ISO 15927-5:2004规定了用于确定建筑物空间供暖设计热负荷的气候数据的定义、计算方法和表示方法。其中包括冬季外部设计空气温度以及相关风速和风向（如适用）。 通过地面的热损失也会增加建筑物的热负荷，这取决于长期的温度变化；ISO 13370中给出了计算地面热损失的方法。

ISO 15927-5:2004 specifies the definition, method of calculation and method of presentation of the climatic data to be used in determining the design heat load for space heating in buildings. These include the winter external design air temperatures and the relevant wind speed and direction, where appropriate. Heat loss through the ground, which also contributes to the heat load for buildings, depends on longer-term temperature changes; methods for calculating ground heat loss are given in ISO 13370.