Patent ID: 7200468

Claim:
A first enviromental control unit comprising a computer readable medium having instructions stored thereon which when executed by a processor, cause the processor to calculate an overall efficiency that is proportional to the ratio of a first building's heat loss divided by the energy inputted into the first building, and where the overall efficiency can be used as a comparison against an overall efficiency of a second building with a second environmental control unit, and wherein the instructions stored thereon further cause the processor to: solve the equation OVERALLEFFICIENCY = Q loss t T I - T O × HDD × 24 ⁢ ⁢ hours 1 ⁢ ⁢ day Q in for the term OVERALL EFFICIENCY, wherein Q loss is the building heat loss in BTUs; t is time, in hours; T I is the inside temperature; T O is the outside temperature; HDD is heating degree days for a specified time period; Q in is the energy put into the building, in BTUs for the specified time period; and 24 hours/1 day is a conversion factor to cancel out the hour unit from the term t.