Average Energy Bills for Existing Houses

In order to provide users an initial estimate of energy savings potential in their house, we estimated average energy bills by climate region from the sample of single-family housing units (including manufactured homes) in the 1993 and 2009 RECS microdata (US DOE 1995a, US DOE 2009). Users see this information immediately following entry of the zip code.

Energy bills by end-use are based on the end-use consumption estimates reported in the RECS microdata. For each housing unit in the RECS sample, EIA reports the Census Division in which that housing unit is located, as well as summary climate data (HDD and CDD) from the geographically closest weather station.

In order to provide finer geographic disaggregation of the RECS data, we assign each of the RECS housing units to one of 19 climate regions in the U.S. These climate regions were originally developed by LBNL in a project for the Gas Research Institute (Ritschard et al. 1992) and extended Huang et al. (1999) and Apte (2004). The 19 climate zones are described in Table 24. Using these climate-region assignments, within each climate region we select those single-family housing units that have the most common heating and cooling characteristics (heating fuel, water heating fuel, and presence of central air conditioner) for that region.

The energy consumption for space heating, space cooling and water heating was determined from this subset of housing units. Energy consumption for appliances was derived from the full set of single-family housing units for each climate zone. The 2001 Residential Energy Consumption Survey has not included data on lighting consumption since 1993, so the lighting energy consumptions was taken from the 1993 RECS microdata (US DOE 1995a). The final consumption values are shown in Appendix B, Default Energy Consumption

Table 24. Climate Zone Assignment

                    Alaska = Zone 5; Hawaii = Zone 20

The climate zone assignment is determined by the Census division and heating and cooling degree days (see Table 24) that are directly taken from the RECS micodata set. We determine the most common characteristics through the default house analysis described in Default House Characteristics. These characteristics, and the number of RECS records meeting those criteria, are shown in Table 25. We select only the houses that had the most common characteristics because we want their average energy use to correspond to the default house characteristics for that region (to provide internal consistency within the HES model).

The default energy consumption values from the RECS survey and the calculated energy consumption values returned from the DOE 2.1E building simulation model are converted from Mbtu to utility units (kWh, therm, etc.) for presentation to the user, using the following equations.


EnergykWh = EnergyMbtu * 1,000,000 / 3412             Equation 33

Natural Gas:

Energytherm = EnergyMbtu * 10                                   Equation 34

Fuel Oil (gallon of fuel oil):

Energygallon = EnergyMbtu * 1,000,000 / 138,690      Equation 35

Liquid Propane Gas (gallon):

Energygallon = EnergyMbtu * 1,000,000 / 85,786        Equation 36

Table 25. Typical Heating and Cooling Characteristics for Each Climate Zone