Serious energy conservation efforts have to start with insulating exposed glass!

In late February 2011, a HeatSaver® specimen was tested for insulation performance at the Architectural Testing facility in St. Paul, MN. The parameters used were in accordance with NFRC 102-2010, the most recent – and stringent – standard available.

HeatSaver® Thermal Shades provide an R-Value of 7.40 when used with a double glazed window and an R-Value of 6.39 when used with a single pane window.

A summary of the test results is available here.

On July 11, 2013, we installed eight HeatSaver® Thermal Shades in the Chicago Center for Green Technology. They’re in the Training Center, second floor, southwest corner.
On August 27, 2013, at 3:30 in the afternoon Peter recorded the temperatures listed below. The outside air temperature was 94ºF and the shades were fully deployed when he arrived.
  HeatSaver- CCGT1

A Raytek® MiniTemp™ infrared thermometer was used.

While impressive it was clear a more thorough approach was required.

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South facing window in the sun. Interior, between a shade and a window. The face of a lowered shade.

HeatSaver® and the Center for Green Technology are now conducting tests using Onset sensors and data loggers to more fully understand the contribution our shades could make to the building’s performance. To our knowledge no such research has yet been undertaken or more transparently published with the intent of showing the impact a well designed, fitted thermal shade can have.

Regular updates showing detailed information and the results, including daily and weekly weather conditions, will be posted on our Library/Resources Page.






The summer of 2014 was abnormally cool in Chicago, June 17th was the hottest day.

These graphs show clearly how our shades kept out the heat while interior temperatures remained  comfortable.

The report for this two week period can be found here.









January 8th, 2015 is the coldest day we’ve collected data for thus far.

These graphs illustrate quite well just how important our shades can be for keeping the cold out and moderating interior temperatures.

The report for this two week period can be found here.




On November 1, 2014 The Chicago Center for Green Technology was closed to the public due to a lack of funding.  However we will continue to collect this data at least through the end of February and hopefully throughout 2015.

Thanks in part to one mother’s vision and determination a unique solution has been implemented in a small elementary school in central Wisconsin. HeatSaver® Thermal Shades have been installed in one classroom as a demonstration project. These few shades will offer a different approach and opportunity for energy conservation and savings.

The shades will provide an R-Value of 6.39, stop the chill of cold air from coming off the windows, and keep the warm air going into the classroom where it will have the greatest benefit. This one wall section now has the highest insulation value of the entire building’s exterior.

As you can see, frames were built on which the shades were installed, thus not touching the original windows at all. The architectural integrity of the building’s exterior has not been compromised.



































Thanks also to the Lowe’s Toolbox for Education Grant which made funding for this project possible.
Forum for the Future and Arup gave a presentation recently on various energy conservation measures undertaken in homes in and around the town of Bristol in the United Kingdom. They were quite detailed and thorough in their research and data. Where do you think “high performance glazing” fits in the picture? (Hint – you may need a magnifying glass, it’s the wee small square on the right…)
No doubt the results shown in the slide above are why so many U.S. states are no longer investing in replacement windows. Independent research, like this, has shown that it simply isn’t worth the investment!

HeatSaver® Thermal Shades provide over Seven Times the insulation of Single Glazed Windows. Three Times the insulation of both Double Glazed and High Performance Windows.

Where is your best investment?

A well insulated wall should have an R-Value of 19. The graph below illustrates what happens when 20% to 50% of windows to wall space are entered into that equation. The insulation value of the building envelope drops dramatically.
Energy losses through glass take place in four ways. Conduction, convection, radiation and
infiltration. All of these factors have to be addressed for true insulation performance.
An effective window insulation product must;
1) Seal on all four sides of your windows (conduction, convection, infiltration) and 2) incorporate a reflective film layer (radiation).
HeatSaver® effectively addresses all four.

Thermosiphoning or the ”chimney effect” takes place when conventional draperies are used and is often overlooked for being the energy loss culprit it is, although the physics and reasoning behind it are easy to understand.

It really is quite simple.  Your floor registers are directly below your windows.  The heat kicks on, warm air is funneled directly behind your curtains and up against the cold glass before it even enters the room.  You’ve already lost some of the energy you’re paying for.

Then when the heat turns off, your curtains provide another benefit.  The air behind your draperies cools and falls to the floor, drawing warm air from the ceiling down against cold glass, which then cools and falls to the floor. And the process continues to repeat itself…

If you’re in a particularly hot climate the same holds true, only the effect is just the opposite.  Easily half of your air conditioning investment could be lost by forcing cool air up against very hot glass.

HeatSaver-MIchigan-passive-Solar-Home   HeatSaver-Pool-Rm
These windows face an inlet from Lake Michigan. Once the source of perpetual cold they are now insulated from temperature extremes. When the shades are lowered they provide a measure of comfort and sense of security the homeowner had not previously known.
“We haven’t used any heating oil at all this year. One of the best investments I’ve ever made.

A. B., New Hampshire, February 2014


Let us know when you’re ready to get serious about the
energy being lost through your windows.

HeatSaver® Thermal Shades.
Serious Energy Conservation.