TO-2734 (RP-251) -- Degree-Days Method for Simplified Energy Analysis PDF

One year of energy-consumption and weather data for 57 residences in seven cities were analyzed to update the degree-days method for simplified energy analysis. This research has shown that the mean heating and cooling base temperatures for these homes, constructed in early 1970, were about the same as the 18.3°C (65°F) base temperature in use for many years. Seasonal heating loads for occupied homes were predicted with an absolute error of about 38% and a coef¬ficient of correlation (R) of about 0.83 using a constant correction factor of 0.51 applied to the load computed with the degree-days procedure. The error dropped to about 31 percent and the correlation improved to 0.88 when different correction factors were used for each of the seven cities. For cooling, with a constant correction factor of 0.76, the absolute error increased to 66% and the coefficient of correlation dropped to 0.42. The Harris-type correction factor did not improve the correlation for either heating or cooling.