Paper Conference

Proceedings of ASim Conference 2016: 3rd Asia conference of IBPSA-China, Japan, Korea


Evaluation of Energy Saving Potential of Variable Refrigerant Flow (VRF) Systems Compared with Variable Air Volume (VAV) Systems in the U.S. Climate Locations

Dongsu Kim, Sam Cox, Heejin Cho, Piljae Im

Abstract: Variable refrigerant flow (VRF) systems are known for their high energy performance and thus are able to reduce cooling and heating energy both in residential and commercial buildings. The energy savings potential of this system has been demonstrated in several studies by comparing the system performance with conventional Heating Ventilation and Air Conditioning (HVAC) systems such as rooftop variable air volume systems and central chiller and boiler systems. This paper evaluates the performance of VRF and rooftop VAV (RTU-VAV) with reheat systems in a simulation environment using widely accepted whole building energy modeling software, EnergyPlus. A medium office reference building model, developed by the U.S. Department of Energy (DOE), is used to assess the performance of VRF and RTU-VAV systems. Each system is placed in 16 different locations, representing all U.S. climate zones, to evaluate the performance variations. Both models are compliant with the minimum energy code requirements prescribed in American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) standard 90.1-2010-Energy standard for buildings except low-rise residential buildings. Finally, a comparison study between the simulation results of VRF and RTU-VAV models is made to demonstrate energy savings potential of VRF systems in the 16 climate locations. The simulation results show that the VRF system would save 25% to 55% HVAC energy use compared to the RTU-VAV system in the 16 climate locations.
Keywords: Variable refrigerant flow, Rooftop unit, Variable air volume, Building simulation, U.S. climate zones