When implementing the heat transfer coefficient K value of profile of passive door and window frames, it should be implemented in accordance with the provisions of Classification and Test Methods for Thermal Insulation Performance of Building External Doors and Windows (GB/T 8484), and meet the provisions of KS1.3W/(m · K). This regulation realizes the reasonable control of the overall heat transfer coefficient of the external window, and ensures that the surface temperature of the profile on the indoor side is not lower than the dew point temperature in winter. The materials involved in a passive window roughly include the following aspects: window frame, glass, spacing strip, adhesive strip, L-shaped angle steel, window sill plate, external shading, etc.
1. Profile requirements
The profile should be made of materials such as unplasticized polyvinyl chloride plastic and wood with good insulation performance. Commonly used exterior doors and windows in buildings include plastic steel doors and windows, wooden doors and windows, and aluminum wood composite doors and windows. Currently, there are also fiberglass reinforced polyurethane cool windows. The precision of the original aluminum profile reaches 0.1mm (thickness, strength, and oxide film are all European standards). The glued raw wood needs to be glued in different directions to avoid deformation of the window frame after a long time. High quality plastics require strict proportions to ensure that they do not discolor, deteriorate, age, or crack. The glass fiber reinforced polyurethane material is light, high-strength, anti-corrosion, fireproof, energy-saving, anti-aging and salt fog resistant.
The window frames of passive windows currently include plastic steel window frames, aluminum clad wood window frames, wood clad aluminum window frames, heat-resistant aluminum window frames, and fiberglass reinforced polyurethane frames. On the premise that the performance meets the requirements of passive rooms, the glass fiber reinforced polyurethane cool window has the highest performance, the smallest window frame size, and the highest overall window permeability. Aluminum clad wooden windows or wood clad aluminum windows are significantly superior to bridge cut aluminum alloy windows. Plastic steel windows are not recommended because their products are prone to deformation, not resistant to aging, and are not conducive to achieving the same lifespan as buildings. Plastic steel doors and windows are made of plastic (PVC) with steel lining, which has a relatively low cost and good insulation and sound insulation effect. However, it is prone to aging, has a large self weight, and is prone to deformation, leading to opening failures. The material recycling value is low, and plastic cannot be degraded, which is not environmentally friendly enough. Aluminum windows and wood clad aluminum doors and windows are made of wood on the indoor side, and the color of the wood material can match the decoration style to improve the overall effect of the product. The outdoor side is made of aluminum alloy with high strength, corrosion resistance and aging resistance. It is suitable for use in different regions and climates without deformation and cracking. Long service life, maintenance free. The use of renewable energy meets the requirements of energy conservation and environmental protection.
2. Glass requirements
For the transparent part of glass, its performance shall meet the following requirements: the heat transfer coefficient of glass KS0.8W/(m · K); The total solar transmittance of glass G ≥ 0.35: the selectivity coefficient of glass S=TL/g>1.25 (TL is the visible light transmittance); The glass spacers for exterior doors and windows should use durable warm edge spacers.
3. Spacer Bar
During the use of passive rooms, warm edge spacers composed of composite materials and stainless steel should be selected and filled with desiccant to achieve the function of supporting the structure. The use of spacing strips is beneficial for reducing the energy consumption of doors, windows, and curtain walls. The thermal conductivity coefficient can be reduced by 0.1~0.3, greatly reducing the proportion of building energy consumption in total energy consumption.
4. Adhesive strip
The airtightness level of passive windows is required to be level 8, so the requirements for airtight adhesive strips for passive windows are also high. There are currently several types of modified PVC, vulcanized EPDM rubber sealing strips, and thermoplastic EPDM/PP rubber strips in the market. Passive windows generally use EPDM adhesive strips due to their airtightness requirements. Thermoplastic EPDM rubber is a newly introduced material in the door and window industry, which was mostly used in the automotive industry in the past. Due to the different quality of modified PVC and the presence of heavy metal elements, its environmental friendliness is not high. In addition, the use of PVC adhesive strips has been restricted in developed countries and coastal cities in China.
5. Windowsill panel
The fully protected outer window sill panel can wrap the outdoor window sill in all directions, preventing rainwater from polluting the wall. Guide the water flow away from the outer window sill to avoid rainwater leakage into the interior. The color, material, and other non aluminum gussets are consistent to ensure overall aesthetics. When installing the outer window sill, it should be ensured that the window sill plate is tightly connected to the window frame: if there is a joint between the metal window sill plate and the window frame, a sealing tape should be used for sealing, while ensuring that the adhesive side of the sealing tape is adhered to the window sill plate.
6. External sunshade
Plastic steel windows and aluminum alloy windows should pay attention to the installation position of the external sunshade, which should not affect the window. The size of the external sunshade installation bracket and the sunshade bolts should not penetrate the waterproof and breathable film of the doors and windows. For the passive external window system, an external fixing method should be adopted, with the window frame edge embedded in the external insulation layer and sealed with sealing materials to improve the insulation effect and waterproof function of the window opening. As the energy consumption of the window accounts for about 50% of the total energy consumption of the passive room enclosure structure, the performance of the window plays a crucial role in the insulation performance of the entire passive room. The exterior windows of passive houses should be sealed with three layers of durable sealing materials. The installation method of passive room exterior windows is different from traditional exterior windows, requiring the installation of the outer wall to reduce heat loss. The connection between the external window and the wall should adopt a combination of waterproof and breathable film, vapor barrier film, and sealant connection system.