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Abstract Electrochromic (EC) glazing reduces the cooling load via solar radiation shielding. However, excessive solar radiation shielding increases the heating load. In other words, the energy‐saving effect of EC glazing is dependent on the energy performance of the building. This study compares the heating and cooling loads reduction effects of static and EC glazing under various conditions to evaluate the regional applicability of EC glazing in Japan. Furthermore, to maximize the effect, we employ a machine learning (ML)‐based operation and evaluate its efficiency. A parametric study is conducted based on a standard office model in Japan using the DesignBuilder software. The result shows that the heating and cooling loads reduces by 17.1% compared with low‐E glazing in warm climates (Miyazaki, Zone 7). However, in cold climates (Obihiro, Zone 2), the energy increase is 25.4% and the trend of the effect changes near Zone 4. Therefore, on days when the heating load is expected to occur in Zones 3–5, we incorporate solar heat before working hours. The results show that reduction in heating and cooling loads of 2–3% can be expected and that the operation schedule can be set accurately via ML.

Abstract Airflow windows (AFWs) help to stabilize the thermal environment in the perimeter zone and also allows for switching between solar‐shielding and solar heat acquisition operations. This is based on the method of channelizing the air discharged from its cavity layer, either by using a total heat enthalpy exchanger and choosing to exchange heat or otherwise. It has a certain thickness owing to the blinds that are installed in its cavity layer. The purpose of this research is to develop a window system that uses electrochromic (EC) glass, instead of blinds, as a solar‐shielding device. This study also provides the specifications of the window system of reduced thickness. The performance of the window system is assessed by CFD analysis. The solar heat gain coefficient (SHGC) of the proposed window system is found to range from 0.083 to 0.268 and its solar radiation properties can be controlled in a flexible manner. These characteristics contribute to an improvement in the building environmental performance in the form of climate‐adaptive building shells (CABS) in places with four distinct seasons such as Japan that require solar‐shielding to reduce the cooling load in summer and solar heat gain to reduce the heating load in winter.