Quantity-quality-based Optimization Of Indoor Thermal Environment For Residential Buildings In Hot Summer And Cold Winter Climate Zones

Hot-summer/cold-winter(HSCW)climate zones involve the Yangtze River Basin-based 16 provinces.This densely populated and economically developed region has a GDP of 48% of the national total.With the continuous improvement of the economic level of the local residents,the demand for improving indoo r environment has also continuously increased.In particular,there is an urgent need for the improvement of indoor thermal environment.This further raises the issue of energy efficient utilization in this area.This dissertation is looking at the issue o f the indoor thermal comfort and thermal environment creation of free-running buildings,and the integrated assessment of the heat transfer and energy conversion in the process of creating a high-quality indoor thermal environment.With the in-depth investigation,theoretical analysis,modelling and case study,this dissertation investigates the energy efficiency of free-running buildings(based on dynamic thermal comfort assessment),quantifies the energy efficiency of active technologies(based on extrans y dissipation and exergy loss),and proposes the quantity-quality-based optimization of indoor thermal environment for residential buildings in HSCW climate zones.In the aspect of energy efficiency of free-running buildings,this study analyses the energy flow process of free-running buildings,establishes a load forecasting and dynamic energy analysis model on the basis of the APMV assessment.This model quantifies the relation between various factors(e.g.thermal comfort,building design and climate data)that affect the energy efficiency of free-running buildings,contributing to the building passive design.The energy efficiency of typical building passive design strategies is analysed based on a case room in this particular climate zone.In this case,it finds that if the south-facing fenestration with 35% of the window-wall ratio is promoted for the natural ventilation optimization design,the accumulated hours with indoor thermal comfort that meet the Grade I requirements of GBT 50785-2012 Evaluation Standard for Indoor Thermal Environment in C ivil Buildings is 31.8% of the whole year;compared to the case room without natural ventilation,the annual heat loads are decreased by 12%,the annual cooling loads are decreased by 41%;In addition,if we further enhance the thermal performance of building envelope,to be 10% more optimized than the local building energy efficiency standards,the comfortable hours ratio meeting Grade I thermal comfort basically stays the same,while the annual heat loads will be further reduced by 7% and the annual cooling loads further reduced by 4.8%.In the aspect of energy efficiency evaluation of conventional heating and cooling techniques,based on the theory of extransy and exergy,an energy-efficiency assessment model is set up for quantifying the heat transfer and energy conversion processes,and then the quantity-quality-based optimization method for creating the indoor thermal environment is proposed.First,investigation research,Python analysis and thermal comfort assessment are conducted to determine reasonable thermal loads of residential archetypes in HSCW climate zones.Second,a base technical scheme for indoor thermal environment creation in this climate zones is determined.The entransy dissipation and exergy loss of the base technical scheme are then obtained by the quantitative Entransy-Exergy model.Third,by comparing the entransy dissipation and exergy loss with those values of the base scheme under each conventional technology,the relative rates of entransy-saving and exergy-saving are defined and quantified to rate energy efficiency of each technology.Finally,combined with the life-cycle cost analysis(LCCA),a quantitative analysis of typical techniques for indoor thermal environment creation is conduced.In view of the fact that cooling systems in this climate zones is relatively uniform while the best heating system has not yet reached a consensus,the fixed frequency air conditioner with 3-level energy efficiency is considered to be the base technical scheme for indoor thermal environment creations.The energy efficiency comparisons are made among the inverter air conditioner in cooling conditions,inverter air conditioner in heating conditions,air source heat pump with floor radiant heating system,wall-mounted gas boiler with floor radiant heating systems,wall-mounted gas boiler with radiators and electric heaters.It could conclude that the inverter air conditioner for cooling and air source heat pump with floor radiant heating systems perform with a best energy efficiency.Considering the economic factors together,it could suggest the use of an inverter air conditioner with a higher energy-efficiency level for both cooling and heating.Air source heat pump with floor radiant heating system has the best annual running cost while the LCCA is too high due to exorbitant initial investment and equipment renewal fees.However,in most cases,its life clycle cost is lower than the electric heaters which are currently widely used in residential buildings in HSCW climate zones.