This study proposes a PCM enhanced ventilated window (PCMVW) system for ventilation preheating/precooling purposes for building energy conservation. It is designed into a summer night cooling application and a winter solar energy storage application using different control strategies. An EnergyPlus model of the PCMVW is built to investigate the control strategies. Next, a full-scale experiment is conducted to study the working principle of the PCMVW and to validate the model. With the validated model, the thermal and energy performance of the PCMVW is compared to 2 other ventilation systems and shows that the PCMVW can greatly decrease the cooling/heating energy demand for both summer and winter applications. Finally, the paper proposes control strategies for residential applications under Danish climate conditions. The developed control strategy for summer night cooling application is to use between-glass reflection shading, ventilate directly from PCM heat exchanger to the room while applying VW self-cooling for ventilation pre-cooling mode, and heat the room with air from VW to prevent overcooling of the room. The developed control strategy for winter solar energy storage application is to use between-glass absorption blind, make use of the hot air in VW, and to cool the VW by self-cooling and bypass ventilation to prevent overheating of the room. With the developed control strategies, the building energy saving is up to 62.3% and 9.4% compared to the primitive summer and winter control strategies respectively. (C) 2020 The Authors. Published by Elsevier Ltd.