1. DRMEC Spring 2016 Load Impacts Evaluation Workshop San Francisco, California May 10, 2016 2015 SDG&E Summer Saver Load Impact Evaluation

2. Agenda 2  Summer Saver program overview  Ex post methodology  Ex post results  Ex ante methodology  Enrollment forecast  Ex ante results  Ex post results for subgroups

3. Summer Saver Program Overview 3  Day-of demand response program offered by SDG&E to residential and small commercial customers  Based on central air conditioning (CAC) load control, using direct load control (switches with 1-way paging communication)  Events may be called on any non-holiday from May-October and run between 2 to 4 hours  No more than three event days per week  Participants have a choice of cycling strategy:  Participation is incented with an annual bill credit based on cycling strategy and tonnage of enrolled CAC unit(s)  Residential - $11.50 per ton for 50% cycling, $30 per ton for 100% cycling  Commercial - $ 9 per ton for 30% cycling, $15 per ton for 50% cycling Customer TypeCycling Strategy% of CACs Enrolled Residential 50%57% 100%43% Commercial 30%24% 50%76%

4. Ex Post Methodology 4  Nexant estimated reference loads using a randomized control trial (RCT) for the residential segment, and a matched control group for the small commercial segment  Ex post impacts were estimated for each hour of each event by taking the difference between the same-day adjusted average control group load and the average observed treatment group load  Same day adjustment is based on the ration of usage between the treatment and control groups for the hour prior to the event start  Hourly impact estimates for the residential and nonresidential Summer Saver population were calculated by taking a weighted average of the impact estimates for each cycling option, with weights determined by the number of tons enrolled on each cycling option.

5. Ex Post Results 5  15 Summer Saver events called in 2015 Date Day of Week Start Time End Time 8/13/2015Thursday3:00 PM7:00 PM 8/14/2015Friday4:00 PM8:00 PM 8/16/2015Sunday3:00 PM7:00 PM 8/26/2015Wednesday4:00 PM8:00 PM 8/27/2015Thursday3:00 PM7:00 PM 8/28/2015Friday3:00 PM7:00 PM 9/9/2015Wednesday3:00 PM7:00 PM 9/10/2015Thursday3:00 PM7:00 PM 9/11/2015Friday3:00 PM7:00 PM 9/20/2015*Sunday2:00 PM4:00 PM 9/24/2015Thursday2:00 PM6:00 PM 9/25/2015Friday2:00 PM6:00 PM 10/9/2015Friday3:00 PM7:00 PM 10/10/2015Saturday3:00 PM7:00 PM 10/13/2015Tuesday4:00 PM8:00 PM * Emergency event called from 1:35 PM to 3:35 PM  2015 was the first year since 2012 that weekend events were called  Residential impacts:  Aggregate load impacts ranged from 7.6 MW to 17.8 MW  On average, weekend load impacts were almost 10% higher than weekday impacts  Small commercial impacts:  Aggregate load impacts ranged from 0.4 MW to 2.5 MW Hours of Availability Hours of Actual Use # of Available Dispatches* # of Actual Dispatches 605815

6. Ex Post Results – Residential 6 DateEvent Time Impact Mean17 (°F) Per CAC Unit (kW) Aggregate (MW) 8/13/2015 3 to 7 PM 0.4210.578 8/14/2015 4 to 8 PM 0.369.079 8/16/2015 3 to 7 PM 0.7017.882 8/26/2015 4 to 8 PM 0.359.080 8/27/2015 3 to 7 PM 0.5413.782 8/28/2015 3 to 7 PM 0.5914.984 9/9/2015 3 to 7 PM 0.6817.288 9/10/2015 3 to 7 PM 0.4511.486 9/11/2015 3 to 7 PM 0.5113.084 9/20/2015* 2 to 4 PM 0.348.784 9/24/2015 2 to 6 PM 0.4812.278 9/25/2015 2 to 6 PM 0.4010.179 10/9/2015 3 to 7 PM 0.4310.881 10/10/2015 3 to 7 PM 0.4511.488 10/13/2015 4 to 8 PM 0.307.682 Average** 3 to 7 PM 0.5313.383 *Reflects the emergency event called from 1:35 PM to 3:35 PM **Reflects the average 4-hour weekday event from 3PM to 7 PM

7. Ex Post Results – Nonresidential 7 DateEvent Time Impact Mean17 (°F) Per CAC Unit (kW) Aggregate (MW) 8/13/2015 3 to 7 PM 0.121.3 77 8/14/2015 4 to 8 PM 0.080.8 78 8/16/2015 3 to 7 PM 0.121.3 80 8/26/2015 4 to 8 PM 0.091.0 79 8/27/2015 3 to 7 PM 0.121.3 80 8/28/2015 3 to 7 PM 0.101.1 83 9/9/2015 3 to 7 PM 0.111.2 87 9/10/2015 3 to 7 PM 0.151.7 85 9/11/2015 3 to 7 PM 0.141.6 83 9/20/2015* 2 to 4 PM 0.060.6 83 9/24/2015 2 to 6 PM 0.232.5 77 9/25/2015 2 to 6 PM 0.202.1 78 10/9/2015 3 to 7 PM 0.141.6 80 10/10/2015 3 to 7 PM 0.151.6 87 10/13/2015 4 to 8 PM 0.040.4 81 Average** 3 to 7 PM 0.131.482 *Reflects the emergency event called from 1:35 PM to 3:35 PM **Reflects the average 4-hour weekday event from 3PM to 7 PM

8. Ex Post Results – Utility and System Peak Days 8  SDG&E Peak: 9/9/2015 at 3:43 PM  CAISO Peak: 9/10/2015 at 4:43 PM Event Date Hour Ending Load Impact (MW) ResidentialNonresidential 9/9/2015 1614.52.13 1718.31.42 1817.71.19 1918.4-0.07 Event Date Hour Ending Load Impact (MW) ResidentialNonresidential 9/10/2015 1610.32.73 1713.32.33 1811.71.12 1910.30.44  SDG&E peak corresponds to the HE 16 period on the 9/9/2015 event  CAISO peak corresponds to the HE 17 period on the 9/10/2015 event

9. Ex Ante Methodology 9 Average Ex Post Load Impacts and Ex Ante Predictions from 3 to 5 PM for Residential 100% Cycling Participants

10. Enrollment Forecast 10 Source Nonresidential 30%50% TonsCustomersDevicesTonsCustomersDevices 2015 Analysis Dataset 12,6001,1383,25429,8863,5307,563 2015 SDG&E Forecast 12,544.51,1343,24329,866.73,5407,791 Source Residential 50%100% TonsCustomersDevicesTonsCustomersDevices 2015 Analysis Dataset 51,186.712,51013,94041,569.89,25511,388 2015 SDG&E Forecast 51,54712,59814,70240,741.39,07311,210  Very little difference between ex ante and SDG&E program forecasts  SDG&E enrollment forecast is flat from 2015 – 2026

11. Ex Ante Results – August Monthly Peak under SDG&E 1-in-2 Weather Conditions 11 Customer TypeYear Per Premise Impact (kW) Enrollment Aggregate Impact (MW) Residential 20170.4821,67110.5 20260.4821,67110.5 Nonresidential 20170.654,6743.0 20260.654,6743.0  Same estimates for 2017 and 2026 by customer type because SDG&E enrollment forecast is flat from 2015 – 2026

12. Ex Ante Results – Compare August 2017 1-in-2 Ex Ante Forecast to 2015 Ex Post 12 Customer Type Estimate Type Date Per Premise Impact (kW) Aggregate Impact (MW) Mean17 Residential Ex Post 9/24/2015 (2-6 PM) 0.5812.278 Ex Ante August 2017 (2-6 PM) 0.5010.975 Nonresidential Ex Post 9/24/2015 (2-6 PM) 0.542.4577 Ex Ante August 2017 (2-6 PM) 0.643.075

13. Ex Ante Results – Comparison of 2015 to 2014 13 Analysis Year Customer Type Forecast Year Per Premise Impact (kW) Enrollment Aggregate Impact (MW) 2014 Residential 2017.4823,02611.2 Nonresidential.664,7893.15 2015 Residential 2017 0.4821,67110.5 Nonresidential0.654,6743.0  Differences in estimated impacts arise because:  Residential forecasted enrollment was larger in 2014  Nonresidential per premise impact slightly larger in 2014 and the forecasted enrollment was larger

14. Contact Us Candice Churchwell Senior Consultant, Utility Services CChurchwell@nexant.com CChurchwell@nexant.com (415) 369-1194

15. Ex Post Results by Program Subgroups 15 Date Per CAC (kW)Aggregate (MW) Cycling Option ResidentialCommercialResidentialCommercial 10050 3010050 30 8/13/20150.520.340.110.135.884.750.830.44 8/14/20150.430.290.080.074.934.020.620.23 8/16/20150.880.550.150.0610.027.701.110.19 8/26/20150.390.320.060.154.414.480.48 8/27/20150.540.530.150.066.197.441.140.20 8/28/20150.730.470.080.168.336.580.610.52 9/9/20150.770.610.120.088.748.450.910.25 9/10/20150.620.310.200.047.034.371.490.15 9/11/20150.520.510.140.155.877.081.080.48 9/20/20150.520.210.060.045.882.880.480.13 9/24/20150.450.510.220.235.097.141.700.76 9/25/20150.570.260.190.216.513.671.460.67 10/9/20150.390.460.140.164.416.431.040.52 10/10/20150.640.290.170.097.304.101.290.29 10/13/20150.260.330.010.103.024.580.070.32 Average*0.580.460.130.116.646.451.010.37 *Reflects the average weekday 3-7 PM 2015 Summer Saver event