how are heating degree and cooling degree days computed?

Question

They are reported in the newspaper and are often in excess of the days of the year, which is why I wonder about this.

Answer 1

First, take the average temperature of the day. For example, high 90 degrees, low 70 degrees. The average is 80 degrees. Subtract 65 (this is the benchmark) and you get 15 cooling degree days. If the average temp is less than 65, subtract it from 65 and you get the heating degree days. For example if the high is 50, low is 30, then the heating degree days is 65 - 40 = 25.

If using Celsius, the benchmark is 18°C. Calculate the rest as usual. Note that both heating and cooling degree days will be half of those on the Fahrenheit scale, so you can't directly compare Canadian and U.S heating/cooling degree day scales.

Answer 2

They go by historical averages. Note that heating degree days are usually computed to a 65 F benchmark, figuring that the oven, lights, etc. will warm the house the rest of the way from 65 to 70 or 72. When broken down monthly, they make sense. When looking at annual numbers, there are days when it's cold in the morning and warm enough to run the AC in the afternoon.

Answer 3

I think thet are how many degrees from a certain temp

maybe from 65 or something

so if its 60 that day then 5

if its 30 then 35

Answer 4

see:
http://en.wikipedia.org/wiki/Heating_degree_day