An active pipe-embedded building envelope for utilizing low-grade energy sources

Abstract

An active pipe-embedded building envelope, which is an external wall or roof with pipes embedded inside, was presented. This structure may utilize the circulating water in the pipe to transfer heat or coolth inside directly. This kind of structure is named “active pipe-embedded building envelope” due to dealing with the thermal energy actively inside the structure mass by circulating water. This structure not only deals with thermal energy before the external disturbance becomes cooling/heating load by using the circulating water, but also may use low-grade energy sources such as evaporative cooling, solar energy, and geothermal energy. In the meantime, this structure can also improve the indoor thermal comfort by tempering the internal wall surface temperature variation due to the thermal removal in the mass. This work further presents the thermal performance of this structure under a typical hot summer weather condition by comparing it with that of the conventional external wall/roof with numerical simulation. The results show that this pipe-embedded structure may reduce the external heat transfer significantly and reduce the internal wall surface temperature for improving thermal comfort. This work also presents the effects of the water temperature and the pipe spacing on the heat transfer of this structure. The internal surface heat transfer may reduce by about 2.6 W/m2 when the water temperature reduces by 1 °C as far as a brick wall with pipes embedded inside is concerned. When the pipe spacing reduces by 50 mm, the internal wall surface heat flux can also reduce by about 2.3 W/m2.