How should the application of urban green buildings be analyzed? What is the current status of urban green buildings in my country? Please read the article edited for you by Zhongda Consulting.
Abstract: Our country is in a critical period of promoting the construction of small and medium-sized cities. Green buildings can solve the resource consumption and environmental problems caused by rapid urbanization. Combined with my country's green building evaluation system, this paper attempts to explore the problems and solutions in the implementation of green buildings in small and medium-sized cities.
Introduction
With the growth of the national economy, the construction of small and medium-sized cities has become an important basis for complying with the trend of economic and social development, implementing industry to feed agriculture, and narrowing the gap between urban and rural areas. Due to economic promotion, people's living standards have improved, and their requirements for housing have also increased. They have gradually begun to pursue "green" spiritual concepts from the past material concept of "stable housing", which has prompted the construction industry to move toward "green development, circular development, and low-carbon development" [1].
1 The development status of small and medium-sized urban buildings
1.1 Extensive development model
From 1978 to 2012, my country's small and medium-sized urban buildings increased from 17.9% to 52.6%, with an annual average An increase of 1.02 percentage points [2]. Behind this rapid development is unsustainable extensive development at the expense of resources and the environment. It has taken us decades to complete the industrialization path that took Western countries for one or two hundred years. While promoting the rapid development of the industrialization process, urban construction also faces severe challenges. Extensive construction development has not only swallowed up a large amount of agricultural and ecological land, but also caused many problems such as lax supervision, excessive construction waste that cannot be effectively processed, and real estate planning that purely pursues economic benefits.
1.2 Energy consumption of existing buildings
Building operation is very dependent on energy and resources such as water, electricity, and gas. Before 2000, most of the urban construction and development were non-green energy-saving buildings, accounting for 80% of the urban construction area. A large number of non-green and energy-saving existing buildings not only increase resource and energy consumption, but also cause irreversible environmental pollution. According to statistics, 60% of carbon emissions in cities come from the renovation, expansion and maintenance of normal functions of buildings, while only 30% come from vehicle exhaust. my country's building energy consumption accounts for more than 40% of the country's total energy consumption, far exceeding the energy consumption needs of other industries.
1.3 Small and medium-sized urban environmental resources
Green buildings themselves solve the environmental pollution problem of buildings from the source of construction and development. In the past, the secondary investment of "construction first and greening later" Free, relying on the environmental foundation of small and medium-sized cities, through decentralized and small-scale measures, the hydrology, geology, and landforms after regional development will be consistent with those before development. Taking Hulunbuir City as an example, forestland accounts for 50% of the city's total land area, with a total water resource of 28.66 billion cubic meters and a per capita water resource of 11,000 cubic meters, which is 4.66 times the national per capita share. Compared with large cities that have been affected by smog and water pollution, it is obvious that the construction of small and medium-sized cities must choose the concept of green building development, prompting us to protect the few natural heritages from the source.
2 The necessity of applying green buildings in small and medium-sized cities
2.1 People’s own needs
As people continue to relocate, the scope of urbanization in small and medium-sized cities continues to expand , followed by a mushrooming of building developments. The density of population, the rising price of construction land, and the ever-increasing public material needs force cities to continue to expand outwards. Just like the self-organization principle in synergy theory, urban expansion is not guided by the government, but the inevitable result of public choice. This is also an inevitable process in the construction of developing countries.
2.2 Ecological environment needs
The "2016-2021 China Intelligent Building Industry Analysis Report" by the Forward-looking Industry Research Institute shows that the total energy consumption of buildings in my country is increasing year by year, accounting for 10% of the total energy consumption. 27.45%. Due to the acceleration of urbanization, the proportion will rise to about 35%. Calculated at this rate, by 2020, building energy consumption may reach 108.9 billion tons of standard coal, and the summer air conditioning load is equivalent to the full load operation of 10 Three Gorges Power Stations [4]. With the focus on the development of small and medium-sized cities, demolition of old buildings and construction of new ones has become a common practice, and demolition brings a lot of construction waste that cannot be transformed. The environmental and ecological problems intertwined between new buildings and existing buildings continue to expand, and we must face up to these developing problems.
3 Problems in the application of green buildings in small and medium-sized cities
3.1 Cognitive issues
Low energy consumption brings about reduced use costs and the long-term environment of green buildings Benefits, these advantages cannot be directly converted into market power and consumer demand, nor can they encourage builders and consumers to actively participate in the process of promoting the development of green buildings. The uncertainty of the environmental benefits of green building technology, the long-term nature of the benefits, the intensity of government promotion, and the short-term pursuit of profits by builders all affect the promotion of green building technology.
3.2 Technical Issues
The biggest obstacle to the development of green buildings in small and medium-sized cities is not the technological backwardness of green buildings, but the lack of technical training for relevant companies and their inability to keep pace with the times and understand the current situation. Advanced green technology. This will affect the enthusiasm of enterprises in green construction and slow down the promotion of green buildings.
The construction of small and medium-sized urban universities is imperfect, and there is no connection between university scientific research and corporate technology applications. The development of small and medium-sized urban buildings can only passively accept "emerging technologies" such as "green buildings", and there is no ability to develop research that is in line with the local environment, economy, and culture. The integrated green building system has severely restricted the application and promotion of green building technology.
3.3 Cost issue
Cost issue has always been the main reason that hinders developers from promoting green buildings. Green buildings not only have slightly higher material selection costs than ordinary buildings, but in order to achieve real water saving Local energy conservation requires high costs for ancillary facilities around the building. In recent years, the government has continuously introduced preferential policies for green buildings, but they are of little use to the economic interests of developers. The China Academy of Urban Sciences made statistics on the incremental costs of 148 green buildings in 2014 [2]. The incremental costs of one-star, two-star, and three-star green buildings for residential buildings were 23.9 yuan/m2, 70.9 yuan/m2, and 131.8 yuan/m2. yuan/m2, the incremental costs of one-star, two-star, and three-star green buildings for public buildings are 29.9 yuan/m2, 87.3 yuan/m2, and 216.4 yuan/m2, which proves that green does not mean high price , high cost.
4 Implementation strategies for green buildings in small and medium-sized cities
4.1 Green transformation of existing buildings
The green transformation of existing buildings mainly focuses on building heating and living Energy consumption, which is also 70% of building energy consumption. my country's climate conditions, architectural forms, and economic development vary widely, so energy-saving renovation measures for existing buildings must be adapted to local conditions. Renovation of existing buildings in severe cold areas mainly depends on the insulation of building exterior walls. Improving the thermal performance of the building envelope, improving the heat transfer coefficient of doors, windows, roofs and floors, strictly implementing window-to-wall ratio regulations, and improving the air tightness of doors and windows are all simple measures that can reduce building energy consumption. Renewable energy applications. Small and medium-sized cities generally have small populations and rich resources. The auxiliary facilities of public buildings and residences can use wind power, solar energy and other technologies to achieve simple self-sufficiency. Such as solar lighting, rainwater reuse, small wind power in the square, hydropower landscape, etc. Recycling of gray water not only reduces energy consumption, these simple measures also contribute to reducing urban waterlogging disasters and building sponge ecological cities.
4.2 Passive building design
Passive design refers to maximizing the thermal insulation performance and air tightness of the building envelope and making full use of natural ventilation, natural lighting, solar radiation, etc. Passive technical means minimize the need for heating and air conditioning, and achieve a building system that is in harmony with nature on the basis of achieving a comfortable indoor environment.
① Replace the central air-conditioning and refrigeration system with efficient natural ventilation. By applying the principles of wind pressure and thermal pressure in development or renovation of original buildings, the wind passes through the building and creates a pressure difference due to the obstruction, which prompts the air to flow into the room from the windward openings, while the indoor air is discharged from the leeward openings, forming an effective ventilation system. Wind pressure natural ventilation. If the indoor temperature is higher than the outdoor temperature, a higher pressure will be formed in the upper part of the building space, while the lower pressure will be lower. When there are pores at these locations, the air will enter the upper pores through the lower openings and flow out.
②Replace lighting and heating with natural lighting. Large-scale apartment buildings adopt passive design concepts to consider the angle between the building's orientation and the sun. Natural light enters the room through the glass roof, achieving the effect of natural lighting and increasing indoor temperature. The roof is equipped with automatically opening and closing louvers to prevent excessive direct sunlight in summer and reduce the indoor temperature.
4.3 Reasonably locate planning costs
The application cost of green building is mainly the early technical research, as shown in Figure 1, most of the cost investment is in the research and development and material production process. Design and construction can be referenced and reused in multiple projects, and later operations are the key to project profitability. For builders and consumers, they are not directly responsible for the expensive research and development and production of green building materials in the project, but are involved in the material selection, design, construction and later maintenance and use stages. As far as the entire value chain is concerned, builders and consumers participate in the value-added and profitable part of the whole life cycle costs.
In the cost of green buildings, what we mainly analyze is not the single cost of the building itself, but whether its incremental costs can bring later benefits. The survey and statistics of 21 green building projects cited by Sun Daming et al. are shown in Figures 2 and 3. Generally, the higher the positioning of the project or the higher the star rating selected, the greater the corresponding incremental cost will be. The reasonable positioning and energy-saving grade selection of green buildings by builders and consumers are the key to affecting incremental costs.
5 Conclusion
The application of green buildings in small and medium-sized cities must first realize the connection between green building technology, urban planning, landscape planning and municipal facilities; secondly, the government must use both rewards and punishments in the promotion of green buildings. , realize the development from a single green building to a green urban area; and finally enhance the positioning of consumers and builders for the development of green buildings in small and medium-sized cities, and implement the technical concepts of green building development into the development and construction of small and medium-sized cities with feasible plans. To truly realize the implementation of environmental protection before urban development and utilization, this will become the direction of our continuous efforts.
The above urban green building application analysis was collected and compiled by Zhongda Consulting
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