Contrastive Research On Energy Efficiency From Reflective Roof Room In Hot Summer And Warm Winter Area

Space enclosing structures of buildings,especially those in areas with hot summer and warm winter featured by strong solar radiation and long solar exposure time,are key factors affecting energy consumption of buildings.By optimizing thermoengineering property of buildings’ space enclosing structure,we can effectively reduce their energy consumption.In order to explore the energy saving effects of high reflective roofs of residential buildings in areas with hot summer and warm winter,this paper carries out the following researches by doing measurement and simulation.First of all,this paper does a qualitative analysis of energy-saving benefits of high reflective roofs according to the action mechanism of high reflective coating,the heat transfer mechanism of high reflection roofs and the natural aging mechanism of high reflective roofs.Besides,this paper also sets up a measurement platform for natural aging of high reflective roofs to explore natural aging rules of high reflective roofs.The 9-month exposure results show that the reflectance ratio of white high reflective paint(R=0.76)and that of blue high reflective paint(R=0.62)decreased by 0.14 and 0.10 respectively and that the reflectance ratio of two highly reflective paint had no significant change.Secondly,this paper also conducts a field research on current situations of reflectance ratio of building roofs in Guangzhou and the results show that the reflectance ratio of residential buildings’ roofs is lower than 0.4 and their average roof reflectance ratio is 0.27.This paper also builds an energy saving measurement platform for three top floor rooms with the same orientation,size,window-wall ratio in typical residential buildings of Guangzhou and monitor their outdoor meteorological parameters,indoor thermal environment parameters and air conditioning energy consumption.Roofs of the three rooms are painted with white high reflective paint(R=0.76),blue high reflective paint(R=0.62)and black paint(R=0.09).There is no person,lighting and other indoor heat sources in the room.The actual measurement results indicate that the enhancement of roof reflectivity of residential buildings in Guangzhou has a significant impact on the improvement of indoor thermal environment and air conditioning energy-saving effects in summer(the energy conservation rate is between 8.8% and 26.7%)and had small influence on indoor thermal environment and air conditioning energy consumption(the energy conservation rate is between-5.3% and-2.2%).Finally,this paper uses the Design Builder platform to conduct a simulation analysis of the influence of high reflective roofs on annual energy saving benefits of air conditioners installed in top floor rooms of different residential buildings of Guangzhou.The results show that the energy saving rates of air conditioning with high reflective roof technology installed in single room matching apartment,house types with two rooms and two living rooms and those with three rooms and two living rooms all exceeds 9%.This paper reveals influence rules of high reflective roofs in residential buildings located in areas with hot summer and warm winter on their indoor thermal environment and air conditioning energy consumption,evaluates air conditioning energy saving effects of high reflective roofs in building with variety of houses types and provides data for energy-saving renovation of residential building roofs of houses located in areas with hot summer and warm winter.