The population in urban areas is increasing rapidly around the world in most of the cities. In India, this growth has forced the local governments to review the planning norms regularly with the main focus of making an affordable urban living. This resulted in increasing the built density without evaluating the effect of such developments on human thermal comfort. Outdoor microclimate is one of the significant factors that determine the quality of outdoor spaces. This study investigates the potential impact of the built geometry guided by the newly published development control rules of Chennai, India on the various parameters that influence microclimate. The existing and future scenario has been modelled for three locations in a typical mixed-use neighborhood of Chennai. Further, air temperature and relative humidity were measured in three locations on a typical summer month of May 2018. The recorded data was used for validating the simulated model and calibrating the model settings. Most of the studies on outdoor thermal comfort compare a base case scenario and project future scenarios. This paper is a more realistic comparison of outdoor thermal comfort between the actual resultant built environment guided by the new Tamil Nadu Combined Development and Building Rules, 2019 for selected locations and the existing built geometry which is the outcome of revised development control rules of 2013. The study found a significant reduction of 18 °C in mean radiant temperature (Tmrt) and a reduction of 12 °C in Physiological Equivalent Temperature (PET) between the 2013 and the predicted built geometry as per 2019 building rules. Further the duration of extreme heat stress in the Physiological Equivalent Temperature (PET) scale show a reduction of 3 h during the day time. The study will assist urban planners and designers to include outdoor thermal comfort also as an important factor while developing building rules.

在世界上大多数城市中，城市地区的人口都在迅速增加。在印度，这种增长迫使地方政府定期审查规划规范，其主要重点是使人们能够负担得起的城市生活。这导致增加了建筑密度，而没有评估这种发展对人类热舒适性的影响。室外小气候是决定室外空间质量的重要因素之一。这项研究调查了印度钦奈新发布的发展控制规则指导下的建筑几何形状对影响微气候的各种参数的潜在影响。在金奈典型的混合用途社区中，针对三个地点对现有和未来方案进行了建模。进一步，在2018年5月的一个典型夏季月份，在三个位置测量了空气温度和相对湿度。记录的数据用于验证模拟模型和校准模型设置。关于室外热舒适性的大多数研究都比较了基本情况和项目未来情况。本文是根据新的《泰米尔纳德邦联合开发与建筑规则》（2019年）（针对选定地点）指导的实际建筑环境与现有建筑几何形状之间更现实的比较，该建筑环境是2013年修订的开发控制规则的结果。该研究发现，在2013年和根据2019年建筑规范预测的几何形状之间，平均辐射温度（Tmrt）显着降低了18°C，生理等效温度（PET）降低了12°C。此外，生理等效温度（PET）标度中的极端热应激持续时间显示白天减少了3小时。该研究将帮助城市规划者和设计师在制定建筑规范时将室外热舒适性也作为重要因素考虑在内。