Describes the details of a method for systematically adjusting the parameters of a simulatable building description in order to match the simulated building energy performance to the consumption of the corresponding actual building, as represented by metered utility data. Briefly describes why this is an important problem and the circumstances in which it typically arises. Describes the mathematical basis underlying the approach taken to address this problem and the higher-level aspects of implementing the method as part of an applications program for estimating long-term average retrofit energy savings from utility and fuel consumption data. A test suite developed to validate the method and some testing results are described. Concludes with a brief discussion of planned and potential enhancements to the method.

KEYWORDS: buildings, calculating, energy consumption, performance, computer programs, modernising, energy conservation, testing, validating, calibrating, models, accuracy, efficiency, computers.