Economical and outdoor thermal comfort analysis of greening in multistory residential areas in Xi'an

Global climate change and urbanization have generated increased attention to thermal comfort in urban residential areas. The use of vegetation to improve thermal comfort has been confirmed by many previous studies. However, in actual construction projects, we not only need to know the positive benefits of different greening patterns on outdoor thermal comfort but we also need to consider the cost. In this paper, the main research intent is to analyze the economics of the improvement of outdoor thermal comfort through different greening patterns to provide a theoretical basis for the selection of efficient greening patterns for actual construction projects. All vegetation species, include tree, shrub and ground-cover plant, could reduce the PET difference for whole daytime. To reduce the PET mean value by 1°C, the expenses of tree is 1/31.2 to 1/320.7 of the ground-cover plants or 1/2.9 to 1/18.2 of shrubs. We propose that trees should be planted in areas where improving outdoor thermal comfort is necessary. The dispersed planting of trees can make the improvement of outdoor thermal comfort more economical. Ground-cover plants and shrubs could be planted on a large scale in areas that have a low demand for outdoor thermal comfort.