If you’re considering a conservatory or glass extension, you might be wondering: will it turn into a sauna in summer or lose all its warmth in winter? It’s a fair question—and one we hear often at Room Outside.

That’s why we created something called our ‘tunnel of heat’ demonstration. And the star of the show? A clever little device called a radiometer.

What Is a Radiometer?

Originally invented by British physicist Sir William Crookes in 1873, the radiometer (also known as a Crookes radiometer or light mill) is a simple but fascinating device. Inside a sealed glass bulb are vanes that spin when exposed to light or heat. One side of each vane is black and the other is silver. The heat causes air molecules to move, spinning the vanes—faster when more energy gets through.

This effect isn’t just scientific trivia. It visually shows how much heat is passing through the glass.

How We Use It to Demonstrate New Generation Glass

We place a standard piece of conservatory glass and our exclusive New Generation Glass (NGG) side-by-side. Each has a radiometer behind it. Then we expose them both to the same heat source.

The radiometer behind the standard glass spins wildly—heat is pouring through.

Behind the NGG? It barely spins. That means the heat is being reflected or absorbed before it gets through. Simple, powerful proof that NGG controls temperature far better than ordinary glass.

Why It Matters

New Generation Glass is designed for the British climate. It reflects up to 86% of solar energy in summer and keeps heat in during the winter, thanks to warm-edge technology and a U-value under 1.0. It even features self-cleaning glass and UV protection for your furnishings.

The radiometer test isn’t a gimmick—it’s a way to give you peace of mind. You don’t need to take our word for it. You can see the difference for yourself.

Did You Know?

Radiometers have been used in everything from science classrooms to space research. Modern versions (microwave radiometers) help monitor weather and climate patterns on Earth and beyond. But in our world, it’s all about showing homeowners the hidden science behind better comfort and energy efficiency.

See It in Action

We filmed the tunnel of heat demo so you can see exactly what happens. It’s a quick watch—and well worth it if you want to know why New Generation Glass is different.

👉 Watch the video demonstration here

📞 Thinking of upgrading your glass room?

Book a free consultation or visit our showroom to see New Generation Glass for yourself.