Study Of Ventilated Roof's Heat Insulation Performance

A large part of the cooling load of the building is from its roof heated by solar radiation. It's necessary to improve the heat insulation performance of the roof so as to lower the buildings'energy consumption and inhance thermal environment inside the building. The ventilated roof was studied to find out its heat insulation performance in different weather conditions and some measures to improve its performance are put forward.The temperature and heat flux in different position of the ventilated roof in a small experimental cell room was measured for 40 days in summer. Besides, the solar radiation intensity, the reflected solar radiation intensity of the roof, outside wind speed, the air flow velocity at the inlet and outlet of the ventilation roof were also measured. It's concluded that the ventilated roof shows a good heat insulation performance. But it also concluded that the cooling load may increase if the base part of the roof is too thin and weak when the roof is ventilated.The computing software CFD was used to further the study. A model was set up according to the full size of the experimental cell room and the boundary condtions are all set based on the measured data. It is proved that it is a feasible way to go on the study on the effects of the roof structure such as the length of the roof, the size and distribution of the inlet on the performance of the ventilated roof. Several measures were put forward to improve the performance of the ventilated roof. The research also can relieve the large energy consumption in countryside.Residental buildings with typical roofs in Pingjiang town of Hunan Province were tested for 7 days in the summer. The results show that the heat insulation performance of ventilated roof is similar to tilt tile roof with attic. The conclusion caters to the rising demand of flat roof in countryside.