Uncertainty propagation and sensitivity analysis of thermo-physical properties of phase change materials (PCM) in the energy demand calculations of a test cell with passive latent thermal storage

Abstract

In this work uncertainty propagation and sensitivity analyses have been applied to a case study of an application where PCM is integrated into the envelope of a test cell. The aim of the study is to quantify the influence of the uncertainties associated with the measurements of the thermo-physical properties of PCM on the results of the annual energy consumption. For this purpose, EnergyPlus has been used for the building energy simulation and a Monte Carlo based method has been chosen for the uncertainty and sensitivity analysis. Considering realistic uncertainty ranges for PCM thermo-physical properties, a significant uncertainty of savings on cooling energy demand has been calculated (approximately 10%). Phase change temperature and thermal conductivity have been identified as the most influential input parameters whereas phase change enthalpy is of secondary importance. A method has been proposed in order to calculate a combination of admissible uncertainties for the input variables that reduces output uncertainty to a required value. The method can be used if input variables and the behaviour of the model comply with certain conditions. For the case study, a maximum tolerance for the error of measurements of phase change temperature and thermal conductivity of ±0.3 °C and ±8% respectively is necessary to reduce the uncertainty of savings on cooling energy demand to 5%.