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Will California Do Its Own Thing?

A proposal has also been issued by the California Energy Commission (CEC), which is required by state legislation to develop regulations governing HERS programs operating in the state.

While many aspects of the proposed regulations mirror the federal ones, there are some key differences. For instance, the California system would use the state's Title 24 building energy efficiency standards to set the efficiency level of the reference house, and comparisons for scoring purposes would be made based on source energy use. This contrasts with the national proposal to compare houses based on site energy use with a reference house designed by the HERS council.

According to the CEC, "site energy ignores the generation, transmission, and distribution losses inherent in electricity consumption even though those losses are reflected in energy bills." The national HERS council compensates for this by using a heat pump as the reference equipment in an electrically heated house. The heat pump uses source energy nearly equivalent to that used by the gas furnace designated as the reference for a gas-heated house. However, the national guidelines use an electric resistance water heater as the efficient reference, putting it on par with an efficient gas water heater. Under the CEC regulations, only a solar water heater with electric backup or a heat pump water heater would be considered equivalent to the gas water heater reference.

In addition to the site versus source energy debate, there are differences in assumptions about infiltration, thermal mass, duct efficiency, and thermostat settings. This means that the score for the same house could be different under the California regulations from that calculated using the national proposal.

These differences could put the California Home Energy Efficiency Rating System (CHEERS) and the smaller private California rating system company Energy Plus in the position of complying with two sets of guidelines. The CEC guidelines will be mandatory for a HERS to operate in California. The national guidelines are voluntary, but they may be required by secondary market lenders for energy-efficient mortgages.

Both sets of regulations are out for public comment as this issue of Home Energy goes to press, and they may change substantially before being finalized. For a copy of the CEC's proposed regulations and HERS Technical Manual, call the CEC at (916)654-4067.