First, the concept of energy-saving housing
With the emergence of energy crisis, more and more developers began to pay attention to energy-saving housing. Energy-saving residence needs to control the indoor natural temperature within the comfortable temperature range of human body to the maximum extent through reasonable design and material selection of buildings, provide residents with healthy, comfortable and environmentally friendly living space and reduce building energy consumption.
Beijing Shang Feng took the lead in integrating the advanced European technology system in China, and built a residential building with high comfort and low energy consumption, reaching the living standard of developed countries. Its core technology is summarized as eight subsystems: First, the concrete heating and cooling system. In this system, polybutylene (PB) coils are embedded in reinforced concrete, and water at 20℃ in summer and 28℃ in winter can keep the indoor temperature within the appropriate range of 20℃-26℃. Second, the healthy fresh air system. After unified air purification and cold and hot treatment, fresh air enters the room by "sending it down and sending it back", and it can keep the fresh air constantly changing without opening the window. Third, the external wall system. The external wall adopts European standard thickening external thermal insulation method, which can effectively block cold and hot radiation and rain and snow erosion. Dry-hung brick walls are used for exterior wall decoration, and there is a flowing air layer between the dry-hung brick wall curtain wall and the insulation board, which can keep the insulation board dry. Fourth, the external window system. The window adopts SCHUCO aluminum alloy window and LOW-E insulating glass with low radiation. Fifth, the roof and underground system. The special treatment of roof and underground wall ensures the consistency of comfort between the top floor and the first floor and the standard floor. Sixth, anti-noise system. Noise from outdoor, upstairs and sewer can be prevented by external wall system, ALULUX roller shutter, floor treatment and drainage system on the same floor. Seventh, the garbage disposal system. The garbage disposal system consists of three parts: central dust collection, food garbage disposal and recyclable garbage turnover box. Eighth, water treatment system. A reclaimed water treatment system is set up in the community, and the domestic water treatment in the community is used for watering green space, flushing toilets and replenishing artificial lake water.
Second, foreign energy conservation has become a fashion:
In foreign countries, architects use various forms and methods to save energy:
(1), resource recycling: 1997 An experimental "healthy house" was built in Japan. In addition to using building materials that are harmless to the human body as far as possible, the wall is also designed as a double-layer structure, each room has vents, and the air in the whole house system circulates through a total heat exchanger and a dehumidifier. The total heat exchanger can effectively recover heat and reuse it, and its filter can effectively collect fine dust in the air, thus inhibiting the reproduction of allergic organisms such as mold. The recycling of this resource not only turns waste into treasure, but also reduces environmental pollution sources and saves energy.
(2), new energy development and utilization:
German architect Seddor Tehols built a solar house that can track sunlight. The house is mounted on a disc base, and a small solar motor drives a set of gears. The building base rotates with the sun at a speed of 3 cm per minute on a circular track. When the sun goes down, the house will turn in the opposite direction and return to the starting position. It consumes only 1% of the solar energy generated by the house, and absorbs twice as much solar energy as the general solar house that can't rotate.
Third, the basic situation of building energy consumption in China
China's building energy consumption accounts for about 1/4 of the national total energy consumption, ranking first in energy consumption. In recent years, China's construction industry has developed rapidly, and a lot of energy is needed for construction and operation, especially for building heating and air conditioning. According to statistics, in 1994, the energy consumption of residential buildings in China was 1.54× 108t standard coal, accounting for12.27x109t standard coal. At present, the coal used for heating in urban buildings alone reaches 1.3× 108t standard coal every year, accounting for about 1 1.5% of the total energy consumption in China and more than 20% of the total social energy consumption in heating areas. In some cold areas, the energy consumption of urban buildings is as high as 50% of the local social energy consumption. At the same time, the natural and ecological environment around the building is deteriorating due to the massive burning of mineral energy such as coal. In the process of energy utilization, fossil fuels will emit pollutants into the atmosphere when burning. During the combustion of fossil fuels, 99% of nitrogen oxides, 99% of carbon monoxide, 96% of sulfur dioxide, 78% of carbon dioxide, 60% of dust and 43% of hydrocarbons are produced, of which coal is the majority. Among the air pollutants produced by coal burning, SO2 accounts for 87%, nitrogen oxides account for 67%, CO2 accounts for 765,438+0%, and soot accounts for 60%. As China is a country that mainly consumes high-quality energy such as coal rather than oil and gas, it emits carbon dioxide into the earth's atmosphere every year, second only to the United States. It is predicted that by 2020, China will replace the United States as the world's largest emitter of carbon dioxide. Therefore, China bears great responsibility for global warming, and as a big energy-consuming country, its energy conservation has become a major issue related to the national economy and people's livelihood.
Four, the most basic energy-saving consciousness of residential design:
Winter in Xinjiang is cold and long. Therefore, in the design of residential buildings, the main space facing south, or east to south, or west to south, has always been considered a reasonable design. This is the application of the most basic energy-saving consciousness in residential building design. In the overall planning and individual design of most residential buildings in Leng Xia hot zone in winter, it is undoubtedly the most basic design to improve the indoor thermal environment of residential buildings by striving for a good orientation for the main space of residential buildings, meeting the requirements of sunshine in winter and making full use of natural gas energy.
Five, energy-saving design ideas
(A) building thermal insulation composite energy-saving wall
Composite energy-saving walls are usually composed of thermal insulation materials, traditional wall materials or some new wall materials. If the thermal insulation material is compounded on the inside of the external wall of a building, it is called internal thermal insulation composite wall.
1. Wall structural layer: refers to the external wall of cast-in-place concrete or prefabricated products, and the external brick wall with external masonry or brick-concrete structure. And other load-bearing external walls such as load-bearing porous brick external walls.
2. Air layer: The thermal conductivity of air at 0℃ is 0024 vv/(m k). At 25℃ 5℃, it is 00256 w/(m k), even at 200℃, it is still 00: 384 w/(m k). Therefore, air is also an excellent heat insulation material. Therefore, the air isolation layer surrounded by common materials in buildings can not only keep warm and insulate heat. Moreover, it also has the function of cutting off the capillary penetration of liquid water and preventing the thermal insulation material from being affected with damp, because the outer wall generally has water absorption capacity, and the inner surface often has condensed water due to low temperature. Can be inhaled by structural materials, and constantly transferred and emitted.
3. Insulation layer: This is the main functional part of the energy-saving wall. Commonly used thermal insulation materials can be divided into three categories: organic metals and inorganic metals. Comprehensive consideration is given to thermal conductivity, compressive strength, vapor permeation ratio and combustion performance. Extruded polystyrene board (XPS) is selected as thermal insulation material here.
Glass curtain wall refers to the building's external protective structure or decorative structure, which is composed of supporting structure system and glass, and has certain displacement ability relative to the main structure, and does not share the role of the main structure. Walls with single and double glazing. Reflective insulating glass is 6 mm thick and the weight of the wall is about 40 kg/㎡, which has the advantages of lightness, beauty, less pollution and energy saving. The inner side of the outer glass of the curtain wall is coated with colored metal coating. From the appearance, the whole external wall is like a mirror, reflecting the scenery of the sky and the surrounding environment. When the light changes, the image is rich in color and varied. Under the reflection of light, the room is not exposed to strong light and the vision is soft. China 1983 was first adopted in the Great Wall Hotel project.
Most people who have been to new york will be deeply impressed by its bustling urban landscape. The towering skyscrapers are spectacular, and its glass curtain wall reflects the empty blue sky and dancing white clouds, adding gorgeous colors. So, how is the glass curtain wall made? Glass curtain wall refers to the mirror glass used as the decoration of building exterior wall. It is made of transparent glass with trace amounts of iron, nickel, cobalt and selenium. To float glass and tempering. It can absorb infrared rays, reduce the solar radiation entering the room and reduce the indoor temperature. It can reflect light like a mirror and transmit light like glass.
The glass curtain wall of modern high-rise buildings also uses insulating glass, which is composed of mirror glass and ordinary glass, and the interlayer is filled with dry air. There are two layers and three layers of insulating glass, and the two layers of insulating glass are sealed by two layers of glass and a frame to form a sandwich space; Triple glazing is two sandwich spaces composed of triple glazing. Insulating glass has the advantages of sound insulation, heat insulation, frost resistance, moisture resistance and strong wind pressure resistance. According to the measurement, when the outdoor temperature is-10℃, the temperature in front of single-layer glass window is -2℃, while the indoor temperature with three-layer insulating glass is 13℃. In summer, double-layer insulating glass can block 90% of solar radiation heat. Sunlight can still pass through the glass curtain wall, but most of it won't feel hot in the sun. The room with hollow glass curtain wall can be warm in winter and cool in summer, which greatly improves the living environment.
[Edit this paragraph] Classification and composition
1. Open-frame glass curtain wall Open-frame glass curtain wall refers to the glass curtain wall with metal frame members exposed on the external surface. It takes the aluminum alloy profile with special section as the frame, and the glass panel is completely embedded in the groove of the profile. It is characterized in that the aluminum alloy profile itself has dual functions of skeleton structure and glass fixing.
2. Hidden frame glass curtain wall
The metal frame of the hidden frame glass curtain wall is hidden on the back of the glass, and the metal frame can't be seen outdoors. Hidden frame glass curtain wall can be divided into full hidden frame glass curtain wall and semi-hidden frame glass curtain wall, which can be horizontal, flat and vertical, or criss-crossed. The structural characteristics of the concealed frame glass curtain wall are: the glass is outside the aluminum frame, and the glass and the aluminum frame are bonded with silicone structural sealant. The load of curtain wall is mainly borne by sealant.
3. Point-supported glass curtain wall
Point-supported glass curtain wall is a new type of support in recent years. But once it appeared, it developed rapidly in the city. The following is an introduction to this relatively new type of support:
1. Classification of point glass curtain wall
According to the different supporting structure, point glass curtain wall can be divided into the following types in form:
(1) Point glass curtain wall with metal support structure is the most widely used form at present. It uses metal materials as the supporting structure system, and the glass is firmly fixed on it through metal connectors and fasteners, which is very safe and reliable. Make full use of the flexibility of metal structure to meet the needs of architectural modeling, and people can clearly see the whole structural system supporting the glass through the glass. Crystal clear glass and solid metal structure are the embodiment of "beauty" and "strength". Enhanced the effect of "virtual" and "real" comparison.
(2) The point-type glass curtain wall with all-glass structure connects the glass supporting structure (glass rib) and facing glass into a whole through metal connectors and fasteners, and becomes the building envelope structure. The construction is simple, the cost is low, the glass surface and ribs form a wide field of vision, which is pleasing to the eye, and the indoor and outdoor space of the building achieves the maximum visual integration.
(3) Pull rod (cable) structure Point glass curtain wall adopts stainless steel pull rod or cable corresponding to glass parting as curtain wall support structure. The glass is fixed on it by metal connectors. In architecture, the precision of machining is fully realized, so that all components are tensile components. Therefore, prestress should be applied during construction, which can reduce the breakage rate of glass during vibration.
2. The main components of building point glass curtain wall
(1) Support system The support system directly transfers various loads on the glass to the main structure of the building. Therefore, it is the main force-bearing component, and its structural form and material generally depend on the load and architectural modeling, such as glass ribs, stainless steel columns, aluminum profile columns or steel analysis frames, steel columns and stainless steel tie rods (cables) which have been properly treated for corrosion protection and surface protection.
(2) Metal connector
Metal connectors include fixed parts (commonly known as claw seats and claws) and fasteners. Fixtures are usually made of stainless steel, while fasteners are made of stainless steel. Considering the compatibility of metals, the claw seat must be made of the same material as the support system or mechanically fixed.
Metal connectors are the essence of architectural point technology. Fixing the face glass on the supporting structure not only produces additional stress at the edge of the glass hole, but also allows a small amount of displacement to adjust the construction error caused by building installation, and there are also shock absorption measures to improve the seismic capacity, so there are many factors to be considered in the design.
(3) Metal connectors also have remarkable decorative effect, so they not only meet the functional requirements, but also have beautiful modeling design and fine processing and manufacturing, which plays a "finishing touch" role.
3. Glass
(1) The strength of glass used for building point glass curtain wall is reduced by about 30% due to drilling. Therefore, the point glass curtain wall of the building must use tempered glass with higher strength (the impact strength of tempered glass is 3-5 times that of float glass, and the bending strength is 2-5 times that of float glass). Note that another important feature of tempered glass is its safe use. When it is damaged by a large external force, it will produce small pieces without acute angles.
Buildings in the north or buildings with high thermal insulation requirements often use insulating glass, and there is a layer of dry air or inert gas between two pieces of glass. The reason why insulating glass can greatly improve the thermal insulation performance is that the heat transfer coefficient k of glass is 0.8 w/(m2 k), while that of air is 0.03 w/(m2 k), and the inert gas is lower. Due to the increase of population, the development of industry and the improvement of living standards, the consumption of energy has increased sharply, and the energy crisis is imminent. Therefore, all walks of life have put forward the requirements of energy saving, and saving the secondary energy & electric energy has become the focus of electrical design of civil buildings. Principles of Energy Saving in Building Electrical Design The following three principles should be adhered to in building electrical energy saving:
1. Meet the function of the building.
That is, meet the illumination intensity, color temperature and color rendering index of lighting; Meet the temperature and fresh air volume of comfortable air conditioning, which is comfortable and hygienic; Meet the smooth traffic channels up and down, left and right; Meet special technological requirements, such as electricity consumption for some electrical facilities in entertainment places and lighting for exhibition halls.
2. Consider the actual economic benefits
Energy conservation should consider the actual economic benefits according to the national conditions, and should not consume investment and increase operating costs because of energy conservation. On the contrary, part of the increased investment should be recovered in a few years or a short time, and the operating expenses should be reduced through energy saving.
3. Save unnecessary energy consumption
The focus of energy conservation should be to save unnecessary energy. Find out where energy consumption has nothing to do with building functions before considering what measures to take to save energy. For example, the power loss of transformers and the active loss on transmission lines are useless energy losses. For those with large lighting capacity, advanced technology should be adopted to reduce their energy consumption.
Therefore, energy-saving measures should also implement the principles of practicality, economic rationality and technological advancement.
Ways of building electrical energy saving
1. Reduce the active loss of transformer.
The active power loss of the transformer is expressed as follows: △ Pb = Po+PK β 2, where:
△△p B- active loss of transformer (kW);
Po-transformer no-load loss (kW);
Pk-transformer on-load loss (kW);
β-load rate of transformer.
The no-load loss of Po, also called iron loss, is composed of eddy current loss and magnetic leakage loss of iron core, which is a fixed part, and its size depends on the performance of silicon steel sheet and the manufacturing process of iron core. Therefore, energy-saving transformers, such as S9, SL9 and SC8 oil-immersed transformers or dry-type transformers, should be selected, all of which are made of high-quality cold-rolled oriented silicon steel sheets. Due to the "orientation" treatment, the magnetic domain directions of silicon steel sheets are close to the same, which reduces the eddy current loss of iron core; 45 fully inclined seam structure makes the seam tight and reduces magnetic leakage loss.
Pk is the loss of transmission power, that is, the line loss of transformer, which is determined by the resistance of transformer winding and the current flowing through the winding, that is, the square of load factor β. Therefore, to choose a winding with smaller resistance, a copper core transformer can be used. Starting from Pkβ2, its extreme value is obtained by differentiation. When β = 50%, the energy consumption per kilowatt load of transformer is the minimum. Therefore, in the civil buildings designed in the mid-1980s, the load rate of transformers was mostly around 50%, and half of transformers were not put into operation in actual use. This practice has been used by some designers so far. However, this is only to save energy, without considering the economic value. The following example can illustrate its undesirable degree.
SC3-2000KVA transformer, when β = 50% is compared with β = 85%, the energy saving is P =16.01× (0.852-0.52) = 7.56 kW, which is 365 days per day/kloc-according to the maximum power consumption hours in the mall. H if the operating electricity price is 0.78 yuan per kwh, the annual savings will be 33113× 0.78 = 25,828 yuan.
Investment according to the initial installation fee per kilowatt: 2000KVA transformer should be a large civil building, and double power supply is inevitable, so the initial installation fee is 2240 kva, and the annual energy-saving electricity fee can only be provided (25828/2240 =11.53)11.53. There is also the initial installation cost of 988.5KVA, plus the extra transformer price due to the increase of transformer capacity, the equipment purchase cost due to the increase of outgoing switchgear and bus coupler cabinets, and the civil construction cost due to the increase of civil construction area due to the installation of the above equipment. This is a considerable investment, and depreciation and maintenance costs have not been considered. It can be seen that the 50% load rate of transformer is not worth the loss.
In fact, 50% load rate only reduces the line loss of transformer, but not the iron loss of transformer, so it is not the most energy-saving measure. Considering the initial installation cost, investment in transformer, low-voltage cabinet and civil engineering, and various operating costs, appropriate capacity should be reserved during the service life of transformer, and the load rate of transformer should be 75% ~ 85%. Only in this way can the best use be made, because the full-load service life of transformer insulation is 20 years. After 20 years, there may be better transformers, which will give us the opportunity to replace new equipment and keep the building ahead in technology forever.
In order to reduce transformer loss, when multiple transformers need to be selected due to large capacity, the number of transformers should be reduced as much as possible under the condition of reasonable load distribution, and large-capacity transformers should be selected. For example, if the installed capacity is 2000KVA, you can choose 2 sets 1000KVA instead of 4 sets of 500KVA. Because the former can save energy: △ P = 4× (1.6+4.44)-2× (2.45+7.45) = 4.36 kW (all calculated by β = 100%, under the same conditions, SC3 transformer).
In the choice of transformer, we can master the above three principles, that is, the principle of energy saving and economy.
Reduce the energy loss on the line
Because there is resistance on the line, when there is current flowing, there will be active power loss. The formula is as follows: △ p = 3i φ 2r× 10-3 (kW).
Where: I φ-phase current (A)
R line resistance (ω)
For example, when 60KW electric energy is transmitted on the cable VV-3× 50+2× 25 with L = 100 m and COS φ = 0.8, the active power loss can be obtained by the following formula: i φ = 60×103/(× 380× 0.8) = 65433.
If r0 = 0.44 per kilometer of a 50mm2 copper core with a core temperature of 70℃, then R = 0. 1× 0.44 = R0=0.44 (ω).
△P = 3× 1 13.62×0.044× 10-3 = 1.704 kw
As can be seen from the above, the power loss on the line is equivalent to installing a 100W light bulb every 6m line.
In a project, the lines crisscross from left to right, and the total length of small projects is not less than 10,000 meters, and there are countless large projects. Therefore, the total active power loss on the line is considerable, and designers must pay attention to reducing the power consumption on the line.
The current on the line cannot be changed, and the only way to reduce the line loss is to reduce the line resistance. Line resistance R = p× l/s, that is, line resistance is proportional to conductance P, inversely proportional to line section S, and directly proportional to line length L. Therefore, reducing line loss should start from the following aspects.
Materials with low conductivity should be selected as conductors. Copper core is the best, but the principle of saving copper should be implemented. Therefore, copper conductor is used for Class II and Class I buildings with heavy load, and aluminum conductor is used for Class III or buildings with light load.
Reduce the length of the wire. First of all, the line should go straight as far as possible, take fewer detours and reduce the length of wires; Secondly, the low-voltage line is not connected to the return line or less, which reduces the power loss on the return line; Third, the transformer should be as close to the load center as possible to reduce the power supply distance. When the plane of each floor of the building is about 10000m2, at least two substations should be set up to reduce the length of trunk lines. Fourthly, in high-rise buildings, the low-voltage distribution room should be close to the shaft, and the trunk line provided by the low-voltage distribution room to each shaft will not cause the phenomenon that the branch line is sent backwards along the trunk line. In other words, the layout of the low-voltage distribution room and the location of the shaft should make all the lines forward, and try to reduce the branch lines that transmit electric energy back.
Increase the cross-sectional area of the conductor. First of all, for a relatively long line, in addition to selecting a section that meets the requirements of current carrying capacity, thermal stability, protection coordination, voltage loss, etc., the increased cost is m, and the annual operating cost reduced due to energy saving is m, so m/m is the payback period. If the recovery period is several months or one or two years, the section of the primary conductor should be increased. Generally speaking, it is easier to meet the above conditions when the conductor section is less than 70mm2 and the line length exceeds 100m. Secondly, some lines with seasonal load can be provided to regular users as power supply lines when not in use, reducing lines and resistance. For example, air-conditioning fans, fan coils, lighting, water and other loads with the same charge are concentrated on the same trunk line for power supply, which can not only cut off the non-fire electricity consumption with a fire alarm command, but also make the trunk line section with the same size transmit smaller current when the air conditioner is not used in spring and autumn, thus reducing the line loss, which is equivalent to making full use of the line with seasonal load.
In the design, if the above three measures are carefully implemented, the energy loss on the line can be reduced and the purpose of energy saving on the line can be achieved.
Improve the power factor of the system
Improve the power factor of the system, reduce the transmission of reactive power on the line, and achieve the purpose of energy saving.
Why is it often mentioned that the motor with stable load can make local compensation? Because the terminal voltage of the motor changes when the load changes, the capacitor is not fully discharged and charged. At this time, the capacitor will generate reactive surge current, which is easy to cause overvoltage and damage the motor. Therefore, elevators, escalators, escalators and other intermittent loads should not be equipped with compensation capacitors at the motor end; In addition, the compensation capacitor can not be installed at the motor end of the star delta starting asynchronous motor, because it has an instantaneous transition between open circuit and closed circuit during the starting process, which makes the capacitor recharge at the moment of discharge and will also damage the motor due to overvoltage.
In civil buildings, the centralized installation of capacitors should be changed. On-site compensation devices should be installed at the motor ends of fans, pumps and conveyor belts. Its capacity exceeds 65,438+00 kilowatts. There are often special power distribution stations near the air conditioning main engine and refrigeration pump, which can concentrate compensation. However, if the power supply distance exceeds 20m, it is best to use local compensation.
There are two ways to connect the motor local compensation device. One is that after being connected in parallel to the primary line of the thermal element, the setting current of the thermal element should be based on the working ammeter of the compensation motor, which is suitable for the newly installed motor; The other is to install a compensation capacitor behind the main contact of the contactor and before the primary coil of the thermal element. The setting current of the thermal element will not be affected by compensation, which is suitable for transforming the wiring of the motor so that the capacitor can be switched with the motor.
Dealing with the above three parts, that is, reducing natural reactive power, reactive power compensation and the installation position of compensation device, can realize the reasonable choice of reactive power compensation mode and achieve the purpose of energy saving.
Energy saving of lighting part
Due to the large amount of lighting and wide range, lighting has great potential for energy saving. We should start from the following aspects:
Adopt efficient light source. Incandescent lamps used to be the most widely used in the past. Because of their low price, simple installation and maintenance, and their fatal weakness is low luminous rate, they are often replaced by various new light sources with high luminous rate, good light color and excellent color rendering performance. Table 1 lists the luminous flux per watt of various light sources. Lm？ . As can be seen from the table, low-pressure sodium lamps and high-pressure sodium lamps have the highest luminous efficiency, but because of their low color temperature and warm light color, the color rendering index is between 40 and 60, and the color distortion is great, so they can only be used for street lamps or squares. Among them, the sodium lamp with high color rendering index of 60 can be combined with mercury lamp to form a mixed lamp, which is used for lighting in factories and gymnasiums and is also a large-scale and wide-range lighting part; Metal halide lamps, tricolor fluorescent lamps and rare-earth metal fluorescent lamps with high luminous efficiency have a wide color temperature range from 3,200 K to 4,000 K, good color selectivity, high color rendering index up to 80-95, and little color distortion. Especially, metal halide lamps have excellent color rendering on human skin, and are widely used in waiting rooms of stations and docks besides lighting shopping malls and exhibition halls. General fluorescent lamps and rare earth metal fluorescent lamps can be used for office and residential lighting; Fluorescent high-pressure mercury lamps, self-rectifying high-pressure mercury lamps, sodium lamps and their combinations are often used for lighting in production workshops. Incandescent lamps should not be used or used as little as possible. They are only used for local art lighting or antique calligraphy and painting lighting to prevent high-frequency spectrum irradiation. Although the light color is good and the color rendering index is the highest, it can not achieve the purpose of energy saving.
Buildings should make full use of natural lighting. In the outdoor building area, doors and windows should be opened, and glass doors and windows with good light transmission should be used to make full use of natural light. Where natural light can be used for this part of the lighting, the on-site illumination can be detected according to the degree standard, and the lighting can be automatically adjusted.
For gas discharge lamps, stepless automatic dimming is adopted, that is, dimming is achieved by adjusting the filament. However, the price is too high. Each set of 36W lamps needs to increase the investment of 2000 ~ 3000 yuan, and the electricity price saved is limited, because artificial lighting can only be reduced during the day with strong sunshine (usually from morning 10 to 3 ~ 4 pm), and each lamp can save up to 25% energy, which is 12 hours per day.
M = 36× 0.25×12× 365× 0.78×10-3 = 30.7 yuan.
Therefore, it takes 2000 ~ 3000/30.7 = 65 ~ 97 years to recover the investment under increased control, which has no practical significance. This dimming scheme is not recommended in working lighting. It is only suitable for special conditions, such as meteorological stations, navigation stations and other small control rooms, which require natural coordination between indoor lighting and outdoor natural light. In addition, this dimming device is used in rare earth metal fluorescent lamps, and its stroboscopic effect is unacceptable to human eyes. For occasions where natural light can be fully utilized and dimming is needed, the control scheme of automatic start and stop in groups and sections can be adopted. Although there will be a process of mutation, it will not affect vision or people's mood, which is a desirable way.
For occasions that need to start and stop for a long time, but the illuminance should be automatically adjusted according to the number of people, the fluorescent lamp can be adjusted in several stages by adjusting the voltage, without increasing the investment, such as the Australian dimming equipment used in the Beijing subway.
Fluorescent lamps use voltage regulation and dimming, and the energy-saving effect is not obvious. Because the gas discharge lamp emits light by ion collision under high pressure, it reaches a certain energy level, and the luminous flux is not proportional to the voltage. When the voltage drops by 10% and the luminous flux drops by almost 30% ~ 40%, the lamp will be completely extinguished. Therefore, gas discharge lamps use voltage adjustment to adjust the light, which is rarely used in practical engineering.
In energy-saving lighting, in addition to meeting the requirements of illuminance, light color and color rendering index, efficient light sources and lamps should be used to automatically control the lamps that can be illuminated by natural light or variable illuminance, which can achieve the effect of energy-saving lighting.
Energy saving in motor operation
The motors in building electricity are all matched with the equipment of HVAC, waterway, construction and other types of work, and are uniformly supplied by the equipment manufacturers. Therefore, its energy-saving measures can only be implemented during operation. In addition to the above-mentioned local compensation capacitor to reduce the active loss caused by advanced reactive power transmission, the light load and no-load operation of the motor should also be reduced. Because, in this case, the efficiency of the motor is very low, and the electric energy consumed is not proportional to the reduction of the load. Frequency conversion governor is adopted to automatically adjust the speed through frequency conversion when the load drops to adapt to the change of load. This can improve the efficiency of the motor under light load and achieve the purpose of energy saving. However, the price of this kind of equipment is still high, so its application is limited. Another way to save energy is to use soft starter, which gradually adjusts the conduction angle of SCR according to the starting time to control the voltage change. Because the voltage can be adjusted continuously, the startup is smooth. After starting, put the full pressure into operation. The equipment can also use speed feedback, voltage negative feedback or current positive feedback to control the conduction angle of SCR by using feedback information, so as to realize the speed change with the change of load. It can be used in equipment with large motor capacity and frequent starting, as well as occasions where nearby electrical equipment requires high voltage stability. Because the current changes no more than three times from start-up to operation, the voltage fluctuation of the power grid can be guaranteed within the required range. However, it uses silicon controlled rectifier to regulate voltage, and all the electric energy in the non-conducting part of sine wave is consumed on the silicon controlled rectifier and will not return to the power grid. Therefore, perfect heat dissipation and ventilation measures are needed. Its price is cheaper than that of frequency converter, and it can be used for the control equipment of large-capacity motor in water pump system.
Civil buildings have great energy-saving potential and should be carefully considered in design. However, when choosing new energy-saving equipment, we should know its principle, performance and effect in detail, and then choose energy-saving equipment after technical and economic comparison, so as to achieve the purpose of real energy saving.