Effect of existing residential renovation strategies on building cooling load: Cases in three Chinese cities

To provide a reference for the renovation of existing residential districts, this study quantifies and compares the relationships between common renovation strategies, microclimate, and cooling loads. These common strategies include improving the greening rate, improving the reflectivity of pavement, improving the reflectivity of wall materials, and improving the reflectivity of roof materials or applying green roof. These strategies are applied to a typical model extracted from existing residential areas in Beijing, Shanghai, and Guangzhou. ENVI-met and DesignBuilder are combined to simulate the microclimate represented by the average meteorological parameters in front of building surfaces and the building cooling load on a typical meteorological day in summer. The results show that increasing the vegetation has the most significant effect on the microclimate, and improving the roof reflectivity can yield the most reduction in the cooling load. Generally, all the strategies tend to be more effective under a climate zone with a stronger solar radiation. The sensible cooling load is underestimated and the latent cooling load is overestimated if neglecting microclimate effect. Furthermore, the difference in the total cooling load, between considering microclimate results and not, was affected by the proportion of sensible and latent cooling loads. To sum up, high-reflectivity roofs should be given priority, and building energy consumption should be simulated with microclimate results, especially relative humidity and wind speed.