A type of smart window using thermochromic glazing (TCG) is a promising technology for green buildings owing to the self-regulating feature and low-maintenance need. Its most important feature, thermo-optical properties that regulate the blockage of solar heat, is directly linked to the variation of surface temperatures. However, challenges from the inhomogeneity of thermo-optical properties, the coupled solar radiation and natural convection, and varying outdoor conditions all seriously hinder the understanding of its mechanism. In this paper, a validated Computational Fluid Dynamics (CFD) model achieves the simulation of inhomogeneous tinting of TCG by defining the thermo-optical properties of each finite volume according to the surface temperature. Solar radiation and natural convection at outdoor, indoor and the cavity are solved to reflect glazing temperature more accurately. The case studies compared six different switching temperatures in the range of 20 ∼ 42.5 °C with a transition gradient of 10 °C. Averaged meteorological data for both summer and winter, sunny days and cloudy days are selected to present realistic climate impacts. The result reveals the overall saving in transmitted solar radiation in summer and heating penalties in winter. It suggests the best switching temperatures for each climate condition. With the seasonal operation, the highest saving in solar heat gain is 20.9% when adopting a switching temperature of 25–35 °C, while the lowest saving can be negative, meaning TCG is not suitable for those climate zones. The proposed evaluation criteria help to quantify the applicability of TCG with the input of the summer/winter day ratio and sunny/cloudy ratio. The best region to apply TCG is where summer days are longer and winter solar radiation is significantly lower. The in-depth understanding of this temperature-sensitive process benefits the optimization of TCG in buildings, especially for its seasonal operation needs.

一种使用热致变色玻璃 (TCG) 的智能窗户由于具有自我调节功能和低维护需求，是一种很有前途的绿色建筑技术。其最重要的特征，即调节太阳热量阻挡的热光特性，与表面温度的变化直接相关。然而，热光特性的不均匀性、太阳辐射和自然对流的耦合以及不同的室外条件等挑战都严重阻碍了对其机制的理解。在本文中，经过验证的计算流体动力学 (CFD) 模型通过根据表面温度定义每个有限体积的热光特性，实现了对 TCG 不均匀着色的模拟。室外的太阳辐射和自然对流，解决室内和空腔，更准确地反映玻璃温度。案例研究比较了 20 ∼ 42.5 °C 范围内的六种不同开关温度，过渡梯度为 10 °C。选择夏季和冬季、晴天和阴天的平均气象数据来呈现真实的气候影响。结果揭示了夏季传输的太阳辐射和冬季供暖损失的总体节省。它建议了每种气候条件的最佳切换温度。在季节性运行中，当采用 25-35°C 的切换温度时，太阳能热增益的最高节省为 20.9%，而最低节省可能为负值，这意味着 TCG 不适合这些气候区。建议的评估标准有助于通过输入夏/冬日比和晴/多云比来量化 TCG 的适用性。应用 TCG 的最佳地区是夏季白天较长且冬季太阳辐射明显较低的地区。对这种温度敏感过程的深入了解有利于优化建筑物中的 TCG，尤其是满足其季节性运行需求。