Doors and windows are the weakest links of heat insulation, heat preservation, sound insulation and safety in the whole building envelope. There are three ways of heat loss of doors and windows: 1. Heat conduction between door and window frame and glass; 2. Air infiltration heat exchange between door and window frame, between door and window, between door and window, and between frame and wall; 3. Heat radiation of window glass.
Liefan doors and windows with multiple lock points can greatly enhance the sealing of windows. After the sealing is enhanced, its thermal insulation and sound insulation will also be improved. The design of multi lock points with mushroom head lock greatly enhances the anti-theft performance of the window. The possibility of burglars entering the room through prizing and pressing the window sashes is almost reduced to zero. The use of the internal inverted state can make the indoor natural ventilation, and the wind does not directly blow the body. Especially in the morning, evening and winter, when the indoor air quality needs to be improved, it is not easy to catch a cold, which effectively avoids the problem of forgetting to close the window and swill the rain in the house on rainy days. The indoor pouring does not occupy the indoor space and avoids the horizontal opening Windows and curtains (the most common) water heater, range hood, cabinet and other mutual interference and fighting end, to solve the toilet needs a long time of natural ventilation and anti-theft problems.
According to the relevant data, the energy loss through aluminum alloy doors and windows accounts for about 50% of the building, and the energy loss through glass accounts for about 75% of the door and window. Under certain conditions, the thermal radiation and conduction of glass are the dominant factors leading to indoor energy loss. However, the heat transfer coefficient of the double window is less than that of the glass window, which indicates that the heat transfer coefficient of the double window is not equal to that of the glass window, and the heat transfer coefficient of the double window is not equal to that of the plastic window. The heat transfer coefficient of single glass plastic window only reaches the performance index of building energy-saving doors and windows in some areas of southern China. Compared with the 65% energy saving policy in Beijing, the heat transfer coefficient of doors and windows of 2.8w/m2k and 4.0 ~ 2.0% w / m2k in different heating areas are far behind. Therefore, with the continuous development of national building energy-saving work, using energy-saving glass to effectively improve the thermal performance of door and window glass will become the main target of door and window energy-saving.
In recent years, more and more glass varieties can be selected, which has developed from the traditional functions of lighting, wind protection, rain protection and enclosure to modern composite functions of heat insulation, heat preservation, safety, noise prevention and decoration. The glass used for energy saving mainly includes heat absorbing glass, coated glass, double (or three-layer) glass, insulating glass, vacuum glass, etc. The coated glass is divided into Anti radiation glass, low radiation film glass and multi-functional coating glass.
Glass is a non-metallic material. Although its heat transfer coefficient is only 0.8 ~ 1.0 w / m · K, due to the glass's general thickness of 3 ~ 8 mm, its own thermal resistance is very small, for the window area of about 65 ~ 75%, the heat transfer is still very considerable. Energy saving of glass is mainly reflected in two aspects: heat preservation, that is, to control the loss of indoor heat to the outdoor by reducing the characteristics of heat conduction and convection of glass. For example, the use of insulating glass, vacuum glass and so on; heat insulation is to improve the shielding characteristics of glass on solar thermal radiation, to control the outdoor heat conduction to the indoor. Such as the use of heat absorption, heat reflection, low radiation glass, etc. The above glass properties are briefly introduced