Measurement & Verification

1. Measurement & Verification IBPSA - USA 1

2. The Path to Improved Performanceincludes M&V activities • M&V is part of a performance feedback loop that benefits: • Facility Managers • Designers • Energy Modelers The Path to Improved Performance 2

3. Predicted vs. Actual “ … a quarter of the new buildings that have been certified do not save as 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. From NBI/USGBC, “Energy Performance of LEED for New Construction Buildings”, March 2008. 3

4. M&V Resources 4

5. M&V – Option DActivities Savings Commissioning As-Designed Model Calibrated Model Performance Data Metering 5

6. LEED M&V LEED NC EAc5 Measurement and Verification 6

7. M&V – Option DProcedures 7

8. Develop M&V PlanLEED NC Considerations See http://www.ibpsa.us/workshop/ for more detailed M&V Plan content outline and example LEED EAc5 M&V Plan 8

9. Develop M&V Planbalance risk of savings with value of savings 9

10. Ensure Sufficient Metering 10

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

12. Gather and Check Dataafter building is commissioned 12

13. Gather and Check Dataafter building is commissioned 13

14. Gather and Check DataCreating Custom Weather Files See simulation program documentation for more details on data requirements and processing tools 14

15. Gather and Check DataCreating Custom Weather Files • Download the TMY .CSV file for Atlanta, GA (available from EnergyPlus site) • Request hourly data for 2007 from the EnergyPlus request site • http://apps1.eere.energy.gov/buildings/energyplus/weatherdata_about.cfm • Fill any data gaps in 2007 .CSV files that you receive via email • Convert data to correct units for TMY version (if required) Example Process: Create a custom weather file for 2007 for Atlanta, GA 15

16. Gather and Check DataCreating Custom Weather Files Create a custom weather file for 2007 for Atlanta, GA • Convert Dry Bulb and Dew Point Temperature to % Relative Humidity using the relation: • Tdb = dry bulb temperature, Tdp = dew point temperature, RH = Relative Humidity • Copy the 2007 hourly data (including the calculated RH) to the appropriate columns in the TMY .CSV file. • Try to find hourly solar data…hopefully your site is included here: http://www.nrel.gov/midc/srrl_bms/ • Copy the 2007 solar radiation values to the appropriate columns in the TMY file • Convert the altered .CSV file to the type of weather file required for a given energy modeling tool using various weather file converter tools 16

17. CalibrationBound the Problem 17

18. CalibrationGuide the Investigation 18

19. CalibrationReconciliation 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 19

20. CalibrationReconciliation with Hourly Data 20

21. CalibrationArt versus Science 21

22. CalibrationHow Good is Good Enough? Check if Calibration Criteria are Met 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 The mean bias error may be influenced by offsetting errors 22

23. Calculate 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) 23

24. Measurement & Verification IBPSA - USA M&V Case Study California Office Building 24

25. High-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 25

26. High-rise Office M&V ExampleLEED NC 2.1 M&V Implementation • Project used IPMVP Option D, Method 1 • Current LEED requires Method 2 26

27. High-rise Office M&V ExamplePredicted vs. Actual Step #1 • Compare design model to utility bills  Not very close (details on following slides) 27

28. High-rise Office M&V ExamplePredicted vs. Actual Electricity 28

29. High-rise Office M&V ExamplePredicted vs. Actual Peak Electric Demand 29

30. High-rise Office M&V ExamplePredicted vs. Actual Natural Gas 30

31. High-rise Office M&V ExamplePredicted vs. Actual From EMS Step #2 • Dig deeper… • Data sources in this case • Building automation system (BAS) • Separate Energy monitoring system (EMS) • Short-term monitoring • Chiller kW From BAS 31

32. High-rise Office M&V ExampleModel Calibration Step #3 Calibrate Model • Verify system performance - chillers & air handlers 32

33. High-rise Office M&V ExampleModel Calibration Step #3 (continued) • Verify system performance – computer room air conditioners 33

34. 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 34

35. High-rise Office M&V ExampleModel Calibration Step #3 (continued) • Monthly calibrated model results • Criteria: • Mean ERRmonth +/- 15 • Mean ERRyear+/- 10% • CV(RMSEmonth)+/- 10% 35

36. High-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 savings Step #6 • Think about results… 36

37. Measurement & Verification IBPSA - USA M&V Case Study Bethke Elementary School 37

38. Bethke Elementary Case StudyDesign through Occupancy Owner: Poudre School District Location: Timnath, CO Principal Use: 10-month school with classrooms, gym, media center, office School Capacity: 525 Completion Date: Aug 2008 Cost: $151/sq ft Size: 63,000 sq ft Energy Costs: $0.58/ft2 year Energy Use: 47 kBtu/ft2 year Awards: LEED for Schools Gold, 3 of 4 Green Globes, Energy Star Label of 99 38

39. Bethke ElementaryDesign Approach – Use of Prototypes 39

40. Bethke ElementaryM&V – EAc5 M&V Plan Savings Calculations Operation Verification 40

41. Bethke ElementaryM&V – Implementation • PSD Approach • Commission building • Compare actual against anticipated • Compare actual against other prototypes OK 41

42. Bethke 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? 42

43. Bethke ElementaryM&V – Calibration 43

44. Bethke ElementaryM&V – Calibration Original model Improved Gas Modeling Assumptions 44

45. Bethke ElementaryM&V – Calibration 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 gas 45