Measurement and simulation of the thermal environment in the built space under a membrane structure

This paper presents a study to clarify characteristics of the summer thermal environment in an actual membrane structure with a semi-closed space underneath by using field measurements and simulations. The first part of this paper describes the following findings from the field measurements conducted during a summer period: (1) the solar transmission through the membrane had a greatest impact on the thermal environment in the living space under the membrane structure during the daytime; (2) the mean radiant temperature (MRT) at the central part of the living space went higher than the air temperature due to heat storage in the ground and walls of surrounding buildings where radiation cooling to the sky was obstructed by the membrane. In the second part of the paper, a 3D CAD-based simulation tool (called the thermal environment simulator) developed by the authors' group was used to simulate the thermal environment in the test membrane structure. A comparison between the measured and simulated surface temperature of the membrane was carried out. As a result, it was found that the simulated results agreed well with the measurement data. In addition, the following subjects were discussed using the simulation tool: how the thermal environment under the membrane is influenced by changing the solar transmittance and absorptance of the membrane or changing the ground surface materials. Simulation results show that the simulation tool is able to provide a quantitative prediction and evaluation of the thermal environment in the living space under the membrane structure in terms of the surface temperature and mean radiant temperature distribution.