Patent ID: 8131497

Claim:
A system for calculating a value for the operational efficiency of a heating, ventilation, and air conditioning (HVAC) system comprising: at least one HVAC control system that receives temperature measurements from at least a first location conditioned by at least one HVAC system; one or more databases that store at least said temperatures measured at said first location over time; and one or more processors that receive outside temperature measurements from at least one source other than said HVAC system, wherein said one or more processors are configured to calculate one or more rates of change in temperature at said first location for periods during which the status of the HVAC system is “on” and wherein said one or more processors are further configured to calculate one or more rates of change in temperature at said first location for periods during which the status of the HVAC system is “off”, and to relate said calculated rates of change to said outside temperature measurements.