Presented by

Eveline Killian, CEM

Calibrated Modeling: How Well Does

My Building Perform?

Learning Objectives

By the end of this program, participants will be able to:

Understand the value of energy models

Understand the value of calibrated modeling for:

existing building savings potential

adjustments to future building designs

determine impact of interactive effects

Understand the process of calibrating an energy model

Presentation Overview

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What Is A Calibrated Model?

Building A Model

Common Challenges

Results and Conclusions

Attribution for lightbulb photo: Randy Joy and Co.

Calibrated Modeling Using M&V

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What Is A Calibrated Model?

Attribution for lightbulb photo: Randy Joy and Co.

Definition of Energy Modeling

An evaluation of the energy use of a building through simulation, accounting for the many energy related components

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Modeling Components

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• construction, orientation, location

• HVAC, lighting, controls

• occupancy levels and schedules

• plug loads and internal energy uses (such as refrigeration or process loads)

Uses for Modeling

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• Energy impacts of alternative designs • LEED credits • Efficiency program incentives

Typical issues

Does not incorporate final design changes Actual usage of differs from original intent

Definition of “Calibrated” Modeling

An energy analysis using an energy model calibrated to utility data and/or end-use metering.

Specifications from the International Performance Measurement and Verification Protocol (IPMVP) Option D: Calibrated Simulation

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Why Use Calibrated Modeling?

Increases accuracy and credibility of energy savings claims

Conveys an accurate representation of measure interactive effects

Provides feedback on effectiveness of measures

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Uses for Calibrated Modeling

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LEED EAc5.1 M&V Credit and Verification

Energy Efficiency Programs and Impact Evaluations

Demand Resource Certification

Retrocommissioning (RCx)/Troubleshooting

Performance Contracting / Energy Service Companies (ESCO)

Building Feedback – is the building performing as expected? Energy Audits/Benchmarking/Assessments

Alternatives to Calibrated Modeling

Retrofit Isolation (IPMVP Option B) Submetering of components and subsystems

Approved for LEED verification

Whole Facility Analysis (IPMVP Option C) Utility data analysis of whole building

No modeling

Not approved for LEED verification

Mathematical formulas and spreadsheets Not calibrated to actual energy consumption

Not approved for LEED verification

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What Modeling Tools Exist?

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eQuest

EnergyPlus and DOE2

Software Sponsored by Commercial Firms

Who Performs Such Work

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Energy Consultants

Energy Modeling Firms

Design Engineering Firms

Evaluation, Measurement and Verification Specialists

Calibrated Modeling Using M&V

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Building a Calibrated Model

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I. Obtain and Update or Develop Initial Model

II. Equipment Level Calibration via Metering and Field Validation

III. Utility Data Calibration of As-built Model

IV.Development of Energy Savings

Calibration Modeling Steps

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I. Obtain and Update or Develop Initial Model

II. Equipment Level Calibration via Metering and Field Validation

III. Utility Data Calibration of As Built Model

IV. Development of Energy Savings

Calibrated Modeling - Step I

Model Development with Architectural Elements

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Build model with the available information.

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Example Input Screen

Input available component information:

Equipment types and capacities

Thermal zones

Temperature control schemes

Lighting control schemes

Occupancy schedules

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To The Best of Our Knowledge…

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I. Obtain and Update or Develop Initial Model

II. Equipment Level Calibration via Metering and Field Validation

III. Utility Data Calibration of As Built Model

IV. Development of Energy Savings

Calibrated Modeling – Step II

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Development of M&V Plan

Describe efficiency measures

Identify baseline for each

measure

Describe the analysis approach

• Identify features to field verify

• Describe measure metering

• Determine measure level

sampling

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Meters and Loggers

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Proxy Variables

Remote

temperature

sensor

Light

Intensity

Logger

Determining the required quantity of meters

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Stratified Random Sampling

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Meter Deployment Sheet

Equipment

Logger

Tag Logger Location Logging Interval

CT size

CT Qty

Begin Date

End Date

Chiller 1 main power

EML-5 basement MEP 5 min 500 3 2-Aug 2-Oct

Chiller 2 main power

EML-6 basement MEP 5 min 600 3 2-Aug 2-Oct

P-1 chilled water pump

EML-7 penthouse MEP 5 min 150 3 2-Aug 2-Oct

P-2 chilled water pump

EML-8 penthouse MEP 5 min 150 3 2-Aug 2-Oct

Outdoor air temp and %RH

TRHE-21

outdoors in a safe place away from mechanical air, shaded from direct sun

5 min na na 2-Aug 2-Oct

Interview building operator

Install meters on key equipment

Obtain trend data

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Implementation of the M&V Plan

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Building Management System Data

Implementation of M & V Plan

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Lighting Zones

Ballasts and Lamp Types

Window Type

Roof Type

Square Foot Spot Checks

HVAC Equipment Types and Capacities

Thermal Zones

HVAC System Setpoints

HVAC Control Configuration

Field Verify:

Modify your model using M&V: Is the expected equipment installed?

Is the equipment still in operation?

Scheduled hours and occupancy

Setpoints and control schemes

Match modeled kW to metered kW

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Model Adjustments – Round 1

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Case Study Model Inputs

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HVAC VFD fan kW

Metered and Modeled Equipment Calibration

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Case Study Meter Findings

Corridor Lighting

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Packaged HVAC Schedule

Case Study Meter Findings

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I. Obtain and Update or Develop Initial Model

II. Equipment Level Calibration via Metering and Field Validation

III.Utility Data Calibration of As Built Model

IV.Development of Energy Savings

Calibrated Modeling – Step III

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Obtain All Energy Use Information

Input local weather data for utility period

Compare model outputs to energy use

Adjust system/building level parameters: Infiltration

Thermal mass

Occupancy schedules

Control schedules and setpoints

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Model Adjustments – Round 2

Be Careful That…

The metered component demand and energy values remain true to the meter data

The building’s unmet load hours are appropriate

The adjustments on each immeasurable component remain realistic

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Allowed amount of variation across all of the months (CVRMSE) = 15%

Overall allowed amount of variation in the total annual energy use (NMBE) = 5%

ASHRAE Guideline 14 Section 5.3.2.4 Whole Building Calibrated Simulation

Performance Path

Project Evaluation Tolerances

CVRMSE = Coefficient of Variation Root Mean Square Error NMBE = Net Mean Bias Error

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Case Study Model Correlation to Energy Consumption

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Case Study Model Outputs

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Re-run using local TMY3 data

Weather Normalization

Uses of this Analysis Level

This analysis is sufficient for:

Retrocommissioning/Troubleshooting

Further energy saving opportunities

Energy Audit/Assessment/Benchmarking

Owner information on Building Performance

Performance Contracting

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I. Obtain and Update or Develop Initial Model

II. Equipment Level Calibration via Metering and Field Validation

III. Utility Data Calibration of As Built Model

IV. Development of Energy Savings

Calibration Step IV

Baseline Model

Can be a combination of code and standard practice

Accurately verifies impact of efficiency measures - including interactive effects

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Create Baseline Model by changing: Equipment efficiencies

Building shell properties

Controls

Do NOT change: Occupancy level

Occupancy schedule

Usage Type

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Develop Baseline Model

Example of the Impact of Energy Saving Measures over Baseline:

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Energy Savings Calculations

Modeling Iterations Savings runs MWh MMBtu

As-Built Efficient Building 2,548.5 3,752.2

Iterations toward Baseline Building:

1 As-Built with Code HVAC 2,667.2 3,593.8

2 Iteration 1 with Code Lighting 2,877.3 3,447.5

3 Iteration 2 with Code Windows 2,918.0 3,770.7

4 Iteration 3 with Code Insulation 2,927.5 4,030.1

Baseline Building 2,927.5 4,030.1

Savings 379.0 277.9

Uses of this Analysis Level

Evaluation energy saving realization rates

LEED model comparison metrics (actual vs projected use)

Retrocommissioning implementation

Energy audit

Performance contract: normalized annual savings

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Calibrated Modeling Using M&V

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Common Challenges

Common Challenges

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Typical calibration issues and solutions:

Multiple iterations needed – time consuming

Solutions: Consider overall impact on kWh/MMBtu Consolidate inputs when possible Use global inputs vs. zonal inputs

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Software model assumptions conflict

Solutions: Avoid over-specifying inputs – allow

program to use defaults Avoid conflicts between global and zonal

inputs

Common Challenges

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Analysis Outcomes Can Be Counterintuitive

More Usage = More Savings

Building consumption

Equipment savings

Analysis Examples

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Lower Baseline = Less Savings

Baseline use

Control measure savings

Controls Measures - savings depend strongly on Baseline

Analysis Examples

Calibrated Modeling Using M&V

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Results and Conclusions

Reasons for Using Calibrated Modeling

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Determine if the efficient building design is realizing the predicted claimed savings

Analyze opportunities for more

savings

Building Life Cycle Costing (BLCC)

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Calibrated modeling provides confidence in the value of investing in efficient design, and a measure of the potential risk

Modeling can reveal the reasons for the level of savings impacts over the life of the building

Use of Energy Saving Analysis

This level of analysis is used for:

LEED EAc5.1 M&V Credit and Verification

Energy Efficiency Programs and Impact Evaluations

Identification of energy savings opportunities

Performance Contracting / Energy Service Companies

Building feedback to designers – are the energy measures performing as expected?

Building feedback to owners – how is my building performing compared to my expectations?

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Learning Objectives

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Understand the energy models on the market today

Understand the value of calibrated modeling for architects,

engineers and owners for existing building savings potential and

adjustments to future building designs

Understand the impact of interactive effects and other variables

difficult to quantify at the design stage

Understand the process of calibrating an energy model

References and Resources

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Resource Purpose

Link

Modeling software Select modeling software apps1.eere.energy.gov/buildings/tools_directory/alpha_list.cfm

IPMVP Develop Metering Plan http://www.nrel.gov/docs/fy02osti/31505.pdf

Stratified Random Sampling

Develop Metering Plan implementation and meter selection

http://www.socialresearchmethods.net/kb/sampprob.php

Weather data instructions

Put weather data into eQuest

http://bepan.info/yahoo_site_admin/assets/docs/7_-_Customizing_eQUEST_Weather_Data_by_Jeff_Hirsch.138125735.pdf

ASHRAE Guideline 14 Reference for calibration metrics

http://webstore.ansi.org/RecordDetail.aspx?sku=ASHRAE+Guideline+14-2002

BLCC spreadsheets Impact of savings differentials on lifetime return on investment

http://www.doe2.com/download/lcc/ DOE2 BLCC spreadsheet http://fire.nist.gov/bfrlpubs/build96/art068.html NIST BLCC

LEED modeling reference

Comply with LEED http://www.usgbc.org/ShowFile.aspx?DocumentID=7795

Questions ?

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Eveline Killian

eveline@cx-associates.com

110 Main Street Studio 1B Burlington, VT 05401 802.861.2715