Employing thermochromic material to improve the building thermal environment in Qingdao city

Abstract

Utilizing novel building envelope materials to mitigate urban heat is an effective measure. Among the many new cooling building materials, cooling coatings are notable for their superior solar reflectance and thermal emissivity, properties that help reduce cooling loads by lowering surface temperatures. However, these static reflective coatings are unable to meet the changing thermal demands in regions with significant seasonal temperature differences, such as hot summers and cold winters. To address this challenge, this study proposes a thermochromic material (TCM) with dynamic self-adjusting reflectivity properties. The TCM is able to change its color and solar reflectivity in response to temperature changes, effectively adapting to the varying thermal demands between winter and summer. In addition, this study evaluated the difference in thermal performance of TCM in summer and winter by conducting experiments on a scaled-down building model. The experiments monitored the external surface temperature, internal surface temperature and cavity temperature, revealing the seasonal energy saving benefits of the TCM. Numerical simulations through Energyplus software further evaluated the heating and cooling degree days and energy carbon emission metrics, providing energy saving directions for optimizing the photo-thermal response properties of thermochromic coatings.