Research On The Low-cost Energy-efficient Optimization Of Rural House In Central Liaoning To Meet Indoor Thermal Requirements

Winter in central Liaoning of China is cold and long,and the heating period lasts for 150days.Through actual surveys,it is found that the current situation of indoor thermal environment in rural houses cannot meet the basic thermal requirements of residents.Farmers generally express their hope for a warmer indoor environment.And the envelope of many rural houses has poor thermal insulation performance,which is neither useful to create a comfortable thermal environment nor beneficial to energy saving.Besides,the central Liaoning is the only area with abundant solar energy resources in cold climate areas.By setting up film-covered buffer space,the rural house can maximize the use of solar energy to increase the indoor temperature,and can achieve the purpose of reducing the infiltration of cold wind.The integrated application of film-covered buffer space and rural houses is a common technical measure adopted by low-income farmers.Nonetheless,the existing technology of film-covered buffer space is mainly based on folk experience and lacks sufficient theoretical guidance.In order to obtain the low-cost energy-efficient optimal scheme and the design parameter which meets the indoor thermal environment requirements of rural houses in central Liaoning,this research uses a combination of field survey,theoretical analysis and numerical simulation to carry out research work.First of all,to investigate the conditions of 121 rural houses in 5 locations in central Liaoning,the author adopted the methods of on-site measurement and conducted surveys of occupant responses to environment.The research contents include residents’living characteristics,routines of work and rest,economic conditions,thermal environment requirements,types and plan layout of buildings,etc.The results show that the bedroom and living room are the warmest rooms in the rural house,which average indoor temperature and operating temperature in winter are 15.5℃and 14.7℃.The neutrality operating temperature of 17.4℃and 90%acceptability limits range([15.0℃,18.1℃])were obtained by linear fitting method of operating temperature and thermal sensation vote value.The neutrality operating temperature of 17.4℃was obtained by the linear fitting method of operating temperature and mean thermal sensation vote.The result shows that the current thermal environment cannot meet the actual heat demand of famers.In addition,due to the diversity of rural architectural form and spatial layout form,this paper determines the benchmark rural house model in central Liaoning by the cluster analysis.Through heat transfer analysis,the roof and the wall which directly in contact with the kang accounted for the largest proportion of the total heat dissipation of the kang(The proportion is about 35%and 20%).It is the weakest link in the rural house.The survey results show that measures such as the envelope insulation and the film-covered buffer space are low-cost and energy-efficient optimization methods for indoor thermal environment of rural houses.Second,the author used the NSGA-II algorithm as the solution search engine,Rhino+Grasshopper as the carrier,and the Ladybug+Honeybee integrated Energy Plus simulation kernel as the objective function solving tool in the multi-objective optimization process to build the optimization model of the envelope.The model is based on the indoor thermal requirements of farmers,and takes the low-cost energy-efficient optimization of rural houses as the goal.The optimization results show that the annual heating energy consumption of the building under the Pareto optimal solution conditions varies between180～230k Wh/(m~2?a),which is 26%lower than the reference rural building.The improvement cost is less than 8000 yuan,which is lower than the annual disposable income of farmers.In the Pareto optimal solution,the thickness of the insulation layer of the envelope structure from high to low is the floor,ceiling,and exterior wall of the bedroom and living room,which corresponding to 70mm,50mm,40mm,and 30mm,20mm.Farmers should give priority to heat preservation of these part.On the premise of ensuring the lighting and ventilation of the room,the lower the window-to-wall ratio,the better.In addition,the author gives three kinds of optimal technical schemes that take into account energy consumption and economy at the same time as the reference basis for the renovation design of rural houses.Finally,the author has carried out standardized design for integrated application of low-cost film-covered buffer space and rural houses,and established a numerical heat transfer model for the film-covered buffer space.Based on the calculation of energy consumption and the numerical simulation of indoor thermal environment,the author gave the improvement effect of buffer space material,form and depth on indoor thermal environment.Besides,the author gave the optimal threshold of the envelope in rural house with film-covered buffer space.The results show that PO film,inclined form,and depth range between 1.4m and 1.6m are the optimal morphological parameters of the buffer space.The thickness of the optimal insulation layer on the wall,which is the long side of the kang is recommended to be 40mm.Optimized measures can reduce the annual heating energy consumption of rural houses by 53%.