Energy Implications of Retrofitting Retail Sector Rooftop Units with Stepped-Speed and Variable-Speed Functionality

Commercial retailers understand that retrofitting constant-speed RTU fan motors with stepped- or variable-speed alternatives could save significant energy in most U.S. climate zones. However, they lack supporting data, both real-world and simulation based, on the cost effectiveness and climate zone-specific energy savings associated with this measure. Thus, building managers and engineers havebeen unable to present a compelling business case for fan motor upgrades to upper management. This study uses whole-building energy simulation to estimate the energy impact of this type of measure so retailers can determine its economic feasibility.