Advanced Rooftop Unit Controls -...

E3T Energy

Efficiency

Emerging Technologies

Advanced Rooftop Unit

Controls

Emerging Technologies Showcase January 23, 2013

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E3T Energy

Efficiency


Advanced Rooftop Unit

Controls

Emerging Technologies Showcase

Reid Hart, PE, Pacific Northwest National

Laboratory

Peter Criscione, E Source

January 23, 2013

Sponsored by BPA’s E3T Program

E3T Energy

Efficiency

Emerging Technologies E3T Energy

Efficiency


Reid Hart, PE

Pacific Northwest National Laboratory

Building Codes R&D Lead

Advanced Rooftop Unit Controls

3

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• Bonneville Power Administration

• City of Eugene and Eugene Water & Electric Board

• PECI – Premium Ventilation Proof of Concept Field Test

(funded by BPA)

– Benjamin Lipscomb and Kristine Falletta

• Pacific Northwest National Laboratory – Energy Savings and Economics of Advanced Control Strategies for

Packaged Air-Conditioning Units with Gas Heat (funded by DOE)

– Weimin Wang, Lucy Huang, Srinivas Katipamula, and Michael Brambley

Acknowledgements

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• Packaged air conditioners and heat pumps (RTUs) are used in about 46% of all commercial buildings, serving about 60% of the commercial building floor space (Source: EIA 2003.)

• Most RTUs operate inefficiently

– Lack of equipment maintenance

– Lack of advanced controls strategies that rely on constant supply speed fan and constant ventilation

• Operating efficiency can be improved significantly with the use of advanced controls strategies

Need for an Advanced RTU Controller

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• Meta study covering four studies, 300 units

• Problems were found everywhere – 91% had some problem

– 64% had two or more problems

• Significant impact on delivered efficiency

• Majority of problems come from controls

Common Problems with RTU Controls

46%

64%

42%

58%

27%

0% 20% 40% 60%

Refrigerant

Circuit

Economizer

Air Flow

Thermostat

Sensors

% of units tested with problem

Source: Cowan 2004.

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Premium Ventilation: Moving from “Electronic” to Stand-Alone DDC

A combined programmable thermostat with BACnet DDC controller is now here at a reasonable price from multiple manufacturers.

Network capable.

• Its time to let the low cost, 35 year old solid-state economizer controllers go.

• Just too many wires up on the roof.

Premium Ventilation RTU Controls • Improved Economizer • Supply Fan Control (VSD or Cycling) • Other control upgrades

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Catalyst eIQ

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Integrated Controller Sequence Improvements – Occupancy Sensor based setpoint and ventilation

– Duty cycling circulate air every 30 minutes

– Stand-alone demand reduction

– Allow night flush cooling

Premium Ventilation with Fan Cycling

Advantage of Fan Cycling vs. VSD – Interface with any staged rooftop

unit with an economizer,

– With the fan off when not needed less damper leakage

– Greater savings than VSD power reduction at low speed

– Lower cost as no VSDs and associated wiring or motor upgrades are required.

Summer Typical Mode Setpoints

45.0

50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

90.0

12:0

0 A

M

2:0

0 A

M

4:0

0 A

M

6:0

0 A

M

8:0

0 A

M

10:0

0 A

M

12:0

0 P

M

2:0

0 P

M

4:0

0 P

M

6:0

0 P

M

8:0

0 P

M

10:0

0 P

M

12:0

0 A

M

Sp

ace T

em

pera

ture

/ S

etp

oin

t,

deg

F

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

OS

A D

am

per

OA Damper

Space Temp

Cool Set

Econo Set

Heat SetUnoccupie

d

Nig

ht

Flu

sh

Optim

um

Sta

rt

(Purg

e)

Occupie

d

Sta

ndby

Occupie

d

Pre

-Dem

and

Dem

and

Recovery

Unoccupie

d

9

– Higher reliability, as electronic economizer (solid-state) controls are replaced with digital logic.

– Ventilation monitored and controlled

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Cycle fan and modulate dampers to maintain average ventilation per ASHRAE standard 62.1

DCV Cycling Fan Control

10

Fan Cycling Ventilation (cycles shown to meet ventilation only)

0%

20%

40%

60%

80%

100%

120%

140%

160%

8 A

M

9 A

M

10

AM

11

AM

12

PM

1 P

M

2 P

M

3 P

M

4 P

M

5 P

M

Fan operates 35.1% of time

Vent OA damper CO2 PPM as % of Full Design

% Design Occupancy 3.0 hr Avg OA % of prescriptive

Exceeds design

occupancyAllow ed maximum ventilation increases as

OA approaches space temperature

Note: Startup ventilation compliant w ith 62.1 users manual

is typically below prescriptive levels under CO2 sensor

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Yes, ASHRAE Standard 62.1 allows fan cycling

• Section 6.2.6.2 of ASHRAE Standard 62.1-2010 allows

– Short-term interruption of ventilation

– If average ventilation levels are maintained

62.1 & DCV Cycling Fan Control

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Continuous ventilation requires the fan switch to be “ON” during the occupied modes.

– Studies found close to 40% of thermostats have fan switch in the “Auto” mode resulting in intermittent fan operation and no ventilation control

– Bringing together DCV and cycling fan control can improve current delivered ventilation while saving energy

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Basic Products Matrix

• Features

• Cost

• Savings potential

Measure Definition

• Functionality/testing

• Accuracy/specifications

• Usability

• Standard packages

Research Needed

Savings Verification

• Verify monitoring

• Field operation

• Lab based or emulation method?

• Deemed savings

Persistence Designs

• Product generation tracking and adjustment

• Performance verification

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Are Advanced RTU Controls Cost-Effective?

Source: Hart 2009.

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Eugene of HVAC of Group

Fan 8% 19%

Cool 7% 16%

Fan + Cool 15% 35%

Heat 31% 55%

Total 46%

Modeled PNW Savings

Boise of HVAC of Group

Fan 6% 16%

Cool 6% 17%

Fan + Cool 12% 33%

Heat 31% 48%

Total 42%

Eugene, OR Office with Heat Pump Heating

Boise, ID Office with Heat Pump Heating

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• VSD and “fan cycling” both about the same savings – Both require DCV or advanced economizer controller

– In dX coil RTUs, VSD operates at multi-speed

– VSD higher cost, better sound impact for space

– Existing units designed to cycle, VSD retrofit can be a challenge

• Basic concept on speed control – High speed for full cooling or heating

– Low speed for ventilation or partial cooling (if multi-stage)

Fan Control

*Jacobs et al. 2003.

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Recreation Center in Eugene, Oregon – Intermittent occupancy

– Fans generally in “Auto” during baseline

Field Results of Fan Cycling

Source: Hart et al. 2012.

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Savings issue when fan is in auto • Not meet ventilation

standards, but 37%* of units in “Auto”

• Balanced by 30%* units operating 24/7 that are re-scheduled

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Digital economizer operation improvement

DCV with Economizer Tune-Up

Source: Hart et al. 2012.

Percent Sensible Cooling Provided by Economizer

Comparison periods of between 14 and 30 days with similar outside temperature averages

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Category Fans Cooling Total Electric

Heating Gas

Pre-Installation Energy Use 61,500 kWh 111,700 kWh 173,200 kWh 1,910 Therms

Energy Savings 18,800 kWh 37,000 kWh 55,800 kWh* -93 Therms**

Energy Savings as % of Base 31% 28% 29% -5%

Hypothetical Adjusted Model 30% 39% 36% 22%

Catalyst Billing Analysis

Weather-Adjusted HVAC Energy Use and Savings – Actual Setpoints and Operation

*The electric savings estimate is statistically significant at a 90/10 confidence level.

**The estimated gas increase is not statistically significant at an 80/20 confidence level.

23,000 square

foot Retail

Everett, WA

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• Base: Non-integrated economizer, single-speed fan

• Improved: Integrated economizer, multi-speed fan, DCV

Summary of HVAC Energy Savings

Building Type Small office Stand-alone retail Strip mall Supermarket

Maximum percentage savings 42% 40% 40% 41%

Location for maximum percentage savings Los Angeles Los Angeles San Francisco Miami

Minimum percentage savings 20% 23% 21% 14%

Location for minimum percentage savings Fairbanks Fairbanks Fairbanks Fairbanks

Average percentage savings 28% 32% 32% 22%

Maximum absolute savings (MMBtu/yr) 91 1,268 1,165 1,770

Location for maximum absolute savings Fairbanks Fairbanks Fairbanks Fairbanks

Minimum absolute savings (MMBtu/yr) 29 232 237 500

Location for minimum absolute savings San Francisco Los Angeles Los Angeles Los Angeles

Average absolute savings (MMBtu/yr) 46 560 547 906

Source: Wang et al. 2011.

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Additive measures:

DCV and economizer

Add fan control (VSD or cycling)

Premium Ventilation: Add night flush, optimum start, standby control

Regional Electric and Gas Savings

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Regional Savings: 10-Ton RTU with Gas Heat

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Regional Savings and Payback: 10-Ton RTU with Gas Heat

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Costs for Premium Ventilation with Local DDC and Fan Cycling

• “First time” bid costs ranged $1,900 to $3,200

– (Manufacturers A, B, C)

– Expected to become more favorable over time

• Favorable comparison to advanced thermostat with digital economizer controller (P)

$500

$1,500

$2,500

$3,500

2010 2015 2020 2025 2030

Insta

lled

Bid

(2

01

0 R

ea

l $

)

A

B

C

P

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Better Acceptance Testing Needed

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Cowan, N. “Review of Recent Commercial Roof Top Unit Field Studies In the Pacific Northwest and California”. New Buildings Institute (NBI) for Northwest Power and Conservation Council [NPCC], October 2004. Accessed September 19, 2012 at www.newbuildings.org.

EIA. “2003 Commercial Buildings Energy Consumption Survey (CBECS)”. U.S. Energy Information Administration, September 2008. Accessed September 19, 2012 at www.eia.gov/consumption/commercial/index.cfm.

Hart R. 2012. “Advanced Unitary HVAC Control Sequence.” ASHRAE Transactions. Vol. 118, Part 1.

Hart R, J Callahan, K Anderson, and P Johanning. 2011. “Unitary HVAC Premium Ventilation Upgrade.” ASHRAE Transactions. Vol. 117, Part 1.

Hart R, K Falletta, and B Lipscomb. 2012. RTU Premium Ventilation: Proof of Concept Field Test. Portland Energy Conservation, Inc. for Bonneville Power Administration, Portland, Oregon.

Hart R. 2009. Premium Ventilation Package Testing: Short-Term Monitoring Report – Task 7. Portland Energy Conservation, Inc. for Bonneville Power Administration, Portland, Oregon. Accessed September 19, 2012 at www.peci.org/resources/commercial-retail.html.

Hart R, W Price, J Taylor, H Reichmuth, and M Cherniack. 2008. “Up on the Roof: From the Past to the Future.” In Proceedings of the 2008 ACEEE Summer Study on Energy Efficiency in Buildings, pp. 3.119-3.130. American Council for an Energy-Efficient Economy, Pacific Grove, California.

Hart R, W Price, and D Morehouse. 2006. “The Premium Economizer: An Idea Whose Time Has Come.” In Proceedings of the 2006 ACEEE Summer Study on Energy Efficiency in Buildings, pp. 3.103-3.115. American Council for an Energy-Efficient Economy, Pacific Grove, California.

Jacobs, P., V. Smith, and C. Higgins. “Small Commercial Rooftops: Field Problems, Solutions and the Role of Manufacturers.” In National Conference on Building Commissioning: May, 20:22, 2003.

Wang W, S Katipamula, Y Huang, and M Brambley. 2011. Energy Savings and Economics of Advanced Control Strategies for Packaged Air-Conditioning Units with Gas Heat. PNNL-20955, Pacific Northwest National Laboratory for the U.S. Department of Energy. Accessed September 19, 2012 at www.pnnl.gov.

References

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Peter Criscione

Manager, Research

E Source

Advanced Rooftop Unit Controls

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• Catalyst

Transformative Wave Technologies

• Enerfit

Enerfit LLC

• Digi-RTU Optimizer

DTL Controls

• Unnamed controller (available 2013)

Optimum Energy

RTU VFD Retrofit Devices

27

Sources: Transformative Wave Technologies, Enerfit, and DTL Controls

http://www.catalysteec.com/About.aspx

http://www.enerfit.com/

http://www.dtlcontrols.com/poptimizer.html

http://www.optimumenergyco.com/

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Product Annual HVAC Energy Savings (%)

Simple Payback Period (years)

Cost ($)

Catalyst 25-40 2 4,000 (15 ton)

Enerfit 50-70 1-3 4,700 (20 ton)

Digi-RTU 45-64 1-4 3-10,000 (<20 ton) 5-20,000 (>20 ton)

Optimum’s 25-45 NA NA

Manufacturer’s Claims

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© E Source

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Testing organization Product Savings/payback Sample size

Omaha Public Power District (OPPD)

Digi-RTU 41% kW, 52% kWh

20–60% range 24 RTUs, 2010 +6 RTUs, 2011

Snohomish County PUD

Catalyst 48% kWh 1 facility

TES Engineering Enerfit 2.0- to 3.5-year payback:

Not cost-effective: 9 of 11 buildings 2 of 11 buildings

2011 Test Results

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© E Source

Source: Wikimedia Commons

Notes: kW = kilowatts; kWh = kilowatt-hours.

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OPPD: Reduced kW for Fitness Center RTU

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0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Ele

ctri

city

De

man

d (

kW)

Time

Date

Outside air temperature

Average Maximum Minimum

July 23 (without Optimizer) 82 91 73

August 31 (with Optimizer) 82 93 71

Courtesy: Omaha Public Power District

—— July 23, w/o Optimizer —— August 31 w/ Optimizer

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OPPD: Reduced Energy Use for Fitness Center

31

65.65

34.64

0

10

20

30

40

50

60

70

W/O Optimizer

W/ Optimizer


kW

h

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OPPD: Fitness Center Temperature Held Steady

32

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Tem

per

atu

re (

°F)

Time



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OPPD: Reduced Relative Humidity

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0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00

Re

lati

ve H

um

idit

y (%

)

Time



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Testing organization Product Savings Sample size

Snohomish County PUD Catalyst 17–18% kW, ~20% kWh 2 Drugstores

National Renewable Energy Lab

simulation 29–75% annual fan electricity savings

16 U.S. cities, big-box retail

Pacific Northwest National Lab

simulation 14–56% annual HVAC energy

savings 16 U.S. cities, 4 building

types

Latest Results (end of 2012)

34

© E Source


Notes: kW = kilowatts; kWh = kilowatt-hours.

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Testing organization Product Savings Sample size

National Renewable Energy Lab

simulation 53–72% annual fan electricity savings

big-box retail

Pacific Northwest National Lab

simulation 20-39% annual HVAC energy

savings 4 building types

Pacific Northwest Savings (Seattle, WA)

35

© E Source

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What’s Behind the Curtain?

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Product Evaporator fan Condenser fan Compressor

Catalyst

Enerfit

Digi-RTU

Optimum’s controller

Variable-Frequency Drives (VFDs)

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© E Source


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Catalyst

• Indexed

Enerfit

• Continuous

Digi-RTU and Optimum’s controller

• Continuous

Theoretical VFD Savings

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Stage 2 Cooling

Stage 1 Cooling, Heating

40

75

90

Fan speed (%)

Ventilation

Damper for face-

split DX coils

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Product DCV Economizer controls Web interface FDD

Catalyst Optional Some

Enerfit (V2) Optional Some

Digi-RTU IP IP Optional IP

Optimum’s controller

IP IP Standard Some

Built-in Controls

39

© E Source Notes: DCV = demand-controlled ventilation; FDD = fault

detection and diagnosis; IP = in progress; V = version.

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Ongoing Testing: RTU VFD Controllers

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Organization Products Amount

BC Hydro Catalyst 26 RTUs

Bonneville Power Administration Catalyst Up to 75 RTUs

Minnesota Center for Energy and Environment

Catalyst, Digi-RTU 55 RTUs

National Renewable Energy Laboratory Catalyst 11 RTUs

Pacific Northwest National Laboratory Catalyst 120 RTUs

Puget Sound Catalyst 6 RTUs

San Diego Gas & Electric Catalyst, Digi-RTU, Enerfit 1 building

Seattle City Light Catalyst 1 building

Southern California Edison Catalyst 4 RTU

Tacoma Power Catalyst 1 building

Western Cooling Efficiency Center Catalyst 4 RTUs © E Source

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Catalyst and Enerfit (pictured) have simplified wiring

Quicker, More-Reliable Installs

41

Courtesy: Enerfit

Old

New

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Catalyst Fault Detection and Diagnostics

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Courtesy: Transformative Wave Technologies

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Catalyst FDD: Details

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Courtesy: Transformative Wave Technologies

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The Uber-HVAC Program

44

FDD

Tune up

VFD

Source: Open Clip Art Library

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What About the Small RTUs?

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Premium Ventilation Package (PVP) with Fan Cycling

46

• Demand-controlled ventilation

• Integrated and differential economizer controls

• Optimum start—delays until needed

• Resistance heat lockout when heat pump meets load

• Ventilation lockout for morning warmup

• Improved outside air damper seals

• Integrated: – Night flush cooling

– Standby (with occupancy sensor)

– Demand adjust (moves setpoint up during peak)

+ Fan cycling based on ASHRAE 62.1 (ventilation)

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• Alerton Visual Logic Display

• Honeywell Jade Economizer controller – Working on fan cycling

• Innotech Micro- or Minimax – With innTouch Smart Sensor

• KMC Flexstat

New DDC Options for <10 Ton Market

47

Sources: Alerton, Honeywell, Innotech, KMC

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0

2,000

4,000

6,000

8,000

10,000

12,000

Kil

ow

att

-ho

urs

pe

r 1

,00

0 s

qu

are

fe

et Total HVAC energy use (baseline) HVAC energy use with PVP

• HVAC savings: 27 to 46 percent

• Versus upgrading SEER 13 to 15: 1.5 to 6.7 percent

PVP Simulation Using VFD on a HP

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© E Source

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Ongoing Testing: PVP Controllers

49

Organization Products Amount

Bonneville Power Administration Honeywell Jade, KMC Flexstat up to 75 RTUs (including Catalyst)

Minnesota Center for Energy and Environment

KMC Flexstat 55 RTUs (including Catalyst and

Digi-RTU)

Southern California Edison Honeywell Jade, KMC Flexstat, Innotech Visual Logic Display

3 RTUs

© E Source

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MNCEE’s Experience with RTU Controls Pilot Program

50

Working with Catalyst, Digi-RTU, KMC Flexstat

• Research requirements have delayed launch

• Controls products have no mass production experience

• Of the three, Catalyst has most mature install process

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• Reid Hart, RTU Premium Ventilation: Proof of Concept Field Test, Portland Energy Conservation Inc., (dated May 2012, but just released October 2012)

• CA HVAC Contractor and Technician Behavior Study, Energy Market Innovations (September 2012; Kristin Heinemeier’s “candid camera” study)

• Robert Mowris et al, Laboratory Measurements of HVAC Installation and Maintenance Faults, ASHRAE Transactions, Vol. 188, Pt. 2 (2012)

• Energy Implications of Retrofitting Retail Sector Rooftop Units with Stepped-Speed and Variable-Speed Functionality (PDF), National Renewable Energy Laboratory (April 2012)

• Energy Savings and Economics of Advanced Control Strategies for Packaged Air-Conditioning Units with Gas Heat (PDF), Pacific Northwest National Laboratory (December 2011)

• Unitary HVAC Premium Ventilation Upgrade: 2011 ASHRAE Winter Conference Technical Program (PDF), Portland Energy Conservation Inc.

• Air-Side Economizers, E Source, CEMC-RG-10 (2009)

Resources

51

http://www.bpa.gov/energy/n/emerging_technology/pdf/38702_RTU_Premium_Ventilation_Proof_Of_Concept_FINAL.pdf

http://www.bpa.gov/energy/n/emerging_technology/pdf/38702_RTU_Premium_Ventilation_Proof_Of_Concept_FINAL.pdf

http://www.calmac.org/publications/CA_HVAC_Behavior_Study_FinalReport_2012Sept14_FINAL.pdf

http://www.calmac.org/publications/CA_HVAC_Behavior_Study_FinalReport_2012Sept14_FINAL.pdf

http://www.nrel.gov/docs/fy12osti/51102.pdf






http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20955.pdf




http://www.peci.org/sites/default/files/unitary_hvac_premium_ventilation_upgrade.pdf

http://www.peci.org/sites/default/files/unitary_hvac_premium_ventilation_upgrade.pdf

http://www.esource.com/members/CEMC-RG-10/Resource_Guide/Air_Side_Economizers




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• Potential savings:

– Upgrading RTU controls has good potential savings ~35%

– Field testing has verified operation with custom controllers

• Next steps:

– Work with manufacturers to lower the cost and the barriers for technology deployment

– More field testing to verify savings, explore web-based options

– Contractor training and acceptance tools need improvement

– Expand impact assessment to packaged heat pumps, more building types, and other control technologies

• Future

– Integrate advanced control with fault detection and diagnostics to achieve persistent savings

Conclusions and Next Steps

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Reid Hart, PE

Pacific Northwest National Laboratory [email protected] 541-485-1570

Peter Criscione

E Source [email protected] 303-345-9109

For More Information

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mailto:[email protected]


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BPA Contact

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Mira Vowles, PE

Bonneville Power Administration [email protected] 503-230-4796


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Demand Controlled Ventilation for Commercial Kitchens

February 13, 2013 at noon Pacific time

More information about emerging technologies: E3T database: www.E3Tnw.org

E3T Program: www.bpa.gov/energy/n/emerging_technology/

Conduit: www.ConduitNW.org

Next Webinar

55

http://www.e3tnw.org/

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