# Building Energy Retrofit Measures in Hot-Summer-Cold-Winter Climates: A Case Study in Shanghai
## 7 Conclusions  
This article presents a brief overview of recent studies on building retrofit measures and their application on a variety of different building types in Shanghai. It identifies key elements needed for developing sustainable buildings in this region. Furthermore, the review elucidates a basic systematic approach for appraising sustainable retrofit packages in addition to plausible challenges facing these measures. Based on this study, the following conclusions are deduced:  
1. Shanghai is characterised by rapid urban development. However, there are limited research studies on the building retrofit measures for the large proportion of existing buildings. 2. The limited previous studies have demonstrated that the most applied building retrofit measures are upgrades in the building envelope, HVAC and lighting systems. In some cases, these measures are supported by PV systems. The degree of application of each measure varied with the building typologies. Based on their degree of application, the measures followed the particular order: Building envelope \(>\) HVAC \(>\) lighting for office buildings; building envelope \(>\) lighting \(>\) HVAC for residential buildings; and HVAC \(>\) building envelope \(>\) lighting for other buildings. 3. Key elements identified to affect building retrofit measures include policies and regulations, retrofit technologies, client resources and expectations, human factors, building specific information and other uncertainty factors. Lack of most of these promoting factors contributed to key barriers facing the retrofit measures, among which financial barriers and lack of policies and regulatory support are considered as the most challenging. 4. Appropriate selection criteria and weighting factor assignments are necessary in determining the optimum retrofit solution for buildings. These criteria should include comprehensive energy simulation and audit, risk assessment, environmental and economic analysis. Also, the following remarks and recommendations are suggested in the line of future studies:  
1. Studies posit that appropriate retrofits for individual buildings can improve the energy and environmental performance of existing buildings. An optimum improvement of building energy-saving potential requires a whole (\"deep\") building retrofit. Nonetheless, extensive studies on economic evaluation and risk assessment in this regard are needed. 2. Based on limited publication, extensive studies on the evaluation of building retrofit measures that include the UHI index and other urbanisation indicators in Shanghai should be considered. These studies will be valuable for designing sustainable buildings in rapidly expanding cities like Shanghai. 3. This study also recommends that more practical experimentation should be included to augment and increase the confidence level of model-based results. Most retrofit studies adopted the model-based approach to determine and evaluate retrofit options. Estimated energy conservation/ efficiency may differ from actual measurements. In addition, human factors have been shown to affect building energy usage due to the rise in population density. Hence, a comprehensive study to investigate the impact of this factor on building retrofit measures is needed. 4. The nascent nature of building retrofit measures in Shanghai demands an adaptive retrofit package, which can be achieved by designing a whole energy-cyber-physical system (eCPS)promoted by fully-integrated hybridisation of the embedded building equipment, computational tools, sensing and control mechanisms and physical network with real-time communication via digital signals and information processing algorithms. In summary, China, in particular Shanghai, still has a long way to go in building retrofit measures; promoting and implementing necessary policies and regulations in this regard; and establishing maintenance and management methods to ensure existing buildings are energy-efficient and environment-friendly.