The following verification of lighting input is performed: The lighting in conditioned spaces is within 20% of the average Wh/SqFt/Day as entered on the Weather/Defaults  -> Advanced screen. The default value that the Model Inspector uses for the average is 3 Wh/SqFt/Day if a different value has not been entered.

According to a pilot study “Incorporating Lighting and Appliance Energy Consumption into the Home Energy Rating Score” prepared by Architectural Energy Corporation, the statistical average connected lighting load in single family houses is 1.25 W/sqft and the lamps are lit on average 2.34 hours/day.

A monitoring project commissioned by the Bonneville Power Administration and Tacoma Public Utilities referenced on LBL website (, Tribwell and Lerman, 1996) showed similar results, with an average of 2 hours per day operating time and lighting load of 1.47 W/sqft.

Both studies yield similar daily lighting usage of around 3 Wh/SqFt/Day. This usage is used by TREAT as default. You may modify the default on the Advanced window of the Weather/Defaults screen.

Another helpful link for determining the lighting load of particular building is, which opens a document prepared by Energy Information Administration Office of Energy Markets and End Use of U.S. Department of Energy. The paper presents data on typical lighting energy usage in various residential building types. According to the study, the most of apartments (32.9 percent) consume between 250 and 499 kWh/year. The largest number of mobile homes (24.0 percent) consume between 500 and 749 kWh/year. Among single-family homes, the consumption is higher, with 17.4 percent using between 750 and 999 kWh/year.

The following verification of appliance input is performed:

  1. A summary of the annual appliance usage of each fuel.
  2. There are appliances that use hot water. Typical residential buildings have some appliances, such as clothes washers and dishwashers, which use hot water. Omitting them may result in incorrect DHW consumption.