Energy conversion efficiencies for thermal control in buildings

This paper identifies existing data that may be used to predict the overall efficiency of energy utilization in buildings, including those losses that occur to the building envelope exterior. Energy conversion efficiencies for environmental control systems are often described as the ratio of energy output available for heating or air conditioning to the amount of energy supplied to that system. This simple relationship is useful in performance comparisons of similar building systems when the value of the energy input is known and remains constant. However, when comparisons are necessary between various environmental control systems which do not use the same energy source, additional information must be obtained regarding the energy conversion exterior to the building envelope. The simple input-output model may also be insufficient when multiple energy sources are available, both at the building site and at the electrical power generating plant. In the latter case, the energy conversion efficiency of an environmental control system is susceptible to change even though the performance of the system itself remains constant.