Heat-Activated Tinting Could Solve a Daylighting Dilemma
Nanotechnology makes it possible to apply a film on office windows that blocks sunlight when it's hot outside. Denis Du Bois saw Ravenbrick's demo and interviewed the company's CEO.
November 30, 2009
This is a highlight from the Building Priorities Briefing.
LISTEN to the BriefingTranscript
Denis Du Bois: Architects face a design dilemma when adding windows to let in more daylight. South-facing fenestration admits heat, and that's not always desirable.Ravenbrick has a window film that gets darker when it's hot outside. I asked CEO Alex Burny to tell us more about it.
Alex Burny: The window technology that we have is a solar control device. So it's what we call a dynamic or a smart window, meaning that it changes its properties. In this case we have a window that changes its properties based on the outside temperature. So it will tint or it will get darker like a pair of sunglasses when it's too hot outside and then it will turn back into a regular window when it's cool outside.
The reason you want that is that windows tend to roast you and cause excessive cooling costs. You can have a tinted window, a simple, dumb tinted window, but then that hurts you in the winter time when you want the solar heat to come in. So our window basically does both angles of the teeter-totter. It helps you in the summer and winter.
Denis : How do you quantify the advantage of that?
Alex: The advantage is that when you combine it with a low-E window, it's double the savings of a low-E window.
Denis: And what you're demonstrating here is the tint in action -- you have this window in a frame, you're taking a hair dryer and blowing hot air on it. Evidently the temperature is changing the tinting of the window and it's quite a dramatic difference.
Alex Burny, thanks very much for showing me Ravenbrick's windows.
Alex: My pleasure, thank you for having me.