As of January 1, 2008 there has been changes to the City of Austin TX energy code.

Residential buildings, as defined by Chapter 2 of the 2009 International Energy conservation code and not having natural gas service or equivalent district gas service located within the adjacent right-of-way, may install electric resistance water heaters having a minimum efficiency of 93% in conjunction with a preprogrammed water heater timer in lieu of gas fired water heating. The timer shall be preprogrammed to turn the water heater off between the hours of 3:00PM and 7:00PM from June 1 to September 30 and from 12:00AM to 4:00AM throughout the year. The timer shall have a readily accessible override, as defined by the building official, capable of restoring power to the water heater for one hour when activated.

Section 504.8 Electric water heater timers. For Group R buildings electric resistance water heaters must be installed in conjunction with a preprogrammed water heater timer. The timer shall be preprogrammed to turn the water heater off between the hours of 3:00 p. m. and 7:00 p.m. from June 1 to September 30 and from 12:00 a.m. to 4:00 a.m. throughout the year. The timer shall have a readily accessible override, as defined by the building official administrative rule, capable of restoring power to the water heater for one hour when activated.

ASAP A-1 Programmable Energy Saving Water Heater Timer meets this code.