Author: Jingjing PAN (polyu) - Building passive thermal storage, as the inherent storage of building structures and internal mass, offers a fundamental and cost-effective resource for energy flexibility provision in high-renewable power grids. However, existing methods often assess building flexibility at the system level, which limits the applicability and generalizability across different building configurations. Moreover, the impact of both design and operational parameters on thermal performance remains insufficiently understood, limiting model adaptability across building contexts and demand response (DR) applications.
This study directly addresses these gaps by focusing solely on the intrinsic contribution of passive thermal storage to building energy flexibility and systematically analysing its determining factors. Firstly, a real-world experiment involving typical DR scenarios was conducted to quantify the thermal response across various building mass components. A high-resolution finite difference model is then developed and validated to simulate the dynamic behaviour of building thermal mass. Subsequently, a global sensitivity analysis using the Morris screening and Sobol method is conducted to assess the impact of ten major parameters governing the design and operation. Results reveal that only surface-near layers of thermal masses are effectively activated during short-duration DR events, causing the internal thermal mass (e.g., furniture) significantly affects performance, particularly when characterized by surface. Furthermore, internal heat gain and window-to-wall ratio are important to discharge behaviour, with convection heat transfer coefficient and pre-DR operation also playing critical rolesThese insights refine the understanding of thermal mass behaviour during DR events, offering practical guidance for improving physical model accuracy and optimizing building-grid flexibility strategies.