Hourly Average Power (kW)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hour of Day Figure 18. Interior and garage lighting profile (International Falls, Minnesota)
In Option 2, the plug-in lighting for the Prototype house (or unit) is determined by the difference between the required footcandles (Table 18 and Table 19) for a given room type and the total installed hard-wired footcandles for that room. Efficacy values for the Benchmark (See Table 17) are used as defaults for the plug-in lighting in the Prototype.
To use Option 2, details such as lamp type (e.g., incandescent versus compact florescent) and fixture type (e.g., track versus pendant light) must be known variables. Default values for all relevant variables are also available in the BA spreadsheet. The analyst may override any default values if better information is available and the revisions are documented. It is important to note that for the Prototype, rooms that contain more lighting than is recommended by Table 18 and Table 19 will be penalized.
The illuminance for each room type is based on an engineering interpretation of the horizontal illuminance levels in the IESNA Lighting Handbook (Rea et al. 1993). Values for each indoor space type, for all housing types, are shown in Table 18. Note that some of the entries include a series of several room types with similar illuminance requirements. For simplicity, in the tables that follow and in the BA Analysis Spreadsheet, the first room type in each series will be used as shorthand for all similar room types. Multi-family common space illumination values are found in Table 19. Note: All footcandle levels are measured at a three-foot work plane for most indoor spaces and on the ground for hallways.
For outdoor lighting, there is no footcandle requirement. Instead, the total lumens used for the Prototype are also used for the Benchmark. Savings are then based on the efficacy of the lamps used in the Prototype compared to the Benchmark.