HUD HCV Guidebook § 3.1.2

An industry best practice is to obtain consumption data for each unit size and type. If consumption data is
available only for an average unit size (2 ½ bedrooms), the utility costs can be multiplied by the following
factors to determine the costs for a specific unit size. Example 1 shows how this calculation can be applied:

                       Example 1: Adjustment Factors by Unit Size
                         Unit Bedroom        Adjustment Factor (times 2 ½ bedroom
                              Size                monthly consumption figure)
                               0                              0.5
                               1                              0.7
                               2                              0.9
                               3                              1.1
                               4                              1.4
                               5                              1.6

                          Example: The natural gas heating cost for an average sized
                                           unit is $18 per month.
                               The allowance for a four-bedroom unit will be:
                              1.4 X $18 = $25 (rounded to the nearest dollar)