Application analysis of energy-saving glass in key nodes of passive low-energy building design
Passive houses have high requirements for the performance of building materials (the term "building materials" is provided by Google). Traditional single-panel glass and ordinary double-layer hollow glass have a high heat transfer coefficient and poor thermal insulation effect. It is a key part of energy loss and energy consumption; in addition, a one-sided increase in the thickness or spacing of glass products will not only affect its transparency and beauty but also increase material consumption and building load-bearing. Therefore, glass has become one of the key nodes of Passive House Design (the entry "Passive House Design" is provided by Google). The emergence of energy-saving glass represented by Low-E insulating glass and vacuum glass has become an ideal solution to this problem.
The high performance of passive low-energy building design 1
1. The basic requirements of the passive house for supporting door and window glass
In Germany, Passive House construction certification must meet 2 criteria:
(1) The annual heating energy consumption of the building does not exceed 15kwh/m² ;
(2) The total annual energy consumption of the building (heating, air conditioning, domestic hot water, lighting, household appliances, etc.) shall not exceed 120kwh/m² .
In the current passive house project, the design and construction of passive house buildings are mainly dedicated to solving the heating problem in winter. The core idea of the design concept is to minimize the heat loss of the building, and the use of high-efficiency energy-saving glass is to strengthen the building envelope. The main technical measures for the insulation performance of the system.
According to the experience of the European Union in the design and construction of passive houses, as the main component of the building envelope system, the heat transfer coefficient of the whole window needs to be lower than 0.8W/(m² .K), of which the glass, which accounts for more than 70% of the door and window area, is satisfying While natural lighting and reducing lighting energy consumption, the heat transfer coefficient of the glass needs to be less than 0.6W/(m² .K), and the infrared rays that cause the indoor cooling load must be isolated outside to ensure that the heat transfer of the window is effectively reduced, And then improve the performance of heat preservation and heat insulation of the entire building (the term "heat insulation" is provided by Google).
The high performance of passive low-energy building design 2
2. Brief introduction of energy-saving glass that meets the requirements of passive house
2.1 Low-E insulating glass (the entry "insulating glass" is provided by Google)
2.1.1 Principles of energy saving
From the perspective of physics, there are three main ways of energy loss: radiant heat, air convection heat loss, and heat conduction. The air layer in the abdominal cavity of the hollow glass is pressure-sealed and does not produce convective heat transfer (the entry "Convective heat transfer" is provided by Google). The heat transfer between the hollow layers is carried out in two ways: long-wave heat radiation between parallel glass plates and heat conduction with air as the medium, among which radiation heat transfer occupies an important position. Low-E glass is made of ordinary glass coated with a Low-E glass film, which has high reflectivity to far-infrared radiation and maintains good light transmission properties. Reduce the surface emissivity of the glass, using Low-E glass can reduce the radiant heat transfer, increase the heat transfer resistance, reduce the heat transfer coefficient of the insulating glass, and increase the thermal insulation performance of the ordinary double-layer insulating glass by 50%, which is good Energy saving effect.
2.1.2 Technical features and functions
In terms of heat preservation in winter, the near-infrared heat radiation and visible light emitted by the sun can enter the room through the film in a large amount; at the same time, indoor objects, walls, air conditioners, heating, and the human body emit long-wave heat energy that is reflected back into the room by the Low-E film. It can effectively isolate the indoor heat from being lost to the cold outdoors through the glass, better maintain the indoor temperature, and reduce heating energy consumption. In terms of heat insulation in summer, Low-E film can put in visible light, and at the same time block solar radiation, long-wave heat released by roads and buildings, and reduce the energy consumption of air conditioning and refrigeration. In addition, it can block the transmission of ultraviolet rays and prevent indoor items from fading.
The high performance of passive low-energy building design 3
2.1.3 Industry advantages
There are currently more than 300 Low-E glass production lines worldwide, with a production capacity of approximately 1 billion m² /year, forming a huge Low-E glass distribution center and a relatively complete supply chain. Low-E glass distribution centers in some developed countries have relevant intellectual property rights. Their equipment, technology, and management have been shaped, reasonable prices, stable and controllable quality, production capacity can radiate market demand within a certain range, and product testing capabilities cover the whole country All developed regions. In addition, local glass industry associations have also established Low-E glass performance databases to facilitate users to screen based on different energy-saving indicators.
2.1.4 Existing configuration
The 6L+16A Warm edge filled with argon+6C+16A Warm edge filled with argon+6L, which is a "three-glass two-cavity" double hollow structure. First, a piece of 6mm Low-E glass is combined with a piece of 6mm float glass. Hollow, the spacing of the hollow layer is 16mm, the interior is filled with argon gas and then sealed with warm edge technology; then it is combined with another 6mm piece of Low-E glass, the spacing of the hollow layer is still 16mm, and the interior is filled with argon gas and then heated again. Edge technology sealing; Finally, to enhance the product’s airtightness (the entry "airtightness" is provided by Google), water tightness and wind pressure resistance (the entry "wind pressure" is provided by Google) capabilities, between the glass and the window frame Reliable sealing tape is also laid to increase the insulation interlayer. Glass compliance performance: heat transfer coefficient U value ≤ 0.6 (W/m² K); Sc value ≤ 0.4; sound insulation (the term "sound insulation" is provided by Google) ≥ 38dB.
The high performance of passive low-energy building design 4
2.2 vacuum glass
2.2.1 Energy saving principle
Since the vacuum degree in the vacuum chamber reaches more than 10-2Pa, the air medium can be ignored, and the air convection heat loss and heat conduction are basically isolated. The original glass sheet also uses Low-E glass, which reduces radiant heat transfer and improves thermal insulation performance. Its heat transfer coefficient is 50% lower than that of Low-E insulating glass with the same original glass. % Above, the energy-saving sound insulation effect is more prominent.
2.2.2 Technical features and functions
In addition to the technical characteristics and functions of Low-E insulating glass, vacuum glass is sealed with glass powder on the edges, so it has better air and water tightness and longer service life. Since there is no convective heat transfer, the convective heat transfer path from the hot end glass to the cold end glass has no effect, so the heat transfer coefficient will not change when it is used in inclined places such as roofs and daylighting roofs.
2.2.3 Industry advantages
At present, only three companies in the world have fully realized the industrialized production of vacuum glass. Two of them are in China with a production capacity of about 500,000 m² /year. In terms of R&D and production of safety vacuum glass, China's vacuum glass production has a leading position in the world. It has a full range of independent intellectual property rights in equipment, technology, products, etc., and the price is becoming more and more reasonable. The product standard JC/T 1079-2008 is also the only vacuum glass industry standard in the world. The Glass Industry Association is also leading the high-end development of the industry. In due course, a professional committee of vacuum glass was established.
2.2.4 Existing configuration
The 5L+16A warm edge filled with argon+5L+0.15V+5C, which is a "vacuum composite insulating glass" structure. First, a piece of 5mm Low-E glass and a piece of 5mm float glass are combined into a vacuum. The distance between the vacuum layers is 0.15mm, the four sides are sealed with glass powder and vacuumed; then it is compounded with another 5mm Low-E glass to form a insulating glass, the spacing of the hollow layer is 16mm, and the inside is filled with argon gas and then sealed with warm edge technology; finally Also, in order to enhance the airtightness, water tightness and wind pressure resistance of the product, a reliable sealing tape is laid between the glass and the window frame, and an insulation interlayer is added. Glass compliance performance: heat transfer coefficient U value ≤ 0.6 (W/m² K); Sc value ≤ 0.4; sound insulation ≥ 38dB.
In Kearns Mancini Architects Passive Low-energy Building-The George Brown College Centre for Hospitality and Culinary Arts & the Chefs' House Restaurant, the whole building adopts double insulating Low-E glass imported from Germany and adopts double insulating Low-E glass vacuum composite insulating Low-E glass produced by Jinan LIJIANG Glass Auotmatic Vertical Insulating Glass Production Line all meet the acceptance criteria of the project.
The Jinan LIJIANG Glass Auotmatic Vertical Insulating Glass Production Line 1
The Kearns Mancini Architects Passive Low-energy Building 1
For more information about Jinan LIJIANG Glass insulating glass processing equipment and insulating glass processing accessories, please click here to learn more.
