CH-85-19-3 -- Variable-Base Degree-Day Correction Factors for Energy Savings Calculations PDF

Heating degree-days are often used as a climatic measure in building energy calculations. To account for the effects of solar and internal gains, degree-days at a base temperature, lower than the heating set point temperatures are used, or the number of degree days is adjusted downward by a degree-day correction factor. In this paper, we present a theoretical derivation, which demonstrates that ASHRAE Cd factors are not the appropriate correction factors for the calculation of energy savings from envelope conservation measures. The results of this derivation can be used to develop new correction factors appropriate for savings calculations.