Research On Low Energy Consumption Renovation Technology Of Existing Residential Roof In Hunan Province

In the process of industrialization and urbanization in China,building energy consumption shows a sharp rise trend,and the proportion of total energy consumption in China has jumped from 10% in 1978 to 20.5%,gradually approaching 33% in developed countries.In 2017,the Ministry of Housing and Urban-rural Development put forward the next step of energy conservation requirements for the work of energy conservation renovation.During the 13 th Five-Year Plan period,it will actively explore the technical routes and strategies for energy conservation renovation of existing residential buildings suitable for application and promotion in hot summer and cold winter and hot summer and warm winter areas,carry out energy conservation demonstration,and complete the implementation of energy conservation renovation of existing residential buildings of over 500 million m2 by 2020.As the part that receives the longest time of solar radiation in summer and obviously consumes heat in winter,the roof is reformed to save energy,which has an important role in improving indoor thermal comfort.Based on the general situation of hunan’s climate and indoor thermal environment,this paper is divided into five parts:The first chapter systematically discusses the necessity of carrying out roof renovation work,and through the research of low energy consumption renovation and roof technology development status,it is concluded that the domestic research on roof renovation technology is mainly focused on the research on roof insulation technology,for the roof needs to meet the conditions of insulation and insulation.The second chapter investigates the current situation of the existing residential envelope structure and indoor thermal environment in hunan,analyzes and summarizes the problems of the existing residential roof,such as poor thermal performance,high energy consumption,poor indoor thermal comfort,serious roof leakage and inconvenience in the later maintenance,and defines the direction of renovation.In the third chapter,through the theoretical study of thermal comfort and the comparative analysis of the standard thermal index of low energy· Vconsumption in hot summer and cold winter areas,the thermal comfort index and the thermal index of low energy consumption renovation of roofing are determined.The fourth chapter summarizes and analyzes the existing roof renovation technologies,and preliminarily puts forward the types of roof renovation technologies suitable for the application and promotion in hunan region,including inverted roof,planting roof,cold roof and flat slope roof.In the fifth chapter,through the simulation analysis,a comparative analysis of several roofs is conducted from the perspective of heat preservation,heat insulation and thermal comfort.It is concluded that the thickness of the insulation layer is very significant for improving the insulation effect of the roof,but the thickness of the insulation layer should not be ≥90mm.In summer,the cold roof has the best thermal insulation effect,and the planting roof is the best in terms of the thermal stability of the indoor environment.Moreover,the soilless planting roof is similar to the planting roof with the soil thickness of 200 mm in terms of thermal insulation performance,and even better than the planting roof with the soil thickness of 200 mm in some time.The sixth chapter makes a comparative analysis of roof renovation technology from the five aspects of low load,economy,thermal comfort,environmental friendliness and enrichment of the fifth facade,and obtains the low-energy renovation technology route suitable for the application and promotion of the existing residential roof in hunan,that is: 1)with low load as the target,soil-free planting roof can be preferred,followed by inverted roof and cold roof;2)with energy-saving,economic efficiency and thermal comfort as the target,planting roof can be selected first,followed by cold roof;3)oriented to environmental friendliness,planting roof and cold roof can be preferred;4)to enrich the fifth facade as the target,planting roof and sloping roof can be preferred.Combined with the problems caused by practical application,the cold roof reconstruction strategy,flat slope roof reconstruction strategy,planting roof reconstruction and optimization strategy are put forward.Finally,through the transformation analysis of the actual cases,it is concluded that the selected roof renovation technology can effectively reduce the energy consumption of existing residential buildings,among which the planting roof energy saving rate is 25.08%,which can reduce the indoor average temperature by up to 1.6℃ in summer.In winter,the highest indoor average temperature increased by 2.1 ℃.According to the technical route and strategy of the existing house roof renovation,the paper can provide reference for the low energy consumption renovation project of the existing house roof in hunan province.