Breathing Buildings

As the need for new houses is hardly ever out of the news, we thought we'd look at how our homes will change over the coming years.

At this time of year, people have the window open, because it's a bit stuffy at home, but they still have the heating on. Shaun Fitzgerald is the managing director of breathing buildings, a Cambridge company who've come up with a way to much more efficiently ventilate our homes.

Ginny - Now, to kick us off, one thing that can be a bit of a problem at this time of year as the sun starts coming out is that it starts getting a bit stuffy at home and you think, "Oh, maybe I'll open a window." But then it's actually really still quite cold outside. So, you end up with this sort of debate in your head about whether you want to put the heating on or open the windows. Well, Shaun Fitzgerald is the managing director of Breathing Buildings, a Cambridge company who've come up with a way to, much more efficiently, ventilate our homes. Apart from the fact that it's a bit of a waste if people open their windows and have the heating on, what's wrong with just opening your windows when it gets a bit stuffy?

Shaun - Well, we all have a problem. If we're sat by the window, that if it's chilly outside, pity the poor granny who's sat next to that window. They're going to be subjected to an unpleasant cold draft. It really is just a local thermal comfort issue because what we have identified through the research that we undertook at the University of Cambridge is that in many buildings, after they have been well-insulated, which is just in accord with building regulations, the heat gains within the space. And maybe even solar gain on a beautiful day like today, there's plenty of it, the gains within the space is significant. So, if you wanted to have a plentiful supply of fresh air, if you do the maths as it were, you would quickly find out that there's enough heat in the building to manage your thermal comfort. But the granny has got a problem right next to the window. And therefore, it's a cold draft problem not a shortage of energy problem.

Ginny - So, the person by the window is getting a cold draft that someone who's a bit further away from the window may be still feeling hot and stuffy. So, how does your system work to sort of even that out?

Shaun - The concept that we came up with at the university which we've now put into a product and announced sort of selling it across the UK, and beginning to sell in the US as well, is a simple system that allows the air to exchange naturally between the exterior and the interior in crude terms you could say, isn't that what a window is. But the extra thing that we do is that we mitigate the cold draft by making sure that the incoming cold air is simply mixed with enough of that room air before that cold air now pre-warmed, hits granny. We've cured the cold draft and we use fan often to do that. but if it's efficiently tall space, we won't even use fans. We'll just calculate how high the vents need to be so that by the time the air has plummeted down as a turbulent plume, it doesn't create a cold draft. And it allows us to then not use energy-hungry mechanical fans which have been the previous way of curing the cold draft problem and that's really been the Achilles heel of ventilation and buildings than massive amounts of fan power being used.

Ginny - So, does this mean you have to design your house with this in mind? Do you have to change the way houses are being built?

Shaun - If we broaden the topic and say actually, buildings in general, then yes, it does. Not because of necessarily the winter issue, but if you want to try and get away from using fans to distribute air throughout the year, everybody within a building needs to be within reasonable proximity of an outside wall, a roof or a big atrium. So, it's really the architecture that is driving the building to be able to be able naturally ventilated by using principles where natural air flows within a building are limited depending on the floor to ceiling height and how far away from an external facade that you are.

Ginny - So, if you've got a big office building and you end up in an office that's right in the middle, then it's not really going to help.

Shaun - It's not and it's really important to identify that if that's the type of building that's being erected for good reasons for example if you're building in London where land is very expensive, you want to maximize the building area, you will end up typically with what we call 'deep planned buildings'. So, people in the middle of a building, multi-story, a million miles away from the external facade. Those buildings have to be mechanically ventilated. But when one looks at the building stock across the United Kingdom, not everybody is living in the middle of London. Most people actually live in areas where land isn't as expensive and buildings can be constructed and are being constructed which lend themselves very well to being naturally ventilated.

Ginny - And what kind of energy savings are we talking about here compared to a traditionally ventilated building?

Shaun - There was some lovely work done in the early '90s by a team at the University of Cambridge. And they identified that if you were to build a typical office building and ventilate it in a classical way, air-conditioning, mechanical ventilation and compare that with the building that had been designed so that it could be naturally ventilated, the energy savings were a factor of two. Now, not all of that is related to the savings in fan power. The savings have to do with, because everyone is now within reasonable proximity of an outside wall. They've got a greater possibility of being able to use natural daylight for a greater proportion of the year. So, you get lighting savings as well. But these buildings can save the energy by a factor of two. With our technology, we are seeing results where the energy savings are a further 50%. So, we're almost a factor of 4 in total we've seen.

Ginny - So, great news both for the environment and for the company. They're spending less.

Shaun - And for your energy bills indeed. So, it is a magnificent result. If you care about the energy story then green energy supply versus using less of it in the first place. Using less of it in the first place is a general rule for where you get a greater return on your investment.

Chris - You install in your office Shaun?

Shaun - We haven't installed it in our office. We lease our office and the office is an old building. We could go into the details, but if it's really old, it's already leaky and I don't need to worry about minimum air supply in the winter.