Window Shade Study Shows Positive Results

(This is from Robb Aldrich of Steven Winter Associates.)


It’s no secret that windows are a liability when it comes to heat loss in homes. Conductance of quality insulated, low-e windows is typically 0.30-0.35 Btu/ft2hr°F, or about R-3. If installed in a wall that performs at R-20, heat lost through windows is 6-7 times higher (per unit area) than heat loss through the rest of the wall. Various window treatments have been used for years to reduce this loss
and make homes more comfortable. Working through the DOE Building America Program with partner Comfortex Window Fashions, SWA performed a simple study measuring how much window treatments can reduce heat loss.


SWA and Comfortex installed double-honeycomb shades in four windows in a relatively new Connecticut home. Two of the shades were equipped with “ComforTrak Plus™” – a system that includes side-tracks and a simple gasket to reduce air movement around the shade (see image). The two other shades did not have any side tracks.


SWA installed several temperature sensors behind each shade, in the rooms, and outdoors; temperatures were recorded for 3 weeks during February and March. Based on these temperature
measurements, SWA calculated approximate, effective R-values for the shades. When shades were installed without side tracks, the shades seemed to add R-1.2 to R-1.5 ft2hr°F/Btu to the window assemblies. When side-tracks were installed, effective R-values were typically between R-4 and
R-5. It’s clear that limiting air movement around the shade assembly has a dramatic effect on heat transfer. Infrared images corroborate this.


In the image below, taken from inside the house when both window shades were closed, the window shade on the left has side tracks; the shade on the right does not. The warmer temperatures behind the shade without tracks – along with the cold edges near the bottom – are a result of much more warm air moving in behind the shade and cold air moving back into the room near the bottom.



While the numbers generated from this simple study are approximate, it’s clear that insulating window treatments can make a big difference in cutting heat loss through windows. Systems like the ComforTrak Plus tested here – which limit air movement through the shade – can reduce heat loss even more.




Views: 178

Tags: Home and Garden, Window blind, Windows

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Tom Conlon commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"I just checked the site Guidelines Kurt, and any true "promotions" should be posted in…"
4 hours ago
Tom Conlon posted a discussion

Whole House Fans - Love 'Em or Not?

I just searched this forum for "Whole House Fan", but I didn't find much about them (except …See More
4 hours ago
Richard Beyer replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Don, Thank you for the praise! I only wish that some of these profiteers could answer my questions…"
7 hours ago
Richard Beyer replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Todd, This report (attached link) below on poor people living in subsidized housing show's…"
7 hours ago
Mike Kandel added 4 discussions to the group Building Performance Institute (BPI)
9 hours ago
Mike Kandel posted discussions
9 hours ago
Nate Adams commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Jim, Glad to help! OK, a touch of soap box. So long as we don't tell people EE is free and…"
9 hours ago
Kurt Shafer commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Bob, Good idea. I see that you are a window energy reduction expert. You might consider adding…"
10 hours ago
Robert (Bob) Bacon commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Kurt, I would explain what energy/efficiency problem this device solves and explain the science the…"
10 hours ago
Ben Jacobs replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"I agree that in many homes the indoor air sucks.  However, a lot of this problem is caused…"
12 hours ago
Kurt Shafer commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Tom, thank you for your odd reference to a leaky duck. It is a bit off topic since I was not asking…"
13 hours ago
Tom Delconte commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Shameless self promotion here sucks like a leaky duck!"
14 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service