296 PART | III Smart Infrastructure, Smart Prices, Smart Devices $1.20 CPP event day $1.00 Commodity energy cost ($/kWh) Non-event day TOU $0.80 $0.60 $0.40 $0.20 $0.00 1 4 7 10 13 Hour ending 16 19 22 FIGURE 12.1 SDG&E TOU & default CPP price profiles--Event Day and Non-Event Day. while the default CPP prices in all other time periods are less than those for the alternative TOU rate. The latter feature illustrates the potential for customer bill savings under the CPP tariff; customers pay somewhat lower prices most of the time in return for facing very high on-peak prices on a limited number (e.g., up to 15) of summer weekdays. CPP Events Table 12.2 lists the CPP event days for each of the utilities in 2009. PG&E and SCE each called 12 CPP events (PG&E's first event was a test event), while SDG&E called 8 events. The utilities often called events on different days, though there was some overlap, particularly in the last week of August. PG&E's events started earliest in the summer and ended earliest in the season, while SDG&E's events did not begin until late August and extended into late September. One of the events occurred on a Saturday. ANALYSIS METHODS Estimation of customer load response to event-based dynamic pricing is rela- tively straightforward compared to, for example, static TOU rates or the effect of modestly changing flat prices over a number of years. In the case of dynamic pricing, hourly load data are typically available for a relatively compact period of time, such as four summer months, and for both days on which consumers