Grand Designs Extras Kevin's Column: IQ Glass

Date Published:

07/05/2009

With the need to reduce our energy consumption more pressing than ever, Kevin McCloud investigates a glazing unit that not only insulates, but also produces its own heat

I wrote about glass last month and I’m carrying on writing about it this month. Because since its invention in Egypt or somewhere else where they didn’t need windows, glass technology has not really evolved much. For generations glass makers have melted sand and soda together and occasionally added metal salts to make pretty colours, and then turned up six weeks late on site with their product. No, nothing’s changed.

Glass is a relatively efficient conductor of heat, making windows an exemplary way of warming the planet. Our buildings lose an embarrassing quantity of heat through glass and so, not surprisingly, the glazing industry has responded by lobbying for a change in the way glazing’s thermal performance is assessed. It has argued that building regulations should take into account (rightly so) the ability of glass to transmit infra-red energy from the sun into a building, where it can be stored as heat in the heavy thermal mass of, say, a concrete plinth or stone floor. This beneficial role, especially useful in Britain where we enjoy mild but damp weather much of the year and can best take advantage of a bit of solar warmth indoors, goes some way to countering the problems of heat loss in a building, especially if the glazed areas primarily face south and you hang some thick curtains at night or fit shutters.

The Belgians have another solution. They enjoy the same miserable weather as we do and consequently also want to trap sunlight in their buildings. They eat a similar diet of pizza and chips and like us have no indigenous car manufacturing. And like us they are innovators in glass. Glass that doesn’t just transmit heat but emits it; glass that will very soon no longer lose heat, but also produce energy.

A window which is also a radiator stretches credulity somewhat, but last year, in pursuit of scientific enquiry, I took my stretched credulity and climbed into a glass box the size of a tiny greenhouse that had been constructed inside a military pressure chamber the size of a bus garage somewhere in Stevenage. This is a test facility normally used to stress satellites and rocket components by taking them from minus 60°C to plus 60°C in a few seconds, by simulating arctic heat and then polar cold, sea level air pressure and that of 50,000 feet. I know this because my father used to run it. On a May morning in 2008, I was taking a trip in my Dad’s time machine to the North Pole, in a greenhouse, but one plugged into the mains. My only protection was a T-shirt, shorts and sandals. Roald Dahl could not have written it better.

The greenhouse was a construction of heavy, triple-glazed units in an aluminium frame. Overall it weighed more than a ton. The metal coatings on the glass, which in a normal double-glazed unit reflect heat in or out of a building (depending on which surface they’re applied to) had been modified by the Belgians to take a low-voltage electric current and act like a thin-film electric heater. As a result they emitted a satisfying warmth. Not outwards, only inwards, and in the very efficient form of direct infra-red radiation that heats bodies not air.

Not that I like being told by a Belgian scientist that I am ‘a body’. At minus 40°C I want still to be alive thank-you – a thought that I kept returning to in the lonely, bleak environment of that test chamber with just the deafening sound of the giant cooling fans as background. Suddenly though, at something like minus 42°C there was another noise, a splintering crack. I looked up and saw that a wall of the glass box had split. A few seconds later and klaxons sounded, lights flashed, the sealed door to the outside world burst open and the glass suddenly shot opaque as the moisture in the incoming ambient air formed an immediate fog of condensation.

It turned out that the aluminium frame had distorted with the extreme cold and bent to form a pressure point on the windows. The glass itself had behaved impeccably, as you might expect from a robust triple-glazed window. The data that the men in white coats had collected showed that this glazing system is remarkably efficient as an insulating window and remarkably effective as a radiator too, and my own sandal and T-shirt methodology backed this up spiffingly. A glamorous house like Mimi and Andre De Costa’s (featured on Grand Designs – see page 64), which was fitted with large expanses of IQ heated glass, will cost around half what it would conventionally cost to heat with electricity or gas.

Only half I hear you say? You’re right. We should be building houses that are so super insulated, airtight and efficient that they cost nothing to heat. As they would if we put in very tiny windows. There’s the rub. Again. Glass doesn’t keep the heat in very well. IQ’s glass, meanwhile, is an interesting technological step in an interesting Belgian direction. They tell me that they’re now working on a window with a printed translucent photovoltaic panel embedded in it. This will effectively make their infra-red heated windows self-powering. A solar-powered see-through radiator? That I have got to test.

IQ Glass (0844 800 2432 iqglass.co.uk)

This edition of Kevin's Column is taken from the June issue of Grand Designs magazine. If you would like to subscribe for as little as £9 then head here to find out more.

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