Experimental Study On Testing Method For Windows In The Summer Hot And Winter Cold Area

As the prevalence use of glass curtain wall in hot summer and warm winter area, glass curtain wall is becoming a great important factor to the city visual comfort and thermal environment. Also, glass curtain wall shows great importance to the indoor environment and building energy consume, which in turn directly affect the discharge of CO2. So, in order to improve city visual comfort, reduce building energy consumption and control the discharge of CO2, it is necessary to know its on-sit thermal performance in the real environment, so as to offer necessary data to design and application of window curtain wall. Traditionally, heat transfer coefficient is measured in the laboratory under the estimated extremely cold winter environment condition of winter cold area in accordance with Graduation and test method for thermal insulating properties of windows (GB8484-1987). This estimated environment condition is quite different from the real environment in the summer hot winter warm area. And the testing method of shading ability, anther important parameter, especially to the summer hot winter warm area, is still left blank. For this purpose, we bring forward the field testing method for glass curtain wall and corresponding testing equipments.This dissertation focuses on the analysis of window curtain wall 's heat gain process, and separates this process into two relatively unrelated process: direct solar radiation through the glass and glass absorbed solar radiation that flow into the room; and the related parameters are also identified: solar transmittance, solar absorptions of the window curtain wall and its inward flow fraction. As a result of above analysis, the on-sit testing method, based on steady state heat transfer, for thermal coefficient and the on-sit testing method, based on the comparison with standard transparent glass, for shading coefficient are established.The Lab for testing window curtain wall's thermal properties was founded in accordance with the testing method. And the testing of window curtain wall with thermal tunnel, which is complex in structure, was also carried out in order to verify the testing method. The outcomes of the experiment show that the result of thermal coefficient is comparable to that of a laboratory hot box. The system uncertainty level is below 10% and the result is well in accordance with the simulated result under the same boundary condition. Shading coefficient is the nodus of the testing. After quiet a lot of experimental testing, we begin to define the window curtain wall itself as thecontrol volume, and direct measure the solar heat gain. This method solves the problems of uncertainty of system and poor simultaneity of data. The testing result is reasonable and believable, and capable of reflecting glass curtain wall's ability to block the solar radiation at different time during the daytime. The shading coefficient average over the whole day is equal to the value measured when the solar radiation incident angle at 45-60 degree. This conclusion is in accordance with the remark in the reference document [45] that the calculation of shading coefficient should base on the optical data when the incident angle is around 45 degree. This testing method proved to be accurate and capable of reflecting glass curtain wall's on-sit thermal performance, can provide necessary basic data for analyzing the city visual and thermal environment, and reduce the discharge of CO2.