| As a key indicator of living environment,indoor temperature in winter is not a special problem in the north of China,but for the middle and lower reaches of the Yangtze river in such a hot summer and cold winter climate,coupled with the lack of common northern heating facilities in winter,the problem is particularly prominent,seriously affecting the comfort of the indoor living environment in this area.Despite the area currently embarks on building a centralized heating network,it is faced with difficult transformation of the major antiquated blocks and high cost,while it cannot be widely adapted except for the development zone and the newly-built residential area,hence,additional means need to be further considered.Accompanied by the enhanced economy growth and living standard,an increasing number of people choose air conditioning to adjust indoor suitable temperature,but it also inevitably increases the consumption of building energy.External wall insulation is one of the most effective approaches to reduce the heating and cooling energy consumption of building.Different thermal properties of thermal insulation material,building energy consumption and the cost will be gradually with the increase of insulation layer thickness is reduced,and the construction of the insulation material cost will be gradually increased with the increase of insulation layer thickness,the energy consumption of the building cost and construction cost of the insulation material with the increase of insulation layer thickness between the existence of mutual influence and role.How to ensure energy saving at the same time be economical,whether there is a reasonable thickness of insulation layer as for a suitable insulation material,and how to maintain insulation layer construction and the corresponding energy consumption of the comprehensive cost to the lowest under such thickness?Consequently,it is crucial for the sustainable development of residential buildings in this area to select suitable insulation materials and optimal insulation layer thickness scheme.This paper focuses on the middle and lower reaches of the Yangtze River,and studies the lowest comprehensive cost solution for the construction and building energy consumption of the insulation layer in the whole life cycle from construction to scrapping,which is the optimal insulation layer thickness selection and construction scheme.The possible innovation of this paper lies in the study the quantitative relationship between insulation layer thickness and insulation layer construction cost.Given the whole life cycle cost theory and the influence of energy electricity price fluctuation,the optimization model of comprehensive cost of insulation layer LCC(Life Cycle Cost)is established,which is applied to evaluate and select the construction scheme of insulation layer in the middle and lower reaches of the Yangtze River.For one thing,it serves as a key index for real estate developers in this area to plan and design new buildings,for another,it can provide effective policy basis for local government departments in building energy conservation.Based on the life cycle cost theory,this study establishes the optimization model of the insulation layer,takes the net present value and annuity value as the economic evaluation index of the insulation layer scheme,and makes use of BIM technology to conduct simulation analysis on the energy consumption of residential buildings in the middle and lower reaches of the Yangtze River,and the optimization problem of insulation layer scheme is studied by consulting literature,simulation analysis,case verification and so on.Specific research can be divided into the following parts:First,through referring toing literature,to recognize the current situation of foreign and domestic research on insulation layer,summarize the research results of insulation layer in technical analysis,economic analysis and so on.Based on the existing domestic and foreign research achievements,this paper explores the basic method of optimizing the external insulation scheme of residential buildings in the middle and lower reaches of the Yangtze River.Second,based on the whole life cycle cost theory,combining the insulation layer with the whole life cycle theory,this paper analyzes the relation between the construction cost of the insulation layer during the construction period,the energy consumption cost during the operation period and the comprehensive cost of the whole life cycle of the insulation layer.Considering the expected influence of energy price,the net present value and annuity value are taken as the indexes of economic evaluation and analysis of insulation layer scheme.Since it is impossible to re-plan and build central heating facilities in the Yangtze River area,this study selected the most convenient,green,economical and feasible energy source of electricity in study.Third,establish the optimization function model of insulation layer thickness and LCC comprehensive cost.Based on the life cycle cost theory,the basic model of the whole life cycle cost of insulation layer is put forward first.Followed by using econometrics research method,the regression model of insulation layer thickness and construction cost during the construction period of insulation layer is established,and the fluctuation rate of electricity price is substituted into the energy consumption cost during the operation period,so as to form the theoretical model of insulation layer LCC optimization.As a result,the thickness of the lowest insulation layer LCC the comprehensive cost can be obtained,that is,the optimal insulation layer thickness,as well as the optimal insulation construction scheme.Fourth,conduct the simulation analysis and result deduction of LCC theoretical model with BIM technology.Taking the residential buildings in the middle and lower reaches of the Yangtze River as the research object,simplified standard layer information model of residential buildings is established by BIM technology,and the climate data of Hangzhou,Nanjing and Hefei cities in the middle and lower reaches of the Yangtze River are introduced into the BIM platform,then the building energy consumption simulation and comparative analysis of different insulation layer schemes are carried out.Besides,the energy consumption data of building refrigeration and heating are counted to obtain the total energy consumption cost data of different insulation layer schemes.At the same time,the price of insulation material is investigated and the unit price of comprehensive construction of insulation material is calculated on the basis of relevant quota,with the cost regression model is constructed by substituting the quantity of BIM model insulation layer to test the validity of the regression model.Furthermore,the above data are substituted into the insulation LCC optimization model to optimize and analyze the different insulation schemes.After the sensitivity analysis of the effect of electricity price change on insulation scheme-it probes into the change of energy consumption cost and the influence of energy price change on insulation scheme optimization.Finally,the results of calculation and analysis are summarized before putting forward the optimal theoretical scheme of insulation layer construction.Fifth,through the case of residential buildings in the middle and lower reaches of the Yangtze River,the applicability of the above insulation layer construction scheme is verified.With the LCC optimization model of thermal insulation layer,three different practical buildings are selected in this study,and the reasonable insulation layer construction scheme which can be applied in engineering is determined by comparing the deduction results.Sixth,summarize the research results and provide energy saving suggestions for the thermal insulation scheme of residential buildings in the middle and lower reaches of the Yangtze River.The results show that different climatic conditions,external wall structure,insulation material type and electricity price fluctuation will pose impacts on the optimal scheme evaluation of insulation layer:climate conditions in Nanjing are more suitable for adding insulation layer than in Hangzhou and Hefei,which brings higher economic benefits of energy saving;the thicker the structure thickness of external wall,the smaller the thickness of additional insulation layer;and the better the energy saving and economic effect of choosing XPS insulation layer when the thickness of insulation layer is small;After the insulation layer reaches a certain thickness,continue to increase the thickness of the insulation layer,choose EPS insulation layer energy saving and economic effect is more favorable;with the increase of electricity price,the optimal insulation layer thickness will gradually increase.When the future electricity price still maintains the current stable trend,the 0.02m-0.05m thick XPS insulation layer is used as the optimal insulation layer scheme for different external wall structures in different cities;taking into account the possible influence of electricity price fluctuation in the life cycle of insulation layer in the future,the optimal insulation layer scheme of different exterior wall structures in each city is to adopt 0.04 m-0.07m XPS insulation layer in thickness.Considering the results of the above research,this study finally put forward a energy saving countermeasure on the choice of external insulation scheme for residential buildings for the most typical city-Nanjing in the middle and lower reaches of the Yangtze River,and it is recommended for unified application of 0.05m thick XPS insulation scheme. |
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