Building energy conservation

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This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Building energy efficiency refers to building material In the process of production, construction and use of buildings and structures, energy consumption shall be reduced as far as possible under the conditions of meeting the same needs or achieving the same purpose.

Methods to reduce energy demand: building planning and design, building envelope, improving energy efficiency of end users, and improving overall energy efficiency.

Chinese name: Building energy conservation
Foreign name: Building energy saving
Increase: Thermal resistance of indoor and outdoor energy exchange

Adopt: Energy saving technology and process
Improve: Energy efficiency
Purpose: Reduce energy consumption

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nine Journal of Building Energy Efficiency
▪ content validity
▪ Main columns

Basic concepts

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Building energy conservation is initially called "improving the energy utilization rate in buildings" in developed countries in order to reduce the energy loss in buildings. Under the condition of ensuring the improvement of building comfort, it is necessary to use energy reasonably and continuously improve the energy utilization efficiency.

Building energy conservation specifically refers to the implementation of energy conservation standards, the adoption of energy-saving technologies, processes, equipment, materials and products, the improvement of thermal insulation performance and the efficiency of heating, air conditioning, refrigeration and heating systems, the strengthening of the operation management of building energy consumption systems, and the use of renewable energy to ensure that Indoor thermal environment On the premise of quality, increase the heat resistance of indoor and outdoor energy exchange to reduce the energy consumption of heating system, air conditioning refrigeration heating, lighting, and hot water supply due to a large amount of heat consumption.

Comprehensive building energy conservation is the sum of energy conservation in every link of the whole life cycle of a building. It means that in the process of site selection, planning, design, construction and use of buildings, energy-saving building materials, products and equipment are used to implement building energy conservation standards, strengthen the operation and management of energy-saving equipment used in buildings, reasonably design the thermal performance of building envelope, and improve heating, cooling, lighting, ventilation, water supply and drainage Piping system As well as the use of renewable energy, it can reduce building energy consumption and reasonably and effectively use energy on the premise of ensuring the use function of buildings and the quality of indoor thermal environment. Comprehensive building energy conservation is a systematic project, which must be led by the national legislation and the government to make comprehensive and clear policy provisions on building energy conservation, and the relevant government departments should formulate comprehensive building energy conservation standards according to the national energy conservation policies; In order to truly achieve comprehensive building energy conservation, it is also necessary to comprehensively implement various energy conservation measures by the design, construction, supervision and management departments at all levels, developers, operation management departments, users and other links in strict accordance with the provisions of the national energy conservation policies and standards, so that every citizen can truly establish a comprehensive concept of building energy conservation and truly implement building energy conservation^[1] 。

Building energy efficiency testing determines whether the completed and accepted project meets the requirements of energy conservation through a series of national standards. GB 50411-2007《 Code for acceptance of construction quality of building energy conservation engineering 》Energy saving detection shall be carried out for indoor temperature, hydraulic balance of outdoor pipe network of heating system, water make-up rate of heating system, heat transmission efficiency of outdoor pipe network, air volume of each air outlet, total air volume of ventilation and air conditioning system, water flow of air conditioning unit, total flow of cold and hot water of air conditioning system, total flow of cooling water, average illuminance and lighting power density.

According to JGJ/T 177-2009 Standard for Energy Efficiency Testing of Public Buildings, the energy efficiency testing of public buildings includes the average indoor temperature, humidity, heat transfer coefficient of non transparent exterior envelope, actual performance coefficient of cold water (heat pump) unit, consistency of return water temperature of water system, temperature difference between supply and return water of water system, pump efficiency, energy efficiency coefficient of cold source system, power consumption per unit air volume of fan, fresh air volume The balance degree of constant air volume system and outdoor temperature of heat source (dispatching center, heating station) shall be tested for energy conservation.

Energy efficiency test of residential buildings is based on JGJ132-2009《 Test standard for energy efficiency of residential buildings 》Energy saving detection shall be carried out for the average indoor temperature, heat transfer coefficient of the main part of the enclosure structure, internal surface temperature of the thermal bridge part of the external protection structure, thermal defects of the external protection structure, thermal insulation performance of the external protection structure, hydraulic balance of the outdoor pipe network, water make-up rate, heat loss rate of the outdoor pipe network, boiler operating efficiency, power consumption and heat transmission ratio, etc.

importance

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on a world-wide scale petroleum 、 coal 、 natural gas The three traditional energy sources are drying up day by day, and mankind will have to turn to higher cost bioenergy, water conservancy, geothermal energy, wind power, solar energy and nuclear energy. The energy problem in China is even more serious. There are four major problems in China's energy development:

① Low per capita energy possession and reserve;

② The energy structure is still dominated by coal, accounting for about 75%. China's annual coal consumption has exceeded 1.3 billion tons;

③ The uneven distribution of energy resources is mainly reflected in the shortage of energy in economically developed areas and the insufficient supply of rural commercial energy, resulting in the transportation of coal from the north to the south, gas from the west to the east, and electricity from the west to the east;

④ The energy utilization efficiency is low, and the energy terminal utilization efficiency is only 33%, 10% lower than that of developed countries. With the rapid development of urban construction, China's building energy consumption has increased significantly year by year, reaching 32% of the total social energy consumption. In addition, the annual energy consumption of housing construction materials production is about 13%, and the total building energy consumption has reached 45% of the total national energy consumption.

China's existing building area is 40 billion m2, most of which are high energy consumption buildings, and nearly 2 billion m2 of new buildings are built every year, of which more than 95% are still high energy consumption buildings. If China continues to implement the design standards with lower energy conservation level, it will leave a heavy energy consumption burden and governance difficulties. Huge building energy consumption has become a huge burden of the national economy. Therefore, comprehensive energy conservation in the construction industry is imperative. Comprehensive building energy conservation is conducive to fundamentally promoting the conservation and rational use of energy resources, and alleviating the contradiction between the supply of energy resources and economic and social development in China; It is conducive to accelerating the development of circular economy and achieving sustainable economic and social development; It is conducive to long-term protection of national energy security, environmental protection, improvement of people's quality of life, and implementation of the Scientific Outlook on Development^[1] 。

Building energy conservation is one of the important links related to building a low-carbon economy, achieving the goal of energy conservation and emission reduction, and maintaining sustainable economic development in China. If we want to do a good job in building energy conservation and achieve various indicators, we need to plan carefully, vigorously promote, and earnestly start from the details.

The work of building energy conservation is complex and arduous. It involves the government, enterprises and ordinary citizens, many industries and enterprises, new buildings and old buildings. It is very difficult to implement. In the initial promotion process of building energy conservation, we must pay energy, cost and price. Seen from the practice effect in recent years, it is very difficult to complete the task and index of building energy conservation only by introducing some simple requirements, measures and methods, which requires us to think again, conduct a more thorough, detailed and in-depth study, and find out the crux.

New buildings must be strictly managed and must meet the building energy efficiency standards, which cannot be ambiguous; For the energy-saving transformation of existing buildings, efforts should be made and more methods should be taken. More pilot experience should be promoted. The principle of "easy before difficult" and "public before private" should be adopted. In the process of building construction, building energy conservation should focus on solving problems such as external wall insulation, window and door insulation, and many building air leaks occur in this regard. In addition, buildings that can use solar energy should maximize the use of this resource, and achieve the integration of solar energy and buildings in the design process to increase the harmony and beauty of the building; Comprehensively promote the water utilization and rainwater collection system, vigorously promote the recycling of waste building materials and construction waste, so that resources can be fully utilized.

For newly-built buildings, as long as the legal system is sound, standards are matched and policies are supported, the energy saving standard can basically reach 50%. However, it is still difficult for many cities to promote the 65% or 75% energy saving standard Building insulation materials Increase measures for requirements of management and technical standards; The transformation of existing buildings and household heating facilities is more difficult, which needs to be considered as a whole, implemented step by step, supported by fiscal and tax policies, and given certain subsidies to speed up the energy-saving transformation of existing buildings. In order to realize that the newly-built buildings can fully meet the energy saving standards, there should be no gaps left; The gradual transformation of existing buildings should be carried out in the order of public buildings, commercial buildings, and then residential buildings, that is, the relatively easy buildings should be transformed first, and then the complex residential energy conservation problems should be solved gradually.

Building energy conservation is a systematic project. In the process of comprehensive promotion, relevant supporting policies and regulations should be formulated, and the mandatory implementation should be strengthened; There should be matching standards, including technical standards, product standards and management standards, to facilitate supervision and inspection during implementation; For new technologies, new processes, new equipment, new materials, new products, etc., we should give policy support and increase market promotion efforts. In a word, to do a good job in building energy conservation, as long as the relevant departments and governments at all levels cooperate and cooperate closely, China's energy conservation goals can be achieved.

China is a large developing country as well as a large construction country. The area of newly built houses is up to 1.7-18 billion square meters every year, more than the total annual building area of all developed countries. With the gradual progress of building a moderately prosperous society in an all-round way, construction has developed rapidly, Building energy consumption Rapid growth. The so-called building energy consumption refers to building use energy consumption, including energy consumption in heating, air conditioning, hot water supply, lighting, cooking, household appliances, elevators, etc. The energy consumption of heating and air conditioning accounts for 60%~70%. There are nearly 40 billion square meters of existing buildings in China, only 1% of which are Energy saving building The rest belong to high energy consumption buildings whether measured from building envelope or heating and air conditioning system. The energy consumption for heating per unit area is 2~3 times that of developed countries with similar latitude. This is due to the poor thermal insulation performance of the building envelope in China, and 2/3 of the heating energy is wasted. However, less than 100 million square meters of new buildings are truly "energy-saving buildings" every year, Building energy consumption Total in China Total energy consumption The share of China has exceeded 27%, gradually approaching 30%.

As China is a developing country with a large population, per capita energy resources are relatively scarce. The per capita arable land is only 1/3 of the world's per capita arable land, and the water resources are only 1/4 of the world's per capita share Coal reserves It only accounts for 11% of the world's reserves, and crude oil accounts for 2.4%. Annual new buildings Solid clay brick And destroyed 120000 mu of fertile land. Compared with developed countries, the material consumption level of steel is 10% - 25% higher, and each cubic meter of concrete is commonly used cement 80 kg, and the sewage reuse rate is only 25%. In order to achieve sustainable development of the national economy, it is imperative and urgent to implement building energy conservation. The waste of building energy in China is extremely serious, and the growth rate of building energy consumption is far faster than the possible growth rate of China's energy production. If such high energy consuming buildings are allowed to continue to develop, the country's energy production will inevitably be unable to support such waste demand for a long time, so it is forced to organize large-scale energy-saving renovation of old buildings, which will consume more manpower and material resources. Actively improving energy efficiency in buildings can greatly alleviate the national energy shortage and promote the development of China's national economic construction. Therefore, building energy conservation is to implement the sustainable development strategy, achieve the national energy conservation planning goals, and reduce emissions greenhouse gases The important measures are in line with the global development trend.

present situation

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The current situation of building energy conservation is divided into the following three points:

1. Building energy consumption accounts for about 1/3 of the total social energy consumption. The total building energy consumption in China has increased year by year, and its proportion in the total energy consumption has risen from 10% in the late 1970s to 27.45%. Building energy consumption in developed countries generally accounts for about 33% of the total national energy consumption. It can be inferred that, according to the research of the Science and Technology Department of the Ministry of Construction, with the acceleration of urbanization and the improvement of people's quality of life, the proportion of building energy consumption in China will eventually rise to about 35%. With such a huge proportion, building energy consumption has become the soft rib of China's economic development.

2. A large proportion of high energy consumption buildings aggravate the energy crisis. Until the end of 2002, China's energy-saving building area was only 230 million square meters. More than 40 billion square meters of houses have been built in China, which belong to high energy consuming buildings. The total amount is huge, and there is a huge potential energy crisis. As pointed out by the relevant person in charge of the Ministry of Construction, by the end of 2000, China's annual consumption of commercial energy amounted to 376 million tons of standard coal, accounting for 27.6% of the total end energy consumption of the whole society, and the "contribution rate" of the increase in building energy consumption to the national greenhouse gas emissions has reached 25%. Due to the large proportion of high energy consumption buildings, 18 million tons of standard coal is consumed annually in the northern heating areas alone, Direct economic loss It reached 7 billion yuan, and discharged 520000 tons of carbon dioxide. If this situation is allowed to continue to develop, China's building energy consumption will reach 108.9 billion tons by 2020; By 2020, the peak load of air conditioning in summer will be equivalent to the full load capacity of 10 Three Gorges power stations, which will be a very surprising number. According to analysis, China is in the peak period of construction. The area of houses built every year is up to 1.6 billion to 2 billion square meters, more than the total annual building area of all developed countries, and more than 97% are high energy consumption buildings. With such construction growth rate, it is estimated that by 2020, the area of high energy consumption buildings in China will reach 70 billion square meters. Therefore, if we do not start to pay attention to building energy-saving design, it will directly exacerbate the energy crisis.

3. The situation of building energy conservation in China is backward and needs to be improved urgently. After the energy crisis in the 1970s, developed countries began to devote themselves to the research and implementation of building energy conservation technology, but China ignored this problem. Today, China's building energy efficiency level is far behind the developed countries. For example, the thermal function of building envelope in most heating areas in China is much worse than that in developed countries with similar climate. The heat transfer coefficient of the external wall is 3.5 to 4.5 times of theirs, that of the external window is 2 to 3 times, that of the roof is 3 to 6 times, and that of the doors and windows is 3 to 6 times. The actual annual heating energy consumption of residential buildings in European countries has generally reached 6 liters of oil per square meter, which is equivalent to about 8.57 kilograms of standard coal per square meter. In China, the heating energy consumption of buildings that achieve 50% energy saving also reaches 12.5 kilograms per square meter, about 1.5 times that of European countries. For example, Germany, whose climate conditions are generally similar to those in Beijing, had the same standard of building heating energy consumption as Beijing's current level before 1984, consuming 24.6 to 30.8 kilograms of standard coal per square meter per year. However, by 2001, Germany's figure had dropped to 3.7 to 8.6 kilograms of standard coal per square meter, reducing its building energy consumption to about 1/3 of the original level, while Beijing has always been 22.45 kilograms of standard coal per square meter.^[2]

Technical approach

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Reduce total energy demand

According to statistics, in developed countries, air conditioning and heating energy consumption accounts for 65% of building energy consumption. The recent growth rate of energy consumption for heating, air conditioning and lighting in China has been significantly higher than that of energy production. Therefore, reducing the energy consumption for cooling, heating and lighting of buildings is an important part of reducing the total energy consumption of buildings, which can generally be achieved from the following aspects.

1 Building planning and design

In the face of global energy and environmental problems, many new design concepts have emerged, such as micro row buildings, low energy consumption buildings Zero energy building In essence, they require architects to start from the overall comprehensive design concept and adhere to close cooperation with energy analysis experts, environmental experts, equipment engineers and structural engineers. In the planning and design of buildings, according to the impact of a wide range of climatic conditions Specific environment Climate characteristics, attach importance to the use of natural environment (such as external air flow, rain, lakes and greening, topography, etc.) to create a good indoor microclimate of buildings, so as to minimize dependence on building equipment. The specific measures can be summarized in the following three aspects: reasonable selection of the building address and reasonable external environment design (the main method is to arrange trees, vegetation, water surface, rockery and enclosure around the building); Reasonably design the building shape (including the overall building volume and Building orientation To improve the existing microclimate; Reasonable architectural form design is to make full use of the outdoor building Microenvironment The key part to improve the indoor microenvironment of the building is mainly realized through the structural design of various parts of the building and the reasonable separation design of the internal space of the building. At the same time, relevant software can be used for optimization design, such as building shadow simulation in Tianzheng Building (II) to assist in the design of building orientation and Residential quarter Road, greening, outdoor leisure space and CFD software, such as PHOENICS, Fluent, etc., are used to analyze whether the indoor and outdoor air flow is smooth.

2 Enclosure

Building envelope components (roof, wall foundation 、 Thermal insulation material 、 sealing material , doors and windows, sunshade facilities) on building energy consumption, environmental performance Indoor Air Quality It has a fundamental impact on the user's visual and thermal comfort environment. Generally, the cost of increasing the enclosure structure is only 3%~6% of the total investment, while the energy saving can reach 20%~40%. By improving the thermal performance of building envelope, outdoor heat can be reduced in summer and indoor heat loss can be reduced in winter thermal environment It can be improved to reduce the cold and heat consumption of buildings. First of all, improving the thermal performance of all components of the enclosure structure is generally implemented by changing the thermal performance of its constituent materials, such as the newly developed thermal diode wall in the European Union (low-cost thin thermal diode only allows one-way heat transfer, which can produce thermal insulation effect) and the glass whose thermal performance changes dynamically with seasons. Then, according to the local climate, the geographical location and orientation of the building, and under the guidance of the calculation results of the building energy consumption software DOE-2.0, the optimal design method of the envelope combination is selected. Finally, the technical and economic feasibility of each component and combination of the enclosure structure is evaluated to determine the enclosure structure that is technically feasible and economically reasonable.

3. Improve energy efficiency of end users

Energy efficient heating and air conditioning systems can really reduce energy consumption of heating and air conditioning only when they are in parallel with the above measures to reduce indoor cooling and heating loads. First, according to the characteristics and functions of the building, design energy-efficient HVAC equipment systems, such as heat pump systems, energy storage systems and district heating and cooling systems. Then, the energy management and monitoring system is used to monitor and control the indoor comfort, indoor air quality and energy consumption. For example, European countries measure the temperature, humidity and sunshine Then, based on the building dynamic model, the heating and air conditioning loads are predicted to control the operation of the HVAC system. For other household appliances and office equipment, energy-saving certified products should be used as far as possible. For example, the United States generally encourages the use of "Energy Star" products, while Australia implements minimum energy efficiency standards (MEPS) for energy intensive household appliances.

4 Improve overall energy efficiency

from Primary energy In the process of converting to the terminal energy used by the building equipment system, there is a great loss of energy. Therefore, the evaluation should be carried out from the whole process (including mining, processing, transportation, storage, distribution and terminal utilization) to comprehensively reflect the energy utilization efficiency and the impact of energy on the environment. Energy consumption equipment in buildings, such as air conditioners, water heaters, washing machines, etc., should be energy efficient Energy supply 。 For example, as fuel, natural gas ratio electric energy The overall energy efficiency of is higher. Adopt the second generation energy system It can make full use of different grades of heat energy to maximize energy utilization efficiency, such as CHP and CCHP.

Utilize new energy

The utilization of new energy plays a vital role in energy conservation and environmental protection. New energy usually refers to unconventional renewable energy, including solar energy, geothermal energy Wind energy , biomass energy, etc. People have carried out extensive exploration on various solar energy utilization methods, gradually defined the development direction, and initially made some use of solar energy, such as: ① As an important project in solar energy utilization, Solar thermal power generation The technology is relatively mature. The United States, Israel, Australia and other countries have invested in the construction of a number of experimental solar thermal power stations, which are expected to realize the commercialization of solar thermal power generation in the future; ② along with Solar photovoltaic power generation Many photovoltaic power stations and "solar roof" demonstration projects have been built abroad, which will promote the rapid development of grid connected power generation system; ③ There are tens of thousands of sets in the world PV water pump Operating in various places; ④ Solar water heater The technology is relatively mature and has corresponding technical standards and specifications, but the function of solar water heater still needs to be further improved and strengthened Solar energy building Integrated construction; ⑤ passive solar building Because of its simple structure and low cost, it has been widely used. Its design technology has been relatively mature, and there are design manuals for reference; ⑥ Solar absorption refrigeration technology appeared earlier and has been applied in the field of large-scale air conditioning; Solar adsorption refrigeration At the stage of prototype development and experimental research; ⑦ Solar drying and Solar cooker It has been popularized and applied to a certain extent. However, in general, the scale of solar energy utilization is not large, the technology is not perfect, and the degree of commercialization is also low. It still needs to continue in-depth and extensive research. When using geothermal energy, on the one hand, high temperature geothermal energy can be used for power generation or directly for heating and hot water supply; On the other hand, with the help of Ground source heat pump And underground air systems use low-temperature geothermal energy. Wind power generation is more suitable for windy coastal mountain areas and high-rise buildings prone to strong wind. There are successful engineering examples in Britain and Hong Kong, but in the building field, the more common Wind energy utilization The form is natural ventilation.

new technique

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The ideal energy-saving building should Energy consumption The following three points shall be met: first, solar radiation can be controlled to receive or prevent in different seasons and regions; Second, it can maintain indoor comfort in different seasons; Third, it can realize necessary ventilation in the room. The ways of building energy conservation mainly include: minimizing Non renewable energy To improve the efficiency of energy use; Reduce the energy loss of building envelope; Reduce the energy consumption of building facilities. In these three aspects, high-tech plays a decisive role. Of course, building energy conservation also uses some traditional technologies, but these traditional technologies can only be used in modern buildings on the basis of advanced experimental demonstration and scientific theoretical analysis.

Reduce energy consumption and improve energy efficiency

In order to maintain the environmental quality of the living space, heating is required to increase the indoor temperature in cold seasons, cooling is required to reduce the indoor temperature in hot seasons, humidification is required when dry, and dehumidification is required when wet, which often requires energy consumption to achieve. From the perspective of energy conservation, the efficiency of the heating (cooling) system should be improved, including the efficiency of the equipment itself, the efficiency of pipe network transmission, the metering of the user end, and indoor environment The efficiency of the control device. These all require the corresponding industries to design, install, operate quality, adjust energy-saving systems, equipment and materials Operation and management mode And so on. If in heating system In terms of energy conservation, there are three new technologies:

① The computer, balance valve and special intelligent instrument are used to reasonably distribute the flow of the pipe network, which not only improves the heating quality, but also saves energy;

② Heat distribution meter and Temperature regulating valve Users can consume and control heat energy as required to achieve the dual effect of comfort and energy saving;

③ Adopt new Thermal insulation material Wrap the heating pipeline to reduce the heat loss of the pipeline.

In recent years, the low-temperature floor radiation technology has been proved to have good energy-saving effect Cross linked polyethylene (PEX) pipes are used as water pipes, and two-way circulating disks are used in the ground floor in a special way to supply low-temperature hot water (geothermal, solar or various low-temperature waste heat) to the pipes in winter; The input of cold water in summer can reduce the surface temperature (only used for heating in China); Compared with the radiator mainly for convection heat dissipation, this technology has the advantages of uniform indoor temperature distribution, comfort, energy saving, easy measurement, convenient maintenance, etc.

Reduce energy loss of building envelope

The energy loss of building envelope mainly comes from three parts: ① exterior wall ；② Doors and windows; ③ roof. The energy-saving technologies in these three parts are of great concern to the construction industry of all countries. The main development direction is to develop efficient and economical thermal insulation and thermal insulation materials and practical structural technology to improve the thermal insulation, thermal insulation and sealing performance of the enclosure structure.

External wall energy saving technology

External wall insulation system

As far as wall energy conservation is concerned, the traditional method of increasing wall thickness with heavy single material to achieve thermal insulation can no longer meet the requirements of energy conservation and environmental protection, and composite walls are increasingly becoming the mainstream of walls. Composite walls are generally made of block materials or reinforced concrete As a load-bearing structure, and insulation material Composite, or use thin wall materials for thermal insulation in frame structures, and use thermal insulation materials as walls. Thermal insulation materials for buildings mainly include rock wool, slag wool, glass wool, polystyrene foam Expanded perlite 、 Expanded vermiculite 、 aerated concrete and Rubber powder polystyrene particles size Foamed cement insulation board Etc. The production and manufacture of these materials require special processes and equipment, which are beyond the reach of traditional technology. It is worth mentioning that the glue powder polyphenyl granule slurry is made by mixing the glue powder and polyphenyl granule light aggregate with water to form a slurry, which is plastered on the external surface of the wall to form a cavity free insulation layer. Polyphenylene granule The aggregate is made of recycled waste polystyrene board by crushing, while the rubber powder is mixed with a large amount of fly ash, which is a waste utilization, energy conservation and environmental protection material. There are three kinds of wall composite technology: internal insulation layer, external insulation layer and sandwich insulation layer. The sandwich insulation method is widely used in China; In European countries, most of them adopt the method of externally attached foamed polystyrene board. In Germany, external thermal insulation buildings account for 80% of the total buildings, and 70% of them use foamed polystyrene board.

Energy saving technology of doors and windows

Doors and windows have the functions of lighting, ventilation and enclosure, and also play an important role in architectural art processing. However, doors and windows are the most likely parts to cause energy loss. In order to increase the area of lighting and ventilation or show the characteristics of modern buildings, the area of doors and windows of buildings is becoming larger and larger, and there are more glass curtain walls. This puts forward higher requirements for energy conservation of external maintenance structures.

The energy-saving treatment of doors and windows is mainly to improve the thermal insulation performance of materials and the airtightness of doors and windows. From the perspective of door and window materials, in recent years, there have been aluminum alloy thermal cutoff profiles, aluminum wood composite profiles, steel plastic integral extrusion profiles, plastic wood composite profiles and UPVC Plastic profile And other energy-saving products with high technical content.

Among them, UPVC plastic profiles are widely used, and the raw materials used are polymer materials -- hard polyvinyl chloride 。 It not only consumes less energy and is pollution-free in the production process, but also has small thermal conductivity of materials and good sealing performance of multi cavity structure, so it has good thermal insulation performance. UPVC plastic doors and windows have been used for many years in European countries, and plastic doors and windows have accounted for 50% in Germany.

Since the 1990s, the consumption of plastic doors and windows has been increasing in China, gradually replacing steel, aluminum alloy and other energy consuming materials. In order to solve the problem of excessive energy loss caused by large area of glass, people have applied high and new technologies to Ordinary glass Processed into Hollow glass , plated FILM GLASS (including reflective glass and heat absorbing glass) High strength LOW2E Fireproof glass (High strength and low radiation coating fireproof glass), magnetron vacuum sputtering method for coating glass containing metallic silver layer, and the most special Smart glass 。 Smart glass can sense and respond to changes in external light. There are two types of smart glass. One is photochromic glass. When exposed to light, the glass will become dark and the light will not be easily penetrated; When the light is stopped, the glass is restored and the light can pass through. stay sunlight When it is strong, it can block the solar radiation heat; When it is cloudy, the glass becomes bright and the sunlight can enter the room again. The other is EC Mirror The two pieces of glass are coated with conductive films and color changing substances. By adjusting the voltage, the color changing substances can change color, and the incoming sunlight can be adjusted (but because of its high production cost, it can not be actually used). These glasses have good energy saving effects.

Roof energy-saving technology

The heat preservation and heat insulation of roof is one of the key points of energy conservation of building envelope. Thermal insulation layer shall be set on the roof in cold areas to prevent indoor heat loss; In hot areas, heat insulation and cooling layers shall be set on the roof to prevent the radiant heat of the sun from being transmitted indoors; In areas where winter is cold and summer is hot (from the Yellow River to the Yangtze River basin), building energy conservation should take into account both winter and summer. The common technical measure for thermal insulation is to set a small thermal conductivity under the roof waterproof layer Lightweight materials Used for thermal insulation, such as expanded perlite, glass wool, etc. (this is the forward laying method); It can also be set above the roof waterproof layer polystyrene Foam (this is the reverse paving method). Another method of insulating layer in Britain is to use recycled waste paper to make paper fiber. This paper fiber has low energy consumption and excellent thermal insulation performance. The paper fiber can also be fireproof after being treated with borax flame retardant. During construction, the nail layer of the roof is sandwiched first, and then the paper fiber is sprayed into the roof to form a thermal insulation layer. The methods of roof thermal insulation and cooling include overhead ventilation, roof water storage or regular water spraying, roof greening, etc. The above practices can be met to varying degrees Roof energy conservation But the most respected is to use intelligent technology and ecological technology to realize the desire of building energy conservation, such as Solar collector Roof and controllable ventilation roof, etc.

Reduce energy consumption of building facilities

Heating, cooling and lighting are the main parts of building energy consumption. Reducing this part of energy consumption will play an important role in energy conservation. Some successful technical measures in this regard are of great reference value, such as the energy-saving office building of the British Building Research Institute (BRE). The office building adopts an advanced energy-saving control system in terms of building envelope, and the interior of the building adopts transparent interlayer for natural ventilation; The air enters through the lattice window on the back of the building, and the air is exhausted through the lattice window on the top wall of the front of the building, forming natural ventilation throughout the building. High efficiency cold and hot boilers and conventional boilers are used in the office building, and the two boilers are alternately controlled by the computer system. The room temperature is regulated by the heating and cooling piping system buried in the floor. The building also adopts the technology of inputting cold water under the floor and cooling through radiators Water pump Cold water is pumped from the ground into the radiator, and then recharged by another water return well near the building. To reduce Artificial lighting The office building adopts all-around combined daylighting lighting , controlled by the building management system; Each unit has daylight, and users and managers can remotely control the system through detectors; In the lecture hall of 100 seats, there are two types of lighting systems, allowing 0%~100% brightness. Energy saving tubular fluorescent lamps and Incandescent lamp So that each audience can enjoy the same good visual effect and appropriate temperature.

Development and utilization of new energy

While saving non renewable energy, human beings are also seeking to develop and utilize new energy to adapt to the reality of population growth and energy depletion, which is the mission entrusted to modern people by history. The effective development and utilization of new energy must rely on high-tech. Such as the development and utilization of solar energy, wind energy Tidal energy Hydraulic, geothermal and other renewable natural energy must rely on advanced technical means, and must be constantly improved and improved to achieve more effective use of these energy. For example, people can not only use Solar heating ， solar heater It can also convert solar energy into electric energy, and integrate photoelectric products with building components, such as photoelectric roof panels, photoelectric exterior wall panels, photoelectric sun visors, photoelectric window walls, photoelectric skylights, and photoelectric glass curtain walls, so as to turn energy consumption into productivity.

Material development

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External wall insulation and finishing system (EIFS)

This system was the last one in the late 1970s energy crisis It was first used in commercial buildings, and then began to be used in civil buildings. Today, EIFS system accounts for 17.0% of the use of external walls of commercial buildings and 3.5% of the use of external walls of civil buildings, and its use in civil buildings is growing at an annual rate of 17.0%~18.0%. This system is a multi-layer composite external wall insulation system, which can be used in both civil and commercial buildings. The ELFS system includes the following parts: the main part is composed of Polystyrene foam The thermal insulation board is generally 30~120mm thick, and this part is fixed to the external wall of the building by synthetic adhesive or mechanical means; The middle part is durable and waterproof polymer mortar Base course, which is mainly used on the insulation board to enhance and convey the role of external forces with glass fiber mesh; The outermost part is a beautiful and durable surface coating. In order to prevent fading and cracking, the coating material generally adopts acrylic copolymer coating technology, which has a variety of colors and textures to choose from, and has strong durability and corrosion resistance.

Building thermal insulation board system (SIPS)

This material can be used in civil and commercial buildings, and is a high-performance wall, floor and roof material. The middle of the board is polystyrene foam or polyurethane foam sandwich layer, which is generally 120~240mm thick. Different flat surface layers can be used on both sides as required, for example, engineering plywood wood products can be used on both sides of the building. The building built with this material has the characteristics of high strength, good thermal insulation effect, low cost, simple construction, energy conservation and environmental protection. SIPS is generally 1.2m wide, and the maximum length can be 8m. The size of SIPS is serialized. Many factories can also customize according to the actual size according to the project needs, and supply complete sets. The contractor only needs to assemble at the site, which truly realizes the industrialization of residential production.

Insulated cement formwork external wall system (ICFS)

The product is an insulation formwork system, which is mainly made of recycled polystyrene foam plastic and cement cementing materials, and is used for on-site pouring of concrete walls or foundations. During construction, horizontal or vertical reinforcement shall be provided inside the formwork. After the wall is completed, the insulation formwork will be used as a part of the permanent wall to form a concrete wall with thermal insulation both outside and inside the wall. The formwork material wrapped on the concrete wall meets the requirements for thermal insulation, sound insulation, fire prevention, etc. required by the external wall of the building.

Energy saving transformation

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The overall and external environment design of the building is based on the analysis of the climate and environmental conditions around the building. Through the design of site selection, planning, external environment and shape orientation, the building can obtain a good external microclimate environment and achieve the purpose of energy conservation.

Reasonable site selection

The site selection of buildings is mainly determined according to the comprehensive conditions of local climate, soil quality, water quality, terrain and surrounding environmental conditions. In architectural design, it is necessary to maintain a suitable microclimate environment in the whole life cycle of the building, create conditions for building energy conservation, and at the same time not destroy the balance of the overall ecological environment.

Reasonable external environment design

After the building location is determined, its microclimate characteristics should be studied. According to the requirements of building functions, the existing microclimate environment should be improved through reasonable external environment design to create a favorable environment for building energy conservation. The main methods are: ① Arrange trees and vegetation around the building, which can effectively block sand, purify air, as well as shade and reduce noise; ② Create artificial natural environment, such as setting water surface near buildings, using water to balance the ambient temperature, reduce wind and sand, and collect rainwater.

Reasonable planning and shape design

Reasonable architectural planning and shape design can effectively adapt to the harsh microclimate environment. It includes the determination of the overall building volume, building shape and building shape combination, building sunshine and orientation. Like the round plane of the yurt, the conical roof can effectively adapt to the harsh climate of the grassland, reducing the heat dissipation area of the building and resisting wind and sand; For humid and hot coastal areas, the introduction of natural ventilation is very important for energy conservation. In terms of planning and layout, different air pressures can be formed on the sunny side and the shady side of the building. Even when there is no wind, ventilation can be formed. In terms of building shape design, wind tunnels can be formed to allow natural wind to whirl in them and obtain good ventilation effect, so as to achieve the purpose of energy conservation. The principle of sunshine and orientation selection is to get enough sunshine in winter and avoid the dominant wind direction, and to use natural ventilation and minimize solar radiation in summer. However, many factors should be considered in the design of the orientation, orientation and general layout of the building. The building is restricted by social, historical and cultural conditions, terrain, urban planning, roads, environment and other conditions. It is usually difficult to make the orientation of the building meet the requirements of both heat protection in summer and heat preservation in winter. Therefore, we can only weigh the gains and losses among various factors to find a balance point, Select the best orientation and better orientation suitable for the climate environment in this area.

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Denmark, as the world's oldest and most stringent building energy conservation regulations, is worth learning. 1956 Suez Crisis The rise in oil prices caused Denmark to worry about the security of energy supply. One of the reasons is that Denmark relied heavily on energy imports at that time. The Suez Canal crisis led Denmark to put forward energy efficiency requirements for the first time in the 1961 building code. In 1970, with the rise of OPEC oil prices, Danes' concerns were further intensified. The Danish government introduced a series of long-term, medium and short-term energy conservation and emission reduction measures. The long-term measure is to re-establish a complete Danish energy supply system; The short-term and medium-term measures include carrying out energy conservation publicity, levying energy consumption tax and putting forward stricter requirements for building energy conservation. Since the 1990s, concerns about global warming and the desire for long-term energy supply security have directly affected Denmark's policy orientation. The Danish government then set itself the goal of "becoming a country with 100% zero dependence on fossil energy by 2050". Denmark's energy conservation policy has achieved remarkable results after decades of implementation. Today, compared with the general standards of most other countries with similar climate, the energy-saving effect of new buildings in Denmark is particularly prominent.

The maximum energy demand allowed per square meter of heated floor space per year is far lower than that of Sweden, Norway, the United Kingdom, the United States, Germany and other countries.

Facts have proved that long-term urban planning is a powerful driving force behind the development of low-energy buildings in Denmark. Denmark has a long tradition of urban planning, which is mainly divided into national planning, regional planning (especially the Greater Copenhagen area) and local planning. In Denmark, local governments are the main planners of sustainable municipal plans. They are responsible for the overall development of independent single buildings in urban areas or energy-saving buildings in designated areas.

Copenhagen, the capital of Denmark, with nearly 3.84 million residents, plans to become the world's first Carbon neutralization city. In August 2012, the city council passed the Copenhagen 2025 Climate Plan. When Copenhagen carbon dioxide When the net emissions are zero, the city will be carbon neutral, that is, Copenhagen's carbon emissions will be reduced to the minimum. The rest is offset by external measures, including large-scale reconstruction of existing buildings, energy supply and transportation mode restructuring.

Danish building code requirements are a very effective means in the process of Danish green urbanization. These specifications not only improve the energy-saving performance of new buildings, but also stimulate innovation, so as to increase cost-effectiveness and promote development in general. It may be called a unique building code requirement in Denmark, which is aimed at the energy performance of the whole building rather than individual components. In addition, it has detailed supplementary provisions for building envelope and installation. These requirements set the only minimum legal goal for the overall energy consumption performance level, but did not specify the method to achieve this goal. This performance approach stimulates innovation and leads to cost-effective solutions. Detailed requirements ensure that the energy performance of all parts of the whole building is taken into consideration. Denmark is a pioneer in the field of green energy system. Its persistent and active policies show that it is possible to reduce the use and dependence on fossil fuels while maintaining economic growth. Classifying the energy efficiency standards of future buildings - Denmark's 2015 and 2020 plans - is an important political message, which provides investors and contractors with a long-term investment perspective, and encourages innovation to develop better and more cost-effective low-energy building technologies and materials. This is a key step towards the goal of Denmark becoming a zero fossil fuel society by 2050.

Denmark aarhus school of architecture The joint teaching of green and sustainable development buildings has been carried out jointly with Tsinghua University in China. China has been tracking and learning the advanced concepts, technologies and experience of building energy conservation in developed countries. Denmark is the earliest in the world Building energy conservation And urban heating energy conservation, and one of the countries that has made remarkable achievements, is also one of the first countries to enter China to spread building energy conservation and Heating metering China has played a positive role in promoting building energy conservation and heat metering in China. China is willing to continue to actively carry out international scientific and technological cooperation with Denmark and other developed countries, further improve the technical level of building energy conservation and low-carbon ecological cities, and make greater contributions to combating climate change.

Journal of Building Energy Efficiency

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from China Northeast Architectural Design and Research Institute It is in charge of the scientific and technological periodicals in the field of building energy conservation that are publicly issued at home and abroad. Promote building energy-saving technologies and products through publicity and promotion of energy-saving policies and standards. Increase the promotion and application of mature technologies and products for building energy conservation, promote independent innovation and development of building energy conservation technology, and improve the level of building energy conservation technology in China. The main content is to publish building energy-saving technology, process, design, equipment and materials.^[3]

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