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

Abstract

The calculation of measured energy savings from\nenergy conservation retrofits is an important step in the\nverification of the success of a retrofit (Claridge et al.\n1992). Several methods for calculating the savings from\nenergy conservation retrofits to HVAC systems in the\nLoanSTAR program have been proposed, including linear\nand change-point linear empirical models and calibrated\nsimulation models. Simple least squares linear regression\nis easiest to use and understand, but is incapable of\ndescribing non-linear temperature dependencies of a\nbuilding's energy use. Change-point linear models are\nmore complex than the simple linear regression and cover\na broader range of buildings. However, there are some\nbuildings for which change-point linear models do not fit\nthe data adequately.\nThis paper presents a first look at an hourly bin\nmethod for calculating energy savings from energy\nconservation retrofits to HVAC systems based on hourly\nwhole-building electricity, sub-metered motor control\ncenter use and thermal energy measurements. A general\nprocedure for determining the appropriate number of bins\nis described and the bin method is applied to data from\nseveral agencies participating in the LoanSTAR program.\nResults are compared to existing savings calculation\nprocedures for two buildings.