Energy saving performance of thermochromic coatings with different colors for buildings

Thermochromic coatings are promising in lowering air conditioning energy consumption of buildings. In this paper, thermochromic coatings with five different colors are prepared and their optical properties are measured. A two-story office building model is established and simulation is conducted to evaluate the energy performance of thermochromic coatings by using a three-step control method based on their dynamic color-changing properties. A comparative analysis is carried out for thermochromic coatings, cool coating and common coating. It is observed that when the building is located in Shanghai, average daily surface temperature of thermochromic coatings is lower than the common coating during cooling period and higher than the cool coating during heating period. Annual energy consumption results indicate that thermochromic coatings can avoid the penalty of increasing heating load for cool coatings. In particular, the annual energy consumption of the office building using thermochromic coatings can be reduced by 4.28–5.02 kWh/m² compared to the common coating, and 0.73–1.47 kWh/ m² compared to the cool coating. Simulation of other cities in different climate zones in China reveals that thermochromic coatings have better energy saving effects especially for the areas with hot summers and cold winters, and relatively uniform distribution of cooling and heating demands.