Calibrated Modeling - How Well Does My Building Perform? by Eveline Killian
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Transcript of Calibrated Modeling - How Well Does My Building Perform? by Eveline Killian
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
110 Main Street Studio 1B Burlington, VT 05401 802.861.2715