Research on technology clusters and the energy efficiency of energy-saving retrofits of existing office buildings in different climatic regions

Background: During the period of the 12th Five-Year Plan, energy demand exhibited a rigorous growth trend along with the acceleration of industrialization and urbanization and the constant upgrading of consumption structure. Therefore, the path that all cities and provinces must take towards sustainable development required by the 13th Five-Year Plan is to enhance research on the energy efficiency of buildings, especially existing buildings; sufficiently evaluate regional building energy demands and the characteristics of resources and environment; and formulate regional technical measures and policies for building practical energy efficiency measures. Methods: In this research, building energy-saving technologies are classified into four categories, i.e., green energy efficiency technologies for building envelopes, renewable energy sources, HVAC equipment systems, and architectural environment control systems. The existing office buildings representing different architectural climatic regions (cold region A, cold region B, and hot-summer cold-winter region) under the jurisdiction of Shaanxi province, China, are selected as the objects of research to discuss typical buildings in-depth. Results and conclusions: The research finds that even for buildings of the same type, the energy efficiency retrofit technologies selected for them are quite different because the buildings are situated in different climatic regions. For example, in regard to the materials, such as low-E hollow glass doors and windows, high transparency materials should be selected for cold regions, whereas sun-shading materials should be selected for hot-summer cold-winter regions. In comparison with the Standard for Energy Consumption of Civil Buildings (GB/T 51161-2016), the energy consumption of the existing office buildings that have been retrofitted can basically reach the threshold values specified by the national standard, but there is still a distance from the guideline values, which is related to the technology clusters selected and the economic category and can be corrected in practical applications. This research establishes technology cluster systems for energy efficiency retrofits that are suitable for different climatic regions. This work also assists relevant departments in formulating the local energy use quotas for existing public buildings, promotes the management of energy efficiency by local governments for public buildings, and provides theoretical and technical support for the low-carbon ecological development of Chinese cities.