Determination of Retrofit Savings Using a Calibrated Building Energy Simulation Model

This paper presents the development of a methodology to determine retrofit energy savings in buildings when few measured preretrofit data are available. Calibration of the DOE-2 building energy analysis computer program for a 250,000 ft2 building at The University of Texas at Austin, using hourly data for a two-month preretrofit period, is detailed.. The process begins with the identification of the DOE-2 input parameters having the greatest uncertainty. Field measurements then determine those uncertain parameters that have a significant impact on total energy use. Finally, the few remaining parameters are systematically adjusted to match the preretrofit data. Using the calibrated model run for the postretrofit period, energy savings were calculated for whole-building electric, cooling, and heating energy use, and were compared with savings calculated using a regression model developed under the LoanSTAR program. Finally, to validate the model, postretrofit DOE-2 results were compared with measured postretrofit data for a seven-month period