Reducing the carbon emissions of the construction and building materials industry will effectively promote China to achieve the goal of carbon peak and carbon neutrality. Traditional building materials and construction industry energy-saving emission reduction and low-carbon development and green transformation and upgrading, has become the inevitable trend of the future development of the industry, and the industry has a very large space for transformation and upgrading, how to tap the potential, the industry is actively exploring. A reporter from China Building Materials News recently learned at the 2021 8th National Passive Assembly Building Summit Forum held in Shijiazhuang, Hebei, that by combining passive and assembly technologies to build passive assembly buildings, it can effectively promote the realization of zero energy consumption and zero emissions in buildings., To maintain building carbon emissions at a low level. Passive assembly building is becoming a new trend in the development of the industry.

Passive assembly, two advantages in one

Passive building is a kind of low-carbon building which only depends on the structural design of the building itself, and can realize constant temperature, constant humidity, constant oxygen, constant cleaning and other properties without special installation of air conditioning or heating facilities. Passive technologies such as building internal heat gain and building waste heat recovery are used to meet the needs of indoor temperature balance and fresh air system. Yao Bing, former chief engineer of the Construction Department of the Ministry of Construction, said in the forum video report: "because passive buildings do not need to be equipped with environmental regulation equipment, thus reducing the energy waste caused by a large number of exposed transmission pipelines, and its design focuses on heat insulation and air tightness, which greatly reduces the ineffective heat exchange inside and outside the building, which saves more than 90% of energy consumption compared with traditional houses."

The prefabricated building transfers a large amount of on-site construction work to the factory, which makes the amount of on-site construction less, and the dust, noise, and sewage generated by the on-site operation of the prefabricated building are also greatly reduced. According to statistics, compared with the traditional construction method, prefabricated buildings can save 80% of water, 70% of energy, 20% of material, 70% of time and 20% of land, and there is no scaffolding and a large number of wet operations in the past, which is in line with the national emission reduction and green development goals.

Passive assembly building has the advantages of both passive and assembled technologies. It has the characteristics of adapting to climate characteristics and natural conditions, making rational use of energy, greatly reducing the demand for heating and cooling of buildings, modular design of BIM system, prefabrication of industrial assembly lines, integration of thermal insulation structure, and improvement of indoor environmental comfort. The heating and cooling energy consumption per square meter of passive assembly buildings is 90% energy-saving compared with traditional buildings, and more than 75% energy-saving compared with ordinary new buildings. Passive house units only need to consume 1.5 litres of fuel oil or 1.5 cubic meters of gas for heating per square meter per year, which is far lower than regular "low energy consumption" buildings.

Passive assembly buildings meet the needs of energy saving and emission reduction in the use of prefabricated buildings, and also improve the construction efficiency of passive buildings. Cui Yuansheng, chief expert of the Building Materials Industry Technology Information Institute and chairman of the China Bulk Cement Promotion and Development Association, said: "In today's environment of rising building energy consumption standards, the integrated and synergistic development of the passive and fabricated fields is a prerequisite for the sustainable development of the construction industry. This is also an effective way to improve the competitiveness of China's construction industry market in the international environment."

Low-carbon buildings bloom in many places, and the material problem remains to be solved.

In recent years, as energy conservation and emission reduction have become the consensus of the whole society, the construction industry has accelerated the promotion of energy conservation and consumption reduction, and ultra-low energy consumption buildings and near-zero energy consumption buildings continue to emerge. These practices provide the basis for the development of dynamic assembly buildings.

Take Hebei Province as an example. As of the end of December 2020, 141 passive ultra-low energy consumption building projects have been built and are under construction in the province, with a cumulative scale of 4.39 million square meters and the largest number of residential buildings. Since January 2019, Hebei Province has successively issued a number of policies such as the "Regulations on Promoting the Development of Green Buildings in Hebei Province" and "Several Policies on Supporting the Development of Passive Ultra-low Energy Building Industry" to support the passive assembly construction industry. Huang Yilong, executive chairman of the Passive Assembly Building Professional Committee of the China Association of Dispersion, said: "Passive assembly buildings are currently in a golden period of rapid development in Hebei Province, and Shijiazhuang has also become a big market for passive assembly buildings in the country. The construction of MCC International Passive Assembly Building Technology Industrial Park around Shijiazhuang and the first domestic passive assembly building industry demonstration base are of great significance for promoting and leading the upgrading of green building materials and buildings, and establishing a typical and model market for high-efficiency and high-quality development."

In Henan Province, the development of low-carbon buildings is also showing a good trend. Up to now, there are more than 30 ultra-low and near-zero energy consumption projects (including projects under construction and completed) in Henan Province, with a total construction area of about 1.5 million square meters. Ultra-low energy consumption projects have been built in 8 cities including Zhengzhou, Kaifeng, Luoyang, Jiaozuo, Xinxiang, Xinyang, Zhumadian, and Puyang.

In addition, as of 2019, there are 32 passive ultra-low energy consumption projects in Beijing, with a total demonstration area of about 650000 square meters; Shandong Province has organized the construction of 6 batches of 53 demonstration projects, with a total construction area of 1.06 million square meters.

It should be pointed out that at present, passive assembly building is in the ascendant, and there are still some problems to be solved in the standard of building materials, which restricts the popularization and development of passive assembly building in China. Cui Yuansheng summarized the main problems of passive assembly building materials in the report "Research on the Development Path of Passive Ultra-low Energy Building Materials Industry. First, key supporting materials need to be imported and introduced; second, there is a big gap between the quality and performance indicators of most products and the international advanced level; third, the national development and distribution of key materials are uneven; fourth, there is a lack of standards, norms, certification, evaluation and supporting systems for material localization; fifth, due to the low degree of industrialization, scale, standardization and systematization, the cost of some materials is on the high side.

Take the road of independent innovation and achieve zero carbon emissions

The development path of passive ultra-low energy buildings and materials in China is roughly divided into three stages: one is the stage of introduction, digestion, absorption and localization; the second is to form an improvement stage characterized by re-innovation, low investment, localization and localization; the third is to finally realize a new stage of re-export, "going out" and facing the world. Cui Yuansheng said that China is still in the first stage of the development of low-carbon and energy-saving buildings, that is, the stage of digestion, absorption, learning and localization after introduction. If you want to move to the next stage, you still need to work hard and make breakthroughs in independent innovation.

Cui Yuansheng said that at present, there have been many attempts in the form of technological innovation in China. Unifying passive and assembly in one system is one of the new trends and new explorations. From the situation of developed countries, the integration of passive and prefabricated buildings has been done well. For example, civil wood structure and steel structure buildings are originally prefabricated. When developing passive buildings, there are no big contradictions or problems. In the construction of reinforced concrete structures in our country, there will be problems of prefabrication or cast-in-place. This is the direction that we can innovate and independently develop. When my country's passive ultra-low energy consumption building and material industry develops to a certain stage, the integration of passive and prefabricated will surely achieve unified and coordinated development while building industrialization.

For the development of low-carbon buildings and materials from the first stage to the second stage, and to make substantial achievements at the innovation level, Cui Yuansheng proposed 10 development paths: the state will increase mandatory laws and regulations and policy support; increase science popularization and improve the whole society's awareness of passive ultra-low energy buildings; fully learn from mature experience and lessons at home and abroad to avoid detours; deepen supply-side structural reforms, promote the development of traditional building materials industry to passive ultra-low energy consumption green building materials industry, and realize the optimization, transformation and upgrading of the whole industry; passive ultra-low energy consumption building materials and prefabricated building materials must be coordinated and organically combined to promote the comprehensive, healthy and orderly development of the building materials industry; increase the research and development of new materials and the pace of industrialization, To achieve innovative development, green development, coordinated development, circular development, inclusive development and sustainable development; coordinated development of vertical and horizontal integration of upstream and downstream of the industrial chain, strengthen cooperation with the National Development and Reform Commission, Ministry of Housing and Urban-Rural Development, Ministry of Land and Resources, Ministry of Environmental Protection, Ministry of Agriculture and other ministries; promote BIM, big data, informatization, industrialization, and intelligence in the building materials industry Construction; increase the construction of high-level demonstration projects, demonstration industrial parks, and lead the green industrialization of passive ultra-low-low-energy building materials; high point positioning to improve the system construction of passive ultra-low energy building materials in China's five major climate zones, and create a diversified development direction of passive ultra-low energy building materials with Chinese characteristics.

At the forum, many experts also said that passive assembly buildings, the integration of building materials and buildings, the secondary development and optimal allocation of resources, and the coordinated development of renewable energy, building materials and buildings are the only way for the future development of passive ultra-low energy consumption building materials industry, which requires overall planning and coordinated development, so as to promote the construction industry to achieve the goal of zero carbon emission, green and sustainable development, Help the country achieve carbon peak and carbon neutrality.