Research On The Thermal Performance Of The Flat Roof Shade Insulation Layer

The Chinese cities in hot summer and warm winter zone and in hot summer and cold winter zone, unusually hot in summer with a lot of solar radiation intensity. Traditional roof insulations due to its poor performance, lead in large heat into the interior environment. In order to improve the insulation performance of the roof, a traditional roof overhead ventilation plate has been used for many years in our country, including the cities in hot summer and warm winter zone and in hot summer and cold winter zone, aimed at improving the performance of roof insulation in the summer, but the insulation of this type roof is not good when in poor airflow. In addition, the lack of research on the overhead panel roof in terms of energy efficiency of winter performance, whether the roof is suitable for in hot summer and cold winter zone is also doubtful. Therefore, the study for the insulation performance of this type roof has important implications.Firstly, we study on ventilation roofing insulation performance. Numerical studies show that trying to further improve insulation performance of the ventilation roof by increasing the wind speed is limited when the wind speed reaches 2.0 m/s. And at low wind speeds, the heat exchanger between the overhead slab roof and floor is mainly carried out by radiation heat transfer. when wind speed is 0～1.0 m/s, the radiation heat accounted for sum of radiation and convection heat transfer 47% to79%, and lower wind speed, the greater the proportion of total. Accordingly, the measures put forward at low wind speeds in ventilation that pasting aluminum foil in the duct surface to weaken the radiation heat transfer.Then, combining these research results, this paper constructs a new type of flat roof insulation panel roof, and analyzes the temperature field and the temperature profile of their typical location in a typical summer and winter weather, compared with the thermal performance of the traditional aerial roofing. To further explore their work performance at low wind speeds in different regions, with four kinds of typical weather (summer sunny, cloudy summer, winter sunny and cloudy winter) as climatic boundary conditions to expand the preliminary study. Studies show that the new flat roof insulation in the summer sun sunny and cloudy day in summer compared to normal overhead panels for roofing and reinforced concrete slab roof, its insulation properties are obvious improvement; however, during the winter days, the new flat roof insulation shade appeared "anti-energy" phenomenon.In order to study the new flat roof shading insulation roof in different areas of the energy savings throughout the year, the paper chose Hangzhou and Guangzhou typical meteorological year meteorological data as climate border, combined with the principles of temperature frequency method, numerical calculation. The results showed that:in summer and warm winter zone of Guangzhou, with respect to the ordinary reinforced concrete slab roof, the average saving rate of new flat roof ventilation layer roof is 63.1% respectively; in the total energy consumption of building, as opposed to ordinary reinforced concrete slab roof can achieve energy savings of approximately 4.3%. In the summer and cold winter zone of Hangzhou, with respect to the ordinary reinforced concrete slab roof, new flat roof insulation roof annual average saving rate of 26.5%; in the total energy consumption of building, as opposed to ordinary reinforced concrete slab roof can achieve energy savings of approximately 1.8%.Finally, in order to compare the differences with respect to the new roofing ordinary roofing in the summer cooling process of thermal performance, through the establishment of full-scale model in a real environment, the ordinary reinforced concrete slab roof as a reference group, additional new sun roof insulation panels as the experimental group, experiments were conducted. Studies have shown that:a new sun roof insulation panels with respect to the common roof, its floor, the outer surface temperature has been significantly reduced. Meanwhile, the use of new insulation panels sun, but also reduces the temperature difference between the inside and outside surfaces of the floor, the inner and outer surfaces of the new floor sun roof insulation panels maximum temperature difference of only about 2℃, and ordinary roofing for 20℃. In addition, by measuring from the roof into the interior of the heat flux found the cooling process new sun roof insulation panels with respect to its common roof into the interior of the average heat flux decreased 76.8%. Visible, after the use of new sun roof insulation panels, as opposed to the traditional reinforced concrete roof, has better thermal performance.