Intelligent, Solar-Managed Windows: The Next Big Thing?

Nary an article on a green building goes to press these days without mentioning the “extensive use of daylighting throughout.” That natural light is, of course, provided free-of-charge by the sun, via the many windows that architects are making sure to include as a strategy for reducing (or in some cases, even eliminating) the the need for electricity in illuminating a building’s interior during the day. And yet, all that glass tends to pour heat into a building during the summer months, requiring more juice to be expended in the form of AC.

Some strategies for reducing solar gain include windows equipped with low-emissions coatings (low-E windows), louvers or shades, and a relatively new (and relatively expensive) technology called electrochromic glass, which tints glass to block the sun’s rays at the touch of a button, or based on a pre-set program. But there’s a new kid on the block, which may just change the game when it comes to solar gain: RavenBrick’s thermochromic glass filters.

NREL Tinted State Inside

image via RavenBrick

Because while electrochromic glass (as the name suggests) relies on electricity to get the job done, RavenBrick’s proprietary nanotechnology-based window filters are controlled by the very thing they were formulated to guard against: heat. Which means there are no wires or switches involved — and, as a consequence, considerably less expense. (Currently, electrochromic glass runs around $70 per square foot, while sandwiching RavenBrick’s RavenWindow filter between the two panes of glass in a standard Insulated Glass Unit [IGU] will only set you back around $16 per square foot.)

“We believe this technology is a game changer because it’s a technology that’s easily applied to the building industry as a whole,” Chris Ketchum, RavenBrick’s Vice President of Sales, told us in an interview. “We went into this market asking ourselves, can we make a product that’s not only energy efficient, but will pay for itself? That’s the difference between [what we offer] and other dynamic window technologies.” He goes on to note that RavenBrick’s filter technology is easy to apply to the window-manufacturing process and pays for itself in under five years.

NREL Clear State Inside View

image via RavenBrick

(RavenBrick figures the return on investment [ROI] for each green building project based on the building’s current heating and cooling bills per square foot, using Lawrence Berkley Lab’s window software.)

And there’s more good ROI news on the horizon. RavenWindow technology is just about to become commercially available next year, which means that, as the demand for the product creates economies of scale, it’s liable to become cheaper still.

Susan DeFreitas has covered all manner of green technology for EarthTechling since 2009. She is a graduate of Prescott College for the Liberal Arts and the Environment, and has a background in marketing green businesses. Her work on green living has been featured in Yes! Magazine, the Utne Reader and Natural Home.