Rob R. wrote:I thought the old rule was 1% for every degree ?
The governments "one answer fits all" guess is (or at least used to be) 3% for every degree. My program does not use pre-determined percentages (rules of thumb) such as 1% or 2% or 3%. It tries to calculate what you will more likely actually experience. No rules of thumb used here.
The basic spreadsheet logic is as follows:
Lets assume a case where someone typically heats their home for 200 days out of the year, and their area typically sees 6,000 HDD's (heating degree days), and they typically burn 7,000 lbs. of coal.
7,000/6,000 = 1.167 lbs. burned per HDD
7,000/200 = 35 average pounds burned per day
Backing down by 1 degree on your thermostat for an entire season is the same as going through a heating season that averages 1 degree warmer outside than the typical season. Call it the
'Theory of Temperature Relativity'.
Therefore, for this example: Instead of averaging 35 lbs per day burned, you will experience 35-1.167 = 33.833 lbs. per average day burned if you set the T-Stat back 1 degree.
(1.167/35 ) x 100 = 3.33% "typical season" savings
33.833 lbs/day x 200 days = 6,767 lbs. burned for the "typical" season (instead of 7,000).
