Outdoor and indoor thermal comfort in the built environment is a crucial factor impacting urban heat island (UHI), building energy consumption and occupant welfare. Building roofs are directly connected to these phenomena since high overheating on both surfaces can affect negatively all these aspects. Several innovative technologies, such as phase change material, green and cool roofs and so on, were proposed and investigated to address these environmental targets. However, an accurate design of traditional roofs is required to limit the use of these technically complex and expensive technologies.

The main objective of this work is to study the role of the inclination and azimuth (orientation) of lightweight and heavyweight roofs, equipped or devoid of an insulation material during the cooling period in Italy and Greece. The investigation was carried out by means of a dynamic model in a steady periodic regime proposed by the authors that accurately takes into account all the building roof heat exchanges. The surface temperature fluctuations, in terms of amplitude and maximum peak, were employed to find the optimal configurations to mitigate the UHI effect and cooling load. In addition, the temperature decrement factor and time lag were used to summarise the overall roof thermal behaviour. The results showed that an accurate roof design leads to a reduction of the amplitude and maximum peak of the temperature on the external surface of 12.5 °C and on the internal surface of 4.7 °C. Instead, the decrement factor varies also of 29.9 % and the time lag of 7 h.

建筑环境中的室外和室内热舒适度是影响城市热岛（UHI），建筑能耗和居住者福利的关键因素。建筑屋顶与这些现象直接相关，因为两个表面上的过热都可能对所有这些方面产生负面影响。为了解决这些环境目标，人们提出并研究了几种创新技术，例如相变材料，绿色和凉爽的屋顶等。但是，需要对传统屋顶进行精确设计，以限制对这些技术复杂且昂贵的技术的使用。

这项工作的主要目的是研究意大利和希腊在冷却期间配备或没有隔热材料的轻型和重型屋顶的倾斜度和方位角（定向）的作用。作者通过在稳态周期内的动态模型进行了研究，该模型精确地考虑了所有建筑物屋顶的热交换。根据振幅和最大峰值，使用表面温度波动来找到最佳配置，以减轻UHI效应和冷却负荷。另外，温度递减因子和时间滞后被用来总结屋顶的整体热行为。结果表明，正确的屋顶设计可降低12的外表面温度的振幅和最大峰值。5°C，内表面为4.7°C。取而代之的是，递减系数也变化29.9％，时滞为7 h。