| In the context of intensifying climate change,the promotion of energy conservation and emissions reduction is an inevitable choice for achieving sustainable development and adapting to increasingly frequent extreme weather disasters.Currently,building energy consumption accounts for over 45% of China’s total energy consumption,with urban residential buildings being the largest energy consumers.This trend is due to the prevalence of old,inefficient neighborhoods in major cities,with more than 30% of such neighborhoods exhibiting poor energy efficiency.It is evident that old neighborhoods,within the current context of a large building stock,offer substantial potential for energy saving and emission reduction.Exploring the energy consumption and energy-saving potential of buildings in old urban-scale neighborhoods and optimizing the design of energy-saving renovation plans for old neighborhoods are crucial issues that must be addressed at this stage.Unfortunately,most of the existing studies,both domestically and internationally,lack a systematic application guide for energy efficiency retrofitting in urban-scale old neighborhoods.Additionally,these studies tend to focus on identifying the best solutions for individual energy efficiency measures to be applied to specific buildings.Within this context,this study constructed an urban-scale building energy consumption measurement model for old neighborhoods using Geographic Information System(GIS)technology and a heat balance model.The model provides an accurate measurement of overall building energy consumption in old neighborhoods.Additionally,the energy-saving potential of the old neighborhoods in the study area was explored in conjunction with the current building energy design codes.An optimization algorithm was then used in combination with a retrofit efficiency assessment framework to develop a comprehensive and efficient energy-saving design plan for the old neighborhoods based on the current code framework.Finally,a case study was conducted in the central city of Nanjing.The study results indicate that the total annual energy consumption of the old neighborhoods in the study area varied across districts,with 76.89 GWh in Yuhuatai District,547.95 GWh in Gulou District,and 322.58 GWh,251.89 GWh,and 206.63 GWh in Qinhuai District,Jianye District,and Xuanwu District,respectively.Furthermore,after complete retrofitting,the annual energy consumption of buildings decreased by 288.55 GWh,which represents a reduction of 20.52% compared to the unretrofitted scenario.This reduction accounts for 2.96% of the city’s total urban and rural residential electricity consumption.The results of the scenario optimization demonstrate that upgrading the thermal performance of the exterior walls of old residential buildings and setting reasonable air conditioning target temperatures are the most efficient and cost-effective retrofitting measures over a 20-year NPV calculation period.Moreover,replacing air conditioning systems with higher energy efficiency ratios is also a more cost-effective measure for buildings built relatively late.Finally,refining retrofitting strategies to address the unique characteristics of different old neighborhoods can significantly reduce costs and improve overall retrofitting benefits.The findings and technical methods of this study can provide valuable theoretical support and technical guidance for optimal energyefficient retrofitting design in old neighborhoods throughout China. |
