Published On: Mon, Jan 28th, 2013

Lateral thinking sees windows used as an energy capture technology

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OLYMPUS DIGITAL CAMERAWhen is a double-glazing window not a window? Possibly when it is a solar panel. As anyone who has installed an energy efficient glass based secondary glazing system will know the customer is usually very pleased with the radical drop in heating costs during winter months. Unfortunately they are less enthusiastic when fried in their conservatories during summer months.

There is of course a thriving market in air conditioning and blinds living off the back of energy efficient glass installations. But here is some lateral thinking that sees windows not merely as passive insulation but, instead, as energy capture technology. Steinkrug’s ‘EnergyCrowd’ project used Pilkington K glass to lock heat inside a conservatory and a similarly glazed solar chimney above it (see photograph of prototype system) to channel the heat into house via ducting running through the loft.

The passive solar system, besides regulating the temperature within the conservatory also reduces the heating bill for the house itself. Although not providing all the heat a home requires it delays turning on conventional heating in the autumn and sees it shut down earlier in the spring – in each case by up to six weeks. This, combined with a reduction in conventional energy use during sunny winter days, reduces the energy needed to heat the house by around a third. All this for the price of two fans and ducting – over and above the cost of the double-glazing itself.

However as double-glazing also traps heat inside the house during summer months it makes sense to do something sensible with this free energy. The main thrust of the project is to store the heat and retrieve it when the weather cools. Once again this time shifting of heat energy is most effective during autumn when the weather can change markedly from one week to the next. And once again the intention is to use relatively simple equipment to add value to a double-glazing installation. A secondary aim is to change the perception of double glazing itself by associating it with a heat energy storage technology – something that has, pardon the pun, become a hot topic.


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