Building energy conservation includes new (including reconstruction and expansion) building energy conservation and existing building energy conservation. China's existing building area is 40 billion square meters, most of which are not energy efficient. whole country Public buildings The area is about 4.5 billion square meters, of which 500 million to 600 million square meters are public buildings (shopping malls, office buildings, hotels) using central air conditioning. The energy consumption per unit area of public buildings accounting for 11% of the existing building area is about 10 times that of ordinary residential buildings, which can be called a large energy consumer. The area of doors and windows in some public buildings accounts for more than 20% of the building area, and the energy consumption through doors and windows accounts for about 50% of the whole building. Through glass Building energy conservation includes new (including reconstruction and expansion) building energy conservation and existing building energy conservation. China's existing building area is 40 billion square meters, most of which are not energy efficient. The national public building area is about 4.5 billion square meters, of which the public buildings (shopping malls, office buildings, hotels) using central air conditioning are 500 million to 600 million square meters. The energy consumption per unit area of public buildings accounting for 11% of the existing building area is about 10 times that of ordinary residential buildings, which can be called a large energy consumer. The area of doors and windows in some public buildings accounts for more than 20% of the building area, and the energy consumption through doors and windows accounts for about 50% of the whole building. The energy loss through glass accounts for about 75% of the energy consumption of doors and windows, and the energy consumption of glass, which accounts for about 80% of the window area, ranks first. The key point of building energy conservation transformation is public buildings. The transformation of doors, windows and curtain walls is the key to building energy conservation, and the transformation of glass is the top priority of energy conservation work. There are only two options for energy-saving transformation of glass in existing buildings: one is to smash the original glass and replace it with energy-saving glass, and the other is to stick thermal insulation safety film for building on the original glass.
Types and functions of energy-saving glass 1. Coated glass: coated glass is to coat one or more layers of metal, alloy or metal compound on the glass surface to change the performance of the glass. According to different characteristics, it can be divided into heat reflection glass and low radiation glass. Heat reflective (sunlight controlled) glass is usually coated with one or more layers of metal or compound films such as chromium, titanium or stainless steel on the surface of the glass to make the product rich in color, with appropriate transmittance to visible light, high reflectance to near-infrared light, and low transmittance to ultraviolet light. Therefore, it is also called sunlight controlled glass. Compared with ordinary glass, the shading coefficient is reduced, that is, the shading performance is improved, but the heat transfer coefficient has little change. Low radiation (LOW-E) glass is a film composed of several layers of silver, copper, tin and other metals or other compounds coated on the surface of the glass. The product has high transmittance to visible light, high reflectivity to infrared light and good thermal insulation performance. Due to the poor strength of the film, it is generally made into insulating glass and not used alone. 2. Insulating glass: insulating glass is framed by two or more pieces of glass with aluminum hollow frame, sealed by cementation or welding, forming a free space in the middle, which can be filled with dry air or inert gas. Its heat transfer coefficient U is smaller than that of single layer glass, and its heat preservation performance is good, but its sunshade coefficient SC decreases very little, and the heat reflection of solar radiation is not improved much. 3. Composite of coated glass and insulating glass: including heat reflection coated insulating glass and low radiation coated insulating glass. The former can reduce the heat transfer coefficient and shading coefficient at the same time, while the latter has better light transmittance. Types and functions of building glass films Architectural glass film is made of high-quality polyester (PET) film and metal coating layer by bonding and pressing through vacuum magnetic jet spraying process, which can provide excellent sunlight control function for various types of glass.
Building glass films can be roughly divided into three categories: 1. Building thermal insulation glass films. Building thermal insulation films are mainly aimed at energy conservation, with UV protection and safety explosion-proof functions. This kind of building thermal insulation films can be divided into heat reflective films and low radiation films. The heat reflective film (also called sunlight control film) is pasted on the glass surface to make the room transmit a certain amount of visible light, high infrared reflectance IR, and low solar energy heat acquisition coefficient SHGC, which can keep the indoor temperature from rising too much in hot summer, thus reducing the electricity consumption of indoor air conditioning. The low radiation film (also known as LOW-E film) can pass through a certain amount of short wave solar radiation energy, so that the solar radiation heat (near infrared) enters the room, and at the same time, it can reflect the long wave infrared (far infrared) radiation of more than 90% of indoor object heat sources (such as heating equipment) back to the room. LOW-E film can make full use of outdoor short wave solar radiation and the long wave radiation energy of indoor heat sources, Therefore, it can play a significant role in heat preservation and energy conservation when used in heating buildings in cold regions. 2. The main function of building safety glass film is to prevent explosion, theft and bullet. This kind of film has good impact resistance (anti explosion strength), puncture resistance, and UV blocking ability, with high transparency or full transparency. 3. Decorative glass film The main function of this film is decorative. There are many kinds of film, such as basic color, translucent, opaque, and printed with various geometric patterns. The opaque film, such as one-way perspective film, and the translucent film, such as frosted film. Compared with frosted glass and process glass manufacturing, it has the advantages of durability, fast installation, and low cost, You can also change the decorative patterns anytime and anywhere according to your own wishes. The Ministry of Construction and the National Development and Reform Commission stipulate that safety glass must be used in 11 parts of buildings that need glass as building materials. The non safety glass in the existing building can be upgraded to safety glass after being coated. The safety of laminated glass is better than that of tempered glass, which can prevent the glass from exploding and scattering. Cost comparison between replacing energy-saving glass and sticking thermal insulation film Case: 12MM tempered transparent glass is used for the point supported curtain wall of an exhibition center hall. If it is replaced with 12mm tempered glass with heat reflection coating, the material cost is 210 yuan/m2, the disassembly cost of old glass is 70 yuan/m2, and the total reconstruction cost is 280 yuan/m2. If two pieces of LOW-E insulating glass with a thickness of 10mm and a thickness of 12mm are replaced, the material cost will be 375 yuan/m2, and the total cost will be 445 yuan/m2 when the disassembly cost is 70 yuan/m2. With the method of adding heat reflection film, the material cost is 100-130 square meters, the installation cost is 30 yuan/square meter, and the total cost is 130-160 yuan/square meter. The cost of applying heat reflection film is about 50% of the cost of heat exchange reflection glass. The energy saving effect of LOW-E insulating glass can be achieved when the original glass is pasted with a heat reflective film and a low radiation (LOW-E) film. In the energy-saving transformation of building doors and windows and glass curtain walls.
The existing glass film has the following six advantages: 1. It is more economical. The total cost of the existing tempered transparent glass or tinted glass with thermal reflective film is 50% less than that of the replacement of thermal reflective glass. The rest can be analogized, for example, the original ordinary insulating glass with thermal reflective film or low radiation film is upgraded to hollow thermal reflective coated glass or hollow low radiation coated glass respectively. 2. Faster. The existing glass film has shorter construction period and easier operation than the old glass removed and replaced with new glass. 3. More environmentally friendly. Replacing glass will produce a large amount of construction waste of broken glass, which will increase the transportation and landfill costs. The film can use the existing glass to upgrade its thermal insulation and safety performance. It can also prevent fading of indoor carpets, curtains, fabrics and paints, effectively protect indoor furniture, computers and other office equipment, and extend their service life. 4. More secure. The general thermal insulation film also has a certain safety enhancement function, and has the chip adhesion performance of laminated (adhesive) glass. Its safety is better than that of tempered glass, and the safety of professional safety film is stronger. 5. Healthier. The installation glue in the glass film contains UV (ultraviolet ray) absorbent, which can block 98% - 99% of the ultraviolet ray. 6. Lighter. If the hollow glass or hollow LOW-E glass is replaced, the total weight of two pieces of glass and the hollow part will be doubled or more, which will greatly increase the building load.
