Focus interview： buildings with ultra-low energy consumption become ＂green＂

　　Cctv news(Focus Interview): This week is the National Energy Conservation Publicity Week, and August 25th is the National Low Carbon Day. The theme of this year’s National Energy Conservation Publicity Week is "Green Development of Energy Conservation and Carbon Reduction". When it comes to a green and low-carbon lifestyle, we may immediately think that we should pay attention to saving electricity and saving solar terms, use less air conditioners at home, and raise the temperature when using air conditioners for refrigeration in hot days. And in winter, don’t turn the heating too hot. These are all measures to reduce carbon emissions, but it seems that it will affect the comfort of life, as if to reduce energy consumption, the house will not be so comfortable to live in. However, there is such a building that is environmentally friendly and low-carbon, and it is warm in winter and cool in summer. Many people have already experienced it. How do they feel when they live?

　　Mr. Zhang, who lives in Gaobeidian City, Hebei Province, moved to a new home in January this year. Although he has only lived for more than half a year, Mr. Zhang found that the feeling of living in this house is different from all the houses he has lived in before. The APP in his mobile phone records various real-time data such as temperature and humidity at home.

　　Mr. Zhang said that after he moved into his new house, he no longer needed heating and air conditioning, and generally did not open the windows. Instead, the unified fresh air system of the building worked 24 hours a day to change the air and adjust the humidity, so that the indoor air temperature and humidity were in the most comfortable state for the human body, and the temperature remained at 20— Between 25 degrees, the pm2.5 value of the air also decreased to single digits. In our traditional impression, it is not an energy-saving way to adjust the temperature and change the air by using the fresh air system for 24 hours, because the power consumption may be very high. Therefore, Mr. Zhang is also very concerned about how much electricity and money this fresh air system will consume every month.

　　Mr. Zhang calculated an account for us: he lived in a new house before the Spring Festival, and the heating season lasted for one and a half months. And such a house of more than 80 square meters, if it is a traditional central heating method, the heating cost for one and a half months is at least 700— 800 yuan, and the cost of fresh air system in these four months is less than that in 300 yuan, which solves the problem of heating and heat preservation. Living more comfortably, the cost of heating and heat preservation is greatly reduced, and the energy consumption is also greatly reduced. How did such a good thing come about? It turns out that the residential area where Mr. Zhang lives is one of the earliest ultra-low energy consumption residential areas built in China. So what is an ultra-low energy-consumption building? Why can you live comfortably and save energy greatly?

　　Wei Xu, dean of the Institute of Building Environment and Energy Conservation of China Institute of Building Research, said: "From a big perspective, it is three points. One is to make the building envelope achieve high performance, such as using high-performance windows, good external structure with heat preservation and insulation; Another technology is to effectively and greatly improve the efficiency of building energy system; The third part is open source, using renewable energy, solar energy, etc., which directly supplies energy to buildings, effectively reducing the consumption of fossil energy. "

　　One of the reasons why traditional houses don’t save energy is that the house is not tightly sealed, and the heat exchange between indoor and outdoor is fast, so it is necessary to continuously use external energy sources, such as central heating or air conditioning, to heat up or cool down. The passive architectural design of ultra-low energy consumption building makes up for this. The thickness of the thermal insulation material on the facade of the building is 2 to 3 times that of ordinary houses, just like putting a thick cotton-padded jacket on the house; The three-layer double insulating glass used in the window has a better heat insulation and cold protection effect than ordinary glass. In addition, the indoor and outdoor steam barrier and gas permeable membrane are set to ensure the air tightness of the building and minimize the loss of heat. On this basis, the energy consumption will be greatly reduced by using high-efficiency fresh air system to adjust the temperature.

　　Wei Xu said: "In the northern heating-oriented residential buildings, if ultra-low energy consumption buildings are realized, they will be roughly reduced by more than 50% compared with the current energy-saving standards. It is not simply energy saving, but actually improves energy saving when the comfort level is high. "

　　In the process of ultra-low energy consumption construction, it is very important to ensure the air tightness of the building, that is, to minimize the exchange speed of indoor and outdoor gases, to prevent the loss of indoor heat in winter and to prevent outdoor hot air from entering the room in summer.

　　Wang Changming, head of the engineering function of Longhu Group Beijing Company, said: "The whole air tightness is in the building with near zero (ultra-low) energy consumption, not only in the doors and windows of the external protection; In addition, some vapor permeable membranes and gas barrier membranes will be used in all the peripheral guards to strengthen the weak parts. Only in this way can we finally present the index required by near-zero (ultra-low) energy consumption, and the number of air changes within one hour will not exceed 0.6 times. "

　　It is understood that the number of air changes per hour in traditional houses is generally 2 to 3 times when there is a certain air pressure, but the number of times must be reduced to less than 0.6 times in ultra-low energy buildings. With less ventilation, the thermal insulation is naturally greatly improved. In addition, the thermal bridge is also an important factor to save energy. "Thermal bridge", as its name implies, is a bridge for heat conduction. Thermal bridges often appear at the joints of doors and windows, brick walls and concrete floors. The basic principle of thermal bridge design is to block thermal bridges at the joints of different materials by adding insulation layers appropriately.

　　In this construction site in Haidian District, Beijing, the largest single ultra-low energy consumption building in Beijing is being built here. The project engineer told the reporter that the heat-free bridge link of the main structure here has just been completed.

　　The so-called broken bridge treatment of cold and hot bridge is to put an end to the direct contact between metal parts and concrete by adding heat insulation pads, thus avoiding unnecessary heat loss. From the appearance of a small sample of the top floor of a building being built on a construction site, it can be seen intuitively that multi-layer heat insulation treatment should be added at the joint of an air outlet and the building to ensure the heat insulation effect.

　　Now, China’s ultra-low energy consumption buildings have come to a new starting point. This is because China has promised to strive to reach the peak of carbon dioxide emissions before 2030, and carbon dioxide emissions before 2060 should be completely offset in various ways, which is carbon neutrality. To achieve these two goals means that our future production and lifestyle will undergo profound changes. The construction sector accounts for a large proportion of the total carbon emissions. Taking heating as an example, most central heating directly consumes coal. While cooling by air conditioning, most of the power resources used also rely on fossil energy such as coal and electricity. Therefore, how to implement emission reduction in the construction field has also become an important issue.

　　Wei Xu said: "According to our country’s statistics, the carbon emissions from construction operations account for about 20% of the country’s total carbon emissions. If you add invisible carbon emissions, including the use and construction of building materials, it will be nearly 40%. How to achieve peak carbon dioxide emissions and carbon neutrality of buildings? One of the measures is to make new buildings realize ultra-low energy consumption buildings as soon as possible. "

　　In recent years, China has successively promulgated relevant policies to support the construction of ultra-low-energy buildings. In 2016, the State Council issued the Comprehensive Work Plan for Energy Conservation and Emission Reduction in the 13th Five-Year Plan, proposing to carry out pilot projects of ultra-low-energy and near-zero-energy buildings. During the 13th Five-Year Plan period, the cumulative promotion of ultra-low and near-zero-energy buildings nationwide reached 12 million square meters, covering various building types such as residential buildings, public buildings and industrial buildings.

　　The Government Affairs Service Center in xiong’an new area, Hebei Province, which was completed in 2018, adopted many ultra-low energy consumption building technologies. In summer, when the air conditioner is not open, the government service center can still maintain a comfortable temperature.

　　In Qingdao, the Sino-German Ecological Park Forest Kindergarten was newly established in October 2020. The main building of this kindergarten also adopts the architectural concept of "ultra-low energy consumption" to realize indoor constant temperature and humidity without heating and air conditioning, which can ensure a comfortable and dust-free indoor environment and provide a comfortable park environment for children.

　　From pilot to popularization, ultra-low energy consumption buildings have gone through more than ten years of development in China. However, there is still a certain distance to truly become the residence of ordinary people on a large scale, so what are the obstacles that need to be broken through? It is understood that because it is a new thing, this ultra-low-energy building has shortcomings in many aspects such as material supply, design and professional talents.

　　It is precisely because ultra-low energy consumption buildings have higher requirements in design, materials and construction technology than traditional buildings, so the construction cost is undoubtedly higher than that of traditional buildings, and not all ordinary people can accept this kind of buildings.

　　Obviously, in order for more people to actively choose ultra-low energy-consumption buildings, in addition to technology and market, we also need to understand this technology and the guidance and support of relevant policies. Now, under the guidance of the overall goal of peak carbon dioxide emissions and carbon neutrality, all localities are actively formulating relevant goals from supporting ultra-low energy-consumption buildings. Beijing, Shanghai, Hebei and other places also encourage the development and construction of ultra-low energy-saving buildings in various ways, such as financial incentives, floor area ratio incentives, and support for commercial housing development. In the future, more people will live in comfortable and energy-saving high-quality houses.

　　Tian Guomin, director of the Standards and Quotas Department of the Ministry of Housing and Urban-Rural Development, said: "In the next step, our department will continuously improve the level of building energy efficiency by formulating mandatory standards, and comprehensively and forcefully promote ultra-low energy-consumption buildings in suitable climate areas. At the same time, our department is also formulating the peak carbon dioxide emissions implementation plan in the field of urban and rural construction, coordinating the promotion of energy conservation and emission reduction, conscientiously implementing the decision-making arrangements of the CPC Central Committee and the State Council, and making positive contributions to the country’s realization of peak carbon dioxide emissions and carbon neutrality. "

　　In China, the construction and operation of buildings account for nearly 40% of the total carbon emissions. Controlling and reducing energy consumption and emissions in this field is very important for achieving emission reduction targets. This kind of ultra-low energy consumption building is energy-saving and comfortable, constant temperature and humidity and clean, which is worth popularizing. Of course, while promoting the construction of ultra-low energy-consuming buildings, all localities need to choose appropriate technical routes and methods according to their own conditions, and cannot engage in "one size fits all". In fact, it is not only the construction industry, but also the countdown to the goal of peak carbon dioxide emissions in 2030, which urgently needs the participation of the whole society. From the office to the assembly line, from home to travel, energy saving and carbon reduction is not only a healthy and green production and lifestyle, but also an environmental responsibility related to all walks of life, which requires concept renewal and mode innovation.