A Comparison of Measure Avoided Cost Calculations

1. A Comparison of Measure Avoided Cost Calculations using Utility TOU Load Shapes and DEER Hourly Measure Savings 14 March 2006

2. Measure Avoided Cost Calculations For this analysis, we compared annual avoided costs for selected measures determined using IOU load shapes and using DEER hourly savings results. This work does NOT examine or compare the magnitude of measure savings in the IOU filings vs. DEER savings for the same measure; this work only shows the relative avoided cost values when the SAME measure annual savings has an avoided cost calculated using the DEER hourly profile, or the IOU hourly or TOU profiles.

3. Measure Avoided Cost Calculations The components used for the analysis include: • cpucAvoided26.xls from E3 • levelized hourly avoided cost values were extracted from this spreadsheet for each utility/climate zone combination examined and for a range of measure expected life values. • contains hourly TOU period definitions for each utility • Utility specific “shape viewer” spreadsheets • “SCE-res2.xls”: SCE residential spreadsheet provides TOU values by end-use and climate zone for new construction, and by end-use for retrofit. • “SCE-nonres2.xls”: SCE non-residential spreadsheet provided TOU values by building type, end-use/measure-type and climate zone for new construction, and by building type and end-use for retrofit. • “SDG&E3.xls”: SDG&E spreadsheet provides TOU values by building type and end-use for both residential and commercial building types. • “ComViewer.xls” and “ResViewer.xls”: PG&E spreadsheets that provided TOU load shapes by end-use for building sector. These spreadsheets also contain the hourly load profiles by building type and end-use. • Attachment II-T3 tables • For each of the utilities, these tables map the TOU load shapes used for each of the measures.

4. Measure Avoided Cost Calculations The DEER version of eQUEST was used for this analysis, with minor modifications. • hourly whole-building electricity use for both the base case run and the measure run is now written to a file. End-use hourly values are not yet available. • some improvements were made to the DEER process to fix known problems: • minor changes to schedules (open-closed hours) • night-cycle control added for hot climates • residential HVAC performance curves updated

5. Measure Avoided Cost Calculations

6. Preliminary conclusions Use of TOU load shapes typically under-predicts the avoided cost of Commercial measures relative to hourly load shapes by up to 20% (or more) • For the commercial building cases examined, the average difference between TOU avoided cost to Hourly Avoided cost is 12%

7. Preliminary conclusions Use of TOU load shapes typically under-predicts the avoided cost of Commercial measures relative to hourly load shapes by up to 20% (or more) • For the commercial building cases examined, the average difference between TOU avoided cost to Hourly Avoided cost is 12%

8. Preliminary conclusions Use of TOU load shapes typically under-predicts the avoided cost of Commercial measures relative to hourly load shapes by up to 20% (or more) • For the commercial building cases examined, the average difference between TOU avoided cost to Hourly Avoided cost is 12%

9. Preliminary conclusions Use of TOU load shapes typically under-predicts the avoided cost of Residential measures relative to hourly load shapes by up to 30% • For the residential cases examined, the average difference between TOU avoided cost to Hourly Avoided cost is 19%

10. Preliminary conclusions The agreement between annual avoided costs calculated with hourly and with TOU load shapes varies by building type and measure

11. Preliminary conclusions Use of a Super-TOU load shape for the DEER TOU Avoided Cost calculation improved the agreement between the hourly and the TOU annual avoided costs by about 20% • For the cases examined, the average difference between Super-TOU avoided cost to Hourly Avoided cost is 11% (compared to 13% for the standard TOU). • For commercial buildings, the use of a super TOU period improved the comparison of Lighting vs. HVAC measures only slightly (about 10%). • For the single-family residential building, the use of a super TOU period did bring the Lighting and HVAC ratios closer together (by about 25%). • For this analysis, Super-TOU is defined as a new TOU period containing the 100 highest levelized avoided cost hours in the Summer On-Peak period.

12. Preliminary conclusions

13. Preliminary conclusions Use of IOU load shapes can under-predict and over-predict the avoided cost of measures relative to DEER hourly load shapes by up to 30% (or more) • For the cases examined, the average difference between the Utility TOU avoided cost to DEER Hourly Avoided cost is 20%.

14. Preliminary conclusions Use of IOU load shapes can under-predict and over-predict the avoided cost of measures relative to DEER hourly load shapes by up to 30% (or more) • For the cases examined, the average difference between the Utility TOU avoided cost to DEER Hourly Avoided cost is 20%.

15. Preliminary conclusions Use of IOU load shapes can under-predict and over-predict the avoided cost of measures relative to DEER hourly load shapes by up to 30% (or more) • For the cases examined, the average difference between the Utility TOU avoided cost to DEER Hourly Avoided cost is 20%.

16. Preliminary conclusions Use of IOU load shapes can under-predict and over-predict the avoided cost of measures relative to DEER hourly load shapes by up to 30% (or more) • For the cases examined, the average difference between the Utility TOU avoided cost to DEER Hourly Avoided cost is 20%.

17. Use of the IOU load shapes under-predicts the avoided cost for HVAC measures by a wider margin than lighting measures For the cases examined, the average difference between the Utility TOU avoided cost and the DEER Hourly Avoided cost is 9% for the indoor lighting measure. All other measure categories had significantly higher differences between Utility TOU and DEER Hourly avoided costs. Preliminary conclusions

18. The agreement between annual avoided costs calculated with hourly and with Utility TOU load shapes varies by building type and measure. Preliminary conclusions

19. Preliminary conclusions Building and end use load shapes, as used by the current E3 calculators, do not well represent measure impact shapes in most cases The use of older building and end use load shapes used for the current filings amplify this difference.

20. Preliminary conclusions IOU load shapes can work quite well … when the IOU load shape follows the same trends as the measure load shape.

21. Preliminary conclusions But if the TOU load shape doesn’t match the Measure load shape … then the annual avoided cost may be significantly under or over-estimated.

22. Preliminary conclusions But if the TOU load shape doesn’t match the Measure load shape … then the annual avoided cost may be significantly under or over-estimated.

23. Preliminary conclusions And even a TOU load shape that is quite different from the measure load shape … can lead to a “correct” answer due to compensating errors.

24. Preliminary conclusions Measures that save energy during some TOU periods but use more energy during other TOU periods cannot be approximated by an end-use load shape. Some measures do not lend themselves to be summarized by any TOU end-use load shape: This measure saves over 5000 kWh per year in a typical sized grocery store, but increases demand during the summer on-peak period.

25. Hourly Load Shape Comparison The hourly impact of economizer maintenance has little in common with the hourly cooling profile.

26. Hourly Load Shape Comparison The impact of low shading coefficient glass on the East has a much different load shape than cooling in general.

27. Hourly Load Shape Comparison The impact of low shading coefficient glass on the West has a much different load shape than cooling in general.

28. demand definition