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Overview Goal today: RTF provisional approval of approach for pilot projects In brief:

Regional Technical Forum Recommissioning commercial retail facilities: A whole building approach to energy savings April 7th, 2009 Presented by: Jeremy Litow Jamie Anthony Mark Effinger. Recommissioning commercial retail facilities: A whole building approach to quantifying energy savings.

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Overview Goal today: RTF provisional approval of approach for pilot projects In brief:

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  1. Regional Technical ForumRecommissioning commercial retail facilities:A whole building approach to energy savingsApril 7th, 2009Presented by:Jeremy LitowJamie AnthonyMark Effinger

  2. Recommissioning commercial retail facilities:A whole building approach to quantifying energy savings • Overview • Goal today: RTF provisional approval of approach for pilot projects • In brief: • Project approach and value • Market potential and benefits • In detail • Origins • Energy savings methodology • Next steps

  3. Project approach and value • What is whole building recommissioning? • Optimize all building systems, 80%+ of usage • Why is it a useful approach? • Missed opportunities • Why now? Evolution • Market • Energy cost • Technology • Program • Technical approach • Persistence

  4. Overview - project approach • Interval metering at the building level, pre and post • Pre inspection and documentation, sensors and logs • Recommissioning process • Post inspection and documentation • Energy savings quantified (more later) • Persistence monitoring (three year)

  5. Market potential • Building types – refrigeration is important • Convenience stores • Grocery stores and standard supermarkets • Large stores • Savings range • Average of 7-10% annual savings • Typical range 5-15% • 1 in 10, 20% or more possible

  6. Benefits of taking a whole building approach • Big picture • Leveraging AMI investments • Leadership • Capacity building • Drive market to systems approach • Measurement to determine savings more powerful than estimation • Local picture - Optimized buildings • Systems approach • No missed opportunities • Persistence monitoring (3 years)

  7. Origins of the whole building approachand basis of the methodology • Long history, 1980s PRISM • IPMVP, 1997 • ASHRAE Guideline (GL) 14-2002 • ASHRAE Research project 1050, 2002 • California Commissioning Collaborative – Guideline for Verifying Existing Building Project Savings Using Interval Data Energy Models: IPMVP Options B and C, 2008 • “Verification of Savings” methodology • Whole building energy use • Many, interactive ECMs

  8. Verification of whole building approach:normalized savings • Acquire baseline data, utility or logged • Model energy use as function of variable(s) (e.g. DB) for pre ReCx • Estimate savings and savings uncertainty and required post period • Acquire post-ReCx data, utility or logged • Model energy use as function of variable(s) for post • Drive each model with “normal” conditions (TMY or influential variables) to determine annualized pre and post energy use • Savings = modeled annualized baseline - modeled, annualized post-ReCx • Evaluate overall uncertainty using ASHRAE GL 14

  9. Energy use Ambient Temp Energy use C B2 B1 B3 B1 C Verification of Savings (VoS) methodology: discussion of the method, 1 VoS is a proven method • Change point model, all hourly power data points with corresponding DB temperature • We also looked at other methodologies Ambient Temp 2 Parameter model 4 Parameter model

  10. Verification of savings methodology: discussion of the method, 2 Example follows a proven method among several options • Method uses statistics to determine accuracy • R2: proportion of variability in a data set that is accounted for by the statistical model • 0 to 1 range, >.7 considered “good” • CV (RMSE): differences between values predicted by a model and the values actually observed from the thing being modeled • %, <7% “good” • R2: provides a measure of how well future outcomes are likely to be predicted by the model. • CV (RMSE): evaluates the relative closeness of the predictions to the actual values

  11. Verification of savings methodology: discussion of the method, 3 Example follows a proven method among several options • Range of post data to see temp variation, typically over swing season • Latent loads (case infiltration/defrost) accounted for? • DB is proven for other building types • DB is provides best correlation to power vs. WB, RH, DP, W • Will look at other variables, evaluate if DB is best for PNW CZ and refrigeration • Need to field test • Estimated savings uncertainty–CCC meets approach, ASHRAE GL 14 requirements • 68% confidence with < or = to 50% uncertainty ok

  12. Example: Verification of savings methodology • Sample site • Grocery 100,000 ft2 • ReCx and retrofits • 591 days of interval data • 411 pre • 180 post • OATDB 1F to 110F • Average 56F • RH 4.5-100% • Average 53% • Observed OAT 73% of TMY range

  13. Pre change point Post change point Energy savings calculation methodology • Change point on all data, DB R squared: .74 and .64 CV (RMSE): 5.5% and 5.2% Annual savings: 541,520 kwh

  14. Energy savings calculation methodology • Method comparisons • Change point on all data, DB • Change point on all data, WB • Linear on all data, DB • Linear on all data, WB • 2nd degree polynomial, averaged power vs. weather bin, DB • 2nd degree polynomial on all data, DB • 2nd degree polynomial on all data, WB

  15. Energy savings calculation methodology • Other areas of interest • Post period perspectives • Post ReCx duration • Season very important, range of temperatures needed • Period can be shorter if timed right • Estimated savings uncertainty

  16. Change point for this building, this CZ Post period duration and timing 1+ year pre project: R2 .72 and CV RMSE 5.7%

  17. Post period duration and timing 2 months post project Dec 07-Jan 08: R2 .27 and CV RMSE 6.7%

  18. Post period duration and timing 2 months post project Mar-Apr 08: R2 .69 and CV RMSE 4.2%

  19. Post period duration and timing 3 months post project Dec 07-Feb 08: R2 .36 and CV RMSE 6.2%

  20. Post period duration and timing 3 months post project Feb-Apr 08: R2 .67 and CV RMSE 4.8% Nearly as good as 5th mos post!

  21. Post period duration and timing 4 months post project Dec 07- Mar 08: R2 .49 and CV RMSE 5.8%

  22. Appropriate change point visible Post period duration and timing 5 months post project Dec 07- April 08: R2 .60 and CV RMSE 5.6%

  23. Energy savings calculation methodology • Uncertainty – using CCC Verification of Savings method

  24. Conclusions on methodology • Use change point models with driving variable(s) • Look for importance of latent loads in pilots • Post required will vary with season • Shorter in the spring than in the winter • Uncertainty – follows VoS guidance, meets ASHRAE GL 14

  25. Next steps – pilots • Provisional approval to claim savings using this approach • Pilots on several facilities • Refine approach • Present findings to RTF

  26. Recommissioning commercial retail facilities:A whole building approach to energy savings Discussion

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