Measurement & Verification

Measurement & Verification

IBPSA - USA

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Modeling Fundamentals

Performance Rating Method Best Practices Inform Design Measurement &

Verification

IBPSA - USATHE PATH TO IMPROVED PERFORMANCEINCLUDES M&V ACTIVITIES

On-goingCommissionin

gEnergy

Management

Comparison Against Predicted

Performance

The Path to Improved Performance

M&V is part of a performance feedback loop that benefits:• Facility Managers• Designers• Energy Modelers

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Verification

IBPSA - USA

PREDICTED VS. ACTUAL

From NBI/USGBC, “Energy Performance of LEED for New Construction Buildings”, March 2008.

“ … a quarter of the new buildings that have been certified do not saveas much energy as their designs predicted ..”

“If you’re not reducing carbon, you’re not doing your job.” Scott Horst, Senior Vice President, USGBC

New York Times, August 31, 2009, Some Buildings Not Living Up to Green Label.

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IBPSA - USA

M&V RESOURCESDocument Description Links

IPMVP Volume I Basic concepts and methods, measurement, uncertainty, examples

http://www.evo-world.org

IPMVP Volume III – New Construction

Baseline definition, overview of methods

http://www.evo-world.org

FEMP M&V Guidelines, version 2.2

ESCO focus, owner support; application document, calibration methodology, sample selection

http://www.nrel.gov/docs/fy00osti/26265.pdf

FEMP M&V Guidelines, version 3.0

http://www1.eere.energy.gov/femp/pdfs/mv_guidelines.pdf

ASHRAE Guideline 14 – 2002

IPMVP concepts +, calibration criteria, instrumentation, data management, regression techniques, examples

http://www.techstreet.com/cgi-bin/detail?product_id=1645226

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Verification

IBPSA - USAM&V – OPTION DACTIVITIES

Savings

Metering

Commissioning

Performance Data

As-Designed Model

Calibrated Model

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Verification

IBPSA - USA

LEED M&VLEED NC EAc5 Measurement and Verification

Intent Provide for ongoing accountability of energy consumption over time

Requirements • M&V Plan – Option B, D savings method 2, Vol. III• 1 Year M&V Period• Process for corrective action

Reference Guide • M&V rigor and value• IPMVP Volume III overview• M&V activities timeline

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Verification

IBPSA - USAM&V – OPTION DPROCEDURES

Develop M&V Plan

Ensure sufficient metering

Gather and check data

Calibrate

Calculate verified savings

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Verification

IBPSA - USADEVELOP M&V PLANLEED NC CONSIDERATIONS

M&V Plan – General Considerations√ Responsible party for implementing the M&V Plan√ Activities addressing ongoing accountability√ M&V option B or D√ Baseline definition√ One-year M&V period √ Calibration of predicted performance analysis√ Use of weather data coinciding with M&V period√ Energy savings calculation√ Metering requirements

See http://www.ibpsa.us/workshop/ for more detailed M&V Plan content outline and example LEED EAc5 M&V Plan

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http://www.ibpsa.us/workshop/



Verification

IBPSA - USADEVELOP M&V PLANBALANCE RISK OF SAVINGS WITH VALUE OF SAVINGS

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Verification

IBPSA - USAENSURE SUFFICIENT METERING

Review CD documents and coordinate with Cx agent to ensure systems in place to monitor building energy performance• May not be monitoring energy usage directly• Monitor to ensure building is operating per its design intent

Prioritize what to monitor by considering• Owner’s needs• At risk “savings”• Confirmation of modeling assumptions

10

IBPSA - USAENSURE SUFFICIENT METERING

SystemMeasure /

Verification Component

Verify Measure / Condition Monitoring Points

Hot Water

Variable-flow loop; hot water pumps equipped with VFDs.

- variable-flow operation, to maintain pressure differential set point between supply and return heating water piping mains

- interlocked with boiler operation; two minute delay on boiler disable

- VFD speed- pump status- differential pressure between supply and return- water flow rate- heating water supply and return temperatures

Chillers Equipped with VFDs. Reset chilled water supply temperature to maintain air handler discharge air temperature.

- chiller efficiency (NPLV = 0.50)- chiller VFD operation- chilled water supply temperature

reset from 48ºF to maintain air handler discharge air temperature

- chiller power- chiller efficiency (calculated point)or/- CHWS/RT- CHW flow

See http://www.ibpsa.us/workshop/ for example LEED EAc5 M&V Plan with monitoring points 11

http://www.ibpsa.us/workshop/



Verification

IBPSA - USAGATHER AND CHECK DATAAFTER BUILDING IS COMMISSIONED

Building Description Data

• Climatic data• Utility Data• As-built documents• Sequence of operations• Specs• Submittals

12

IBPSA - USAGATHER AND CHECK DATAAFTER BUILDING IS COMMISSIONEDSurvey and Audit Data

• Occupant feedback

• Operator interview

• Survey / audit forms

• TAB reports• Monitored

data

13

IBPSA - USAGATHER AND CHECK DATACREATING CUSTOM WEATHER FILESParameters DOE-2 EnergyPlusDry Bulb √ √Wet Bulb √ √Dew Point √Humidity DP RHAtmospheric Pressure √ √Horizontal infrared √Total horizontal radiation √Direct normal radiation √Diffuse normal radiation √ √Wind direction √ √Wind speed √ √Present weather codes Clouds √Snow Depth Flag √

See simulation program documentation for more details on data requirements and processing tools

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Verification

IBPSA - USAGATHER AND CHECK DATACREATING CUSTOM WEATHER FILES

1. Download the TMY .CSV file for Atlanta, GA (available from EnergyPlus site)

2. Request hourly data for 2007 from the EnergyPlus request site http://apps1.eere.energy.gov/buildings/energyplus/weatherdata

_about.cfm3. Fill any data gaps in 2007 .CSV files that you receive via

email4. Convert data to correct units for TMY version (if required)

Example Process:Create a custom weather file for 2007 for Atlanta, GA

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http://apps1.eere.energy.gov/buildings/energyplus/weatherdata_about.cfm

http://apps1.eere.energy.gov/buildings/energyplus/weatherdata_about.cfm



Verification

IBPSA - USAGATHER AND CHECK DATACREATING CUSTOM WEATHER FILES

5. Convert Dry Bulb and Dew Point Temperature to % Relative Humidity using the relation:

Tdb = dry bulb temperature, Tdp = dew point temperature, RH = Relative Humidity

6. Copy the 2007 hourly data (including the calculated RH) to the appropriate columns in the TMY .CSV file.

7. Try to find hourly solar data…hopefully your site is included here: http://www.nrel.gov/midc/srrl_bms/

8. Copy the 2007 solar radiation values to the appropriate columns in the TMY file

9. Convert the altered .CSV file to the type of weather file required for a given energy modeling tool using various weather file converter tools

Create a custom weather file for 2007 for Atlanta, GA

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http://www.nrel.gov/midc/srrl_bms/



Verification

IBPSA - USACALIBRATIONBOUND THE PROBLEM

• Strong parameters

• Range of probable values

Identify Values and Ranges

• Electric kWH• Electric kW• Gas

Visually compare

• As-built info• Operating

schedules • Plug loads• Controls

Revise Modeling Assumptions

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Verification

IBPSA - USA

Run Building SimulationPerform

sensitivity analysis

Identify plausible solutions

Refine solution through

reconciliation with actual data

CALIBRATIONGUIDE THE INVESTIGATION

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Verification

IBPSA - USACALIBRATIONRECONCILIATION WITH UTILITY DATA

Rough calibration of components• DHW from gas in summer• Cooling from electric in summer• Heating from gas in winter• Swing season for schedules, plugs

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Fiscal Year 2009

Elec

tric

(kW

h)

050100

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250300

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(MBt

u) Modeled Elec

FY 2009 Elec

Modeled Gas

FY 2009 Elec

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Erik Kolderup

No notes



Verification

IBPSA - USACALIBRATIONRECONCILIATION WITH HOURLY DATA

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Verification

IBPSA - USACALIBRATIONART VERSUS SCIENCE

“… a detailed simulation program involving numerous input parameters is a highly under-determined problem (i.e. , the presence of too many parameters is likely to result in any solution being non-unique. “ • Reddy T.A. and Itzhak Maor, 2006. “Procedures for Reconciling Computer-Calculated

Results with Measured Energy Data, ” ASHRAE Research Project 1051-RP

“.. It seems like most of the world’s conventional wisdom is to treat the building simulation like it is some kind of academic exercise and as though it really doesn’t make any difference whether the model of a building accurately reflects reality, just as long as it looks good.”• Waltz, James, 1999. Computerized Building Simulation Handbook, Fairmont Press,

Liburn, GA.

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Verification

IBPSA - USACALIBRATIONHOW GOOD IS GOOD ENOUGH?

Check if Calibration Criteria are MetMean ERRmonth (+/- 15%) =100 * (M-S) / MMean ERRyear (+/- 10%) = ∑ ERRmonth / 12CV(RMSEyear ) (+/- 10%) =(∑ [(M-S)2 / 12])0.5

From FEMP M&V Guidelines v. 2.2

The mean bias error may be influenced by offsetting errors

Jan Feb Mar Apr May

Jun Jul Aug Sep Oct Nov Dec0

102030405060

Model Utility Bills

Elec

tric

al U

sage

(kW

h x0

00)

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Verification

IBPSA - USACALCULATE ENERGY SAVINGS• Make baseline model adjustments (schedules, setpoints,

variable dependent on operation, conditions beyond the control of ESCO)

• Calculate Savings

Savings = Adjusted Baseline Energy – Actual Energy (Option D, Method 2)

Savings = Adjusted Baseline Energy – Modeled Actual Energy (Option D, Method 1)

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M&V CASE STUDYCALIFORNIA OFFICE

BUILDING

IBPSA - USA

24

IBPSA - USAHIGH-RISE OFFICE M&V EXAMPLELEED NC 2.1 M&V IMPLEMENTATION

New Construction

Size: Approx 400,000 ft2

Principal Use: Office, Cafe, Parking Garage, Fitness Center, Data Center

Energy Costs: $2.35/ft2-year

Source Energy Use: 209 kBtu/ft2 year

Site Energy Use: 69 kBtu/ft2 year

Awards: LEED NC 2.1 Gold

Efficiency Features:• Under-floor air distribution• Chiller efficiency, 0.51 kW/ton• Variable-speed chiller• Low lighting power, <0.7W/ft2

• Daylighting controls• Efficient glazing, SHGC 0.24

$0.22 $0.24

$1.79 $1.38

Budget Case Design Case

Predicted Energy Cost ($/ft2-yr)

Electricity

Gas

19% savings

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IBPSA - USAHIGH-RISE OFFICE M&V EXAMPLELEED NC 2.1 M&V IMPLEMENTATION

• Project used IPMVP Option D, Method 1

• Current LEED requires Method 2

Design CaseUsing design parameters

Budget Case Using Title 24 parameters

Verified Design Case Actual operating parameters

Verified Budget Case Title 24 performance & actual operating schedules

Calibration

Savings

Verified Savings

Adjustments

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IBPSA - USAHIGH-RISE OFFICE M&V EXAMPLEPREDICTED VS. ACTUAL

Step #1• Compare design model to utility bills Not very close (details on following slides)

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Electricity (kWh)

Predicted Actual

0200400600800

100012001400160018002000


Peak Electric Demand (kW)

Predicted Actual

0

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4,000

6,000

8,000

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Natural Gas (therms)

Predicted Actual

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Electricity

0

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200,000

300,000

400,000

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600,000

700,000


Electricity (kWh)

Predicted Actual

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Peak Electric Demand

0200400600800

100012001400160018002000


Peak Electric Demand (kW)

Predicted Actual

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Natural Gas

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14,000

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Predicted Actual

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Step #2 • Dig deeper…• Data sources in this case

– Building automation system (BAS)

– Separate Energy monitoring system (EMS)

– Short-term monitoring• Chiller kW

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(kW

)

June 2010 - Typical Week

Actual Predicted

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6000000

CHW

Loa

d (B

tu/h

r)June 2010 - Typical Week

Actual Predicted

From BAS

From EMS

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IBPSA - USAHIGH-RISE OFFICE M&V EXAMPLEMODEL CALIBRATION

Step #3 Calibrate Model• Verify system performance - chillers & air handlers

0.10

0.20

0.30

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0.60

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0.80

0.90

1.00

0 100 200 300 400 500

Cooling Load (tons)

Chiller Efficiency (kW/ton)

Actual Model

0.000.200.400.600.801.001.201.401.601.802.00

0 50000 100000 150000 200000 250000 300000

Supply Air Flow (cfm)

Fan Power (W/cfm)

Actual Model

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Step #3 (continued)• Verify system performance – computer room air conditioners

0

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10000

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35000

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/10

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5:16

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8:38

CRAC Power (watts)

CRAC 1 (representative of 1 - 8) CRAC 9

3333

IBPSA - USA

0

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2000000

3000000

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5000000

6000000

CHW

Loa

d (B

tu/h

r)


Actual Model

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and

(kW

)


Actual Model

HIGH-RISE OFFICE M&V EXAMPLEMODEL CALIBRATION

Step #3 (continued) • Make adjustments

– Data center & CRACs– Parking garage

nighttime lighting– Telecom/electrical

room loads– Off-hour plug loads– Exterior lighting– Outdoor air ventilation

rate

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Step #3 (continued)• Monthly calibrated

model results

0100,000200,000300,000400,000500,000600,000700,000


Electricity (kWh)

Calibrated Model Actual

0

2,000

4,000

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Calibrated Model Actual

Elec kWh Gas

Min ERRmonth -1% 64%

Max ERRmonth -7% 13%

ERRyear -4% 16%

CV(RMSEmonth) 6% 51%

Meet Criteria? Yes No

Criteria:Mean ERRmonth +/- 15Mean ERRyear +/- 10% CV(RMSEmonth ) +/- 10%

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IBPSA - USAHIGH-RISE OFFICE M&V EXAMPLECALCULATE SAVINGS

Step #4 • Adjust budget model

– Add data center, other loads…– Match schedule adjustments– Match OA ventilation rate

Step #5• Calculate verified savingsStep #6• Think about results…

$2.01

$1.62

$2.85

$2.35

Budget Case

Design Case

Verified Budget

Case

Verified Design

Case

Energy Cost ($/ft2-yr)

19% savings 17% savings

$1.53

$1.15

$1.63

$1.13

Budget Case

Design Case

Verified Budget

Case

Verified Design

Case

"Regulated" Energy Cost ($/ft2-yr)

25% savings 31% savings

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M&V CASE STUDYBETHKE ELEMENTARY

SCHOOL

IBPSA - USA

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IBPSA - USABETHKE ELEMENTARY CASE STUDYDESIGN THROUGH OCCUPANCY

Owner: Poudre School DistrictLocation: Timnath, COPrincipal Use: 10-month school with classrooms, gym, media center, officeSchool Capacity: 525Completion Date: Aug 2008Cost: $151/sq ftSize: 63,000 sq ftEnergy Costs: $0.58/ft2 yearEnergy Use: 47 kBtu/ft2 yearAwards: LEED for Schools Gold, 3 of 4 Green Globes, Energy Star Label of 99

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IBPSA - USA

2010 Fiscal Year (July 2009 - June 2010)

Floor Area Max Peak Demand Energy Cost Energy Use

[ft2] [W/ft2] [$/ft2 Year] [kBtu/ft2 year]Operations Office 2002 8,753 3.4 0.44 19.0 99Zach Elementary* 2002 67,412 1.7 0.54 42.6 96Bacon Elementary 2003 65,299 1.6 0.54 45.7 97Fossil Ridge High School 2004 296,375 2.3 0.56 40.9 94Kinard Middle 2006 112,735 2.6 0.39 21.6 98Rice Elementary 2007 62,691 1.4 0.75 41.5 99Bethke Elementary 2008 62,691 1.5 0.58 41.7 99*Includes 7,200 sq.ft. of modular classrooms

Energy Star

RatingBuilding Year

Constructed

BETHKE ELEMENTARYDESIGN APPROACH – USE OF PROTOTYPES

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IBPSA - USABETHKE ELEMENTARYM&V – EAC5 M&V PLAN

BUDGET CASE DESIGN CASE(using ASHRAE 90.1 (using design paramters)

standards)

BUDGET CASE VERIFIED CASE(using ASHRAE 90.1 (using actual building

standards) operational/performanceparameters)

difference = "savings"

difference = "verified savings"

3 Cooling tower (CT -1)

VFD. Occupied / Unoccupied mode. - cooling tower fan operation interlocked with cooling water pump operation.

- VFD will modulate fan speed to maintain chilled water supply at 60°F (adj.)

4 Cooling water circulation loop (P -4)

Pump interlocked with chilled water pump.

- pump operation interlocked with chilled water distribution pump operation.

Savings Calculations

Operation Verification

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IBPSA - USABETHKE ELEMENTARYM&V – IMPLEMENTATION

2010 Fiscal Year (July 2009 - June 2010)

Floor Area Max Peak Demand Energy Cost Energy Use

[ft2] [W/ft2] [$/ft2 Year] [kBtu/ft2 year]Operations Office 2002 8,753 3.4 0.44 19.0 99Zach Elementary* 2002 67,412 1.7 0.54 42.6 96Bacon Elementary 2003 65,299 1.6 0.54 45.7 97Fossil Ridge High School 2004 296,375 2.3 0.56 40.9 94Kinard Middle 2006 112,735 2.6 0.39 21.6 98Rice Elementary 2007 62,691 1.4 0.75 41.5 99Bethke Elementary 2008 62,691 1.5 0.58 41.7 99*Includes 7,200 sq.ft. of modular classrooms

Energy Star

RatingBuilding Year

Constructed

PSD Approach• Commission building• Compare actual against anticipated

• Compare actual against other prototypes

OK

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IBPSA - USABETHKE ELEMENTARYM&V – IMPLEMENTATION

Option D Approach• Collect performance data*• Update proposed-design energy model• Adjust baseline model for independent

variables such as occupancy, schedules, ..• Calculate energy savings* Assumes building is operating as intended

Risk versus value?

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Elec

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h)

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FY 2009 Elec

Modeled Gas

FY 2009 Elec

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IBPSA - USABETHKE ELEMENTARYM&V – CALIBRATION

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Sensitivity Analysis

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IBPSA - USA

05,000

10,00015,00020,00025,00030,00035,00040,000

050100150200250300350400450

Bethke Elementary Modeled ElecActual ElecModeled GasActual Gas

Fiscal Year 2009

Elec

tric

(kW

h)

Gas

(MBt

u)

BETHKE ELEMENTARYM&V – CALIBRATION

05,000

10,00015,00020,00025,00030,00035,00040,000

050100150200250300350400450

Bethke Elementary Modeled Elec

Actual Elec

Modeled Gas

Actual Gas

Fiscal Year 2008/2009

Elec

tric

(kW

h)

Gas

(MBt

u)

Original model

Improved Gas Modeling Assumptions

OriginalElec Gas Total Cost

kBtu/ft2 year $Modeled 15.7 12.0 27.7 34,590 FY 2009 Actual 13.1 26.0 39.1 36,387 Error 20% -54% -29% -5%

Improved GasElec Gas Total Cost

kBtu/ft2 year $Modeled 17.2 24.9 42.1 42,900 FY 2009 Actual 13.1 28.6 41.7 36,387 Error 32% -13% 1% 18% 44 44

IBPSA - USA

Checking calibration criteria (monthly data)*• Mean ERRmonth +/- 15% 100 * (M-S) / M• Mean ERRyear +/- 10% ∑ ERRmonth / 12• CV(RMSEyear ) +/- 10% (∑ [(M-S)2 / 12])0.5

* From FEMP M&V Guidelines v. 2.2 and ASHRAE Guideline 14 2002

Example calculations for gasCALIBRATION DATA Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Year Average Model (MMBtu) 254 229 213 131 93 31 7 15 47 99 189 253 1,560 130 Utility FY 2009 (MMBtu) 320 216 181 146 42 4 10 20 33 111 185 363 1,631 136 Mean ERR 21% -6% -18% 10% -124% -658% 27% 24% -41% 11% -2% 30% 4%MSE 366 14 84 19 221 60 1 2 15 12 1 1,002 RMSE 42 CV(RMSE) 31%

Elec GasMin ERRmonth 5% -2%Max ERRmonth -66% -658%Mean ERRyear -32% 4%CV(RMSEmonth) 40% 31%

BETHKE ELEMENTARYM&V – CALIBRATION

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Measurement & Verification

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