The heat preservation and insulation performance of building envelope (including roof, exterior wall, door and window, etc.) has an important impact on indoor thermal environment and energy consumption of heating and air conditioning in winter and summer. The buildings with good thermal insulation and insulation performance of envelope structure not only have warm winter and cool summer, but also have good indoor thermal environment, and low energy consumption of heating and air conditioning. With the development of national economy and the improvement of people's living standard, people pay more and more attention to improving indoor thermal environment and saving energy consumption of heating and air conditioning in winter and summer, and the problem of improving thermal insulation and insulation performance of envelope structure is becoming increasingly prominent.
The heat preservation performance of envelope structure usually refers to the ability of heat transfer from indoor to outdoor under indoor and outdoor conditions in winter, so as to keep indoor proper temperature. The thermal insulation performance of envelope usually refers to the ability of the envelope to maintain a lower temperature on its inner surface under the action of outdoor comprehensive temperature (combined by outdoor air and solar radiation) and indoor air temperature wave under natural ventilation in summer. The main difference between them is:
First, the heat transfer process is different. Heat insulation performance reflects the heat transfer process from indoor to outdoor in winter, usually considered as stable heat transfer; heat insulation performance reflects the heat transfer process from indoor to outdoor in summer and from indoor to outdoor, usually considered as fluctuating heat transfer with a period of 24 hours.
二、评价的指标不同。保温性能通常用围护结构的传热系数k值[w/(㎡.k)]或传热阻R0值[(㎡.K /W]来评价；隔热性能通常用夏季室外和室内计算条件下（即当地较热的天气），围护结构内表面温度Qi.max（℃）来评价。如果在同样的夏季室外和 室内计算条件下，其内表面温度Qi.max来评价。如果在同样的夏季室外和室内计算条件下，其内表面温度Qi.max低于或等于当地夏季室外计算 温度te.max，（大体上相当于240mm厚砖墙的内表面温度），则认为符合夏季隔热要求。
Two, the indicators of evaluation are different. The thermal insulation performance is usually evaluated by the heat transfer coefficient K [w / (. k)] or the heat transfer resistance R0 [(. K / W)] of the enclosure structure; the thermal insulation performance is usually evaluated by the temperature Qi. max () of the interior surface of the enclosure structure under the outdoor and indoor calculation conditions in summer (that is, local hot weather). If in the same summer outdoor and indoor computing conditions, the internal surface temperature of Qi.max will be evaluated. If the temperature Qi. Max is lower than or equal to the calculated temperature te. Max (roughly equivalent to the inner surface temperature of 240 mm thick brick wall) in summer, it is considered to meet the requirements of thermal insulation in summer.
三、构造的措施不同。由于围护结构的保温性能主要是取决于其传热系数K值或传热阻R0的大小，而围护结构的 隔热性能主要取决于夏季室外和室内计算条件下内表面温度Qi.max的高低。对于外墙来说，由多孔轻质保温材料构成的轻型墙体（如彩色钢板聚苯或聚氨 酯泡沫夹芯墙体）或多孔轻质保温材料内保温性能较好，但因其是轻质墙体，热稳定性较差，或因其是轻质温度和室内空气温度波作用下，内表面温度容易升得较 高，亦即其隔热性能较差。也变是说，保温性能通常受构造屋次排列的影响较小，而隔热性能受构造层次排列的影响较大。相同材料和厚度的复合墙体，内保温构 造，隔热性能较差；外保温构造隔热性能较好。造成上述情况的原因从保温和隔热性能指标的计算方法和计算的结果中可以了解得更为的清楚。
Three, the structural measures are different. Because the thermal insulation performance of envelope structure mainly depends on the value of heat transfer coefficient K or heat transfer resistance R0, and the thermal insulation performance of envelope structure mainly depends on the temperature of Qi. Max in summer outdoor and indoor calculation conditions. For exterior walls, lightweight walls made of porous lightweight thermal insulation materials (such as colored steel polystyrene or polyurethane foam core wall) or porous lightweight insulation materials have better thermal insulation performance, but because they are lightweight walls, their thermal stability is poor, or because they are light temperature and room temperature air waves. It is easy to rise higher, that is, its insulation is poor. In other words, the thermal insulation performance is usually less affected by the arrangement of structural roofs, while the thermal insulation performance is more affected by the arrangement of structural levels. Composite walls with the same material and thickness have poor thermal insulation performance due to internal insulation structure and external insulation structure. The cause of the above situation can be clearly understood from the calculation method and results of the thermal insulation performance index.