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Install double glazing or low-E windows

A poorly insulated window lets heat in during summer — and out during winter.

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Quick answer

Double glazing, especially with a low-emissivity (low-E) coating, significantly cuts solar heat gain in summer while also reducing heat loss in winter.

Single-pane windows are one of a building's biggest thermal weak points: they let in a lot of heat in summer and let a lot of heat escape in winter. Upgrading to double glazing, ideally with a low-emissivity (low-E) coating, improves both situations at once.

40-50%less solar gain vs single pane

2xbetter thermal insulation

Year-roundbenefit in summer and winter

🔬 How it works

Double glazing creates an insulating layer of air (or inert gas) between two panes, limiting heat transfer by conduction. A low-E coating adds a thin metallic layer that reflects part of the infrared radiation, further cutting solar heat gain in summer.

✅ Key benefits

Reduces heat gain in summer, unlike single-pane glass
Also limits heat loss in winter — a double energy benefit
Improves sound insulation as a bonus
Can be combined with external sun shading for maximum effect

🛠️ Getting it done

Audit existing windows (age, glazing type, orientation)
Prioritize replacing the most sun-exposed facades first
Choose a low-E coating suited to your climate (solar control for hot climates)
Have a certified professional install it to ensure a proper seal
Check for available energy-renovation grants or incentives

💡 ROI: a bigger investment than other measures on this list, but often eligible for energy-renovation grants, which lowers the real cost.

⚠️ The wrong glazing choice (too transparent to infrared) can actually worsen summer overheating — get advice on the right coating for your building's exposure.

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