Think of energy efficiency and you are likely to think first of clean green power for transport or for industry. But in the developed world, nearly half of all the energy we use is consumed by the buildings in which we live, work and store things.

This surprising statistic was the starting point for E-Stack, a company that sprang from a research project at Cambridge University. From a study of low-carbon buildings it developed a natural ventilation system that is now making

life more comfortable for hundreds of office workers and schoolchildren as well as saving up to 50% of the energy consumed by traditional ventilation systems.

“If you care about the energy problem, there are two things you can do,” said Shaun Fitzgerald, co-founder of E-Stack. “You can start generating energy from clean, alternative sources — which requires new infrastructure and takes time — or you can radically reduce the demand, which should be much quicker. We started from a research programme that was looking at that second option.”

It’s one thing to establish facts like these through academic research, but quite another to turn the conclusions into a marketable product. So although the initial five-year research into low-energy buildings had been well-funded by BP and through a partnership between Cambridge and the Massachusetts Institute of Technology, once Fitzgerald and his co-founder Andy Woods had formed a company in 2006 they needed help to convert their theories into a business and apply their techniques to larger spaces.

How to turn your idea into a working proposition is a question faced by all entrepreneurs at some point, and that was where the Carbon Trust came in. The trust was set up by the government in 2001 to fund and accelerate the development of technologies that promise to make a substantial reduction in carbon emissions.

Fitzgerald and his team had to present the experimental proof of their technology and outline the market for their “stacks” — units in which incoming cold air is mixed with warm internal air, thus reducing the need for energy-greedy radiators. Low-energy fans are built in to ensure circulation when necessary.

Once convinced of the scheme’s viability, the trust came up with a £75,000 applied-research grant. This funded further laboratory tests and monitoring of a prototype ventilation system. “We spent most of that money paying for the time it takes to set up a system like this,” said Fitzgerald.

Once the prototype was developed, the need for a control system became apparent. E-Stack used part of its Carbon Trust funding to develop a programmable controller that is sensitive to external temperature, internal temperature and concentration of carbon dioxide. This enables ventilation to be automatically adjusted to maintain air circulation and a constant temperature.

“We filed patents for a system that brings the air in winter into the building at a higher level and mixes it with the warmer interior air to avoid cold draughts. In summer it’s fairly simple: you open the windows to bring the air in at a low level and let it circulate and leave at a higher level,” said Fitzgerald. “If you need a fan, you can use one that consumes just 45 watts, no more than it takes to power a light bulb.”

E-Stack started marketing its units early in 2007 and delivering and installing them last year. From start-up to market in less than two years is quick by any standards, and would not have been possible without the combined support of the private and public sectors.

The company remains based at a Cambridge science park and now has a team of seven permanent employees, all highly qualified engineers. A manufacturing plant has recently been opened in Ely, Cambridgeshire, where the stacks are produced in standardised units.

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