Sound of Jianlei
Glass Curtain Wall (hereinafter referred to as “curtain wall”) is one of the major exterior envelope structures of modern buildings, its energy-saving merit has became a key link of China’s undertaking of building energy-efficiency. This essay is written to make a economic evaluation to the energy-saving effect of the curtain wall.
1 Design principles for energy-efficient function of curtain wall structures
1 The following measures are put forth as design principles for energy-saving functions of curtain wall structures:
1) Thermal insulation design should be done to the curtain wall for winter in cold and temperate regions.
2) Specific standards or norms for thermal engineering design of the curtain wall hasn’t been established yet in China, thermal engineering design should be implemented according to the current related national standards and regulations of exterior wall and window thermal-engineering design and referring to the related rules from other countries.
3) The complicated processes and modes of heat transfer should be analyzed and researched for thermal engineering design of the curtain wall. There are roughly 3 ways for heat transfer process of curtain walls:
a) The heat transfer between the external surface of the curtain wall and surrounding air and outside environment: convective heat exchange between external surface and surrounding air, radiant heat exchange between the external surface and outside environment, and between external surface and various long waves (such as those from electromagnetic waves, infrared rays);
b) The heat exchange between the internal surface of the curtain wall and interior air and environment: convective heat exchange between internal surface and interior air, and radiant heat exchange between the internal surface and interior environment;
c) Heat exchange between the curtain wall and metal grids: thermal flux exchange through single-layer glass, thermal exchange through metal grids, reducing radiant heat exchange through the coat formed layer of glass.
4) The coefficient of heat transfer of the curtain wall is comprehensively determined by the appearance of the structure, climatic conditions of location, heat transfer coefficient of selected section materials and glass, etc.
2 Economic evaluations for energy-efficient function of curtain-wall structures
People attach great importance to the cost control of constructions in China, and easily ignore the economic and social benefits through proper increase of the cost to add energy-saving functions. An overall economic evaluation to the energy-saving effect of the building curtain wall is analyzed as follows:
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