Research On Energy-saving Retrofit Technologies Of Existing Public Buildings In The Hot Summer And Cold Winter Zone Of China

With the continuous development of the social economy,the global energy shortage has become more and more serious,and people's attitudes towards energy conservation are also deepening.As one of the three key fields of total energy consumption,building energy also plays an important role in implementing energy conservation.The existing buildings are in huge amount and relatively historical,which are different from the established buildings with relevant energy-saving standards from design to acceptance.The problem of high energy consumption of existing buildings is widespread,so it is very necessary for them to implement energy-saving retrofit.Compared with residential buildings,public buildings have larger volume,wider area,more complicated energy consumption systems and more difficult management,which is the focus of energy-saving retrofit.For the energy-saving retrofit projects,the energy-saving performance and the economic performance of technical measures are seen as the goal to pur sue.Therefore,exploring the energy-saving retrofit effects and economics of technical measures has a very broad application prospect,with significant economic benefits and excellent social benefits.Under the above background,the energy consumption rul es of different types of public buildings(shopping malls,offices and hotels)in Changsha were explored by means of measuring and simulating,and nine key technologies for energy-saving retrofit in three categories of the external envelopes,the HVAC syst em and the hot water supply system were selected.By the energy consumption simulation software DeST,the energy-saving rates and the energy-saving amounts per unit retrofit cost were calculated.The energy-saving potential of each technology were characte rized by the two indices,in order to provide references for the actual energy-saving retrofit projects in the hot summer and cold winter area.According to the survey data,the energy consumption values per unit area of shopping malls,offices and hotels are up to 229.6 kWh/(m~2·a),118.4 kWh/(m~2·a)and134.0 kWh/(m~2·a),respectively,and the proportions of Heating,Ventilation and Air Conditioning Systems are up to 55.4%,44.9%,and 50.6%,respectively.Both the indicator and the proportion of HVAC system are at high energy level.In the energy consumption simulation period,the benchmark models were established for three kind of public buildings and the energy consumption simulation values were obtained.It was found that the built models all met the error requirements by parameter calibration.By comparing the different energy consumption values before and after implementing single energy-saving technology,the energy-saving rate corresponding to the technology can be known.The simulation results show tha t for the energy-saving effect,the HVAC system is supreme,and then the hot water supply system,and the external envelopes worst in general.The most energy-saving technologies corresponding to shopping malls,offices and hotels are fresh air free cooling,fresh air free cooling and heat pump hot water system,which are up to 5.60%,7.71%and 15.3%,respectively.Besides,the ratio of the energy saving rate and the retrofit price of single technology in different buildings was defined as the energy-saving amounts per unit retrofit cost.For the energy-saving economy,the sequence is as same as it of the energy-saving effect.The technologies for the most energy-saving amounts per unit retrofit cost corresponding to shopping malls,offices and hotels are pump frequency conversion,secondary pump system and water pump frequency conversion,which are up to 10.9kWh/CNY,3.538kWh/CNY and5.109kWh/CNY,respectively.