Impacts Of Slab Residential Building’s Form And Layout On Outdoor Thermal Comfort:A Study In Xi’an,China

The outdoor thermal environment plays a vital role in improving the quality of occupants’ life and the design of outdoor open space,especially facing severe urban environmental challenges.However,it is rarely involved in design practice in China.Meanwhile,the homogenisation of urban morphology is a common phenomenon during rapid urbanisation.How are these popular building forms going to influence the open space around them? How could we create a more comfortable outdoor environment for users? This study aims to develop a methodology of analysing the outdoor thermal environment of large homogeneous urban areas to inform the stakeholders of the design’s impacts in terms of the thermal conditions,and further provide design promotion strategies.Firstly,the research established a framework of urban morphology extraction,especially for outdoor thermal comfort simulation studies.Secondly,supplemented by statics collected from the on-site investigations and interviews,the framework has been successfully applied to slab residential building,which has been a popular building form in Xi’an for decades.The prototypes extracted are selected to composing 7 scenarios for comparison with the aims of understanding the impact of building metrics separately.The scenarios were then simulated in ENVI-met with the software’s abilities compared and settings justified.Finally,the simulation results were explained by quantitative illustrations.The results indicate that the urban morphology extraction framework and the 9-block simulation method are feasible.And the thermal environment should be treated from a dynamic perspective since it has solar radiation based regular daily pattern.The outdoor thermal comfort promotion strategies should take usage time into consideration.Air temperature and relative humidity are reversely connected and should be discussed on the whole area level with density related building parameters,instead of the urban block scale.High-rise buildings have stronger abilities to influencing the wind flow around them.Space between building rows performs more steadily in terms of wind speed.The mean radiant temperature differences are mainly determined by the shading.The street canyons are inevitably shaded in January,which strengthens the importance of maintaining sunshine spacing.Shading designs are essential in July.Grassland reduces temperatures,but vertical greening is more efficient with its ability of shading.Design principles of different building stages were provide based on the analyses,together with recommendations and feasibility demonstrations of the choices of building shape and combination method,the site layout,the protection of pedestrians,and outdoor facility design.These strategies determined to improve solar radiation acquisition,air movement,and lacking space.