A Bin Method for Calculating Energy Conservation Retrofit Savings in Commercial Buildings

The calculation of measured energy savings from energy conservation retrofits is an important step in the verification of the success of a retrofit. Several methods for calculating the savings from energy conservation retrofits to HVAC systems in the LoanSTAR program have been proposed, including linear and change-point linear empirical models and calibrated simulation models. Simple least squares linear regression is easiest to use and understand, but is incapable of describing non-linear temperature dependencies of a building`s energy use without using additional dummy variables. Change-point linear models are more complex than the simple linear regression and cover a broader range of buildings. However, there are some buildings for which change-point linear models do not fit the data adequately. This paper presents a second look at an hourly bin method for calculating energy savings from energy conservation retrofits to HVAC systems based on hourly whole-building electricity, sub-metered motor control center use and thermal energy measurements. In the previous paper, a general procedure for determining the appropriate number of bins was described and the bin method was applied to data from several agencies participating in the LoanSTAR program (Thamilseran and Haberl 1994). In this paper, previous procedure is improved by exploring the usemore » of a bin model with data that requires the use of occupied and unoccupied period bins. Results are compared to existing savings calculation for two buildings.« less