
* The ranks are calculated by taking the energy consumed per month (in BTU's), divided by the area of the house (in SqFt), divided by the number of Heating degree days (HDD).
- BTU stands for British Thermal Units. One BTU is defined
to be the amount of energy required to raise 1 pound of water, 1o Farenheit.
- A Heating degree day is an indice whose purpose is to reflect
the demand for energy over a period of time. For example, a warmer month will have a lower HDD index than a colder month
because the demand for heat energy is higher in the colder month.
The reason the energy is divided by the square footage of the house is so that compaison between
larger houses (which require more energy to heat) and smaller houses (which require less energy to heat) is fair. The resulting quantity is then divided by the HDD index in
order to make comparisons between consumption during different years consistent.