Industry News

Solar Energy Information: Building Energy Efficiency Technology and Solar Green Buildings Application and Development Vision

2018-09-17

The use of solar energy technology will be an important way for humans to obtain energy in the future. In human social activities, the use of underground resources has already faced a lack of dilemma, which is bound to affect human survival. Building with solar energy will be a path that will work. Building energy conservation has become a major concern. Today's society pays great attention to the energy consumption of building engineering and the long-term energy consumption in the use of buildings. Therefore, it is necessary to promote the application of solar energy building technology according to the energy-saving requirements of building design.

The use of solar energy technology will be an important way for humans to obtain energy in the future. In human social activities, the use of underground resources has already faced a lack of dilemma, which is bound to affect human survival. Building with solar energy will be a path that will work. Building energy conservation has become a major concern. Today's society pays great attention to the energy consumption of building engineering and the long-term energy consumption in the use of buildings. Therefore, it is necessary to promote the application of solar energy building technology according to the energy-saving requirements of building design.



Solar thermal technology is the most widely used in building energy conservation. Currently, solar power generation systems have low photoelectric conversion rate to solar energy, and are solar hot water and passive solar heating technologies. China's solar thermal light and heat are largely lost, and the thermal → electric → thermal energy secondary conversion, the development of the water system began in the 1980s, but the solar energy simplification increased the energy in the process of conversion and transmission. The loss is simply converted directly into the heating of domestic water, staying at a low level of application, and the utilization rate of solar energy is lower. In view of the above situation, the solar hot water system in Europe is mainly used as an auxiliary heat source to operate in conjunction with a conventional energy system. It proposes the integration of solar walls, photovoltaic modules and building walls. The solar energy system that combines power generation, heating, ventilation and building protection structures while supplying living and bathing hot water is also typical solar low-temperature floor radiation for building heating. . The outermost layer of the wall is the photoelectric curtain wall, the principle of the ampere heat exchange system. The integration with the building has become the goal and direction of the development of the solar water heating system by the fresh air system or the direct discharge chamber entering the air conditioner through the air duct at the top; and the insulation performance of the enclosure structure is significantly improved.

1 Advantages and advantages of combining solar energy with architecture

1.1 The combination of solar technology and construction can effectively reduce building energy consumption.

1.2 Solar energy is combined with building. The panels and collectors are installed on the roof or roof, which does not require additional land occupation and saves land resources.

1.3 The combination of solar energy and construction, on-site installation, on-site power generation and supply of hot water, does not require additional transmission lines and hot water pipes, reducing the dependence on municipal facilities, and reducing the pressure on municipal construction.

1.4 Solar products have no noise, no emissions, no fuel consumption, and are easily accepted by the public.

2 Energy-saving technologies for buildings

Building energy conservation is an important indicator of technological progress, and the use of new energy is an important part of achieving sustainable development of buildings. Under the current conditions, the following five technical measures are taken for building energy conservation:

2.1 Reduce the external surface area of the building. The measure of the external surface area of a building is the figure factor. The focus of controlling the shape factor of a building is the flat design. When there are too many planes and convexities, the surface area of the building will increase. For example, in the design of residential buildings, the problem of opening windows in bedrooms and bathrooms is often encountered. Because the windows in the bathroom are recessed into the plane, the external surface area of the building is invisibly increased. In addition, there are bay windows, drying platforms and other structures to save energy. Very unfavorable. Therefore, when designing a plane, it is necessary to comprehensively consider a variety of factors, while satisfying the function of use, the shape coefficient of the building is controlled within a reasonable range. In addition, in the façade modeling, the layer height control also affects the building shape factor. In the 21st century, many high-rise buildings adopt rectangular flat and rectangular combinations, which reduce the external surface area of the building, and the overall size is harmonious. It also maintains the appearance of the building and is beneficial to building energy conservation. It reflects the new thinking of architectural design concepts.

2.2 Pay attention to the design of the envelope structure. The energy and thermal consumption of buildings is mainly reflected in the external protective structure. The design of the envelope structure mainly includes: selecting the material and structure of the envelope structure, determining the heat transfer coefficient of the envelope structure, calculating the average heat transfer coefficient of the outer wall under the influence of the surrounding cold and hot bridge, thermal performance index of the envelope structure and insulation layer Calculation of thickness, etc. Adding a certain thickness of thermal insulation material on the outside or inside of the outer wall to improve the thermal insulation performance of the wall is an important measure for energy saving of the wall at this stage. At present, most of the external wall insulation is made of polystyrene foam board. In the construction process, according to the construction procedure of the thermal insulation material, the bonding and fixing of the thermal insulation board are strengthened, and the quality of the edge and the bottom is ensured to achieve the thermal insulation effect. At the same time, the roof is the part with the most heat fluctuations, and effective measures are needed to increase the insulation effect and durability.

2.3 Reasonable control of the proportion of window wall area. There are also external doors and windows that are in contact with the natural environment. Many analyses and tests have shown that doors and windows account for about 50% of total thermal energy consumption. Energy-saving design of doors and windows will significantly improve energy-saving effects. Door and window frame materials with high thermal resistance values must be selected. Nowadays, many door and window frame materials are commonly used in plastic-lined steel frames, heat-dissipating aluminum alloy frames, and low-emission coated insulating glass. The airtightness of the window should be good, and the proportion of the window wall area should be carefully controlled. There should be no large windows and bay windows in the north, and the bay window should not be used in other directions. In engineering practice, many residential buildings take large windows for facade effects. In the case that the large area of the window cannot be reduced, measures should also be taken: if the window is arranged as far as possible on the south side, the fixed fan of the window is added, the sealing of the frame and the edge of the fan is tightened, and the calculation and calculation are carried out according to the regulations to achieve the building. Overall energy efficiency.

2.4 Strengthen the thermal insulation measures of other parts. Other parts of the thermal insulation measures such as floor, floor, slab and hot and cold bridge parts for thermal insulation. Floor treatment inside and outside the building in cold and cold regions, no heating stair wall and light transmission window, unit door entrance treatment, balcony floor and door window treatment. Need to pay attention to is: the door that meets the outside world should choose the insulation door, the outer bay window should use the upper and lower pick-up plate and the side plate, and all the plates that come into contact with the outside must be insulated and energy-saving. Nowadays, the building uses special energy-saving design software to meet various thermal indicators through comprehensive calculation. According to the thermal index, the corresponding structural measures should be taken to make the building as a whole meet the energy-saving requirements.

2.5 Take other energy-saving measures to achieve energy-saving goals. In addition, other energy-saving control measures such as installing a heat meter, a heat control switch, etc., to maintain a balanced temperature are also necessary means to reduce energy consumption. In fact, the main content of building energy conservation, in addition to heating and air conditioning, should include ventilation, household electrical, hot water and lighting. If all household electrical energy is energy-saving products, the potential for energy conservation is even more pronounced.

3 Solar building technology

Solar buildings can be divided into active and passive types. Buildings that use mechanical devices to collect and store solar energy and provide heat to the room when needed are called active solar buildings; according to local climatic conditions, through the use of building layout, construction processing, selection The high-performance thermal materials enable the building itself to absorb and store the amount of solar energy, thereby achieving heating, air conditioning, and hot water supply, called passive solar buildings.

The layout of solar buildings should try to use the long side as the north-south direction. Make the heat collecting surface within plus or minus 30° in the positive south direction. According to the local meteorological conditions and location, make appropriate adjustments to achieve the best sun exposure. The heat received between the heat collecting and heat storage walls is a form of passive solar building. It makes full use of the characteristics of solar radiation heat in the south direction, and adds a light-transmissive outer cover on the south wall to form an air layer between the light-transmitting cover and the wall. In order to maximize the sun exposure inside the light-transmitting cover, a heat absorbing material is applied to the inner wall surface of the air interlayer. When the sun is shining, the air and the wall in the air interlayer are heated, and the heat absorbed is divided into two parts. After heating a part of the gas, the airflow is formed by the temperature difference pressure, and the indoor air is circulated and convected by the upper and lower vents connected to the indoor room, thereby increasing the indoor temperature; and the other part of the heat is used to heat the wall, and the heat storage capacity of the wall is utilized. The heat is stored, and when the temperature is lowered after the night, the heat stored in the wall is released to the room, thereby achieving a suitable temperature for day and night.

When the summer heat comes, the air layer in the light-transmitting cover is opened to the outdoor vent, and the vent connected to the indoor is closed. The upper part of the outdoor vents is open to the atmosphere, and the lower vents are preferably connected to a location where the ambient air temperature is low, such as in the shade of the sun or in the underground space. When the temperature of the air layer is heated, the airflow rapidly flows to the upper vent, and the hot air is discharged to the outside. As the air continues to flow, the cool air passing through the lower vent enters the air layer, and then the air layer The temperature is lower than the outdoor temperature, and the indoor hot air dissipates heat through the wall to the air layer, thereby achieving the effect of lowering the room temperature in summer.

As can be seen from the passive working principle, material properties occupy an important position in solar buildings. The light-transmitting material is traditionally used for glass, and the light transmittance is generally between 65 and 85%, and the light-receiving plate used now has a light transmittance of 92%. Material for heat storage: use a wall of a certain thickness, or change the material of the wall, such as taking a water wall as a heat storage body to increase the heat storage of the wall. In addition, the heat storage room is also a heat storage method. The traditional practice of the heat storage room is to stack the pebble in the heat storage room, heat the pebbles when the hot air flows through the heat storage room, and enter the night or rainy days. The heat that is dissipated is then delivered to the room. Because passive solar buildings are simple and easy to implement, solar buildings are widely used, such as multi-story buildings, communication stations, and residential buildings. Nowadays, the high-rise building also adopts this principle: the glass curtain wall is layered, and the controllable inlet and outlet vents are arranged at the lower joint of the outer wall slab. This not only adopts solar energy but also beautifies the building façade, which is a concrete embodiment of solar energy technology.

Active solar buildings use mechanical equipment to transport the collected heat to various rooms. In this way, the absorption surface of the solar energy can be expanded, such as the roof, the slope and the courtyard, where the sunlight is strong, and it can be used as the absorption surface of the solar energy. At the same time, you can also set up a heat storage room where you need it. In this way, the heating system and the hot water supply system are combined into one, and effective heat control equipment is applied to make the utilization of solar energy more reasonable.

The operation process of the active solar heating system is: the system is equipped with two fans, one is a solar collector fan and the other is a heating fan. When directly heating by solar radiation, the two fans operate at the same time, so that the air in the room directly enters the solar collector. Then return to the room, such as rainy days, when the heat is low, the auxiliary heating is used, and the heat storage room does not work. The hot air system uses an electric damper to control airflow, and when direct heating occurs, the two electric dampers in the air controller are diverted to allow air to flow into the room. The hot water coil at the outlet of the solar collector allows the hot water supply system of the room to be integrated with the solar heating system.

When the heat collected by the solar collector exceeds the needs of the room, the collector fan starts and the heater fan stops. The motor door leading to the room is closed. The hot air from the solar collector flows down to the pebble layer of the heat storage room, and the heat is stored in the pebble until the pebble layer is heated, so that the heat storage in the heat storage room is saturated. When there is no solar radiation at night, heat is taken from the heat storage room. At this point, the first electric damper in the air controller is closed, the second electric damper is opened, and the heating fan is started, so that the indoor air circulation is heated from bottom to top through the cobble layer of the heat storage room, and then returned to the heating regulation system. When there is sufficient heat in the heat storage room, the temperature of the air entering the air conditioner is only lower than the temperature directly from the solar collector. This cycle will continue until the heat difference between the cobble layers in the heat storage room is not exhausted. Then, if there is an auxiliary heater, activate the auxiliary heater. If the heat storage in the heat storage reaches saturation or there is no heating requirement in summer, the solar collector still works for heating to use the hot water supply system.

There are many types of solar energy buildings, and the working principles are basically similar. Some buildings use water as a medium for heat exchange. In this way, all the equipment in the system can be reduced in volume under the same thermal effect and can also use a hot water system together with other energy sources. This is the biggest advantage of using water as a medium. Another kind of energy is to use geothermal heat as a heat source. The working process is to extract the heat from the groundwater, send the heat to the room through the heating system, and run in reverse when cooling. The working principle is like an air conditioning unit. The disadvantage is that when the unit is working continuously for a long time, the heat may be insufficiently supplied. Therefore, it is more suitable in places rich in geothermal resources.

4 Energy Building Expectations

The collection of solar energy can only be carried out when there is a sun. On a cloudy day and at night, no heat is collected, so the heat collected is limited, but the rainy days and nights often require heat, which affects solar buildings. development of. If we use geothermal resources in combination with solar energy, learn from each other's strengths, adopt effective technical measures to convert energy, reasonable thermal control technology, and excellent thermal materials, then new buildings with environmental protection and energy conservation will be vigorously developed. It can be seen that the application of environmental protection and energy conservation is a very comprehensive technology, and it is necessary to solve some specific problems in order to be vigorously developed.

4.1 Energy-saving measures should be practical: the use of new energy is based on energy-saving measures, and the insulation performance of building envelopes is very important. Therefore, the outer wall and the outer door and window, where the beam is in contact with the outside world, the floor part should also be insulated, which is the cold bridge part. In short, it is necessary to meet the requirements of specifications, regulations and industry insulation.

4.2 It is necessary to solve the comprehensive utilization control technology of thermal energy; while the use of solar energy alone, geothermal energy has certain limitations. The use of new energy sources must be based on the local natural resources, and comprehensive application will be effective. Plus the necessary auxiliary heat source to ensure normal heating. The integrated control technology automatically converts the heat supply to the room according to the indoor temperature demand of the building and the supply of the heat source to achieve temperature stability. According to the advancement of automation control technology, thermal materials, heat exchange equipment, and thermal and electrical components, it is entirely possible to solve these technologies.

4.3 The best choice for energy saving and new energy is still solar energy, and the application of energy saving and solar energy has some influence on the appearance of the building. For this reason, in the design of the building, the facade of the building is processed, and the appearance of the heat source is collected by the roof. Not only is it related to thermal efficiency, but it is also related to the overall effect of the building.

At present, the most research on solar photovoltaic power generation technology and buildings is the Building Photovoltaic Integration System (BIPV), which integrates solar power generators perfectly on the wall or roof of buildings. Its working principle is common. The photovoltaic system is identical, the only difference being that the solar module is used both as a system generator and as a building exterior material. The photovoltaic components used in the BIPV system can be either transparent or translucent so that light can still enter the room through the photovoltaic components without affecting indoor lighting. The BIPV system can be used for local power generation and local use, and has many advantages: using the sun as an energy source can achieve energy saving and environmental protection requirements; saving grid investment and reducing transmission losses; color photovoltaic modules can replace expensive exteriors The material not only has the decorative effect but also reduces the cost of the solar power generation system; alleviates the power demand; it has the function of sound insulation and heat insulation as the outer protection of the building; and improves the indoor thermal environment. Foreign research on building photovoltaic integrated systems has been for a long time, but it is still in the stage of building experimental rooms. The United States, Europe, and Japan have all launched the national development plan for BIPV systems; the solar energy research institute of Shanghai Jiaotong University has carried out this Research, trial production of solar photovoltaic roof integration system, built an ecological