Thermal shutters

07 June 2009

Interview with

Professor Stephen Gage, UCL

A feature we are going to look at in the future of buildings is controlling the natural light that comes into a building and the heat which is lost through all the different surfaces. Now Stephen Gage is a professor of innovative technology at University college London and he is investigating the use of thermal shutters to control the amount of light that enters a building an also the amount of heat that is lost.

Helen -   What made you come up with the idea for thermal shutters in the first place?

View out a window from a darkened room. Fort Sam Houston, San Antonio Texas (December 2006).Stephen -   I have to say the idea is not new. It has been put forward in the states in the 70's and 80s. The reason I came back to it was that I was looking at retrofitting thermal insulation on typical Victorian buildings. And I realised that these buildings had windows that were larger than the equivalent buildings today. I had seen new housing developments going on around our cities and realised that the windows there were getting smaller and smaller. And the reason is that windows let through a lot more heat than walls by a factor of 5-9 times. So in order to stop buildings letting out too much heat there is a real pressure on architects and designers to reduce the window area.

Helen -   Yes I live in a Victorian house and I love the fact that our windows are nice and big, but I do worry that we loose a lot of heat across them because they are not double glazed. So what are these thermal shutters going to do to help that?

Stephen -   Well the situation applies generally that we live in houses traditionally where we use windows to let in light, and as the windows get smaller and smaller we have to put our lights on. And we start using energy in lighting. And we start using in my mind rather nasty low energy fittings to get around that, and we get into a rather vicious declining spiral. And it struck me that perhaps we should look into the idea of turning our windows into walls when we are not there. And this is really interesting and research done by a colleague of mine on offices convincingly shows that we are not in our buildings for a large amount of time in a 24 hour cycle, and when we are in our homes at night when there is no external light. This all leads to the possibility of thinking perhaps we should put thermal shutters on the outsides of our buildings to essentially turn the windows into walls when we are not there.

French window shuttersHelen -   We have had shutters on traditional buildings, but traditionally made out of wood. Presumably you are thinking of using something more advanced than that.

Stephen -   Yes the kind of materials we are looking at, are the kind of materials which go into modern highly efficient fridges, especially fridge doors Where you can get the equivalent thickness of a well insulated wall inside something between 20-40mm thickness. Which makes these really not terribly big to open and close

Helen -   Is the idea that you would open and close them yourself, or are they going to do it themselves?

Stephen -   Well obviously the interest would be to have the things opening and closing on their own, but if they do this they have to have either some knowledge of your presence or the possibility that you can override them as they go on their way. I think that one thing one has to say, that if you are in a space, say your large Victorian living room, you it may be a bit cold outside, but if you are there, perhaps you don't mind loosing a bit of heat through the window.

Windows of a brick building in Washington DCHelen -   So it will be able to control itself to some extent. And this will help us in both summer and winter?

Stephen -   That's right, because obviously if a shutter stops heat getting out of a window it will stop heat getting into a building and especially they will stop solar gain.

Helen -   Also the idea of the fact that we are not in our building very much of the day. Is there going to get to a point where the window knows when you get home at the end of the day.

Stephen -   Well there are plenty of intelligent systems which can tell when you are there. You can tell a window when you are coming home, people do this all the time already, with building management systems.

Helen -   Are we already seeing these thermal shutters in use, or are they just in development?

Stephen -   We've got a project where we are taking these into development of these with a commercial product. There aren't any standard products yet, although architects have used commercially available doors to achieve this effect.

Add a comment