Buying a conservatory? – Roof glazing choices

It would be entirely true to say that in the early models of conservatories, temperatures could fluctuate wildly. The absolute biggest culprit when it came to letting heat in and out was the roof glazing.

Our first conservatories in the 1980s and 90s were built with 16mm twin-wall polycarbonate, which is a very poor insulator. The good news was that it allowed in lots of lovely light; the bad news was that it drew in intense heat during the summer (turning the conservatory into a sauna) and let the heat flood out in the winter (turning it into a freezer).

All too aware of this, the UK glass industry has spent the past three decades trying to solve the heat-light dilemma. Let’s look at the incredible innovations that have changed the way we build glazed extensions today.

1. What is Low-E & Solar Control Glass?

You can now buy high-performance glass panes filled with the dense but invisible gas, Argon. Because Argon is heavier than standard air, it makes it much more difficult for either warm or cold air to physically pass through the sealed unit.

As well as this, Low-E coatings play a critical role in insulation. But what exactly is Low-E glass?

The “E” stands for emissivity; this is the ability of the glass to radiate heat. To drastically reduce this, microscopic metallic coatings have been developed to lower the amount of ultraviolet (UV) and infrared light that can pass through the glass, without significantly altering the amount of visible light you see.

• Reduced Fading: By blocking UV rays, your furniture and carpets are protected from sun bleaching.
• Glare Control: Solar control options can also control the harsh visual glare of the sun. There are many beautiful architectural tints available, including Aqua, Bronze, Green, and Blue.
• Condensation Control: Modern glass units are built with ‘Warm Edge Spacer Bars’. These non-conductive strips separate the glass panes, significantly reducing the freezing cold edges that cause winter condensation inside your conservatory.

2. The Honest Truth About “Self-Cleaning” Glass

The final popular option on roof glazing is “self-cleaning glass”. It is a genuinely brilliant product that utilises a dual-action microscopic coating.

First, it uses daylight (UV radiation) to break down organic dirt on the surface of the roof. Secondly, when it rains, the coating causes the water to “sheet” rather than form droplets, washing the broken-down dirt away without leaving streaks.

3. Acoustic Performance: Silencing the Rain

If you own an old polycarbonate roof, you know the sound. During a heavy British downpour, 16mm or 25mm polycarbonate sheets act exactly like a snare drum, making the room so deafeningly loud you cannot hold a conversation or watch television.

Upgrading to modern double-glazed glass dramatically improves the acoustic performance of your extension. The dense mass of the glass, combined with the sealed Argon gas cavity, severely disrupts sound waves. If you live near a busy road or simply want to silence the rain, high-performance glass transforms a noisy add-on into a peaceful, quiet sanctuary.

4. Glass vs Hybrid vs Solid (Comparing U-Values)

The U-value is a specific mathematical measure of how well a material serves to minimise heat loss. The lower the number, the better the product performs as an insulator.
(For more technical information on glass energy efficiency ratings, visit the Glass and Glazing Federation (GGF) External Link).

To summarise glazing today: it is vastly superior to when we started in business. The better-insulated glass reduces “the greenhouse effect” considerably, making the room far easier to heat in the winter and cooler in the summer. But how does it stack up against modern solid roofs?

5. The Importance of Ventilation

It is worth explicitly stating at this stage: a glass conservatory that sits in the height of the summer sun all day without being ventilated will still get warm!

Even with the most expensive solar control glass on the market, you must design your conservatory with adequate airflow. This means incorporating opening roof vents (either manual or climate-controlled automatic vents) and specifying high-quality opening side windows to allow the hot air to escape.

6. Interactive Roof Glazing Assessor

Unsure which roof upgrade path is right for your lifestyle? Use our quick assessment tool below.

7. Frequently Asked Questions