Evaluation of phase change material and thermochromic layers in a “smart wall” in different climates for improving thermal comfort in a building

Abstract

In this research work, a new smart configuration with two Phase Change Materials is proposed to enhance energy efficiency in buildings. It is based on developing adaptive external walls in order to adopt dynamic responses to external climate conditions, by controlling and adjusting the absorption and reflection of solar radiation. A numerical model is developed to simulate the thermal behavior of five wall configurations including passive techniques, namely an optically intelligent thin film of tungsten doped with VO2, a mono or double layer of Phase Change Materials. Numerical simulations are performed for different climate conditions during the summer and winter seasons. Additionally, a comparison analysis is carried out to compare climate conditions in seven cities: Marrakech, Dubai, Nice, London, Tianjin, Mexico City and Ottawa. In the summer season, the results show that using W-doped VO2 can reduce the indoor surface temperature, while in the winter season, this solution does not significantly influence the indoor temperature when compared to a reference case, where the climates have a shallow outdoor temperature, and the thermochromic material behaves as a transparent semiconductor to heat. In addition, the results show that a configuration that includes two Phase Change Materials with different melting temperatures can minimize the effects of external climate conditions during the summer and winter seasons. According to our analysis, this configuration has the best performance and can achieve better thermal comfort in buildings when compared to other existing configurations. The proposed configuration also achieves a significant phase shift and a lower dampening factor than the different studied configurations in respect to thermal optimization.