Is your home too hot when the sun shines?

Discover the science behind modern glazing. Learn how to keep your home warm in the winter, and stop your conservatory boiling in the summer.

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Low-E glass technology features an invisible metallic coating that acts as a thermal mirror, bouncing heat back into your room.

Gone are the days when glass was simply a fragile, clear material used to fill a hole in the wall. Today, the glass installed in your replacement windows, bi-fold doors, and conservatory roof is a highly engineered, high-tech component.

However, the technical jargon used by the glazing industry can be incredibly confusing. Homeowners frequently ask us to explain the difference between “Low-E” glass and “Solar Control” glass. While they sound similar, they perform two completely different—and equally vital—jobs for your home’s comfort.

1. What is Low-E Glass? (The Winter Warmer)

Low-E stands for Low Emissivity. This technology is specifically designed to tackle the freezing British winter by reducing heat loss.

Standard, old-fashioned clear glass is a terrible insulator; the expensive heat generated by your radiators simply radiates straight through the glass and out into the garden. Low-E glass completely changes this. During manufacturing, a microscopically thin, completely transparent coating of metal oxide is applied to the internal pane of the double-glazed unit.

Because of its incredible thermal efficiency (drastically lowering your U-Values), Low-E glass is no longer a luxury upgrade—it is a strict legal requirement under modern UK Building Regulations (Part L) for all replacement windows.

2. What is Solar Control Glass? (The Summer Cooler)

While Low-E glass is designed to keep heat in, Solar Control Glass is explicitly designed to keep heat out.

If you have a conservatory, an orangery with a roof lantern, or a large wall of south-facing bi-fold doors, you are likely intimately familiar with the “greenhouse effect.” Standard glass magnifies the sun’s infrared rays, turning beautiful, light-filled rooms into unbearable saunas during July and August.

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Solar control coatings reflect the harsh infrared heat of the sun while still allowing natural visible light to flood the room.

Solar control glass tackles this by using advanced, highly specialised exterior coatings (often tinted slightly blue, neutral, or bronze) that actively reflect a massive percentage of the sun’s solar heat energy away from the building before it ever penetrates the glass. This keeps the internal room cool, comfortable, and usable all year round, without requiring expensive, power-hungry air conditioning.

3. Can You Have Both? (The Ultimate Glass)

Yes! For massive expanses of glass—specifically conservatory roofs—you absolutely need both technologies working simultaneously. You need the room to stay cool during a summer heatwave (Solar Control) and retain the radiator heat during a frosty winter night (Low-E).

At KJM Group, we highly recommend high-performance dual-action products like Pilkington Activ SunShade™ or Saint-Gobain Planitherm 4S. These elite glass units are manufactured with the Solar Control coating on the outside pane to reject the summer sun, and the Low-E coating on the inside pane to trap your winter heating.

4. Hampshire Climate Advice

5. Official Pilkington Specifications

We believe in total transparency. If you are researching a new conservatory roof or upgrading your existing glazing, download the official manufacturer technical brochures below to explore the exact performance statistics of Pilkington’s Solar Control range.

6. Frequently Asked Questions