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

Patrick Carter replied to Patrick Carter's discussion Minneapolis Blower Door & Test Equipment for Sale! in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"As of yesterday 09/19/2014, the equipment has been sold..."
9 hours ago
Hal Skinner replied to Hal Skinner's discussion An example of what an RCC can do with no R- insulation in the walls.
"Mornin Brett. 90 to 85, yes a slight variance there.  Same ASTM test, different scientists,…"
yesterday
Bret Curry replied to Hal Skinner's discussion An example of what an RCC can do with no R- insulation in the walls.
"Great information Hal. It appears the thermal emissivity in your test was .85 rather than .90. Are…"
yesterday
Juan Roca commented on Dale Stephens's blog post LED Lighting - Garage Door opener interference
"Hi,There is a real problem with remote controls and LED lights. However, there is a solution in the…"
yesterday
Profile IconJuan Roca and Elizabeth Coe joined Home Energy Pros
Thursday
Casey Gesell posted videos
Thursday
Gerald Shechter posted videos
Thursday
Hal Skinner replied to Hal Skinner's discussion An example of what an RCC can do with no R- insulation in the walls.
"Bret,  here are the 2 reports I referred…"
Thursday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service