Detailed Explanation of Methodology for Residential Calculations

Residential Sector Energy Savings
Data on existing energy use for the existing residential sector are from the Energy Information Administration (EIA) 2001 Residential Energy Consumption Survey (RECS) data by climate zone and end use (space conditioning (HVAC), water heating, appliances, and lighting). Major energy sources include electricity, natural gas, propane, and fuel oil. RMI data derived from EIA data were used as the baseline for energy use for new residential construction.

The Energy Information Administration (EIA) data that drive the Finder's calculations are broken out in a number of different ways: by census region, building age, and climate, among others. The designers of the Finder chose to use census region and climate to analyze residential energy savings potential because energy use varies widely across climates, and these data are easy to gather.

Estimates of potential savings are based on the experience of RMI energy experts for each of the four major residential end uses.

*RECS data on fuel types used for space conditioning, water heating by census region were used to calculate energy savings, dollar savings, and emissions reductions. (Lighting and appliances were assumed to be 100 percent electric.) For example, in the Northeastern U.S., 54 percent of the energy used for space heating comes from natural gas, 34 percent from fuel oil, and the rest from electricity, kerosene, and propane. (Compare that to the Midwest, where 80 percent of energy comes from natural gas and only 3 percent from fuel oil.) Although the four census regions: West, South, Midwest, and Northeast are large areas, and certainly encompass a great deal of variation, they are the finest level of detail for which data are available, and they do provide a finer level of detail than a national average.

Example of how total energy savings estimates are calculated for the results section:

Energy Savings
Energy savings for space conditioning is estimated to be 30 percent on the low end. That 30 percent savings estimate is applied individually to each of the different energy sources used for space heating (electricity, natural gas, fuel oil, and propane) and air conditioning (electricity only). This is important, because each fuel source has different costs and emissions factors, with electricity being the highest in both categories, and to obtain accurate results, each source must be treated individually. The estimates of savings potential in space conditioning is then calculated as a weighted average based on all energy sources used for space conditioning. The same is done for water heating. Appliances and lighting are assumed to be 100% electric. Then the total energy savings potential for the low estimate is calculated as a weighted average based on the percent of total energy use dedicated to each of the four major energy end uses. The same process is repeated for the high estimate.

Dollar Savings
The Finder relies on your data (or default data) for the costs of electricity, natural gas, fuel oil, and propane to calculate current energy expenditures and cost savings.

As with the energy savings, dollar savings were calculated by applying savings factors to the costs of each fuel type used in each energy end use (such as space conditioning and water heating).

Emissions Reductions
The Finder generates data on fossil fuel emissions (and reductions in emissions) for three major pollutants: carbon dioxide (CO2), sulfur oxides (SOx), and nitrogen dioxide (NO2). Additional, toxic air pollutants such as mercury, which can be generated from a number of sources including coal fired power plants and waste incinerators, are of great concern, but are not included in this analysis due to a lack of reliable, accessible data.

Calculations on emissions and emissions reductions for natural gas, fuel oil, and propane are derived from standard emissions factors from the Energy Information Administration.

Data on emissions associated with electricity are from one of 27 power regions in the U.S. power grid. Users can access these data from the EPA’s Power Profiler tool, which is populated by data from the eGRID database, a comprehensive source of data on the environmental characteristics of virtually all electric power generated in the United States. The 27 power regions are the finest level of detail for which accurate data are available.

Emissions reductions for electricity are assumed to be reductions in source energy, or the energy produced at the power source, as opposed to site energy, or delivered energy, which is diminished by line losses—the loss of electricity during transmission from the power source to the consumer. Therefore, by basing emissions reductions on source electricity reductions, we are assuming that each kilowatt-hour saved by a consumer equals a kilowatt-hour saved at the power source

Job Creation
Estimates of jobs created from energy efficiency programs are derived from a model developed by John “Skip” Laitner at the U.S. EPA. Skip can be reached at Laitner.Skip@epamail.epa.gov for questions.