In the hot south area, there is still some blindness in the choice of energy-saving glass. In the previous paragraph, it was learned from the exchanges between Xiamen and glass merchants Lao Li that they still lacked understanding of the performance of energy-saving glass. "Insulating glass is the best and certainly the most expensive." This is what he has been emphasizing when he talks about energy-saving glass. For the energy-saving characteristics of glass, glass manufacturers do not understand; designers do not understand; Party A is less likely to understand, but it is taken for granted: the most expensive must be the best! This is a misunderstanding. This problem has already been analyzed in the discussion of "insulating glass is not suitable for hot regions in the south".
In the southern region where I live, what kind of glass is conducive to energy conservation? In order to explore this issue, we first analyzed and summarized the thermal characteristics and regional adaptability of various glasses. In general, glass can be classified into transparent glass, heat-absorbing glass, heat-reflecting glass, and low-emissivity glass according to its properties, and various types of glass can be made into insulating glass.
analysis--
(1) Transparent glass Normal transparent glass has almost the same reflectance for various spectra, and it has fast heat and fast heat dissipation. Its shading coefficient is extremely high, and its ability to block solar radiation is poor. Most solar radiation heat energy enters the room through the glass. During the daytime in summer, the heat energy that enters the room through the transparent glass is far greater than the heat energy that the glass radiates outwards, causing the indoor temperature to rise. Transparent glass insulation performance is very poor.
(2) Heat absorbing glass The heat absorbing glass adds some metal ions or some substances to the glass so that the glass shows some colors and enhances the absorption of light. The sunshade coefficient of the heat-absorbing glass is lower than that of the transparent glass, and its sunshading principle is to weaken it into the room by absorbing solar energy. This kind of occluding nature is actually the absorption of radiation, and the heat absorbed by the glass will still be transmitted to the indoor and outdoor, and it will not block the heat outside.
The heat-absorbing glass shields part of the solar radiant heat energy in summer or winter, so it can be used in the southern areas where heat prevention is dominant, but not in the north. The endothermic glass has no selectivity to the spectrum, and it also reduces the transmission of sunlight and also hinders the projection of visible light, which may affect the lighting. In the summer, the endothermic itself will be hot, and the radiant rate itself will be high. The absorbed heat will be partially radiated to the interior, which may cause people's discomfort.
(3) Heat-reflecting glass The heat-reflecting glass is coated with a metal film and some interference layers on the surface, so that the glass product can reflect more solar radiation so as to achieve the effect of shading, and has a rich color. Heat-reflecting glass has a strong reflection of visible light and long-wave radiation, and its role is to limit solar radiation into the room.
Heat-reflecting glass has a similar heat-insulating property to that of transparent glass, so it is not suitable for indoor cold areas where there is a large temperature difference. However, in a hot, hot area, the heat-insulating effect is very good. It is suitable for hot summer and warm winter areas. use. It should be noted that reflective glass, while reflecting the thermal energy of solar radiation, also restricts the entrance of visible light, which can cause adverse effects on indoor lighting. In addition, too high reflectivity can cause light pollution, too low and can not achieve energy-saving effects.
(4) Low-E glass Low-E glass, also known as Low-E glass, uses a vacuum deposition technique to form a low-E coating on the glass surface. The role of the Low-E coating is to reflect far-infrared radiation first, which effectively reduces the heat transfer coefficient of the glass; secondly, it reflects the thermal radiation in the sun, selectively reduces the shading coefficient; at the same time, compared with the low-emissivity glass and the heat-reflective glass, Do not limit the penetration of visible light too much.
The biggest feature of Low-E glass is its spectral selectivity. In the manufacturing process, processes can be adjusted to produce products with various optical properties, such as the shading coefficient, light transmittance, etc. that we care about. Different Low-E glass varieties should be selected for different areas or orientations to achieve the best results. Sun-protected Low-E glass is suitable for use in hot areas, and its shading coefficient and light transmittance are low. In the heating area, traditional high-transmission Low-E glass with high light transmittance and shading coefficient can be selected.
(5) Hollow glass Insulating glass has higher thermal resistance, can effectively prevent heat conduction due to temperature difference in the room, and has high insulation performance, which is very suitable for use in northern regions. The dry, non-convective gas in the hollow glass interlayer can block the heat conduction path, thereby limiting the temperature difference of the glass heat transfer, effectively reducing the heat transfer coefficient of the glass. Its interior is generally filled with inert gas to further reduce the heat transfer coefficient. The gas layer of the insulating glass does not effectively limit the transmission of solar radiation, so its contribution to improving the shading coefficient is limited. The two layers of insulating glass can be selected according to the needs to meet the requirements of various occasions. Transparent hollow glass, heat insulating hollow glass, heat reflecting hollow glass, Low-E hollow glass and other forms. In general, the greatest improvement in insulating glass is its thermal conductivity, not its thermal insulation. In the summer in the south, the heat entering the room through the glass is dominated by radiant heat, while the indoor and outdoor temperature difference only accounts for a small part, especially in the summer evening, the good thermal insulation performance of the insulating glass makes it difficult for indoor heat to be emitted. It is not good for energy conservation.
in conclusion--
According to the previous analysis, the following requirements should be observed in the selection of window glass outside the hot regions of the South:
In a variety of common glasses, glasses with a low shielding factor should be selected. Suitable glass types are mainly heat-absorbing glass, heat-reflecting glass and low-e glass. Because the heat absorbing glass absorbs a large amount of solar radiation heat, causing its own temperature to rise, causing heat to the room, it is not the best choice. Therefore, in the hot areas of the South, the glass suitable for heat insulation needs mainly heat reflective glass and low-e glass.
1 heat reflective glass. Can reflect most of the solar heat radiation, visible light transmittance of 8% to 40%, is a good heat reflective material. The heat-reflecting glass has remarkable effect on heat insulation, but there is also a big disadvantage in that the visible light transmittance is too low, which will seriously affect the indoor lighting and lead to an increase in the energy consumption of indoor lighting.
2 low-e glass. It can solve the contradiction of heat reflecting glass. Low-e glass has spectral selectivity, high thermal insulation and high visible light transmission. Low-emissivity glass allows about 80% of visible light to enter the room, while reflecting the long-wave portions of sunlight. Things always have a two-sided nature. Low-emissivity glass can keep most of the indoor infrared radiant heat in the room while reflecting the long wave outside the house. It has a good thermal insulation effect. This is unfavorable for cooling in summer. In the use of natural ventilation measures should be strengthened to reduce the negative effects of Low-E glass.
In addition, the glass film is also a way to enhance the thermal insulation properties of the outer window glass. Sticking polyester film on the surface of the flat glass can improve the performance and strength of the glass, so that the glass has the functions of energy saving, heat insulation, heat preservation, explosion-proof, anti-ultraviolet radiation, beautification appearance, privacy shielding, and safety. In the energy-saving renovation of existing building windows and doors, the construction of the post film is convenient, without changing the main structure of the original building, and the effect is good. It is an operation method worthy of promotion.
Don't forget to recommend this to friends posted on QQ/MSN (Jiangsu Construction Team, Xi'an 20 years experience in construction, consulting Q1057545818)
In the southern region where I live, what kind of glass is conducive to energy conservation? In order to explore this issue, we first analyzed and summarized the thermal characteristics and regional adaptability of various glasses. In general, glass can be classified into transparent glass, heat-absorbing glass, heat-reflecting glass, and low-emissivity glass according to its properties, and various types of glass can be made into insulating glass.
analysis--
(1) Transparent glass Normal transparent glass has almost the same reflectance for various spectra, and it has fast heat and fast heat dissipation. Its shading coefficient is extremely high, and its ability to block solar radiation is poor. Most solar radiation heat energy enters the room through the glass. During the daytime in summer, the heat energy that enters the room through the transparent glass is far greater than the heat energy that the glass radiates outwards, causing the indoor temperature to rise. Transparent glass insulation performance is very poor.
(2) Heat absorbing glass The heat absorbing glass adds some metal ions or some substances to the glass so that the glass shows some colors and enhances the absorption of light. The sunshade coefficient of the heat-absorbing glass is lower than that of the transparent glass, and its sunshading principle is to weaken it into the room by absorbing solar energy. This kind of occluding nature is actually the absorption of radiation, and the heat absorbed by the glass will still be transmitted to the indoor and outdoor, and it will not block the heat outside.
The heat-absorbing glass shields part of the solar radiant heat energy in summer or winter, so it can be used in the southern areas where heat prevention is dominant, but not in the north. The endothermic glass has no selectivity to the spectrum, and it also reduces the transmission of sunlight and also hinders the projection of visible light, which may affect the lighting. In the summer, the endothermic itself will be hot, and the radiant rate itself will be high. The absorbed heat will be partially radiated to the interior, which may cause people's discomfort.
(3) Heat-reflecting glass The heat-reflecting glass is coated with a metal film and some interference layers on the surface, so that the glass product can reflect more solar radiation so as to achieve the effect of shading, and has a rich color. Heat-reflecting glass has a strong reflection of visible light and long-wave radiation, and its role is to limit solar radiation into the room.
Heat-reflecting glass has a similar heat-insulating property to that of transparent glass, so it is not suitable for indoor cold areas where there is a large temperature difference. However, in a hot, hot area, the heat-insulating effect is very good. It is suitable for hot summer and warm winter areas. use. It should be noted that reflective glass, while reflecting the thermal energy of solar radiation, also restricts the entrance of visible light, which can cause adverse effects on indoor lighting. In addition, too high reflectivity can cause light pollution, too low and can not achieve energy-saving effects.
(4) Low-E glass Low-E glass, also known as Low-E glass, uses a vacuum deposition technique to form a low-E coating on the glass surface. The role of the Low-E coating is to reflect far-infrared radiation first, which effectively reduces the heat transfer coefficient of the glass; secondly, it reflects the thermal radiation in the sun, selectively reduces the shading coefficient; at the same time, compared with the low-emissivity glass and the heat-reflective glass, Do not limit the penetration of visible light too much.
The biggest feature of Low-E glass is its spectral selectivity. In the manufacturing process, processes can be adjusted to produce products with various optical properties, such as the shading coefficient, light transmittance, etc. that we care about. Different Low-E glass varieties should be selected for different areas or orientations to achieve the best results. Sun-protected Low-E glass is suitable for use in hot areas, and its shading coefficient and light transmittance are low. In the heating area, traditional high-transmission Low-E glass with high light transmittance and shading coefficient can be selected.
(5) Hollow glass Insulating glass has higher thermal resistance, can effectively prevent heat conduction due to temperature difference in the room, and has high insulation performance, which is very suitable for use in northern regions. The dry, non-convective gas in the hollow glass interlayer can block the heat conduction path, thereby limiting the temperature difference of the glass heat transfer, effectively reducing the heat transfer coefficient of the glass. Its interior is generally filled with inert gas to further reduce the heat transfer coefficient. The gas layer of the insulating glass does not effectively limit the transmission of solar radiation, so its contribution to improving the shading coefficient is limited. The two layers of insulating glass can be selected according to the needs to meet the requirements of various occasions. Transparent hollow glass, heat insulating hollow glass, heat reflecting hollow glass, Low-E hollow glass and other forms. In general, the greatest improvement in insulating glass is its thermal conductivity, not its thermal insulation. In the summer in the south, the heat entering the room through the glass is dominated by radiant heat, while the indoor and outdoor temperature difference only accounts for a small part, especially in the summer evening, the good thermal insulation performance of the insulating glass makes it difficult for indoor heat to be emitted. It is not good for energy conservation.
in conclusion--
According to the previous analysis, the following requirements should be observed in the selection of window glass outside the hot regions of the South:
In a variety of common glasses, glasses with a low shielding factor should be selected. Suitable glass types are mainly heat-absorbing glass, heat-reflecting glass and low-e glass. Because the heat absorbing glass absorbs a large amount of solar radiation heat, causing its own temperature to rise, causing heat to the room, it is not the best choice. Therefore, in the hot areas of the South, the glass suitable for heat insulation needs mainly heat reflective glass and low-e glass.
1 heat reflective glass. Can reflect most of the solar heat radiation, visible light transmittance of 8% to 40%, is a good heat reflective material. The heat-reflecting glass has remarkable effect on heat insulation, but there is also a big disadvantage in that the visible light transmittance is too low, which will seriously affect the indoor lighting and lead to an increase in the energy consumption of indoor lighting.
2 low-e glass. It can solve the contradiction of heat reflecting glass. Low-e glass has spectral selectivity, high thermal insulation and high visible light transmission. Low-emissivity glass allows about 80% of visible light to enter the room, while reflecting the long-wave portions of sunlight. Things always have a two-sided nature. Low-emissivity glass can keep most of the indoor infrared radiant heat in the room while reflecting the long wave outside the house. It has a good thermal insulation effect. This is unfavorable for cooling in summer. In the use of natural ventilation measures should be strengthened to reduce the negative effects of Low-E glass.
In addition, the glass film is also a way to enhance the thermal insulation properties of the outer window glass. Sticking polyester film on the surface of the flat glass can improve the performance and strength of the glass, so that the glass has the functions of energy saving, heat insulation, heat preservation, explosion-proof, anti-ultraviolet radiation, beautification appearance, privacy shielding, and safety. In the energy-saving renovation of existing building windows and doors, the construction of the post film is convenient, without changing the main structure of the original building, and the effect is good. It is an operation method worthy of promotion.
Don't forget to recommend this to friends posted on QQ/MSN (Jiangsu Construction Team, Xi'an 20 years experience in construction, consulting Q1057545818)
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