Glazing in buildings can help capture solar energy to reduce climate change, but it also causes heat loss. Using insulated glazing can help, but it reduces the solar heating potential. The research estimates the potential for passive solar heating in Europe based on different types of glazing. The findings show that the energy savings from south-facing windows vary widely and may not always offset a building's energy consumption. Balancing thermal resistance and solar factor is crucial. The most efficient glazing can be costly and have a long environmental and economic payback time. Designing windows as adjustable elements can enhance passive solar heating potential.