As the variation and timely meeting thermal environment requirement of indoor air temperature has a close relationship with the thermal performance of building external wall under discontinuous radiant heating condition, one appropriate assessment method or index for assessing the building external wall thermal performance is very necessary. In order to reasonably evaluate the thermal performance of external wall under discontinuous radiant heating condition and build the direct connections and interactions among the indoor air temperature, external wall inner surface temperature and outdoor air temperature, the first and second impact factors of temperature deviation were established, based on one mathematical model of room heat transfer. For one experimental room and four types of external walls under discontinuous radiant heating condition, both the influence of the external wall inner surface temperature deviation on the indoor air temperature and that of the outdoor air temperature deviation on the external wall inner surface temperature were determined effectively with the first and second impact factors of temperature deviation. In addition, favourable performance for the self-insulation and inner insulation walls were found, due to their superiority in effectively and timely improving the indoor thermal environment under discontinuous radiant heating condition. 在非连续辐射供暖条件下，室内空气温度的变化与及时响应热环境要求程度问题都与建筑外墙热工性能有密切关系，因此需要一种合理评价建筑外墙热工性能的方法或指标。为了合理评价在非连续辐射供暖条件下建筑外墙的热工性能以及建立室内空气温度、外墙内表面温度、室外空气温度之间的直接联系和相互影响作用，本研究基于房间传热数学模型提出了温度偏离第一和第二影响因子。其次，针对实验房间以及非连续辐射供暖条件下的四种外墙构造形式，采用温度偏离第一和第二影响因子研究分析确定了外墙内表面温度偏离对室内空气温度的影响以及室外空气温度偏离对外墙内表面温度的影响。此外，研究发现自保温和内保温在非连续辐射供暖条件下具有很好的性能，这归因于其能够对室内热环境的有效及时改善。