Study on Thermal Performance and Ventilation Strategy of Tubular Ventilation Roof

Abstract

For residential building in rural areas of China, precast concrete hollow-core slabs are widely used as building roofs. However, due to the poor thermal insulation performance and simple structure of the slab, a large amount of heat is transferred to room through the roof structure when the outdoor temperature is high, causing an increase in the indoor temperature and energy consumption of air conditioner. In order to improve the thermal performance, tubular ventilation roof is introduced by ventilating the cavity of precast concrete hollow-core slab in summer. A two-dimensional frequency-domain finite-difference model (FDFD model) and a simplified dynamic thermal network model (RC model) of the tubular ventilation roof were developed in this paper. The thermal performance under different ventilation speeds and temperature differences was evaluated. The simulation result also showed that the tubular ventilation roof had the optimum thermal performance at a ventilation speed of 4 m/s during a typical summer day in Wuhan. Compared with non-ventilated conditions, the internal surface peak temperature is reduced by 5.34 °C and the internal surface average temperature is reduced by 2.28 °C, greatly improving the thermal insulation performance of the tubular ventilation roof.