One of the technologies I have tried in my house is an insulating window shade with side tracks. I got four Ecosmart cellular shades from Gordon Clements at Gordon’s Window Decor. One is translucent, and the other three are blackout shades, achieving that by using aluminum foil inside the cells. Because the foil is reflective to radiant heat transfer, these shades have a higher insulating value than the translucent version. They also have two rows of cells, to further increase insulating value (see Image #1 on the right).
The side edges of the shades are slit; a plastic fin that is installed on the sides of the window opening runs in the slit and makes a rudimentary and simple seal. The bottom has a weatherstrip to seal to the window sill. Image #2 (below) is a close-up of the shade and side fin.
Image #3 (below) shows what the shade looks like when it is pulled fully down. Image #4 shows the shade with the top partially down — nice for daylight with some privacy.
They’re not cheap, but they work
So how do they work? Well, they definitely insulate — when opened in the morning a little puff of cold air drops out. And there is condensation on the glass, notably more than the unsealed, single row cellular shades we have elsewhere in the house.
My colleague and friend Andy Shapiro did some careful measuring on one of his and calculates that the effective added R-value is about R-4.
These shades aren’t cheap, although they are a lot less money than a window replacement. If you have leaky windows, these won’t solve that problem — they’re not that airtight. A storm window will do a better job of sealing, but won’t add as much insulating value.
I think that if you are considering shades at all for privacy reasons, and have reasonably tight windows, an insulating shade such as these can make sense, and they handle fairly large windows well. We’ve noticed that the largest one, covering a triple window about 7 feet wide and 5 feet tall, is perhaps a bit too large for the hardware that rolls it up — we help it up with one hand as we retract it in the morning.
Putting the two shades in the living room down definitely makes that room more comfortable to be in, as the two largest windows in the house are on the east and south of that space, and it’s where we spend a lot of time. The change in the radiant temperature is noticeable. So all in all we consider this to be a success as we’ve applied it here.
Marc Rosenbaum is director of engineering at South Mountain Company on the island of Martha’s Vineyard in Massachusetts. He writes a blog called Thriving on Low Carbon. Marc teaches a 10-week online Zero Net Energy Home Design course as part of NESEA’s Building Energy Master Series. You can test drive his class for free.