Study on the impact of cool roofs on energy consumption at a railway station

The solar radiation through a roof has considerable influence on air-conditioning energy consumption and indoor lighting in a single-story large volume building, for example, a railway station. The roof reflectance and skylight shade reflectance are two significant factors which affect solar radiation from roof and natural lighting. After a qualitative analysis of the effect of cool roofs on building performance, a model is built for a railway station using EnergyPlus. The model was then verified with field data, and applied to study the effect of cool roof reflectance and skylight shade reflectance on the installed capacity of the air-conditioning system, lighting energy consumption and indoor thermal comfort in different climate regions. The results show that with the appropriate utilization of non-transparent cool roof, high reflectance can help to reduce cooling energy consumption and installed capacity of the air-conditioning system effectively, and to improve the indoor thermal comfort in the summer. However, more energy is consumed in winter, resulting in more total energy consumption during the whole year. On the other hand, high reflectivity of the skylights reduces energy consumption for cooling in summer, and only slightly increases energy consumption for heating and lighting, which saves vast energy in the whole year. Moreover, the inherent properties of the roof structure and local climates should be considered when employing the cool roof technology in practice.