Energy Efficiency Design Of Residential Building's External Window In Cold North Area

China is in high speed socio-economic development process, energy consumption of running buildings keeps going up. So energy-efficiency is a critical component of building an economical society, building energy efficiency is a top priority. The energy efficiency task of resident building is hard, but it has great development potentiality. The window is comparative large component of heat consumption, therefore energy efficiency design of external windows can enhance its heat preserving and thermal insulating properties, reduce energy consumption, improve housing quality. But at present the external windows of building has many questions requiring urgent to solve: in its research of energy efficiency design,in its manufacture and installation process, and in acceptable attitude of the developers and owners, all of these may directly reduce the effectiveness of energy-saving. To this end, this paper mainly centers on the following points:According to the cold north area's climate characteristics, after study on external window's heat transfer process, indoor comfort, and some practical engineering, the writer come to a conclusion that energy efficiency design of external window must consider these three factors: the use of solar energy, thermal insulation properties of windows, air tightness of windows and reasonable natural ventilation. Then has summarized out these energy efficiency tactics for the window energy efficiency design in the cold north area: to use the small heat transfer coefficient window, to utilize adequate and controllable sunlight, to have good adjustable natural ventilation, so that we can not only increase heat income but also decrease heat expenditure.According to the above tactics , having detailed calculated and studied in the view of thermal insulation properties, solar heat gain, and natural ventilation, then this paper puts forward a comprehensive feasible specific energy-saving measures in building external window's orientation, location, material, structure, open mode, outside the window appendages, southern terrace of the sunny room, its sun-shading and so on.Aim at the existing standards'rules to the area ratio of window to wall and convex window, based on solar radiation theory, the writer figure out the solar heat gain in every hour, the net heat gain of window every day, the amount heat loss in the same area of external wall on the twentieth January in Beijing area every day, then compare these data between southern common hollow plastic-steel window and southern convex hollow window, finally obtain an new conclusion: in north cold area, those rooms having enough solar radiation, under the precondition that its external windows have good heat-retaining properties, must not be limited to the area ratio of window to wall of southern window and the area of southern convex windows in its design process.