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  Presently, combination of solar power with civil building is reflected in solar power heating: hot water heating system, solar thermal pump combined heating supply, solar heating and cooling collective system.
   Solar heating hot water composite system
   Solar heating and hot water composite system provides hot water for people’s daily life and heating for houses. In Europe and North America, people have used solar supplied hot water and house heating for decades, however it is mainly used as mini-system and for individual building only. The recent decade saw the rapid development of complex solar heating and hot water supply program inclusive of heating supply project for communities.
   Germany has applied solar power heating technology at relatively early time. Now, House heating by solar power has been widely used and incorporated into heating equipment rehabilitation and associated construction in residential communalities. Like Germany, most European countries encourage and support solar power application. They provide subsidy to those families installed with solar device which is generally 20% to 50% of device cost.
   In Israel, 80% buildings are furnished with solar collectors because the government legislates that newly constructed building of less than 27m high must be provided with solar collectors.
  Denmark’s Marstal Solar Hot Water Supply and Heating project is the largest solar project in the world. The collectors all together 18,300 sq.m are constructed on vast empty land, connected with local heating network. After the project completion in 1996, the system has been providing thermal load of 28GWh/year. The system is also constructed with 2,100m3 capacity tanks, 4,000m3 water volume gravel layer and 10,00m3 underground hot water tank.
As early as middle 1980s, France set out to study solar power combination system and introduced a type of so named “Direct Solar Floor” system. Entering 1990s, Austria, Denmark, Finland, Germany, Sweden and the Netherlands in succession designed many types of solar combination system. Many scientist conducted lab test, research and theoretical analysis towards thermal performance of these systems.
  In Northern Europe, solar contribution to hot water requirement in these systems is 40% to 60%. The development trend is that, the research focus in these countries has been shifted from mini-type domestic solar system to collective heating system, which is good to reduce investment per unit thermal power. Currently, European Standardization Commission’s Solar Utilization Technique Commission （CEN/TC312）is organizing to lay down European standard relevant to solar power combination system.
  China is developing solar industry at very rapid pace. By 2006, annual production capacity of solar heaters reached 15,000,000 sq.m. Totally 100,000,000 sq.m solar collectors are in use. Both production capacity and using quantity are No.1 in the world. Despite the fact, house heating by solar power is still at early stage in China. All constructed projects are on individual model buildings, such as Beijing Tsinghua Sunlight Office Building, Tianpu New Energy Exhibition Plaza. No practical case is available as a solar hot water supply and house heating project.
  Amid the recent solar heating construction program, one collective and representative case is solar house heating scheme undertaken for new residential area of Beijing’s suburban districts and counties. Due to the dispersed location of houses, heavily invested and high costly maintained collective heating system is inapplicable. Conventional coal burning heating is costly, polluting air and low in heating efficiency. Application of safe, environmentally friendly low cost solar house heating system is in line with objective requirement of new rural construction program. Heat collecting area of solar house heating system is much larger than that of solar water heater. It should be installed on wide space. It is unsuitable for high rise building and densely resided district. Different from cities and towns, dimensional rate of rural houses is small and no obvious structure is on the way of sunlight, so the physical condition is good to launch solar heating house program. New residence solar house heating program for Beijing Pinggu District was carried out in early years and plenty of experience could be learnt.
  The above said composite system consists of solar collectors, hot water tanks, auxiliary heating device and thermal converters. The combination of floor radiation heating and solar collective heating system may keep the indoor temperature 2℃～3℃ lower than the temperature kept by radiator, saving energy by 20%～30%. Temperature of heat emitted source should not be very high. The temperature of floor place where people stay should not be over 29℃. Floor heating temperature is usually below 60℃. Heating efficiency of solar collector is high at low ambient temperature condition, thus it is one the optimum solutions for house heating in winter.
  Compared with conventional heating manner, the composite system saves operation cost, reduces pollution. However, its disadvantages are: outdoor space condition, high initial financial input, auxiliary heating combination limit and heating timing limit, all resulting in heating efficiency decline, extraordinary long term input recovery or non recovery. In this way, the advantages are not duly exercised.
  Solar thermal pump combined heating system
  Quite a number of solar thermal pump water supply and heating supply system are in successful operation and for technical study in other countries. Japan, USA, Sweden and Australia have input heavy resources on thermal pump in-depth study, research and development. These countries have also launched model program of many thermal pump heating systems and achieved certain economic benefit and good social interest.
  In recent years, many developing countries like Turkey and Indonesia carried out a lot of study and research on thermal pump. USA Solarng Series solar thermal pumping equipment and Australian Quantilln Series heaters are typical model products amid the industrialization process.
  The startup of research on thermal pump in China is quite late. Tianjin University, Tsingtao Building Engineering Institute and Shanghai Jiaotong University carried out relevant theoretical and laboratory test so far.
  1. Tianjin University once carried out relevant theoretical and laboratory test on series connected solar thermal pumps (collectors are of vacuum tube type). The research reveals that the system may be able to supply 50℃ hot water for all seasons. Energy saving effect was observed. Thermal pump COP is approx. 3. Vacuum tube collector may individually supply hot water in summer; in winter however, it must be combined with a thermal pump for normal operation.
  2. Study and research on series connected thermal pumps carried by Tsingtao Building Engineering Institute shows average thermal generating performance coefficient is 2.55 for one thermal pump unit and 2.19 for an entire heating supply system. No auxiliary heating source is used in the system.
  3. Shanghai Jiaotong University set up a direct expanding solar thermal pump supplied hot water system test platform. It was found that average COP of thermal pump was 4.18.
  4. Harbin Institute of Technology carried out analysis research on thermal pump operation performance under different working condition.
  With respect to industrialization, thermal pumps are mainly used for centralized hot water supply in China. Model buildings are Beijing Yuetan Sport Complex Training Center, Beiing Olympic Village, Tianpu New Energy Model Building. It can be concluded thermal pump application is only at initial stage. Its development is encouraging.
  Depending on the connection type between pump and collector, thermal pump is categorized direct expansive type and non-expansive type. In direct expansive system, evaporator and collector are combined into one unit in which cooling agent vaporizes directly inside collector subject to solar radiation, in which case, collector plate itself is evaporator. As for non-expansive pump system, it can be defined a basic solar heating supply system comprising collector, hot water tank, circulation pump, water-air heat converter, auxiliary heating device, in which, thermal pump system is extended. Both systems are featured with high efficient heat collection, wonderful heating supply coefficient, variety of types, flexible installation, multi-purpose use and wide application. When equipped with outdoor air heat converter, the system is provided with summer cooling function. Its disadvantages like low density, intermittent supply and instability should be taken into account when you select the type of collector and water tank. Therefore it is advised that reasonable heat requirement and necessity of auxiliary heating device should be ascertained to achieve the optimum result from investment.
  Solar power cooling and heating system
  Late 1970s witnessed the rapid development of solar application technology, subsequently solar power cooling technology emerged too.
  Professor Fab of Florida University USA in early years set out research in this field and he put ammonia absorbing refrigerator into operation. The 21℃ cool water is taken from well and refrigerator’s cooling coefficient is set 0.45.
  Japanese made solar power cooling system consists of a 32.2m2 panel collector, 7kW bromized lithium absorbing refrigerator and a 2.5m3 hot water tank. The system provides all energy required for heating in winter and 70% power for driving absorptive refrigerator in summer.
  In China, achievement was also made in solar power cooling and air conditioning technology. In 1975, Tianjin University designed a constant type ammonia-water absorptive solar icing machine with daily ice production of 5.4kg.
In 1979, the Capital Teachers College developed an 8m2 panel automatic tracing constant solar cooling cabinet.
  Huazhong University of Science and Technology fabricated a 1.5m2 light collecting 70L capacity freezing ammonia-water material mini-sized solar power cooling device.
  In 1980s, Hong Kong University completed solar power absorptive air conditioning design and operation trial and carried out performance test.
  Cooling and Low Temperature Research Institute of Shanghai Jiaotong University proposed a type of solar heating supply and cooling combined circulation composite device.
  In 1987, Guangzhou Energy Research Institute of Chinese Academy of Science in collaboration with Hong Kong Polytechnic University established in Shenzhen one set of research and application combined model solar air conditioning and hot water supply combined system with totally 120m2 heat collecting area and 14kW capacity cooling facility.
  In January 1998, Guangzhou Energy Research Institute of Chinese Academy of Science successfully developed applicable solar air conditioning hot water system which was put into commissioning in Jiangmen Guangzhou. The temperature of hot water used for cooling is 65～75℃ and temperature of hot water for living purpose is 55～60℃. It used a 500m2 highly efficiently panel collector and one 100kW two steps absorptive cooling machine. The system meets the air conditioning load for over 600m2 space.
  In 1990s, 600m2 vacuum tube collector and bromized lithium absorptive cooler were introduced into market. Temperature of hot water in vacuum tube of collector in Summer is above 85℃, absolutely meeting the requirement for solar air conditioner. The required temperature of hot sources is just above 60℃ for low mercury hot water type 2-step absorptive cooler developed by Guangzhou Energy Research Institute of Chinese Academy of Science successfully developed, which is especially suitable for solar air conditioner. With the maturity of key technology in solar collector and cooling machine, solar power air conditioner industry will be booming.
  Solar heating and cooling composite system is founded on the basis of solar absorptive cooling and solar floor radiation heating. The system comprises glass vacuum tube collector, hot water tank, hot water type bromized lithium absorptive cooler, auxiliary heating source (electric heating), circulation pump, heating reel pipe, terminal reel pipe, thermal pump, load pump and cooling pump etc.
  The system meets the requirement for hot water-heating-cooling of civil building in all seasons a year. Stronger the summer solar radiation is, more the cooling load is. At this time, collected thermal capacity is near the maximum, supplying the adequate heat for cooler. In winter, heating floor required less tempered water. At this time, tempered hot water in collector is able to supply heating. Owing to the auxiliary heating device, the system can be running stably. In the mean time, the time and efficiency of collecting heat and heating storage technology must be improved in proper way as what we can do to maintain water temperature in tank is to increase capacity to enhance heat preservation effect. The key technology lies with the collector and water tank. Only by research on collector and water dimension should the most economic and reasonable solar heating and cooling composite system be established.
  Given the above, what we can do is to comprehensively learn advantage and disadvantage of various types of solar technology. As for different types of civil building, the selection of suitable solar heating type, research on the matching relationship among systems, establishing a most economic and reasonable solar heating system, and meanwhile seeking a appropriate balance point in terms of economy, utilization of solar resource in wiser and more realistic manner and making it the real associated facility of a building, will effectively mitigate building energy consumption, protect the environment and tremendously promote progress of solar industry of China.
  The significance of solar application in building.
  1. Energy saving
  The ratio of Chinese building energy consumption in China’s total energy consumption tends to be rising. Heating energy consumption in China’s Northern towns and cities accounts for 36% of China’s total, becoming the major part of total energy consumption of building. Average unit area heating energy consumption is equivalent to 20kg/m2•year, 2 to 2 times of that consumed in Northern European countries under the same latitude climate condition.
  The unreasonable energy consumption structure in China results in enormous pressure to environment management. Being clean, environmentally friendly and renewable energy, solar power has been popularly applied in construction of civil building. Research unveils the fact that the areas with most economic potential in utilizing solar power are those with totally over 2200 hours solar radiation a year. Thus, the good physical condition is already there in promoting application of solar power technology in building in most regions of China. This is especially true for power thirsty areas as solar power will produce certain economic and social effect there.
  2. Economy
  The rapid development of civil building heating results in residents’ high demand for electric power. Owing to China power system special feature (i.e., the major power is generated from thermal power plants), the system is subject to substantial load difference between peak and bottom although it is unsuitable for the same.
  3. Improve people’s living standard.
  With the rapid growth of national economy and the gradual improvement of the people’s living standard, people’s desire for living comfort becomes stronger and stronger, especially for people in remote rural area where energy supply is in shortage. The application of solar power in civil building effectively reduces the circumstance of power shortage and at the same time improves people’s living comfort.