Overheating South-Facing Rooms: How Solar Control Glass Helps

Standard clear glass allows the majority of the sun's short-wave solar radiation to pass through, which then converts to heat once absorbed by furniture, floors and walls inside the room — a greenhouse effect that is especially pronounced in conservatories with large expanses of roof and wall glazing facing the sun for much of the day. Blinds and curtains help block light but do little to stop the heat that has already entered before they're closed.

Solar control glass has a microscopically thin, transparent metallic coating applied to one surface of the glass, which reflects a significant proportion of incoming solar heat before it enters the room, while still allowing high levels of visible light through. The result is a noticeably cooler room without the darkening effect of tinted or reflective glass, and without needing to keep blinds permanently drawn.

Tinted glass reduces glare and light but does relatively little to reduce heat gain, since it absorbs heat into the glass itself, some of which still re-radiates into the room. Solar control coatings are specifically engineered to reflect and manage heat, making them significantly more effective at genuinely reducing indoor temperature rather than just dimming the view.

A well-specified solar control unit doesn't have to compromise winter warmth — many solar control coatings are combined with a low-E coating on another surface of the same unit, giving a glass specification that keeps heat out in summer and keeps heat in during winter, rather than trading one for the other.

Roof glazing receives far more direct overhead sun than vertical windows, making it the single biggest contributor to conservatory overheating. Upgrading just the roof glazing to a solar control specification, even where wall glazing remains standard, often delivers the most noticeable improvement in comfort for the investment involved.