Dynamic thermal performance metrics for adaptive building constructions

Abstract

Contemporary building envelopes are becoming adaptive and multifunctional in order to further improve the energy efficiency of buildings. However, the selection and characterization of building façade components are still based on traditional metrics - a steady-state U-value and g-value, which does not provide information on the improved thermal performance of adaptive building envelopes. Therefore, much effort is invested in the development of new dynamic performance metrics. This paper presents the development of a new dynamic thermal performance metric Ú, which is determined from numerical results of the building construction thermal response (the inner surface heat flux and the air temperature difference data) at the Sol-air outdoor boundary conditions. The results of the analysis have shown that by adaptive building construction the new metric Ú is lower than the construction U-value; it decreases with the decreased daily heat transfer and with the increased specific heat capacity. Further research and development of the proposed U metric is needed for adaptive building constructions with low U-value and at boundary conditions, which result in the daily heat gains.