Study On Optimization Of Energy Saving Potential Of College Teaching Buildings In Beijing

With the rapid development of China’s construction industry,building energy consumption is also rising rapidly.Reducing building energy consumption is of great significance to ensure China’s energy security and the healthy development of social economy.Colleges and universities are an important member of the social organization structure,with a huge building base and obvious energy-saving potential.The newly issued"Assessment standard for green campus"puts forward the campus energy-saving technology in line with China’s national conditions.Accelerating the construction of green campus is not only the requirement of national policy,but also the important responsibility of colleges and universities to the whole society.There are a large number of existing university buildings in China.Most of them have been built for a long time.There are many problems,such as large energy consumption,high operation energy consumption and so on.As the main functional building of university campus,teaching building has the characteristics of high personnel density,high personnel activity frequency,complex operation and management,but simple energy consumption type.It is easier to optimize the energy conservation of building subdivisions.Therefore,exploring the energy-saving optimization technology suitable for college teaching buildings is of great significance to the energy-saving research of college teaching buildings.Taking the teaching building of a university in Beijing as the research object,this paper first studies and analyzes the current situation of the envelope structure,HVAC system and indoor thermal environment of the teaching building.It is found that the teaching building was built earlier,and the thermal coefficient of the envelope structure exceeds the limit specified in the code"Beijing public building energy efficiency design standard".During the heating period,the measured operating temperature of the secondary side pipe network is far lower than the design temperature,and the measured supply and return water temperature of the chilled water during the cooling period reaches the design temperature.The refrigeration unit has a high load rate,the refrigerator operates well,the heating hot water system and air conditioning water system are in the state of"large flow and small temperature difference",and the energy consumption of circulating water pump is high.The indoor temperature of the classroom is low in winter and suitable in summer.Secondly,according to the actual situation of the teaching building,select the appropriate envelope and energy-saving optimization technology of air conditioning system.The benchmark energy consumption model of teaching building is established through dest energy consumption simulation software.Based on the accuracy verification of energy consumption simulation data and measured data,the sensitivity of various envelope factors affecting energy consumption of teaching building is studied by using local sensitivity analysis method,and the average sensitivity ranking of envelope structure to building energy consumption is obtained:external window heat transfer coefficient>external window shading coefficient>external wall heat transfer coefficient>roof heat transfer coefficient,This paper puts forward the corresponding optimization scheme of the envelope structure.Through the energy-saving optimization of the envelope structure,the total energy consumption of the building can be reduced by 5.76%.At the same time,the energy-saving optimization of the air-conditioning system is discussed,and the energy consumption of exhaust total heat recovery,water pump energy saving and air source heat pump as heat source are simulated and analyzed respectively.The results show that the energy-saving effect of water pump frequency conversion scheme is the best,followed by exhaust total heat recovery,and finally air source heat pump.The total energy-saving rates are 14.15%,8.14%and 7.62%respectively.Finally,the energy-saving benefit and economy of the energy-saving technology proposed by the teaching building are analyzed.The results show that after the optimization of water pump frequency conversion,exhaust total heat recovery,air source heat pump and enclosure structure,the annual energy saving is converted into standard coal,which is equivalent to saving 84852.02 yuan,48818.97 yuan,45680.61yuan and 34521.99 yuan respectively.After analyzing the carbon emission intensity and emission reduction rate of each building energy-saving technology scenario,it is found that after the frequency conversion of water pump,the building carbon emission intensity can be reduced to 31.90 kg/（m~2·a）,the highest carbon emission reduction rate is 14.15%,followed by the total heat recovery scheme,the carbon emission intensity is34.13 kg/（m~2·a）,and the carbon emission reduction rate reaches 8.14%,followed by the air source heat pump,the carbon emission intensity is 34.32 kg/（m~2·a）,and the carbon emission reduction rate is 7.62%,Finally,the enclosure structure is optimized.The carbon emission intensity is 35.01 kg/（m~2·a）,and the carbon emission reduction rate is 5.76%.Using the annual return investment ratio SIR value to study the energy-saving technology of teaching buildings,it is found that the energy-saving potential of energy-saving optimization technology of HVAC system is as follows:water pump frequency conversion>exhaust total heat recovery>air source heat pump;The order of energy-saving potential of energy-saving optimization technology of peripheral protective structure is:External Window>roof>external wall.The whole life cycle cost analysis of the benchmark building and the building after adopting all energy-saving optimization technologies is carried out.It is found that the initial investment of the optimized building is 26.5%higher than that of the benchmark building,and the annual operation cost of the optimized building is 25.7%lower than that of the benchmark building.In the whole life cycle,the life cycle cost of the optimized building is 38.9%lower than that of the benchmark building,and the energy-saving benefit is remarkable.