used include electricity, natural

gas, propane/LPG11, fuel oil and kerosene. Based on the climate region, Table 10 lists the

data for total gross square feet area for all housing units, the energy consumption and energy

cost data for different fuel types (all expressed in kBtu and US$ respectively). The table also

has values the total fuel consumption by all fuel types and the total energy use cost for all

fuel types. The EUI for every particular climate zone is also calculated and shown in the

table. The values from this table are used in further feasibility screening processes which will

be discussed later.

4.2 Procedures for GSHP Application Feasibility Screening

To develop the prescreening methodologies for GSHPs suitable for the different climate

zones across USA, a comprehensive literature review was conducted with an emphasis on

precedents of GSHP implementations for residential and commercial facilities. The

information gathered to develop the methodology includes utility usage in various census



effectiveness based on the capital investment and expected energy and operating cost savings

compared to the typical existing systems in these locations, were also conducted.

Using the prescreening methodologies, a prioritized feasibility list to implement GSHP

technologies into residential housing units and commercial buildings were developed. The

list includes high level analysis results based on a five level scale of feasibility (very high,

high, good, moderate, and fair), along with expected O&M cost savings, and potential energy

savings. Following sections describe the detailed prescreening methodologies and processes.

4.2.1 Process Flow Chart

Figure 4.5 shows the pre-screening methodology flow diagram, which includes 19. This

diagram has been inputted as a tool in an Excel spreadsheet for users to automatically find

the feasibility answers before implementing the GSHP systems. The feasibility pre-screening

tool is provided as a separate file along with this report. The steps below explain a step-by-

step process on how the user gets answers about the GSHPs project feasibility for a specific



62

Figure 4.5: Process Flow Diagram of Pre-Screening Processes



Step-1. User looks up a city from list based on the 7 climate zones12 in USA.

Step-2. Based on the selected location, the corresponding satellite image using

Google Maps is displayed along with a brief description.

Note: Steps 3 -7 and Steps 11, 12 and 17 do not affect the results for this research. However

they can be used if individual case studies for GSHP feasibility analysis are performed. Thus

these steps have been explained below but their deduction is left to the reader’s discretion.

Step-3. For the selected location, and based on information from satellite images,

the available real estate is estimated, especially for the open land area (for

vertical GCHPs) and the surface water area (for SWHPs).

Step-4. Estimation of available real estate includes: surface water source(s)

available nearby for SWHP systems.

Step-5. Estimation of available real estate includes: ground area available for

ground-coupled loop for GSHP systems.



Step-8. Running on parallel to the location selection in Step-3, the information

regarding the facility is extracted from the database, both in general

(Weather & Ground) and site-specific (residential housing unit or

commercial facility).

Step-9. (i) The Weather Condition (HDDs & CDDs) information for the location

is used to conduct the Prescreening Analysis-1 (Environmental

Condition). Note-1) This is a general environmental factor, not

considering the specific factors that individual locations have such as

building types and their operations. Note-2) HDDs & CDDs are used here

as indicators of thermal energy requirements, although Heating/Cooling

design temperatures are used for peak load calculations (for equipment

sizing). (ii) The Ground Condition (ground temperature) information for

the location is used to conduct the Prescreening Analysis-2 (Ground/Water

Source Feasibility).

Step-10. The information for the site also includes site specific information in the



Step-12. A comparison is made between the total required tons calculated in Step-

11 and the estimated total available Tons for GSHP and SWHP systems as

processed in Step-6 and Step-7.

Step-13. Prescreening Analysis-1, Environmental Condition Feasibility, is

performed based on the weather conditions, which will be discussed in one

of the following sections.

Step-14. Prescreening Analysis-2, Ground Condition Feasibility, is performed

based on the ground conditions, which will be discussed in one of the

following sections.

Step-15.

Prescreening Analysis-3, Energy Savings Potential, is performed based on

the location specific information such as energy use, RECS EUIs and

CBECS EUIs, which will be discussed in one of the following sections.

Step-16. Prescreening Analysis-4, Economic Feasibility, is performed based on the

cost savings calculations, which will be discussed in one of the following

sections.



Step-19. Using the Combined Pre-Screening Analysis data from Step-18, the final

results are displayed for the feasibility of GSHP systems in the selected

location. The results show both feasibility scores and rankings for

residential housing units and commercial buildings.

The prescreening results are designed to give one of the five different feasibility levels based

on the integrated scores; i.e., 1) VERY HIGH (81-100), 2) HIGH (61-80), 3) GOOD (41-60),

4) MODERATE (21-40), and 5) FAIR (0-20). The specific scores of individual locations are

shown in the results. In addition, as there are 15 locations representing 7 climate zones,

rankings (or Comparative Feasibility) are indicated to show the feasibility results based on

the comparisons between the 15 locations. The 15 locations are ranked based on the

integrated pre-screening analysis, which combines four different prescreening analyses; i.e.,

1) Analysis-1 from the weather conditions, 2) Analysis-2 from the ground conditions, 3)

Analysis-3 from site energy use, and 4) Analysis-4 from economic calculations, along with

weighting factors. The specific methodologies and basic assumptions are explained in the



temperature. Based on this main independent parameter or outdoor air temperature, HDDs

and CDDs are typical indicators to show the thermal (heating and cooling) requirements or

demand of building in a specific climate location. In this first prescreening process, these

indicators were used to score the implementation feasibility of GSHPs. As Heat Pumps (HPs)

provide both heating and cooling to buildings, the HDDs and CDDs of a site location were

combined or summed together to show the magnitude of the thermal requirements. The more

the combined HDDs and CDDs are, the higher the feasibility scores.

The information of HDDs and CDDs, based on the change point temperature of 65 F, was

obtained from the ASHRAE Handbook Fundamentals (ASHRAE, 2009). Fairbanks, Alaska

shows the highest combined HDDs and CDDs, but since this location and climate zone is not

considered, Duluth, Minnesota is considered to have the highest combined HDDs (9,425

HDDs) and CDDs (209 CDDs) of 9,634, which, as a result, received the highest score of 84

with the number one ranking. In contrast, Los Angeles, California, which show the least

combined HDDs (1,284 HDDs) and CDDs (617 CDDs) of 1,901, which in turn received the



If:

If:

If:

If:

Where,

DDn = Combined HDD and CDD for a given location

DDmax = Maximum combined HDD and CDD out of 15 locations



4.2.3 Prescreening Analysis - 2 (Ground Condition)

Ground conditions are critical in the feasibility analysis of GSHP projects, since GSHPs use

the underground environment as heat source in the winter and heat sink in the summer. It is

clear that the higher temperature difference between the outdoor temperature and the ground

temperature means the higher potential benefits from having GSHPs for energy savings. This

is because, in contrast to GSHPs, other thermal energy proving systems or HVAC systems

utilizes either outdoor weather conditions as their heat sink/source environment or water such

as cooling tower, which varies significantly dependent on outdoor conditions as compared to

the relatively constant ground conditions.

Figure 4.2 shown earlier depicted the undisturbed ground temperatures in across USA. In

general, the temperature of the soil remains constant at a depth of greater than thirty feet. So

the mean earth temperature is the temperature at which the ground below 30 feet of depth is

consistent year round and independent of seasonal variations. As shown in Figure 4.2, the

undisturbed ground temperatures vary from 37 °F in the northern areas of Minnesota as



for the cooling case. These temperature differences were then multiplied by HDDs and CDDs

and summed together for the individual locations to integrate with the annual thermal energy

requirements. The following equations show these relationships.

n

n

n

n

Where,

αn = Product of CDD and difference in temperature for the given location

βn = Product of HDD and difference in temperature for the given location

γn = Sum of the two parameters α and β for the given location

Once again Fairbanks, Alaska shows the highest “γ” value, but since this location and climate

zone is not considered Duluth Minnesota is considered to have the highest “γ” value or



If:

If:

If:

If:

Where,

γmax = Maximum γ value out of 15 locations



The EUIs for the 5 climates zones were calculated by summing the energy use for all fuel

types, and dividing the sum with the total square footage for all residential units in each

climate zones. The % Energy Use and % Energy Cost for each fuel type in each climate zone

is calculated by:

Table 11 below shows the EUI values for all 5 climate zones. These values are useful

because they were used for calculating the residential housing unit EUIs in the 15 locations

across USA which was selected to represent all 7 climate zones and regions.

Table 11: EUI for 5 climate zones based on RECS data

No. Climate RegionRECS-EUI

(kBtu/sqft-yr)

1 Very Cold/Cold 50.64

2 Mixed-Humid 44.38

3 Mixed Dry/Hot Dry 40 87



The international climate zone definition

The values of HDD, CDD (Table 3) and their sum at these locations.

The 15 cities were split in 5 groups based on their geographic location and climate zone

classification. Table 12 lists the cities which fall under each group.

Table 12: 5 Group classifications for 15 cities

GROUP

1 2 3 4 5

DULUTH BALTIMORE LAS VEGAS MIAMI SAN FRANCISCO

HELENA ATLANTA ALBUQUERQUE HOUSTON LOS ANGELES

MINNEAPOLIS PHOENIXCHICAGO

DENVER

SEATTLE

For each group, the EUI for the location(s) were then determined based on the influence of

HDDs, CDDs or their sum. The deciding factor in group 1 is HDDs because the HDD value

i i ifi l h CDD l f h l i I 2 3 d 5 h d idi



Next, the maximum, minimum and range14 for each group based on values of the deciding

factor as discussed above are calculated. Table 13 lists these values for the 5 groups noted

previously.

Table 13: Maximum, Minimum and Range values for 5 groups

Combining values from Table 11 and Table 13 the EUIs for the 15 locations were calculated

using the following relation:

Where,

difi d l b d d f h i l i (k / f )

1 2 3 4 5MAXIMUM 9,425 5,795 5,453 4,458 2,850

MINIMUM 4,729 4,535 5,168 3,103 1,901

RANGE 4,696 1,260 285 1,355 949

BASIS HDDSUM (HDD +

CDD)

SUM (HDD +

CDD)CDD

SUM (HDD +

CDD)

GROUP VALUE TYPE



ERCZn = EUI value of RECS Climate Zone in which the given location falls under

(kBtu/sqft-yr).



77

Table 14 lists the adjusted EUI values per residential housing unit in the 15 cities, based on calculation methods described in this

section.

Table 14: Adjusted EUI per residential housing unit in 15 locations

No. Location State

Climate Region

(as per Building

America Climate

Region map)

Climate Region (as

per International

Climate Zone Def.)

Climate

ZoneHDD CDD SUM

Adjusted EUI

(kBtu/sqft-yr)

1 DULUTH MN Very Cold/Cold Very Cold 7 9,425 209 9,634 51.64

2 HELENA MT Very Cold/Cold Cold - Dry 6B 7,679 374 8,053 51.27

3 MINNEAPOLIS MN Very Cold/Cold Cold - Humid 6A 7,565 751 8,316 51.25

4 CHICAGO IL Very Cold/Cold Cool - Humid 5A 6,311 842 7,153 50.98

5 DENVER CO Very Cold/Cold Cool - Dry 5B 5,942 777 6,719 50.90

6 SEATTLE WA Marine Mixed - Marine 4C 4,729 177 4,906 50.64

7 BALTIMORE MD Mixed-Humid Mixed - Humid 4A 4,567 1,228 5,795 45.38

8 ATLANTA GA Mixed-Humid Warm - Humid 3A 2,694 1,841 4,535 44.38

9 LAS VEGAS NV Mixed-Dry/Hot-Dry Warm - Dry 3B 2,105 3,348 5,453 41.87

10 ALBUQUERQUE NM Mixed-Dry/Hot-Dry Mixed - Dry 4B 4,069 1,348 5,417 41.74

11 PHOENIX AZ Mixed-Dry/Hot-Dry Hot - Dry 2B 1,245 3,923 5,168 40.87

12 MIAMI FL Hot-Humid Very Hot - Humid 1A 130 4,458 4,588 40.54

13 SAN FRANCISCO CA Marine Warm - Marine 3C 2,708 142 2,850 40.05

14 HOUSTON TX Hot-Humid Hot - Humid 2A 1,204 3,103 4,307 39.44

15 LOS ANGELES CA Mixed-Dry/Hot-Dry Warm - Dry 3B 1,284 617 1,901 39.05



Energy savings from GSHP systems over conventional ASHP systems can vary significantly

based on the location, the prevailing energy costs, construction and labor costs. A study

performed by Navigant Consulting, Inc. for the DOE concluded that typical GSHP systems

on an average provided 25% to 50% energy savings over typical ASHPs, for a 3,000 square

feet single family residential home (Navigant Consulting Inc., 2009). The same study also

concluded that GSHP systems on an average provided 20% to 45% energy savings over

typical ASHPs, for a 6,000 square feet office building (Navigant Consulting Inc., 2009).

Based on the literature review, a conservative assumption was made for this study regarding

the energy savings potential of GSHP systems over conventional ASHP systems. The energy

savings potential was calculated based on the comparison between the adjusted EUIs from

the RECS report for a corresponding location and considering the baseline design case as

80% of the adjusted RECS EUIs. The adjusted RECS EUIs are the average performance

values, so for the design case, 20% lower EUIs were implemented, based on the conservative

approach that GSHPs can save in general about 20% of total energy in buildings.



For residential homes, the average GSF area per housing unit was considered to be the

average GSF values of Single-Family Homes in all climate zones. This is because single

family homes accounted 63% of all housing units for the 2009 RECS survey. The average

GSF area values per housing unit for single family homes in all climate zones are listed in

Table 10. Table 15 lists the normalized energy saving values for all cities based on the

methodology discussed above. The normalized energy saving values was used for generating

Prescreening Analysis – 3 scores for residential housing units the 15 locations.



80

Table 15: Normalized Total Energy Savings value per residential housing unit

No. Location StateClimateZone

Climate Region(as perBuilding America

Climate Region map)

Avg. GSF RECS-EUIBaseline-

EUI

NORMALIZED

ENERGY

SAVINGS

sqft/householdkBtu/sqft-

yr

kBtu/sqft-

yrkBtu/sqft-yr

1 MIAMI FL 1A Hot-Humid 2,023 40.54 32.43 8.11

2 HOUSTON TX 2A Hot-Humid 2,023 39.44 31.55 7.89

3 PHOENIX AZ 2BMixed-Dry/Hot-

Dry2,000

40.8732.70 8.17

4 ATLANTA GA 3A Mixed-Humid 2,546 44.38 35.51 8.88

5 LAS VEGAS NV 3BMixed-Dry/Hot-

Dry2,000

41.8733.50 8.37

6 LOS ANGELES CA 3B

Mixed-Dry/Hot-

Dry 2,000 39.05 31.24 7.81

7 SAN FRANCISCO CA 3C Marine 2,090 40.05 32.04 8.01

8 BALTIMORE MD 4A Mixed-Humid 2,546 45.38 36.31 9.08

9 ALBUQUERQUE NM 4BMixed-Dry/Hot-

Dry2,000

41.7433.39 8.35

10 SEATTLE WA 4C Marine 2,090 50.64 40.52 10.13

11 CHICAGO IL 5A Very Cold/Cold 2,696 50.98 40.79 10.20

12 DENVER CO 5B Very Cold/Cold 2,696 50.90 40.72 10.18

13 MINNEAPOLIS MN 6A Very Cold/Cold 2,696 51.25 41.00 10.25

14 HELENA MT 6B Very Cold/Cold 2,696 51.27 41.02 10.25

15 DULUTH MN 7 Very Cold/Cold 2,696 51.64 41.32 10.33



Just like in Prescreening Analysis – 1 and Prescreening Analysis – 2, a similar methodology

was used to determine scores for Prescreening Analysis – 3. Once again Duluth, Minnesota is

considered to have the highest “ NES” value or 10.33kBtu/sqft-yr, and received the highest

score of 64. In contrast, Los Angeles, California, shows the lowest “ NES” value or

7.81kBtu/sqft-yr, and received the lowest score of 36. The scores were calculated based on

maximum, minimum and median “NES” value. The following equations show the details of

score calculations for individual sites.

If:

If:



NESmed = Median NES value (kBtu/sqft-yr)

PS3n = Prescreening Analysis-3 Score for the given location

Prescreening Analysis – 3 for Commercial Buildings: The data obtained from 2003

CBECS report was used to analyze energy consumption, energy cost, and EUI for specific

census divisions as shown in Figure 4.3. There are 9 census divisions which cover the

CBECS data namely: Pacific, Mountain, West North Central, East North Central, West South

Central, East South Central, South Atlantic, Middle Atlantic and New England. Based on the

type of fuel used values for Energy Used (Btu), % Energy Use, Energy Cost ($), % Energy

Cost, Cost/MMBtu ($), Total Energy Used (MMBtu), Total Energy Cost ($), Total GSF

(sqft), and CBECS-EUI (kBtu/sqft-yr) were determined for all 9 census divisions. These data

and other data related to Prescreening Analysis – 3 for Commercial buildings are shown in

Appendix C.

The EUIs for the 9 census divisions were calculated similarly to that of residential housing



4. For every location, take the % deviation between the EUI value from Step 3 and the

adjusted EUI value from Table 14.

5. The % deviation from Step 4 serves as the % change factor for every location.

Table 17 below shows the % change values for all 15 locations based on the steps discussed

above.

Table 17: % change values for all 15 locations

No. Location

Adjusted

RECS-EUI

(kBtu/sqft-

yr)

Climate Regions used

for obtaining mean

EUI

Adjusted EUI

as per census

division

(kBtu/sqft-

yr)

% CHANGECensus

Division

1 DULUTH 51.64Very Cold/Cold,

Mixed-Humid47.51 -8.00%

West North

Central

2 HELENA 51.27Very Cold/Cold,

Mixed-Dry/Hot-Dry45.76 -10.76% Mountain

3 MINNEAPOLIS 51.25Very Cold/Cold,


West North

Central

4 CHICAGO 50.98Very Cold/Cold,


East North

Central

5 DENVER 50.90Very Cold/Cold,

Mixed-Dry/Hot-Dry45.76 -10.11% Mountain

6 SEATTLE 50.64

Very Cold/Cold,

Mixed-Dry/Hot-Dry,Marine

43.52 -14.07% Pacific

7 BALTIMORE 45.38Hot-Humid, Mixed-

Humid41.91 -7.65%

South

Atlantic



The energy savings potential in commercial buildings was calculated similarly to that of

residential housing units. Just like for residential houses, a 20% lower EUIs for the design

case was implemented.

Thus the total energy savings per residential housing unit was calculated by taking the

difference between the Baseline EUI and CBECS EUI and multiplying the number with the

average GSF area per commercial building for every location.

As explained earlier, for commercial buildings the average GSF area per commercial

building was considered to be the average GSF value of office buildings in all census

divisions. The average GSF area values per office building in all census divisions are listed in

Table 9. Table 19 lists the normalized energy savings per commercial office building in all

cities based on the methodology discussed above. The normalized energy saving values was

used for generating Prescreening Analysis – 3 scores for commercial buildings in the 15

Table 19: Normalized Total Energy Savings value per commercial office building



87

Table 19: Normalized Total Energy Savings value per commercial office building

Avg. GSF CBECS-EUI Baseline-EUINORMALIZED

ENERGY SAVINGS

sqft/building kBtu/sqft- yr kBtu/sqft-yr kBtu/sqft- yr

1 MIAMI FL 1A Hot-Humid South Atlantic 15,664 81.85 65.48 16.37

2 HOUSTON TX 2A Hot-Humid West South Central 15,988 97.30 77.84 19.46

3 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 10,145 103.24 82.59 20.65

4 ATLANTA GA 3A Mixed-Humid South Atlantic 15,664 74.75 59.80 14.95

5 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 10,145 100.77 80.62 20.15

6 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 14,368 72.61 58.09 14.52

7 SAN FRANCISCO CA 3C Marine Pacific 14,368 70.79 56.64 14.16

8 BALTIMORE MD 4A Mixed-Humid South Atlantic 15,664 73.11 58.49 14.62

9 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 10,145 101.08 80.86 20.22

10 SEATTLE WA 4C Marine Pacific 14,368 55.98 44.78 11.2011 CHICAGO IL 5A Very Cold/Cold East North Central 16,343 111.92 89.54 22.38

12 DENVER CO 5B Very Cold/Cold Mountain 10,145 82.89 66.31 16.58

13 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 8,237 71.94 57.55 14.39

14 HELENA MT 6B Very Cold/Cold Mountain 10,145 82.29 65.83 16.46

15 DULUTH MN 7 Very Cold/Cold West North Central 8,237 71.39 57.11 14.28

Census Division No. Location State Climate Zone

Climate Region (as

per Building America

Climate Region map)



For commercial office buildings Chicago, Illinois is considered to have the highest “NES”

value or 22.38kBtu/sqft-yr, and received the highest score of 83. In contrast, Seattle,

Washington, shows the lowest “NES” value or 11.20kBtu/sqft-yr, and received the lowest

score of 17. The scores were calculated based on maximum, minimum and median “NES”

value. The following equations show the details of score calculations for individual sites.

If:

If:

If:



4.2.5 Prescreening Analysis - 4 (Cost Savings)

The cost savings is an important factor for the implementation of GSHPs. The cost savings

analysis was conducted for both residential housing unit and commercial office building

separately. The values are based on total energy savings in each location, and the

corresponding cost of utility ($/MMBtu). The energy savings from individual fuel types were

calculated using the % energy use for each fuel type in each location and multiplying the

value with the total energy savings. The energy savings from each fuel type was then

multiplied with the cost/MMBtu of fuel to obtain the energy cost savings. The sum of all cost

savings for individual fuel types was used as the total cost savings from installing a GSHP

system. The values for the same are indicated in Appendix C. It is to be noted that the values

are an average value, and will most likely be different for individual cases. The normalized

cost savings ($/sqft-yr) for both residential and commercial buildings were used for

generating Prescreening Analysis – 4 scores. Tables 20 and 21 below list the normalized

energy cost saving value per residential home and commercial office building for all cities

respectively, based on the methodology discussed above.

Table 20: Normalized Total Energy Cost saving per residential housing unit



90

Table 20: Normalized Total Energy Cost saving per residential housing unit

Avg. GSF

sqft/household

1 MIAMI FL 1A Hot-Humid South Atlantic 2,023 509.34$ 0.2518$2 HOUSTON TX 2A Hot-Humid West South Central 2,023 495.57$ 0.2450$

3 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 2,000 398.61$ 0.1993$

4 ATLANTA GA 3A Mixed-Humid South Atlantic 2,546 530.34$ 0.2083$

5 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 2,000 408.36$ 0.2042$

6 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 2,000 380.84$ 0.1904$

7 SAN FRANCISCO CA 3C Marine Pacific 2,090 359.70$ 0.1721$

8 BALTIMORE MD 4A Mixed-Humid South Atlantic 2,546 542.28$ 0.2130$

9 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 2,000 407.13$ 0.2036$

10 SEATTLE WA 4C Marine Pacific 2,090 454.89$ 0.2176$

11 CHICAGO IL 5A Very Cold/Cold East North Central 2,696 525.73$ 0.1950$

12 DENVER CO 5B Very Cold/Cold Mountain 2,696 524.92$ 0.1947$

13 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 2,696 528.49$ 0.1960$

14 HELENA MT 6B Very Cold/Cold Mountain 2,696 528.74$ 0.1961$

15 DULUTH MN 7 Very Cold/Cold West North Central 2,696 532.57$ 0.1975$

Normalized Total

Cost Savings

($/sqft-yr)

Total Cost

Savings ($/yr)Location State

Climate

Zone

Climate Region (as


Climate Region map)

Census Division No.

Table 21: Normalized Total Energy Cost saving per commercial office building



91

Table 21: Normalized Total Energy Cost saving per commercial office building

Avg. GSF

sqft/building

1 MIAMI FL 1A Hot-Humid South Atlantic 15,664 4,646.99$ 0.2967$2 HOUSTON TX 2A Hot-Humid West South Central 15,988 5,442.63$ 0.3404$

3 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 10,145 4,410.57$ 0.4347$

4 ATLANTA GA 3A Mixed-Humid South Atlantic 15,664 4,244.24$ 0.2710$

5 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 10,145 4,305.23$ 0.4244$

6 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 14,368 5,275.42$ 0.3672$

7 SAN FRANCISCO CA 3C Marine Pacific 14,368 5,143.69$ 0.3580$

8 BALTIMORE MD 4A Mixed-Humid South Atlantic 15,664 4,150.72$ 0.2650$

9 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 10,145 4,318.26$ 0.4256$10 SEATTLE WA 4C Marine Pacific 14,368 4,067.40$ 0.2831$

11 CHICAGO IL 5A Very Cold/Cold East North Central 16,343 5,416.89$ 0.3314$

12 DENVER CO 5B Very Cold/Cold Mountain 10,145 3,541.20$ 0.3491$

13 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 8,237 2,093.78$ 0.2542$

14 HELENA MT 6B Very Cold/Cold Mountain 10,145 3,515.66$ 0.3465$

15 DULUTH MN 7 Very Cold/Cold West North Central 8,237 2,077.72$ 0.2522$

Census DivisionTotal Cost

Savings ($/yr)

Normalized Total

Cost Savings

($/sqft-yr)

Location StateClimate

Zone

Climate Region (as


Climate Region map)

No.



For commercial office buildings, Phoenix, Arizona showed the highest “NCS” value or

$0.4347/sqft-yr, and received the highest score of 77. In contrast, Duluth, Minnesota, showed

the lowest “NCS” value or $0.2522/sqft-yr, and received the lowest score of 23. The

following equations show the details of score calculations for all commercial sites.

If:

If:

If:



For residential housing units, Miami, Florida showed the highest “NCS” value or 0.2518

$/sqft-yr, and received the highest score of 69. In contrast, San Francisco, California, showed

the lowest “NCS” value or 0.1721 $/sqft-yr, and received the lowest score of 31. The

equations used for generating scores for residential housing units are similar to those used for

commercial sites.

4.2.6 Integrated Feasibility Analysis

The four prescreening analyses (environmental condition, ground condition, energy savings,

and cost savings) were integrated using weighting factors. The weighting factors are not

fixed values, rather the numbers that the user can decide and change based on the specific

conditions that the individual cases have.

In this research, the default values for the weighting factors are shown in Table 22 below.

Table 22: Weighting Factors for 4 prescreening analysis



systems more. Prescreening – 2 takes into consideration the design temperatures, ground

temperature, and the degree day values for every location. These parameters thus have a

higher weight. Prescreening – 4 considers the cost savings from a GSHP system over

conventional HVAC systems. Since simple payback period (which is directly related to cost

savings) typically serve as a key component in understanding project feasibility, the

importance for this criteria is rendered higher. The values for the weighting factors remain

the same for both residential houses and commercial buildings. A selection option of the

weighting factors is given in the prescreening tool provided in a separate Excel spreadsheet,

and users are encouraged to use weighting values as they feel fit.

The integrated feasibility also uses a score system to generate ranks for individual locations.

The integrated scores are generated based on the scores from individual prescreening

analyses and their corresponding weighting factors. The integrated score is calculated based

on the following formula:



4.3 GSHP Feasibility Analysis Prescreening Tool

The prescreening tool serves as a graphical user interface for users to generate results and

input certain values that might seem fit. The tool was created using Microsoft Excel 2007

with a macro-enabled worksheet. The tool is made up of the following worksheets:

DashBoard

Residential_Results

Commercial_Results FlowChart

Methodology

Instructions

Residential_IntegratedFeasibility

Commercial_IntegratedFeasibility

Prescreen-1_OA

Prescreen-2_Ground

Residential_Prescreen-3_Energy

Commercial_Prescreen-3_Energy

Residential_Prescreen-4_Econo

Commercial_Prescreen-4_Econo

RECS UtilityAnalysis

RECS SavingsCalculation CBECS UtilityAnalysis



The colder climate zones got the highest scores primarily because they have high HDD

values. Table 23 lists the scores, the feasibility level and the ranking for all 15 cities. The

cities are arranged in the order of their climate zone, starting from 1A to 7.

Table 23: Scores, Feasibility Levels and Rankings for Prescreening Analysis - 1

No. Location State

Climate

Zone HDD CDD HDD+CDD Score

5

FeasibilityLevels

Ranking

1 MIAMI FL 1A 130 4,458 4,588 30 MODERATE 13

2 HOUSTON TX 2A 1,204 3,103 4,307 37 MODERATE 12

3 PHOENIX AZ 2B 941 4,557 5,498 48 GOOD 7

4 ATLANTA GA 3A 2,694 1,841 4,535 39 MODERATE 11

5 LAS VEGAS NV 3B 2,105 3,348 5,453 47 GOOD 8

6 LOS ANGELES CA 3B 1,284 617 1,901 16 FAIR 15

7 SAN FRANCISCO CA 3C 2,708 142 2,850 25 MODERATE 14

8 BALTIMORE MD 4A 4,567 1,228 5,795 50 GOOD 6

9 ALBUQUERQUE NM 4B 4,069 1,348 5,417 47 GOOD 9

10 SEATTLE WA 4C 4,729 177 4,906 43 GOOD 10

11 CHICAGO IL 5A 6,311 842 7,153 62 HIGH 4

12 DENVER CO 5B 5,942 777 6,719 58 GOOD 5

13 MINNEAPOLIS MN 6A 7,565 751 8,316 72 HIGH 2

14 HELENA MT 6B 7,699 311 8,010 69 HIGH 3

15 DULUTH MN 7 9,425 209 9,634 84 VERY HIGH 1



Figure 5.2: Five Level Environmental Feasibility and number of sites appeared in each category

1

3

6

4

1

0

1

2

3

4

5

6

7

Very High High Good Moderate Fair

N o .

o f S i t e s

FEASIBILITY



5.1.2 Prescreening Analysis - 2 Results

Similar to prescreening – 1, the results for prescreening – 2 are common to both residential

homes and commercial buildings. Figure 5.3 below shows the prescreening – 2 score

distribution in 7 climate zones.

Figure 5 3: Distribution of Scores of the Ground Conditions in Relation to the Design and Degree Days

0

10

20

30

40

50

60

70

80

90

100

1A 2A 2B 3A 3B 3B 3C 4A 4B 4C 5A 5B 6A 6B 7

S c o r e

Climate Zone



Figure 5.4 depicts the number of sites that fall into one of the five feasibility categories. As

shown in Figure 5.4, there is 1 site in the VERY HIGH category, 3 sites in HIGH, 2 sites in

GOOD, 5 sites in MODERATE, and 3 sites in FAIR.

Figure 5.4: Five Level Ground/Design Condition Feasibility and number of sites appeared in each

1

3

2

5

3

0

1

2

3

4

5

6


N o .

o f S i t e s

FEASIBILITY



Table 25: Prescreening Analysis -3 Scores, Feasibility Levels and Rankings for residential homes


shown in Figure 5.6, there are no sites in the VERY HIGH category, 6 sites in HIGH, 4 sites

in GOOD, 5 sites in MODERATE, and no sites in FAIR.

No. Location State

Climate

Zone

Climate Region (as per

Building America ClimateRegion map)

NORMALIZED

ENERGY

SAVINGS

(kBtu/sqft-yr)

Score

5 Feasibility

Levels Ranking

1 MIAMI FL 1A Hot-Humid 8.11 39 MODERATE 12

2 HOUSTON TX 2A Hot-Humid 7.89 37 MODERATE 14

3 PHOENIX AZ 2B Mixed-Dry/Hot-Dry 8.17 40 MODERATE 11

4 ATLANTA GA 3A Mixed-Humid 8.88 48 GOOD 8

5 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry 8.37 42 GOOD 9

6 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry 7.81 36 MODERATE 15

7 SAN FRANCISCO CA 3C Marine 8.01 38 MODERATE 138 BALTIMORE MD 4A Mixed-Humid 9.08 50 GOOD 7

9 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry 8.35 42 GOOD 10

10 SEATTLE WA 4C Marine 10.13 62 HIGH 6

11 CHICAGO IL 5A Very Cold/Cold 10.20 62 HIGH 4

12 DENVER CO 5B Very Cold/Cold 10.18 62 HIGH 5

13 MINNEAPOLIS MN 6A Very Cold/Cold 10.25 63 HIGH 3

14 HELENA MT 6B Very Cold/Cold 10.25 63 HIGH 2

15 DULUTH MN 7 Very Cold/Cold 10.33 64 HIGH 1



Figure 5.6: Five Level Energy Savings Feasibility and number of sites appeared in each category for

residential homes

In case of commercial buildings similar results were generated and their graphical

representations are shown below. Figure 5.7 below shows the prescreening – 3 score

distribution for commercial buildings in 7 climate zones. Table 26 lists the prescreening – 3

f ibili l l d ki f id i l h i ll 15 i i Th i i

0

6

4

5

00

1

2

3

4

5

6

7


N o .

o f S i t e s

FEASIBILITY



Figure 5.7: Distribution of Scores for Normalized Energy Savings in commercial buildings

Table 26: Prescreening Analysis -3 Scores, Feasibility Levels and Rankings for commercial buildings

0

20

40

60

80

100

1A 2A 2B 3A 3B 3B 3C 4A 4B 4C 5A 5B 6A 6B 7

S c o r e

Climate Zone

No. Location StateClimate

ZoneCensus Region

NORMALIZED

ENERGY

SAVINGS

(kBtu/sqft-yr)

Score5 Feasibility

LevelsRanking

1 MIAMI FL 1A South Atlantic 16.37 47 GOOD 8

2 HOUSTON TX 2A West South Central 19.46 66 HIGH 53 PHOENIX AZ 2B Mountain 20.65 73 HIGH 2

4 ATLANTA GA 3A South Atlantic 14.95 39 MODERATE 9




shown in Figure 5.8, there is 1 site in the VERY HIGH category, 4 sites in HIGH, 3 sites in

GOOD, 6 sites in MODERATE, and 1 site in FAIR.

Figure 5.8: Five Level Energy Savings Feasibility and number of sites appeared in each category for

commercial buildings

1

4

3

6

1

0

1

2

3

4

5

6

7


N o .

o f S i t e s

FEASIBILITY




shown in Figure 5.10, there are no sites in the VERY HIGH category, 2 sites in HIGH, 11

sites in GOOD, 2 sites in MODERATE, and no sites in FAIR.

Figure 5.10: Five Level Cost Savings Feasibility and number of sites appeared in each category for

residential homes

0

2

11

2

00

2

4

6

8

10

12


N o .

o f S i t e s

FEASIBILITY



Figure 5.11: Distribution of Scores for Normalized Cost Savings in commercial buildings

Table 28: Prescreening Analysis - 4 Scores, Feasibility Levels and Rankings for commercial buildings

0

20

40

60

80

100

1A 2A 2B 3A 3B 3B 3C 4A 4B 4C 5A 5B 6A 6B 7

S c o r e

Climate Zone


ZoneCensus Region

NORMALIZED

COST

SAVINGS

($/sqft-yr)

Score5 Feasibility

LevelsRanking

1 MIAMI FL 1A South Atlantic 0.2967$ 36 MODERATE 10

2 HOUSTON TX 2A West South Central 0.3404$ 49 GOOD 8

3 PHOENIX AZ 2B Mountain 0.4347$ 77 HIGH 1

4 ATLANTA GA 3A South Atlantic 0.2710$ 29 MODERATE 12




shown in Figure 5.12, there are no sites in the VERY HIGH category, 3 sites in HIGH, 6 sites

in GOOD, 6 sites in MODERATE, and no sites in FAIR.

Figure 5.12: Five Level Cost Savings Feasibility and number of sites appeared in each category for


0

3

6 6

00

1

2

3

4

5

6

7


N o .

o f S i t e s

FEASIBILITY



and tables project the final results for integrated feasibility as generated in the tool. The cities

are arranged in the order of their climate zone, starting from 1A to 7.

Figure 5.13: Distribution of the Integrated Scores for residential homes in 7 climate zones

0

20

40

60

80

100

1A 2A 2B 3A 3B 3B 3C 4A 4B 4C 5A 5B 6A 6B 7

S c o r e s

Climate Zone

T bl 29 I t t d F ibilit S F ibilit L l d R ki f id ti l h



Table 29: Integrated Feasibility Scores, Feasibility Levels and Rankings for residential homes


Zone

Integrated

& Weighted ScoreRanking

5 Level

Feasibility

1 MIAMI FL 1A 38 13 MODERATE

2 HOUSTON TX 2A 41 11 GOOD

3 PHOENIX AZ 2B 42 9 GOOD

4 ATLANTA GA 3A 40 12 MODERATE

5 LAS VEGAS NV 3B 43 8 GOOD

6 LOS ANGELES CA 3B 24 15 MODERATE

7 SAN FRANCISCO CA 3C 25 14 MODERATE

8 BALTIMORE MD 4A 47 6 GOOD9 ALBUQUERQUE NM 4B 41 10 GOOD

10 SEATTLE WA 4C 43 7 GOOD

11 CHICAGO IL 5A 56 4 GOOD

12 DENVER CO 5B 53 5 GOOD

13 MINNEAPOLIS MN 6A 62 3 HIGH

14 HELENA MT 6B 63 2 HIGH

15 DULUTH MN 7 70 1 HIGH

8

456

7

8

9

t e s



Figure 5.15: Distribution of the Integrated Scores for commercial buildings in 7 climate zones

Table 30: Integrated Feasibility Scores, Feasibility Levels and Rankings for commercial buildings

0

20

40

60

80

100

1A 2A 2B 3A 3B 3B 3C 4A 4B 4C 5A 5B 6A 6B 7

S c o r e

Climate Zone


Zone

Integrated

& Weighted ScoreRanking

5 Level

Feasibility

1 MIAMI FL 1A 29 14 MODERATE

2 HOUSTON TX 2A 40 9 MODERATE

3 PHOENIX AZ 2B 58 4 GOOD



Figure 5.16: Five Level Integrated Feasibility and number of sites appeared in each category for


For residential homes, as shown in Figure 5.14, the overall results show that there are no sites

in the VERY HIGH category, 3 sites in HIGH, 8 sites in GOOD, 4 sites in MODERATE, and

no sites in FAIR.

0

1

7 7

00

1

2

3

4

5

6

7

8


N o .

o f S i t e s

FEASIBILITY



intensit o ld tend to get a higher rank In the act al case this is a oided b considering



intensity would tend to get a higher rank. In the actual case this is avoided by considering

other parameters and assigning weights to these parameters to obtain an integrated feasibility

rank. Overall the colder climate zones have better feasibilities as compared to the hot and

humid locations. One of the primary reasons for this trend is because of the high HDD values

in colder locations. A high HDD value increases energy use, thus favoring implementation of

GSHP systems.

Another important analysis is the simple payback period for GSHP systems. Although the

payback period was not considered in the overall feasibility ranking process, it is one of the

key factors that indicate the viability of a project. The simple payback period is calculated

based on the total cost (this includes system and installation costs) difference between a

GSHP and a conventional ASHP system, which is divided by the annual energy cost savings

from installing a GSHP system. For GSHP systems the cost/ton on average was considered to

be $4,600/ton for residential units and $7,000/ton for commercial units (DoD, 2007) without

any government or any other incentive(s). Corresponding to this, the cost/ton of ASHP

Table 32 shows the simple payback period in years based on the implementation cost



Table 32 shows the simple payback period in years based on the implementation cost

differences for residential homes and commercial buildings without any incentives.

Table 32: Simple payback period for GSHP systems without incentives

As shown the payback period ranges from 14 to 21 years with an average of 18 years for

LocationClimate

Zone

Simple Payback

without

incentives for

Residential

homes(yrs)

Simple Payback

without incentives

for Commercial

buildings(yrs)

MIAMI 1A 14.3 17.3

HOUSTON 2A 14.7 15.0

PHOENIX 2B 18.1 11.8

ATLANTA 3A 17.3 18.9

LAS VEGAS 3B 17.6 12.1

LOS ANGELES 3B 18.9 13.9

SAN FRANCISCO 3C 20.9 14.3

BALTIMORE 4A 16.9 19.3

ALBUQUERQUE 4B 17.7 12.0

SEATTLE 4C 16.5 18.1

CHICAGO 5A 18.5 15.4

DENVER 5B 18.5 14.7

MINNEAPOLIS 6A 18.4 20.1

HELENA 6B 18.4 14.8

DULUTH 7 18.2 20.3

the federal tax credits certain state tax credits and utility rebates may be applicable



the federal tax credits, certain state tax credits and utility rebates may be applicable

depending on the location and utility service provider. Considering only the federal tax

incentives for qualified GSHP systems the cost/ton on average is reduced to $3,220/ton for

residential units and $6,300/ton for commercial units. Table 33 shows the simple payback

period in years for residential homes and commercial buildings with federal tax incentives.

Table 33: Simple payback period for GSHP systems with Federal tax incentives

LocationClimate

Zone

Simple Payback

with incentives

for Residential

homes(yrs)

Simple Payback

with incentives

for Commercial

buildings(yrs)

MIAMI 1A 3.3 12.5

HOUSTON 2A 3.4 10.9PHOENIX 2B 4.2 8.6

ATLANTA 3A 4.0 13.7

LAS VEGAS 3B 4.1 8.8

LOS ANGELES 3B 4.4 10.1

SAN FRANCISCO 3C 4.9 10.4

BALTIMORE 4A 3.9 14.0

ALBUQUERQUE 4B 4.1 8.7

SEATTLE 4C 3.9 13.1

CHICAGO 5A 4.3 11.2

the life of the buildings Furthermore if the maintenance costs are incorporated in the



the life of the buildings. Furthermore, if the maintenance costs are incorporated in the

payback calculation, the feasibility will be much higher since the GSHP systems have less

maintenance costs with longer life cycle compared to the ASHP systems. Thus proper market

analysis for benefits and incentives is very crucial in the implementation of GSHP systems

across USA.

Based on the methodology discussed in this research, GSHP systems tend to have higher

feasibility in the colder climate regions in USA. When installed properly, GSHP systems in

general will contribute towards energy and cost savings irrespective of the location. The

performance metric for these systems becomes relative to each other, thus justifying the

classification categories used in this research. At the same time, due to the high installation

costs involved upfront, GSHP systems on their own do not seem to be a viable option over

ASHP systems without government incentives and other forms of subsidies. However there

seems to be a shift towards this technology as energy prices keeps escalating. An example of

estimated increasing energy costs is shown in Figure 5.17 (EIA, 2010).



Figure 5.17: Estimated Energy Expenditures – Total Non-Renewable United States (EIA, 2010)

The total energy cost projections in Figure 5.17 indicates that if the current trend in energy

prices continues, GSHP systems will most likely become a necessity and perhaps such

projects might as well payback on their own without any outside incentives.

CHAPTER 6: CONCLUSION



CHAPTER 6: CONCLUSION

Overall, GSHP feasibility analysis was performed for all major climate regions in the United

States. 16 cities were selected to represent the different climate conditions and energy

consumption and cost data at these locations were used to perform the feasibility analysis.

The feasibility analysis was made for residential homes (single family detached homes), and

commercial buildings (office buildings) based on RECS 2009 and CBECS 2003 data sets

respectively.

Based on the available data, the energy savings and cost savings potential of GSHP systems

over conventional ASHP systems at the selected locations were calculated. The savings

potential, along with system design parameters such as heating and cooling design

temperatures, average annual ground temperature, and heating and cooling degree day values

were graded separately assigned scores between 0 – 100. Furthermore, using weighting

factors, an integrated feasibility score was generated to understand the overall feasibility of

GSHP systems for specific climate conditions A five level classification system was used to



CHAPTER 7: FUTURE STUDIES



CHAPTER 7: FUTURE STUDIES

Going back to the objectives of this research, the intention has been to equip building

practitioners and engineers with a tool that can judge the feasibility of GSHP systems over

conventional HVAC systems. The methodologies used for this research were based out of a

limited and specific data set and certain assumptions. A few concepts have been introduced

and the accuracy for the same remains to be tested on real life projects. Two interesting

future projects that can be related to this work are briefly introduced below.

1. Testing the tool in a specific location (preferably a standalone residential home or

commercial building) which has recently been installed with GSHP systems.

Historical and current data from site can be used to compare the performance of the

project with the predictions from the tool. The tool can also be modified and the new

data set can be used for generating results, which can be compared to the historical

performance of the unit.

2. Building energy simulation modeling can be carried out for select residential homes

and commercial buildings in the 15 locations used for this research The performance

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APPENDICES

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https://new.usgbc.org/leed



APPENDICES



A2: Census Region and Division, Floor space for Non-Mall Buildings, 2003



New

England

Middle

Atlantic

East

North

Central

West

North

Central

South

Atlantic

East

South

Central

West

South

Central Mountain Pacific

All Buildings* ............................... 64,783 2,964 9,941 11,595 5,485 12,258 3,393 7,837 3,675 7,635

Building Floorspace

(Square Feet)1,001 to 5,000 ................................ 6,789 360 666 974 922 1,207 538 788 464 8715,001 to 10,000 .............................. 6,585 359 764 843 722 1,387 393 879 418 82010,001 to 25,000 ......... ........... ........ 11,535 553 1,419 1,934 1,164 2,240 810 1,329 831 1,25625,001 to 50,000 ............................ 8,668 347 944 1,618 949 1,672 498 998 511 1,13250,001 to 100,000 .......................... 9,057 516 1,524 1,618 642 1,470 650 1,314 374 948100,001 to 200,000 ........................ 9,064 414 1,703 1,682 614 2,087 Q 1,131 Q 895200,001 to 500,000 ........................ 7,176 Q 1,673 1,801 395 1,072 Q 664 339 947Over 500,000 ................................. 5,908 Q 1,248 1,126 Q 1,123 Q Q Q 766

Principal Building ActivityEduc ation ....................................... 9,874 Q 1,384 1,990 552 2,445 341 1,198 640 1,027Food Sales ..................................... 1,255 Q Q 218 Q 223 Q Q Q QFood Service ................................. 1,654 Q 127 248 206 433 99 232 Q 232Health Care .................................... 3,163 Q 464 551 247 749 219 309 230 323Inpatient ....................................... 1,905 Q 310 316 Q 469 Q 235 Q 176Outpatient .................................... 1,258 Q Q 235 Q 280 Q Q Q 147

Lodging .......................................... 5,096 374 797 548 595 939 368 387 438 649Retail (Other Than Mall).................. 4,317 Q 419 544 337 897 353 594 210 753Of f ice ...... ........... ........... .......... ....... 12,208 578 2,434 2,190 799 1,958 481 1,343 629 1,796Public Assembly ............................ 3,939 Q 769 635 377 440 Q 498 Q 468

Public Order and Safety ................ 1,090 Q Q Q Q Q Q Q Q QReligious Worship .......................... 3,754 Q 474 720 395 721 310 467 Q 341Service 4 050 Q 620 775 514 753 307 298 345 319

Total Floorspace (million square feet)

All

Buildings*

Northeast Midwest South West



A6: Natural Gas Consumption and Conditional Energy Intensity by Census Division for Non-Mall



Buildings, 2003: Part 1

New

England

Middle

Atlantic

East

North

Central

New

England

Middle

Atlantic

East

North

Central

New

England

Middle

Atlantic

East

North

Central

All Buildings* ............................... 73 343 512 1,465 7,716 9,570 49.5 44.4 53.5

Building Floorspace

(Square Feet)

1,001 to 5,000 ................................ Q 41 68 Q 417 729 Q 99.5 93.6

5,001 to 10,000 .............................. Q 31 43 Q 482 654 Q 64.8 66.0

10,001 to 25,000 ............................ Q 45 90 Q 931 1,681 Q 47.9 53.6

25,001 to 50,000 ............................ Q 39 70 Q 829 1,422 Q 47.4 49.5

50,001 to 100,000 .......................... Q 43 73 Q 1,263 1,554 Q 34.1 47.2

100,001 to 200,000 ........................ Q 41 67 Q 1,445 1,264 Q 28.3 52.7

200,001 to 500,000 ........................ Q 55 56 Q 1,484 1,277 Q 37.3 44.1

Over 500,000 ................................. Q 47 44 Q 865 989 Q 54.0 44.4

Principal Building Activity

Education ....................................... Q 49 99 Q 1,247 1,804 Q 39.5 54.6

Food Sales ..................................... Q Q Q Q Q Q Q Q Q

Food Service ................................. Q Q 35 Q Q 228 Q Q 152.9

Health Care .................................... Q 41 49 Q 396 484 Q 103.8 100.6

Inpatient ....................................... Q 37 38 Q 306 287 Q 120.3 131.2

Outpatient .................................... Q Q Q Q Q Q Q Q Q

Lodging .......................................... Q Q 39 Q Q 507 Q Q 77.5

Retail (Other Than Mall).................. Q 13 29 Q 269 485 Q 48.2 59.2

Of fice ............................................. Q 72 84 Q 1,887 1,929 Q 38.2 43.7Public Assembly ............................ Q 12 35 Q 602 550 Q Q 64.2

Public Order and Safety ................ Q Q Q Q Q Q Q Q Q

Total Natural Gas

Consumption

(billion cubic feet)

Total Floorspace of

Buildings Using Natural Gas

(million square feet)

Natural Gas

Energy Intensity

(cubic feet/square foot)



A8: Natural Gas Consumption and Conditional Energy Intensity by Census Division for Non-Mall




West

South

Central

Moun-

tain Pacific

West

South

Central

Moun-

tain Pacific

West

South

Central

Moun-

tain Pacific

All Buildings* ............................... 151 162 149 4,704 2,797 5,016 32.2 57.9 29.7

Building Floorspace

(Square Feet)

1,001 to 5,000 ................................ 29 18 Q 334 265 363 87.9 68.4 60.2

5,001 to 10,000 .............................. 23 Q Q 519 Q 496 44.2 Q 53.4

10,001 to 25,000 ............................ 14 38 22 514 630 748 28.1 61.1 29.0

25,001 to 50,000 ............................ 17 23 21 512 464 733 33.5 49.1 28.7

50,001 to 100,000 .......................... 18 Q 18 888 Q 730 20.5 Q 24.2

100,001 to 200,000 ........................ 16 Q 12 760 Q 651 21.5 Q 17.8

200,001 to 500,000 ........................ Q Q 14 470 Q 675 Q Q 20.8

Over 500,000 ................................. Q Q Q Q Q Q Q Q Q


Education ....................................... 16 21 28 797 420 802 20.6 48.8 34.8

Food Sales ..................................... Q Q Q Q Q Q Q Q Q

Food Service ................................. 37 Q Q 211 Q Q 175.7 Q Q

Health Care .................................... 26 19 19 282 162 274 91.4 115.5 68.7

Inpatient ....................................... 23 Q Q 235 Q Q 96.0 Q Q

Outpatient .................................... Q Q Q Q Q Q Q Q Q

Lodging .......................................... Q Q 16 Q Q 515 Q Q 31.5

Retail (Other Than Mall).................. 7 Q 5 436 Q 455 16.2 Q 11.4

Of fice ............................................. 12 19 17 Q 379 1,165 15.2 50.0 14.2Public Assembly ............................ Q Q Q Q Q Q Q Q Q

Public Order and Safety ................ Q Q Q Q Q Q Q Q Q

Total Natural Gas

Consumption

(billion cubic feet)

Total Floorspace of

Buildings Using Natural Gas


Natural Gas

Energy Intensity

(cubic feet/square foot)

A9: Consumption and Gross Energy Intensity by Census Division for Sum of Major Fuels for Non-Mall




New

England

Middle

Atlantic

East

North

Central

New

England

Middle

Atlantic

East

North

Central

New

England

Middle

Atlantic

East

North

Central

All Buildings* ............................... 294 978 1,254 2,964 9,941 11,595 99.0 98.3 108.1

Building Floorspace

(Square Feet)

1,001 to 5,000 ................................ 33 85 146 360 666 974 91.2 128.1 149.7

5,001 to 10,000 .............................. Q 64 73 359 764 843 Q 83.7 86.8

10,001 to 25,000 ............................ Q 115 163 553 1,419 1,934 Q 81.2 84.3

25,001 to 50,000 ............................ Q 74 140 347 944 1,618 Q 78.7 86.8

50,001 to 100,000 .......................... Q 134 148 516 1,524 1,618 Q 87.8 91.5

100,001 to 200,000 ........................ Q 150 203 414 1,703 1,682 Q 87.9 120.8

200,001 to 500,000 ........................ Q 177 214 Q 1,673 1,801 Q 105.8 118.8Over 500,000 ................................. Q Q Q Q 1,248 1,126 Q Q Q


Education ....................................... Q 143 175 Q 1,384 1,990 Q 103.1 87.7

Food Sales ..................................... Q Q Q Q Q 218 Q Q Q

Food Service ................................. Q Q 68 Q 127 248 Q Q 276.6

Health Care .................................... Q 102 122 Q 464 551 Q 219.0 220.7

Inpatient ....................................... Q Q Q Q 310 316 Q Q Q

Outpatient .................................... Q Q Q Q Q 235 Q Q Q

Lodging .......................................... Q Q 70 374 797 548 Q Q 126.7

Retail (Other Than Mall).................. Q 30 59 Q 419 544 Q 72.3 108.4Office ............................................. 66 239 263 578 2,434 2,190 114.6 98.0 120.1

Public Assembly Q Q 80 Q 769 635 Q Q 126 8

Sum of Major Fuel

Consumption

(trillion Btu)

Total Floorspace

of Buildings


Energy Intensity for

Sum of Major Fuels

(thousand Btu/

square foot)



A11: Consumption and Gross Energy Intensity by Census Division for Sum of Major Fuels for Non-Mall




West

South

Central

Moun-

tain Pacific

West

South

Central

Moun-

tain Pacific

West

South

Central

Moun-

tain Pacific

All Buildings* ............................... 575 381 530 7,837 3,675 7,635 73.4 103.8 69.4

Building Floorspace(Square Fee t)1,001 to 5,000 ................................ 87 44 64 788 464 871 110.9 94.7 73.05,001 to 10,000 .............................. 60 36 76 879 418 820 68.2 86.7 92.910,001 to 25,000 ............................ 53 76 73 1,329 831 1,256 40.2 91.7 58.425,001 to 50,000 ............................ 64 49 65 998 511 1,132 63.9 96.5 57.250,001 to 100,000 .......................... 73 29 60 1,314 374 948 55.7 77.6 63.6100,001 to 200,000 ........................ 90 Q 66 1,131 Q 895 79.5 Q 73.8200,001 to 500,000 ........................ 54 Q 65 664 339 947 81.6 Q 69.0Over 500,000 ................................. Q Q Q Q Q 766 Q Q Q

Principal Building ActivityEduc ation ....................................... 74 53 76 1,198 640 1,027 61.4 82.9 74.3Food Sales ..................................... Q Q Q Q Q Q Q Q QFood Service ................................. Q Q Q 232 Q 232 Q Q QHealth Care .................................... 59 Q 57 309 230 323 192.3 Q 177.7

Inpatient ....................................... Q Q Q 235 Q 176 Q Q Q

Outpatient .................................... Q Q Q Q Q 147 Q Q QLodging .......................................... Q Q 47 387 438 649 Q Q 71.8Retail (Other Than Mall).................. 39 Q 40 594 210 753 66.3 Q 52.8

Sum of M ajor Fuel

Consumption

(trillion Btu)

Total Floorspace

of Buildings

(million square fe et)

Energy Intensity for

Sum of Major Fuels

(thousand Btu/

square foot)



A14: Total Energy Expenditures by Major Fuel for Non-Mall Buildings, 2003



Number of

Buildings

(thousand)

Floorspace

(million

square feet)

Sum of

Major

Fuels Electr icity

Natural

Gas Fuel Oil

District

Heat

All Buildings* ............................... 4,645 64,783 92,577 69,032 14,525 1,776 7,245

Building Floorspace(Square Feet)

1,001 to 5,000 ................................ 2,552 6,789 12,812 10,348 2,155 292 Q5,001 to 10,000 .............................. 889 6,585 9,398 7,296 1,689 307 Q10,001 to 25,000 ............................ 738 11,535 13,140 10,001 2,524 232 Q25,001 to 50,000 ............................ 241 8,668 10,392 7,871 1,865 127 Q50,001 to 100,000 .......................... 129 9,057 11,897 8,717 1,868 203 Q100,001 to 200,000 ........................ 65 9,064 13,391 9,500 1,737 272 Q200,001 to 500,000 ........................ 25 7,176 10,347 7,323 1,343 272 QOver 500,000 ................................. 7 5,908 11,201 7,977 1,344 71 1,810


Education ....................................... 386 9,874 12,008 8,111 1,889 362 QFood Sales ..................................... 226 1,255 4,990 4,627 332 Q NFood Service ................................. 297 1,654 6,865 5,176 1,615 Q QHealth Care .................................... 129 3,163 7,440 4,882 1,538 79 QInpatient ....................................... 8 1,905 5,329 3,198 1,241 67 QOutpatient .................................... 121 1,258 2,111 1,684 297 Q Q

Lodging .......................................... 142 5,096 7,445 5,288 1,581 272 QRetail (Other Than Mall).................. 443 4,317 5,980 5,132 719 117 QOf fice ............................................. 824 12,208 20,841 17,050 2,201 149 1,441

($/sq.f t) for Office fuel types......... 1.3966$ 0.1803$ 0.0122$ 0.1180$Public Assembly ............................ 277 3,939 5,790 3,943 775 230 QPublic Order and Safety ................ 71 1,090 1,917 1,216 234 Q Q

All Buildings * Total Ene rgy Expe nditur es (m illion dollar s)

APPENDIX B: 2009 RECS Report Data

B1: Household Fuel Consumption in the U.S., Totals and Averages, 2009



143

Total U.S...................................................... 113.6 10.18 4.39 4.69 0.49 0.58 0.02 89.6 38.6 67.8 42.4 76.4 14.5

Census Region

Northeas t.................................................. 20.8 2.24 0.57 1.06 0.08 0.50 0.02 107.6 27.6 77.3 38.1 80.3 30.0

Midw es t.................................................... 25.9 2.91 0.94 1.75 0.19 0.03 (*) 112.4 36.1 90.3 66.8 61.4 3.2

South........................................................ 42.1 3.22 2.09 0.94 0.14 0.04 0.01 76.5 49.7 53.1 29.8 58.7 10.6

Wes t......................................................... 24.8 1.82 0.79 0.94 0.08 0.01 (*) 73.0 31.7 51.2 41.2 50.0 6.4

Urban and Rural3

Urban........................................................ 88.1 7.79 3.06 4.21 0.09 0.42 0.01 88.5 34.7 68.4 26.9 75.4 13.0

Rural......................................................... 25.5 2.39 1.33 0.49 0.40 0.16 0.01 93.5 52.0 63.1 48.6 79.2 16.1

Metropolitan and M icropolitan

Statistical Ar ea

In metropolitan s tatis tic al area.................. 94.0 8.48 3.50 4.19 0.29 0.49 0.01 90.2 37.2 68.4 41.5 76.4 13.3In mic ropolitan s tatis tic al area................... 12.4 1.08 0.55 0.38 0.09 0.05 0.01 87.3 44.5 65.9 41.3 77.8 17.7

Not in metropolitan or micropolitan

s tatis tic al area.......................................... 7.2 0.62 0.34 0.13 0.11 0.05 (*) 86.1 46.9 57.8 46.1 74.9 14.7

Climate Region4

V ery Cold/Cold.......................................... 38.8 4.32 1.25 2.44 0.23 0.38 0.02 111.4 32.2 89.0 53.9 84.2 19.4

Mix ed-Humid............................................. 35.4 3.24 1.54 1.32 0.18 0.19 0.01 91.5 43.5 66.5 41.0 65.6 11.8

Mixed-Dry/Hot-Dry.................................... 14.1 0.95 0.44 0.47 0.03 Q Q 67.2 31.5 41.7 31.4 Q Q

Hot-Humid................................................. 19.1 1.26 0.96 0.27 0.04 Q Q 66.1 50.2 39.7 22.4 Q Q

Marine....................................................... 6.3 0.42 0.20 0.20 0.01 Q Q 66.6 32.1 50.2 36.5 Q Q

Housing Unit Type

Single-Family ............................................. 78.6 8.14 3.44 3.80 0.42 0.47 0.01 103.6 43.7 75.5 45.7 85.1 10.8

Single-Family Detac hed........................ 71.8 7.59 3.23 3.50 0.41 0.44 0.01 105.7 44.9 76.8 45.9 85.6 10.4

Single-Family Attached......................... 6.7 0.55 0.21 0.30 0.01 0.03 Q 81.3 30.8 63.2 38.2 78.8 Q

Multi-Family ............................................... 28.1 1.57 0.64 0.81 0.02 0.11 Q 55.9 22.6 47.0 37.1 54.2 Q

Apartments in 2-4 Unit Buildings........... 9.0 0.69 0.22 0.41 0.01 0.04 Q 76.1 24.4 67.3 53.3 59.9 Q

Apartments in 5 or More Unit Buildings. 19.1 0.89 0.42 0.39 0.01 0.06 Q 46.4 21.7 35.7 29.0 50.9 Q

Mobile Homes ............................................ 6.9 0.47 0.32 0.09 0.05 (*) 0.01 67.8 45.6 50.6 27.1 36.7 23.7

Electricity

Housing Unit Characteristics and

Energy Usage Indicators

Total Consumption

(quadrillion Btu)

Average Consumption

(million Btu per household using the fuel)

Fuel Oil KeroseneElectricity

Natural

Gas

Total

Housing

Units1

(millions)

Propane/

LPGTotal2Natural

Gas

Propane/

LPG Fuel Oil KeroseneTotal2

B2: Household Fuel Expenditures in the U.S., Totals and Averages, 2009

Total Expenditures

(billion Dollars)

Average Expenditures

(Dollars per household using the fuel)

Total



144

Total U.S...................................................... 113.6 229.95 152.27 55.67 11.28 10.24 0.49 2,024 1,340 804 973 1,338 294

Census Region

Nor theas t. ....... ....... ....... ........ ....... ....... ...... 20.8 53.91 27.04 15.55 2.18 8.83 0.30 2,595 1,302 1,129 1,052 1,410 563

Midw e st... ....... ........ ....... ....... ....... ....... ...... 25.9 51.34 28.85 18.08 3.84 0.53 0.03 1,981 1,113 933 1,330 985 81

South.... ........ ....... ....... ....... ....... ........ ....... . 42.1 85.70 69.07 12.30 3.47 0.72 0.14 2,037 1,641 693 738 1,074 241

Wes t......................................................... 24.8 39.00 27.31 9.73 1.79 0.15 0.02 1,570 1,099 531 926 877 129

Urban and Rural3

Ur ban....... ....... ....... ....... ....... ........ ....... ...... 88.1 170.32 110.14 50.04 2.38 7.53 0.22 1,934 1,251 813 720 1,337 267

Rur al...... ....... ....... ....... ....... ........ ....... ....... . 25.5 59.63 42.12 5.63 8.90 2.71 0.27 2,335 1,649 732 1,074 1,342 320

Metr opolitan and Micropolitan

Statistical Are a

In metr opolit an s tatis tic al area.... ....... ....... 94.0 189.67 124.26 49.70 6.79 8.62 0.29 2,017 1,322 811 972 1,346 276

In micropolitan statistical area................... 12.4 24.86 17.20 4.52 2.17 0.83 0.14 2,009 1,390 785 958 1,310 339

Not in metropolitan or micropolitan

statistical area.......................................... 7.2 15.43 10.81 1.45 2.32 0.79 0.06 2,136 1,496 664 989 1,286 294

Climate Region4

Ver y Cold/Cold... ....... ....... ........ ....... ....... ... 38.8 82.61 43.76 26.98 5.03 6.55 0.30 2,130 1,128 985 1,159 1,433 375

Mix ed- Humid. ........ ....... ....... ....... ....... ........ 35.4 76.03 50.38 17.65 4.26 3.57 0.17 2,148 1,423 891 958 1,213 259

Mixed-Dry/Hot-Dry.................................... 14.1 22.95 17.17 5.04 0.71 Q Q 1,628 1,218 445 778 Q Q

Hot-Humid................................................. 19.1 39.46 34.80 3.64 1.00 Q Q 2,070 1,826 544 625 Q Q

Marine....................................................... 6.3 8.89 6.16 2.36 0.29 Q Q 1,420 984 592 943 Q Q

Housing Unit Type

Single-Family ...... ....... ....... ....... ....... ........ ... 78.6 181.17 118.71 44.40 9.57 8.24 0.25 2,306 1,511 883 1,039 1,480 226

Single- Family Detac hed.. ....... ....... ....... . 71.8 169.06 111.10 40.72 9.40 7.62 0.23 2,353 1,547 893 1,042 1,487 219

Single-Family Attached......................... 6.7 12.11 7.61 3.68 0.17 0.62 Q 1,802 1,134 786 898 1,404 Q

Multi-Family............................................... 28.1 36.33 23.61 10.19 0.57 1.93 Q 1,292 840 595 927 975 Q

Apartments in 2-4 Unit Buildings........... 9.0 14.47 8.23 5.19 0.27 0.78 Q 1,606 914 848 1,296 1,086 Q

Apartments in 5 or More Unit Buildings. 19.1 21.86 15.38 5.00 0.31 1.15 Q 1,144 805 454 744 912 Q

Mobile Homes............................................ 6.9 12.45 9.94 1.08 1.14 0.07 0.22 1,793 1,432 597 646 658 460

Housing Unit Characteristics and

Energy Usage IndicatorsElectricity

Natural

Gas

Propane/

LPGFuel Oil Kerosene

Total

Housing

Units1

(millions)

Total2 Electricity

Natural

Gas

Propane/

LPGFuel Oil Kerosene Total

2

B3: Total Square Footage of U.S. Homes, By Housing Characteristics, 2009



Total............................................................. 113.6 223.9 2.24E+11 186.8 139.8

0.00E+00

Census Region 0.00E+00

Northeast................................................... 20.8 44.1 4.41E+10 34.5 19.1

Midw est..................................................... 25.9 58.9 5.89E+10 49.2 35.6

South......................................................... 42.1 78.6 7.86E+10 68.9 65.2West.......................................................... 24.8 42.4 4.24E+10 34.2 19.9

0.00E+00

Urban and Rural3

0.00E+00

Urban......................................................... 88.1 163.5 1.64E+11 136.2 101.1

Rural.......................................................... 25.5 60.4 6.04E+10 50.6 38.7

0.00E+00

Metropolitan and Micropolitan 0.00E+00

Statistical Area 0.00E+00

In metropolitan statistical area................... 94.0 185.9 1.86E+11 155.4 117.1

In micropolitan statistical area.................... 12.4 24.3 2.43E+10 19.9 14.9

Not in metropolitan or micropolitan 0.00E+00

statistical area........................................... 7.2 13.8 1.38E+10 11.4 7.8

0.00E+00

Climate Region4

Very Cold/Cold........................................... 38.8 85.3 8.53E+10 70.2 41.9

Mixed-Humid.............................................. 35.4 73.0 7.30E+10 61.8 52.4

Mixed-Dry/Hot-Dry..................................... 14.1 23.0 2.30E+10 18.1 14.9

Hot-Humid.................................................. 19.1 32.2 3.22E+10 28.2 28.2

Marine........................................................ 6.3 10.5 1.05E+10 8.5 2.4

Housing Unit TypeSingle-Family Detached............................. 71.8 178.4 1.78E+11 147.7 112.6

Single-Family Attached.............................. 6.7 11.9 1.19E+10 9.5 6.9

Total Square Footage

Housing Units1 Total2 Total2 Heated Cooled

Housing Characteristics Millions Billions sq.ft Billions Billions



APPENDIX C: Analysis of RECS and CBECS Data for Prescreening Analysis – 3 & 4

C1: Utility Analysis of 2009 RECS Data for all climate zones



147

No. Climate Region Energy (BTU) % Energy Use Cost ($) % Cost

1 Very Cold/Cold 1.25E+15 29% 43,760,000,000.00$ 52.97% 35.01$

2 Mixed-Humid 1.54E+15 48% 50,380,000,000.00$ 66.26% 32.71$

3 Mixed-Dry/Hot-Dry 4.40E+14 47% 17,170,000,000.00$ 74.91% 39.02$

4 Hot-Humid 9.60E+14 76% 34,800,000,000.00$ 88.24% 36.25$

5 Marine 2.00E+14 49% 6,160,000,000.00$ 69.92% 30.80$

Utility Types ElCCost/MMBTU

Energy (BTU) % Energy Use Cost ($) % Cost Energy (BTU) % Energy Use Cost ($) % Cost

2.44.E+15 56.48% 26,980,000,000.00$ 32.66% 11.06$ 2.E+14 5.32% 5,030,000,000.00$ 6.09% 21.87$

1.32.E+15 40.74% 17,650,000,000.00$ 23.21% 13.37$ 2.E+14 5.56% 4,260,000,000.00$ 5.60% 23.67$

4.70.E+14 50.00% 5,040,000,000.00$ 21.99% 10.72$ 3.E+13 3.19% 710,000,000.00$ 3.10% 23.67$

2.70.E+14 21.26% 3,640,000,000.00$ 9.23% 13.48$ 4.E+13 3.15% 1,000,000,000.00$ 2.54% 25.00$

2.00.E+14 48.78% 2,360,000,000.00$ 26.79% 11.80$ 1.E+13 2.44% 290,000,000.00$ 3.29% 29.00$

Cost/MMBTUPPG NAG

Cost/MMBTU

C1 Contd.

Energy (BTU) % Energy Use Cost ($) % Cost Energy (BTU) % Energy Use Cost ($) % CostCost/MMBTU

FSDCost/MMBTU

KER



148


4.E+14 8.80% 6,550,000,000.00$ 7.93% 17.24$ 2.E+13 0.46% 300,000,000.00$ 0.36% 15.00$

2.E+14 5.86% 3,570,000,000.00$ 4.70% 18.79$ 1.E+13 0.31% 170,000,000.00$ 0.22% 17.00$0.E+00 0.00% -$ 0.00% 0 0.E+00 0.00% -$ 0.00% 0

0.E+00 0.00% -$ 0.00% 0 0.E+00 0.00% -$ 0.00% 0

0.E+00 0.00% -$ 0.00% 0 0.E+00 0.00% -$ 0.00% 0

Gross Area RECS-EUI

Sq.Ft kBtu/sqft-yr

4,320,000,000 82,620,000,000.00$ 85,300,000,000 50.64

3,240,000,000 76,030,000,000.00$ 73,000,000,000 44.38

940,000,000 22,920,000,000.00$ 23,000,000,000 40.87

1,270,000,000 39,440,000,000.00$ 32,200,000,000 39.44

410,000,000 8,810,000,000.00$ 10,500,000,000 39.05

Total Energy MBTU Total COST $



C3: Total energy cost use per residential housing unit and corresponding splits based on fuel type

TOTAL

ENERGY USE

TOTAL ENERGY

COST No. Location StateClimate

ZClimate Region UTILITY TYPE ENERGY COST ($/yr.)



150

kBtu/yr. ELC NAG PPG FSD KER $/yr.

1 DULUTH MN 7 Very Cold/Cold 139,234 1,410.39$ 869.57$ 162.12$ 211.11$ 9.67$ 2,662.86$

2 MINNEAPOLIS MN 6A Very Cold/Cold 138,166 1,399.58$ 862.90$ 160.87$ 209.49$ 9.59$ 2,642.43$

3 HELENA MT 6B Very Cold/Cold 138,232 1,400.24$ 863.31$ 160.95$ 209.59$ 9.60$ 2,643.69$

4 CHICAGO IL 5A Very Cold/Cold 137,447 1,392.28$ 858.40$ 160.04$ 208.40$ 9.54$ 2,628.67$

5 DENVER CO 5B Very Cold/Cold 137,235 1,390.14$ 857.08$ 159.79$ 208.08$ 9.53$ 2,624.61$

6 BALTIMORE MD 4A Mixed-Humid 115,547 1,796.68$ 629.44$ 151.92$ 127.32$ 6.06$ 2,711.42$

7 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry 83,739 1,529.58$ 448.98$ 63.25$ -$ -$ 2,041.81$

8 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry 83,486 1,524.96$ 447.63$ 63.06$ -$ -$ 2,035.65$

9 PHOENIX AZ 2B Mixed-Dry/Hot-Dry 81,739 1,493.04$ 438.26$ 61.74$ -$ -$ 1,993.04$

10 SEATTLE WA 4C Marine 105,848 1,590.30$ 609.27$ 74.87$ -$ -$ 2,274.43$

11 MIAMI FL 1A Hot-Humid 82,006 2,247.10$ 235.04$ 64.57$ -$ -$ 2,546.71$

12 ATLANTA GA 3A Mixed-Humid 113,001 1,757.09$ 615.57$ 148.57$ 124.51$ 5.93$ 2,651.68$

13 HOUSTON TX 2A Hot-Humid 79,789 2,186.35$ 228.69$ 62.83$ -$ -$ 2,477.86$

14 SAN FRANCISCO CA 3C Marine 83,700 1,257.53$ 481.78$ 59.20$ -$ -$ 1,798.52$

15 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry 78,095 1,426.48$ 418.72$ 58.99$ -$ -$ 1,904.19$

Zoneg ($/y )



C5: Utility Analysis of 2003 CBECS Data for all census regions

No. Census Region Energy (BTU) % Energy Use Cost ($) % Cost

Utility Types ELCCost/MMBTU



152

1 New England 3.07E+13 47% 900,000,000.00$ 92.29% 29.30$

2 Middle Atlantic 1.37E+14 57% 4,000,000,000.00$ 80.26% 29.30$

3 East North Central 1.43E+14 55% 2,940,000,000.00$ 75.50% 20.51$

4 West North Central 4.10E+13 66% 840,000,000.00$ 76.69% 20.51$

5 South Atlantic 1.19E+14 77% 2,450,000,000.00$ 87.22% 20.51$

6 East South Central 3.07.E+13 61% 630,000,000.00$ 90.97% 20.51$

7 West South Central 9.22.E+13 74% 1,890,000,000.00$ 87.13% 20.51$

8 Mountain 3.41.E+13 59% 1,000,000,000.00$ 81.88% 29.30$

9 Pacific 8.87.E+13 76% 2,600,000,000.00$ 87.89% 29.30$


0.00E+00 0.00% -$ 0.00% 0 3.53.E+13 53.46% 75,140,000.00$ 7.71% 2.13$7.39E+13 30.94% 667,440,000.00$ 13.39% 9.03$ 2.85.E+13 11.94% 316,420,000.00$ 6.35% 11.09$

8.63E+13 32.80% 669,480,000.00$ 17.19% 7.76$ 3.34.E+13 12.69% 284,700,000.00$ 7.31% 8.53$

1.95E+13 31.47% 151,430,000.00$ 13.83% 7.76$ 1.53.E+12 2.47% 103,870,000.00$ 9.48% 67.84$

1.23E+13 7.95% 104,520,000.00$ 3.72% 8.48$ 2.32.E+13 14.98% 254,540,000.00$ 9.06% 10.96$

0.00.E+00 0.00% -$ 0.00% 0 1.93.E+13 38.57% 62,530,000.00$ 9.03% 3.24$

1.23.E+13 9.94% 104,520,000.00$ 4.82% 8.48$ 1.95.E+13 15.75% 174,590,000.00$ 8.05% 8.94$

1.95.E+13 33.64% 139,460,000.00$ 11.42% 7.15$ 4.36.E+12 7.51% 81,770,000.00$ 6.70% 18.77$

1.75.E+13 14.92% 124,780,000.00$ 4.22% 7.15$ 1.08.E+13 9.23% 233,480,000.00$ 7.89% 21.61$

Cost/MMBTU NAG

Cost/MMBTUOTHERS



C6: Total energy use per commercial office building and corresponding splits based on fuel type

TOTAL

ENERGY USECensus Region UTILITY TYPE ENERGY USE (kBtu/yr.) No. Location StateClimate

ZoneClimate Region



154

kBtu/yr. ELC NAG OTHERS

1 DULUTH MN 7 Very Cold/Cold West North Central 588,053 388,457 185,076 14,521

2 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 592,598 391,459 186,506 14,633

3 HELENA MT 6B Very Cold/Cold Mountain 834,847 491,264 280,868 62,714

4 CHICAGO IL 5A Very Cold/Cold East North Central 1,829,195 996,988 600,004 232,203

5 DENVER CO 5B Very Cold/Cold Mountain 840,914 494,834 282,909 63,170

6 BALTIMORE MD 4A Mixed-Humid South Atlantic 1,145,155 882,545 91,051 171,559

7 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 1,022,344 601,597 343,948 76,799

8 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 1,025,438 603,417 344,989 77,032

9 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 1,047,359 616,316 352,364 78,678

10 SEATTLE WA 4C Marine Pacific 804,334 610,043 120,025 74,26711 MIAMI FL 1A Hot-Humid South Atlantic 1,282,071 988,063 101,937 192,071

12 ATLANTA GA 3A Mixed-Humid South Atlantic 1,170,957 902,430 93,102 175,424

13 HOUSTON TX 2A Hot-Humid West South Central 1,555,676 1,156,106 154,614 244,956

14 SAN FRANCISCO CA 3C Marine Pacific 1,017,172 771,469 151,785 93,919

15 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 1,043,222 791,226 155,672 96,324

Zone

C7: Total energy cost per commercial office building and corresponding splits based on fuel type

TOTAL

ENERGY USE

TOTAL ENERGY

COSTCensus Region UTILITY TYPE ENERGY COST ( $/yr.) No. Location StateClimate

ZoneClimate Region



155

kBtu/yr. ELC NAG OTHERS $/yr.

1 DULUTH MN 7 Very Cold/Cold West North Central 588,053 7,967.17$ 1,436.27$ 985.18$ 10,388.62$

2 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 592,598 8,028.75$ 1,447.37$ 992.79$ 10,468.91$3 HELENA MT 6B Very Cold/Cold Mountain 834, 847 14, 393. 92$ 2,007.38$ 1,176.99$ 17,578.28$

4 CHICAGO IL 5A Very Cold/Cold East North Central 1,829,195 20,448.04$ 4,656.31$ 1,980.12$ 27,084.47$

5 DENVER CO 5B Very Cold/Cold Mountain 840, 914 14, 498. 51$ 2,021.96$ 1,185.54$ 17,706.02$

6 BALTIMORE MD 4A Mixed-Humid South Atlantic 1,145,155 18,100.84$ 772.20$ 1,880.57$ 20,753.61$

7 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 1,022,344 17,626.62$ 2,458.21$ 1,441.33$ 21,526.16$

8 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 1,025,438 17,679.96$ 2,465.65$ 1,445.69$ 21,591.30$

9 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 1,047,359 18,057.91$ 2,518.36$ 1,476.60$ 22,052.86$

10 SEATTLE WA 4C Marine Pacific 804, 334 17, 874. 09$ 857.82$ 1,605.09$ 20,337.01$

11 MIAMI FL 1A Hot-Humid South Atlantic 1,282,071 20,264.99$ 864.53$ 2,105.41$ 23,234.93$

12 ATLANTA GA 3A Mixed-Humid South Atlantic 1,170,957 18,508.67$ 789.60$ 1,922.94$ 21,221.21$

13 HOUSTON TX 2A Hot-Humid West South Central 1,555,676 23,711.52$ 1,311.28$ 2,190.37$ 27,213.17$

14 SAN FRANCISCO CA 3C Marine Pacific 1,017,172 22,603.83$ 1,084.81$ 2,029.82$ 25,718.47$

15 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 1,043,222 23,182.71$ 1,112.59$ 2,081.81$ 26,377.11$

Zone

C8: Total energy cost savings per commercial office building and corresponding splits based on fuel type

ENERGY

SAVINGS Total Cost Savings

k / ($/ )

Census Region UTILITY TYPE COST SAVINGS ($/yr.) No. Location StateClimate

ZoneClimate Region



156

kBtu/yr. ELC NAG OTHERS ($/yr.)

1 CHICAGO IL 5A Very Cold/Cold East North Central 365,839 4,089.61$ 931.26$ 396.02$ 5,416.89$

2 HELENA MT 6B Very Cold/Cold Mountain 166,969 2,878.78$ 401.48$ 235.40$ 3,515.66$3 DENVER CO 5B Very Cold/Cold Mountain 168,183 2,899.70$ 404.39$ 237.11$ 3,541.20$

4 LAS VEGAS NV 3B Mixed-Dry/Hot-Dry Mountain 204,469 3,525.32$ 491.64$ 288.27$ 4,305.23$

5 ALBUQUERQUE NM 4B Mixed-Dry/Hot-Dry Mountain 205,088 3,535.99$ 493.13$ 289.14$ 4,318.26$

6 PHOENIX AZ 2B Mixed-Dry/Hot-Dry Mountain 209,472 3,611.58$ 503.67$ 295.32$ 4,410.57$

7 SEATTLE WA 4C Marine Pacific 160,867 3,574.82$ 171.56$ 321.02$ 4,067.40$

8 SAN FRANCISCO CA 3C Marine Pacific 203,434 4,520.77$ 216.96$ 405.96$ 5,143.69$

9 LOS ANGELES CA 3B Mixed-Dry/Hot-Dry Pacific 208,644 4,636.54$ 222.52$ 416.36$ 5,275.42$

10 BALTIMORE MD 4A Mixed-Humid South Atlantic 229,031 3,620.17$ 154.44$ 376.11$ 4,150.72$

11 MIAMI FL 1A Hot-Humid South Atlantic 256,414 4,053.00$ 172.91$ 421.08$ 4,646.99$12 ATLANTA GA 3A Mixed-Humid South Atlantic 234,191 3,701.73$ 157.92$ 384.59$ 4,244.24$

13 DULUTH MN 7 Very Cold/Cold West North Central 117,611 1,593.43$ 287.25$ 197.04$ 2,077.72$

14 MINNEAPOLIS MN 6A Very Cold/Cold West North Central 118,520 1,605.75$ 289.47$ 198.56$ 2,093.78$

15 HOUSTON TX 2A Hot-Humid West South Central 311,135 4,742.30$ 262.26$ 438.07$ 5,442.63$

Zone

APPENDIX D: GSHP Feasibility Prescreening Tool



D1: DashBoard

The “DashBoard” tab is the first tab in the feasibility tool. The user starts from the

“DashBorad” tab to generate results for residential homes or commercial buildings. Figure

D1 illustrates the contents of this tab. The number balloons17 in the screenshot indicate

various contents and options in the tab, and are explained below.

1. The user clicks on the small button to view a drop down list. The list contains the

names of the 15 cities selected for this research. Clicking on a name from the list

selects the city, and corresponding information and results are generated for the same.

2. This section displays certain information relevant to the selected city from the

database. These include State, Geographic Co-ordinates, Climate Zone, certain

Design Conditions, Average annual outdoor temperature18, and Average annual

ground temperature.

3. Based on the selected city, a satellite image based on Google Maps19 is displayed.

4. The user can click on this button to open the “Instructions” tab in the tool.



158

Figure D1: Screenshot of DashBoard Tab

D2: Residential_Results & Commercial_Results

B h h “R id i l R l ” d “C i l R l ” b i il l f



Both the “Residential_ Results” and “Commercial_ Results” tabs generate similar results for

residential homes and commercial buildings respectively. Figures D2 and D3 below are

screenshots of the two tabs. The number balloons for explanatory purposes are only shown in

the screenshot for “Residential_ Results” since the two tabs are similar in nature. The

following is their description:

1. The user can click on this button to open the “Instructions” tab.

2. The user can click on this button" to go back to the “DashBoard” tab and search

results for a new location.

3. This is the “Integrated Feasibility Score” graphic indicator. The cells are numbered

and color coded from 100 to 0 with intervals of 5. Green indicates the maximum

possible integrated feasibility score (100) and red indicates the lowest possible

integrated feasibility score (0). The scores in between fall under various color shades

for the two extreme colors. An example of the color shades is shown below:

100 80 60 40 20 0

7. This is the map of climate zones for RECS and map of census divisions for CBECS.

8 Th ll i di t th I t t d F ibilit S d I t t d F ibilit



8. These cells indicate the Integrated Feasibility Score and Integrated Feasibility

Ranking for the selected city.

9. This button lets the user to open the “Residential_IntegratedFeasibility” or

“Commercial_IntegratedFeasibility” tab as the case maybe. This allows the user to

modify the value of the 4 weights for the weighting factors as needed.

10. This button lets the user to open the “Residential_Prescreen-4_Econo” or

“Commercial_Prescreen-4_Econo” tab as the case maybe. This allows the user to

modify the Cost per ton values for conventional ASHP systems and GSHP systems as

needed.



D3: Residential_IntegratedFeasibility & Commercial_IntegratedFeasibility

Both these tabs allow the user to modify the weights for the weighting factors which are



Both these tabs allow the user to modify the weights for the weighting factors which are

assigned to the four prescreening processes. Both tabs are identical in nature with each

having data based on either RECS or CBECS. Figure D3 shows the screenshot of one of the

integrated feasibility tabs. The number balloons are defined as follows:

1. These cells (colored orange) define the weight for the weighting factors. The user can

modify these values as needed. Any changes made to these cells will affect the

integrated feasibility result for the locations. Both the results for residential and

results for commercial are assigned their own integrated feasibility tabs, so any

changes made to the weight will affect the corresponding results.

2. As the weights are changed, the ranking order for the 15 cities may alter. By clicking

the “SORT RANKS” button, the user can re-arrange the rankings in the ranking

column in an ascending order.

3. The “RESULTS” button allows the user to go back to the “Residential_Results” or

“Commercial_Results” tab as the case may be.



D4: Residential_Prescreen-4_Econo & Commercial_Prescreen-4_Econo

While the Prescreening Analysis 4 score is solely dependent on the normalized total cost



While the Prescreening Analysis – 4 score is solely dependent on the normalized total cost

savings value, room has been provided in the tool for calculating the simple payback (years)

for installing a GSHP system. The simple payback calculation is based on the formula:

Where,

Implementation Cost Difference = Cost difference ($/Ton) between conventional baseline

case and GSHP system.

The implementation cost will vary from region to region for residential and commercial

units. Also, for GSHP systems there are certain federal and state tax credits that can be

applicable for qualified systems. Thus for payback calculations it is recommended that the

user inputs the applicable $/Ton values instead of relying on the default values used in the

tool. Two separate tabs are provided for Residential and Commercial based simple payback



Figure D4: Screenshot of Prescreen-4_Econo Tab

THESIS Ground Source Heat Pumps Feasibility Analysis

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