Velux’s remote-control solar-powered blindsWhile solar engineers have been able to make PV glazing for several years, until recently it has been a brash orange colour, so you feel as if you are looking through a sodium street lamp. The workshop roof, which has just completed its first summer of electricity generation, signals a leap forward. Skyscrapers such as the Shard, in London, may soon be able to generate electricity from their vast areas of glazing — and their occupants will be shielded from summer heat.
“You do get slightly lower light transmission through the panes,” says Burstall, chief operating officer of the start-up energy company Origami, “but there is an upside. Although there is a big expanse of glass — 150ft long by 8ft wide — it doesn’t get intolerably hot in summer. It is bright enough to work under, but there is no harsh glare.”
He paid £16,200 for the panels, plus £2,500 for the electrical connections. This revolutionary glazing is manufactured by Polysolar, an engineering company based in Cambridge, and is being installed on commercial buildings, bus stops and conservatories (polysolar. co.uk). “Because it provides shade as well as electricity, it addresses the problem of overheating in modern buildings,” says Hamish Watson, the firm’s director.
This year marks the 40th anniversary of the first installation of uPVC windows in British homes. Initially seen as cheap, energy-efficient glazing in the midst of an oil crisis, more recently they have been criticised for their looks and longevity, with windows failing and fogging up long before they were supposed to.
Yet as uPVC marks its chequered milestone, Graham Dodd, global materials leader at the engineering firm Arup, is excited about the future. “We are on the threshold of exciting developments in glazing, including dynamic ‘electrochromic’ glass that changes colour as it heats up or cools down,” he says.
The Garden House was built in a Victorian walled herb gardenNICK ISDENDodd reckons humans have been such a successful species because we can change our clothes according to the season and the climate. Now homes are catching up — and windows are leading the way, thanks to innovations such as solar-control glazing, which blocks excess heat without greatly reducing light quality.
One project using such glass is the Garden House, a new home in Speldhurst, Kent, with vast sheets of glazing to show off its setting in a Victorian walled herb garden. The reception rooms look onto the greenery through frameless “soft-coated glass”, which filters out heat.
“The new generation of soft coating is an architect’s dream,” says Simon Skeffington, director of Architecturall (architecturall.co.uk), the firm that designed the house. “We could take advantage of the unique setting, but avoid the problems associated with too much glazing.” The project, which recently won the new-house prize at the London Regional Master Builder Awards, also has a 4ft roof canopy, a “brise-soleil” that shades the glass walls when the sun is at its highest.
This kind of technology isn’t cheap — the sliding doors weigh 300kg and the glazing package costs £70,000 — but there are simpler new glazing technologies. Shaun Lindsay, an IT expert, had interglazed Venetian blinds fitted on the south-facing patio doors of his 1960s home in Cambridgeshire last year. “I wanted to increase solar gain in the winter, but avoid summer overheating,” he says.
The blinds sit between the inner and outer panes of the double-glazed unit, so prevent heat from reaching the inner pane. “The inner panes are vastly cooler than the windows where we don’t have the blinds,” says Lindsay, who lives in Impington, near Cambridge. The blinds, which added £500 to the £2,500 cost of the patio doors, are controlled by a magnet that runs up and down the side of the windows.
Other new windows and glazing technologies
• Hygroscopic strips attached to window inlet vents. When the strips become moist, vent openings are automatically adjusted (passivent.com). Nick and Kate Hawksworth use these in their green new-build in Girton, near Cambridge, combined with a centuries-old cooling technique of unglazed east-facing larder windows to let in cool air at night.
• Suspended film between glass units that further boosts energy efficiency, reducing
u-values (a measure of heat loss) from 1.0 to as little as 0.2. It is being tested by Crystal Units (crystalunits.com).
• Velux’s new solar-powered blinds, each with a small solar panel attached to its back. They generate enough electricity for 600 operations and come with a programmable remote control (velux.co.uk)
• Breathable double glazing, in development by Arup, which allows the moisture that causes fogging to be blown out over a desiccant (arup.com).
• The marriage of glass with IT. This will let you change the colour of your house when you want, and project images such as forests or deserts, according to Steve Bosi, head of facades at WSP, the engineers behind the Shard (wsp.com).
Source: The Sunday Times