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An Analysis of the Hybrid Internal Mass Modeling Approach in EnergyPlus



Zhelun Chen, Jin Wen, Steven T. Bushby, L James Lo, Zheng O'Neill, Vance (Wm.) Payne, Amanda Pertzborn, Caleb Calfa, Yangyang Fu, Gabriel Grajewski, Yicheng Li, Zhiyao Yang


Accurate simulation of building system dynamics is particularly important for understanding building energy flexibility. Among all dynamics in a building, a zone temperature's variation is especially important, as it significantly affects a building's electricity load profile when its heating, ventilating, and air conditioning (HVAC) system is controlled with on/off cycles or setpoint variation strategies. To accurately simulate a zone temperature's dynamics, internal mass needs to be modeled carefully. In this paper, we compare the two internal mass modeling approaches provided by EnergyPlus, i.e., internal mass object and zone air capacitance multiplier, to better understand their impacts on zone temperature simulation. Real building zone temperature dynamic data from small- and medium-sized office buildings are analyzed and compared with simulated data. In particular, we illustrate the effectiveness of a hybrid of the two EnergyPlus modeling approaches, which yields more realistic zone temperature dynamics when the zone is conditioned with heat pump systems with on/off cycling.
Proceedings Title
Proceedings of eSim 2022: 12th Conference of IBPSA-Canada
Conference Dates
June 22-23, 2022
Conference Location
Ottawa, CA
Conference Title
12th eSim Building Simulation Conference


EnergyPlus, HVAC, modeling, energy consumption, internal mass


Chen, Z. , Wen, J. , Bushby, S. , Lo, L. , O'Neill, Z. , Payne, V. , Pertzborn, A. , Calfa, C. , Fu, Y. , Grajewski, G. , Li, Y. and Yang, Z. (2022), An Analysis of the Hybrid Internal Mass Modeling Approach in EnergyPlus, Proceedings of eSim 2022: 12th Conference of IBPSA-Canada, Ottawa, CA, [online], (Accessed April 22, 2024)
Created June 22, 2022, Updated November 29, 2022