Role of Layout in Improving Building Thermal Performance in Bangkok

Selecting a building layout is a fundamental task in the early stage of the architectural design process. High thermal mass buildings with well-insulated envelopes are a common solution for colder climates; however, thinner wall construction and lower mass in most tropical architecture means that a well-designed building layout with good consideration of contextual factors is essential to enhance passive cooling and to decrease heat gain by solar radiation. Building layout factors of perimeter and wall surface area are pivotal in long-term energy utilization. This simulation-based research employs Sketchup, Openstudio, and SPSS to investigate the effect of surface solar radiation on indoor air temperature and sensible cooling energy of 17 geometries with and without a self-shading feature under the identical space volume, floor area, and climatic conditions of Bangkok. The simulation conducted in two phases (with and without an active cooling system) revealed that the lower the F/W ratio is, the lower the DBTindoor-annual and operational cost of the A/C system. The circular plan with the highest F/W ratio (0.47) has the lowest annual wall solar heat gain and DBTindoor-annual (29.43°C), and saves approximately 10% of air cooling energy demand compared to the square design (F/W=0.42). The layouts with S/W ratio less than 2.4 are less effective in lowering the DBTindoor-annual and active cooling energy demand than those with S/W greater than 2.4. It is concluded that the self-shading designs (S/W<2.4) may face challenges due to greater wall surface area and receiving more diffuse solar radiation.