中華民國內政部建築研究所中華民國內政部建築研究所

由於淨零排放議題興起，許多民間環保團體呼籲加強外殼隔熱，並建議政府修改外殼隔熱法規，且以外殼節能而言，外牆的面積雖然較大，但是屋頂是直接受到太陽熱紅外線的照射，受熱情形較外牆嚴峻，因此，屋頂隔熱對於建築的節能效益值得進一步確認。
本研究首先蒐集並分析國內外有關隔熱材料之基準，包括CNS國家標準、施工綱要規範、日本及中國大陸建築屋頂隔熱基準、冷屋頂材料基準等等，經分析探討國內外隔熱材料之基準，部分基準以熱阻（或稱隔熱係數，R，亦為U值之倒數）做為基準，部分則以導熱係數（或稱熱導係數，k），熱阻與厚度相關，厚度越大，材料的熱阻越大，U值越小，而熱導係數則是反應材料的本質，與厚度、長度等尺寸無關。
經本研究分析屋頂隔熱節能效益後，發現在亞熱帶氣候區的臺灣，由於室內室外溫差不大，且目前法規規定之屋頂U值為0.8，在這個U值基準下，再去提高屋頂隔熱能力，對於節能效益極為有限，因此不建議採取再降低屋頂U值的策略，建議採取改善開口部策略，例如水平天窗或外牆窗戶的遮蔽係數。

Due to the rise of the Net Zero Emissions initiative, many non-governmental environmental groups have called for the strengthening of enclosure insulation and recommended that the government revise enclosure insulation regulations. In terms of energy saving of the outer shell, although the area of the outer wall is larger, the roof is directly irradiated by the solar heat and infrared rays, and the heating situation is more severe than that of the outer wall. Therefore, the energy-saving benefits of the roof insulation for the building deserve further confirmation.
This research first collects and analyzes domestic and international standards for insulation materials, including CNS national standards, construction guidelines, Japanese and Chinese mainland building roof insulation standards, cold roof material standards, etc. After analyzing and discussing the benchmarks of insulation materials, it is found that some benchmarks are based on thermal resistance (or thermal insulation coefficient, R, which is also the reciprocal of U value), and some are based on thermal conductivity k) . Thermal resistance is related to thickness of material. The greater the thickness, the greater the thermal resistance of the material, and the smaller the U value. The thermal conductivity is the essence of the material and it is not related to dimensions such as thickness and length.
After analyzing the energy-saving benefits of roof insulation, it is found that in Taiwan, because the temperature difference between indoor and outdoor is not large, and the current regulations that the roof U value is already strict, the energy-saving benefits of roof insulation is extremely limited. Therefore, it is not recommended to adopt the strategy of lowering the U value of the roof, especially when the U value is already very low. It is recommended to adopt strategies to improve openings, such as the shading factor of horizontal skylights or external wall windows. It is not recommended to adopt the strategy of reducing the U value of the roof. It is recommended to adopt the strategy of improving the opening, such as the shading coefficient of horizontal skylights or external wall windows.