Material Properties, Thermal Calculation And Simulation Studies Of Energy-saving Windows

Windows are the indispensable components in the building structure, connectting the indoor and the outdoor. While, windows are the weak links of building energy efficiency. Energy lost through windows and doors is about40%to50%of the total energy consumption through the building envelope components. Therefore, the study of the performance of energy-saving windows is significant for building energy efficiency. Based on a comprehensive review of windows’development and research, the thermal performance of windows were systematically analyzed from physical testing, theoretical calculations and simulation. Combined with the results of the windows’thermal performance, its impact on building energy consumption was studied, using building energy simulation software, founding an important theoretical basis for the study and application of energy-saving windows. The main tasks and conclusions were as follows:Weather resistance and mechanical properties of integrated pine, integrated oak and integrated bamboo were studied.The results showed that integrated pine, integrated oak and integrated bamboo were prone to severe mildew and expansion in salt atmosphere. When grain direction and the direction of the force were same, the bending strength of integrated pine and integrated oak reached the maximum.As a new kind of window materials, integrated bamboo had a higher bending strength, regardless of grain direction.Standard sample windows of wooden windows, broken bridge aluminum windows, wood clad aluminum windows, aluminum clad wood windows and plastic windows were made and their thermal insulating properties, watertightness, air permeability and wind load resistance were tested.In accordance with the relevant standards and algorithms, the heat transfer coefficient of the hollow glass system and windows were calculated.The results showed that using of Low-E glass and being filled with inert gas, can significantly reduce the heat transfer coefficient.The heat transfer coefficient of common hollow glass and Low-E glass with air were2.70W/(m2·K) and1.86W/(m2·K), and when being filled with Ar, the heat transfer coefficient were2.60W/(m2·K) and1.54W/(m2·K). The type of glass and window frame material had an important influence on windows thermal performance. Based on THERM and WINDOW, the thermal performance of hollow glass, window frame and windows were calculated.The impacts of the spacer’s thickness and the filling with inert gas on heat transfer coefficient, SHGC and TV were studied.The results showed that the spacer’s thickness and the filling with inert gas significantly affect the heat transfer coefficients, and have little effect on SHGC and TV.When the spacer’s thickness was12mm, the heat transfer coefficient reached the minimum.The results of physical testing, theoretical calculations and simulation were compared with each other. The results of calculations and simulation were in line with testing results.Combined with the results of window simulation, the building refrigeration energy consumption, heating energy consumption and total energy consumption in the climate of severe cold area, cold area, hot summer and cold winter zone, temperate regions and hot summer and warm winter area were analysed. The results showed that the thermal insulation properties of the window frame system play a more significant role for the heating energy consumption. The glass types had more important effect on refrigeration energy consumption.