I ran across this advertisement video from Hunter Douglas where they claim that their Duette Architella Honeycomb Shades provide up to an R7 and reduce the SHGC down to .15.  They claim the dual cell design or honeycomb within a honeycomb design is the reason why.

Now I find those energy #'s impossible to believe and I think they are doing some really funky calcs to get those numbers. They look like a quality thermal shade but the claims seem totally out of whack. Anyone out there observe any real world data with these Hunter Douglas interior shades?

Hunter Douglas Video

I would have to agree with you. Although I don't have real world data, in listening to her video I find one major issue. yes cold is attracted to heat, and by that concept they may be able to prevent some cold air from contacting the window. But in a cooling environment it will do nothing to keep heat from entering through the window, it will trap some of it between the wndow and the shade, but I can't see how it would prevent it from entering the window. That said will I look at them for our new build? Yep. also with the aftermarket channels to make them fit the sides snugly.

Posted By whirnot on 05 Nov 2012 11:54 AM
That said will I look at them for our new build? Yep. also with the aftermarket channels to make them fit the sides snugly.

In the testing that I have performed, I found that the side seals approximately doubled the measured R-value of double row 3/8" cellular shades, and I would feel comfortable extrapolating that result to window coverings in general, that sealing them is necessary for high R-values (http://www.residentialenergylaboratory.com/r_value_cellular_shades.html). However, you can buy the side seals as a part of the shade purchase, rather than as an aftermarket product. The Comfortex Comfortrack Plus shades include the side seals and modifications to the shade so that the side seals penetrate into the shades. They may have a patent on the design to limit others from offering the same, as I have not seen competitive products. Be warned that while the side seals approximately double the R-value, they also approximately double the effort to install the shades.

In terms of overall R-value for the shades, you could start out guessing that adding a layer of air trapped in the shade between the window and the room might add an R-value of about 1, so a double layer might add an R-value of about 2. Trapping the air in the cells might increase it further. So you might guess that double row cellular shade might provide an R-value of around 2+. The measurements that I have taken show an R-value for double-row cellular shades of about 2.6 at low differential temperatures (30 F delta) and about 1.4 at high differential temperatues (60 F delta), so in the ballpark of what would be expected. These results were for light-blocking cellular shades. For light-filtering shades that may allow more airflow between the cells, the R-values were significantly less. I would expect the results for the Hunter Douglas Duette Architella Honeycomb Shades to be roughly similar, but they certainly would require side seals to be at their best.

Some shade manufacturers have quoted results from Steven Winter Associates, Inc. In the report referenced above, some shortcomings in their approach are documented.

Lee -

What about the SHG reduction with those types of shades?

Let's say a window has a SHGC of 0.35. With those shades installed, how much can it lower that SHGC? Maybe it really can't lower it because the shades are on the inside instead of being on the outside (which is of course better but harder to accomplish).

Posted By Lbear on 05 Nov 2012 05:25 PM
Lee -

What about the SHG reduction with those types of shades?

Let's say a window has a SHGC of 0.35. With those shades installed, how much can it lower that SHGC? Maybe it really can't lower it because the shades are on the inside instead of being on the outside (which is of course better but harder to accomplish).

For shades, we can talk about reflection, absorption, and transmission of solar energy.  I have not measured those characteristics for any cellular shades.  I think all cellular shades are white on the side facing the outside, so their reflectivity is fairly high.  The light-blocking shades have aluminum foil or something similar embedded within the fabric, so they transmit essentially no light.  They absorb only a small amount of solar energy and reflect almost all of the incoming solar energy.  Light-filtering shades reflect most of the sunlight, but also transmit some into the room.  I do not know the fraction transmitted into the room.   

Posted By Lee Dodge on 05 Nov 2012 07:32 PM

For shades, we can talk about reflection, absorption, and transmission of solar energy.  I have not measured those characteristics for any cellular shades.  I think all cellular shades are white on the side facing the outside, so their reflectivity is fairly high.  The light-blocking shades have aluminum foil or something similar embedded within the fabric, so they transmit essentially no light.  They absorb only a small amount of solar energy and reflect almost all of the incoming solar energy.  Light-filtering shades reflect most of the sunlight, but also transmit some into the room.  I do not know the fraction transmitted into the room.   

The reason I ask is that for my application the SHG reduction is more of a vital factor than R-Value. In my climate solar shading on the south is more vital. I know that triple pane windows have a much lower convection rates than double pane windows.

With spring and fall the suns angle is such that it can be beneficial or hurtful depending on the outdoor temps. Right now the area is experiencing 75F highs but by Saturday will see 45F highs. Having solar gain while it's 75F is not good but will be beneficial when its 45F during the day. Having manual control by manipulating shades is what I am after.

Window shades are needed no matter what. Nobody likes living in a fishbowl at night. So I am just going over options, whether solar shades or solar drapes, or a little of both depending on the location and window.

I would be somewhat concerned about the light blocking shades with high SHGC windows if they have an aluminized component, as they will reflect heat. This heat can get trapped between the shade and the glass. I learned this the hard way a number of years ago, when I fitted Polyiso boards with the reflective covering, in the windows of a weekend cabin to
Cut loss through the crappy windows. The heat literally melted two south facing window frames.

Posted By whirnot on 07 Nov 2012 06:14 PM
I would be somewhat concerned about the light blocking shades with high SHGC windows if they have an aluminized component, as they will reflect heat. This heat can get trapped between the shade and the glass. I learned this the hard way a number of years ago, when I fitted Polyiso boards with the reflective covering, in the windows of a weekend cabin to
Cut loss through the crappy windows. The heat literally melted two south facing window frames.

Good point. I would not use anything with an aluminized foil barrier. As you mentioned, the heat can get trapped causing excessive heat buildup and frame issues. I was told by one window manufacturer that if you trap the interior window area by sealing off the frame area by using air tight shading panels, you can damage the window, especially with high SHGC windows and direct sunlight.

I would be curious to see what temps are within the area on a sunny day, with high SHGC windows, and shoot thermal temp readings in the space between the sealed shades and the window frame areas. I would not be surprised to see temps in the upper 160F + range on a window with a SHGC of >0.40

Per GBA, they commented about insulated shades with side tracks to completely air seal the window area:

"If you have insulated shades and double-glazed windows, be careful in the summer. If insulated shades are deployed on a hot, sunny day on south- and west-facing windows, preliminary research indicates that overheating may occur: some modeled temperatures have gone above 200° F (93° C), which could damage seals and shorten the expected window life. "

That is why I would prefer something like the Hunter Douglas shades as they allow some airflow around the window area to prevent from trapping the air and building up to 200F and destroying the windows. I am not worried about "air leakage" around the windows as the windows have a air leakage rate of < 0.03 cfm

That is why I would prefer something like the Hunter Douglas shades as they allow some airflow around the window area to prevent from trapping the air and building up to 200F and destroying the windows. I am not worried about "air leakage" around the windows as the windows have a air leakage rate of < 0.03 cfm

so, Lee, I'm uncertain what you're recommending here about the Hunter Douglas shades vs. the Comfortrax with side tracks. I just moved into a home in southern Colorado (about 6600 ft. altitude) that has garden-variety ("builder quality") dual pane windows that are about 11 years old. Don't know their brand or SHGC. My primary concern is getting shades with a high R value because our winter nighttime temps are cold. However, summer hi temps are commonly in the 90's F, and I don't want to damage the seals on the windows if the Comfortrax shades would trap too much hot air between the shades and the panes. so for this application, what would you recommend: Comfortrax light filtering, Comfortrax Light blocking, Hunter Douglas opaque, or Hunter Douglas light filtering?

Posted By hsamadeus on 12 Nov 2012 11:51 AM I just moved into a home in southern Colorado (about 6600 ft. altitude) that has garden-variety ("builder quality") dual pane windows that are about 11 years old. Don't know their brand or SHGC. My primary concern is getting shades with a high R value because our winter nighttime temps are cold. However, summer hi temps are commonly in the 90's F, and I don't want to damage the seals on the windows if the Comfortrax shades would trap too much hot air between the shades and the panes. so for this application, what would you recommend: Comfortrax light filtering, Comfortrax Light blocking, Hunter Douglas opaque, or Hunter Douglas light filtering?

The buildup of heat between the shades and the window is really a non-issue, since you have control of how tightly you "seal" the shades. In my case, the shades raise from the bottom or drop from the top, so I can leave small gaps at the top and bottom to get a little circulation during the warm season. Or for summer, you could just lift off the side seals since they are only held on magnetically. So it is a trivial exercise to convert to no side seals in the summer if desired.

For energy efficiency in Colorado and other heating-dominated climates, I would recommend getting the shades with the side seals, and the Comfortex Comfortrack are the only ones that I know of. (Maybe there are other brands.) The side seals will approximately double the R-value at a modest increase in price (and installation aggravation). The windows must be recessed enough to accept the side seals, so that is another factor in the decision. See Comfortrack website for details. The light-filtering versus light-blocking decision should probably be made based on esthetics including color choice desired. From an energy conservation standpoint, the light-blocking are definitely superior. There are other things in life besides energy conservation.

When you're trying to reject heat gain at the window you've already lost most of the battle if treating it from the interior, and if you insulate the inside with a really great shade yes, you WILL risk blowing the seals on the windows. That's an issue even with reflective window films on sun-exposed windows! The best way to reject heat is always from the exterior, since that better protects the sealed-glass windows.

Hard-coat Low-E storm windows can cut SHGC by quite a bit without trapping as much heat at the double-pane, and you can still see through it. The double-pane can still cool to the air-conditioned interior, and the peak temps at the window will be much lower than if a low-E interior storm (or window film) were applied. It won't be nearly the same as a shutter or a leafy tree shading the window though, and window-films are usually even more heat rejecting. (I s'pose a window film on a storm window would be pretty good though.)

Thank you, Lee and Dana1, for your responses. I'm still a little confused. Lee, it sounds like you're saying that in summer if I leave the shades open a little at the bottom, I won't risk blowing the seals due to heat build up. But, Dana1, it sounds like you're saying I could blow the seals. Is that true even if I leave the shades open a little? I'm actually more concerned about keeping heat in during winter rather than keeping heat out during summer, but I definitely don't want to ruin the window seals.

Posted By hsamadeus on 12 Nov 2012 07:01 PM
Thank you, Lee and Dana1, for your responses. I'm still a little confused. Lee, it sounds like you're saying that in summer if I leave the shades open a little at the bottom, I won't risk blowing the seals due to heat build up. But, Dana1, it sounds like you're saying I could blow the seals. Is that true even if I leave the shades open a little? I'm actually more concerned about keeping heat in during winter rather than keeping heat out during summer, but I definitely don't want to ruin the window seals.

Since your interest is mostly winter performance, you can leave the shades open in the summer if you are concerned about overheating and ruining seals. If you have shades that open from the top down and the bottom up, which is an option for most cellular shades, then you can leave sufficient gaps at the top and bottom that a chimney effect will keep the heat from increasing very much between the window and the shade, certainly not enough to damage the window.

I think simply removing the side seals would also be sufficient to set up a chimney effect that would keep the space from heating too much. That same chimney effect in reverse occurs in the winter, and causes the space between the window and the shade to be much warmer than with the side seals in place. To better understand this chimney effect, see Figs. 13 and 14 here. From measured data, I have found that removing the side seals in winter reduces the temperature differential between the innermost window and the inside house temperature by about a factor of two. (This is not a postulated effect for some super-insulating shade, but rather measured results.) Again, I would say that I consider the solution to potential window overheating with cellular shades as a non-issue since it can be easily solved using the above approaches.

I will have to take some temperature measurements during summer to see what sort of temperatures occur with and without the shades present, and see if I can find maximum temperatures for the windows.

A disadvantage of the well insulating cellular shades in winter that I usually mention is that they lower the window temperature of the innermost window pane, increasing condensation of water at the bottom of the window. This is not as much of a problem in Colorado as other places due to the dry climate. In my case, I use a whole house humidifier, but the Honeywell thermostat monitors the outside temperature and allows for the humidity setting to be reduced at low outdoor temperatures by a user-selectable amount.

If you let the thing draft to cool the windows to avoid blowing the seals, the shade effectively collector surface of a thermal air panel. While heating up the room air is preferable to letting the sun heat up the furniture, the effect on solar gain reduction is nowhere near as good as if you keep it sealed tight.

The condensation issue in winter is also real, another reason why exterior insulating shutters or shades (or low-E storms) work better than any interior solution.

Posted By Dana1 on 13 Nov 2012 11:25 AM
If you let the thing draft to cool the windows to avoid blowing the seals, the shade effectively collector surface of a thermal air panel. While heating up the room air is preferable to letting the sun heat up the furniture, the effect on solar gain reduction is nowhere near as good as if you keep it sealed tight.

This would be true if the inside surface of the blinds were flat black. Fortunately, all the cellular shades that I have seen are white on the side facing out, independent of the inside color. What brand have you seen that is flat black on the surface facing outside? Whatever brand that is, I would recommend against the purchase of it. I would guess that the white exterior surface reflects about 80% to 90% of the incoming solar radiation, but I have not measured it. This is very effective at reducing the solar heat gain of the window, and minimizing the heat gain of the space between the window and the shade.

The condensation issue in winter is also real, another reason why exterior insulating shutters or shades (or low-E storms) work better than any interior solution.

Agreed. Now if someone could just come up with a practical solution that could withstand high winds, rain, ice, and snow, be easily operated from the inside of the house, look like something other than a jail or industrial building, and be no more expensive than shades, we could all buy them. Until those are invented, I would recommend cellular shades with side seals as a practical, energy-conserving approach to reducing the heat loss and gain of the most "lossy" part of a house. They have certainly worked well for me, allowing very high solar gain in the winter, but at the same time allowing for an R-5+ combined window insulation at night, plus solar heat gain reduction during the summer. All that, and they look nice.

Measure it, then get back to me on just how much of the incident energy that white surface reflects back out the window. (If it's as much as half I'd be shocked!) Being an inefficient solar collector surface doesn't mean it's an 80-90% reflector, or anything close! Even without low-E the window doesn't pass very much of the deep-infra-red being emitted by the warmed-up surface of the shade, which is why it gets pretty hot at the window if you don't let it convect around the shade.

Posted By Dana1 on 13 Nov 2012 05:23 PM
Measure it, then get back to me on just how much of the incident energy that white surface reflects back out the window. (If it's as much as half I'd be shocked!) Being an inefficient solar collector surface doesn't mean it's an 80-90% reflector, or anything close! Even without low-E the window doesn't pass very much of the deep-infra-red being emitted by the warmed-up surface of the shade, which is why it gets pretty hot at the window if you don't let it convect around the shade.

Rather than measuring it, I will just take the word from Dr. Laney Mills and Dr. Ross McCluney of the Florida Solar Energy Center, and their report, "The Benefits of Using Window Shades," that can be found at http://www.blindrage.co.za/files/green/TheEnvironmentalBenefitsOfUsingSolarShades.pdf. According to this report, the shade reflectance for a "Blackout White" roll up shade is 77% (their Table 1), not far off from my guess of 80% to 90%. So, it is time for you to be shocked! Further, they report that for a single pane window with a transmittance of 0.86, the solar heat gain into the room is reduced from around 80% to about 23% (24% measured and 22% modeled) for clear glass, and to an even lower solar gain for low-e glass (their Fig. 5).

They conclude "The use of interior shades and venetion blinds, especially shades which are highly reflective on the side facing the glazing, can exert a significant control over the solar heat gain from windows in buildings." They also include in their conclusion, "If the control afforded by interior shades and blinds is managed in such a way as to reduce the cooling load in the summer and to supplement the heating of the building in the winter, a corresponding reduction in cooling and heating bills can result" I think these conclusions correspond exactly to my experiences that I reported above.

The 77% reflection number for the blackout-white in Table 1 of that document is for the simplified (more easily calculated) single pane case of no relevance to the blown seals discussion.  Table 1 indicates a tau = 0.86  is always a clear single pane, not a sealed double glazed window (with or without low-E coatings.)  The text describing the test indicates that there were contradictions in the test report as to whether the tested pane was a 3/16" vs. 3/32" glass, but it's definitely not a sealed double pane, and definitely not low-E.

Table 5 is also single-pane only, and a somewhat bizarre collection glazing types residential windows.  The the very low-E stainless steel on green glass saw essentially no change in gain with shade reflectivity.

The most relevant glazing in table 5 (other than the clear glass single pane) was the spectrally-selective low-E glass which starts with a  SHGC of 0.5 with no reflectivity to the shade.  (Unfortunately they don't specify what the spectrally selective film was.  If it's the commonly used indium tin-oxide low-E hard coat it would be more relelevant that if it were something exotic, but since they're claiming that these were commercially available glazings it may well have been.)  That coating pass the 50% reduction (SHGC of 0.25) at a reflectivity of about 0.75, which is similar reflectivity to titanium oxide paint.  It only reaches 0.1 (80% reduction) at a reflectivity of 0.95, or about the reflectivity of aluminum foil.

And that's with single pane glazings.  Getting that much reduction with a low-E double pane just won't happen.

Any low-E coatings on any surface of a double-pane sealed window limits the amount of solar gain coming in, but also limits the amount reflection getting back out.  You'd get more than a 50% reduction in solar gain from the sealed-window baseline with with specular aluminum (reflectivity > 0.97) on the exterior face of the shade and no cooling convection.  A translucent shade would cut it less than half (true even for the clear single pane glass used in that test.)

So I guess I'm still waiting for the shock to set in.

[edited to add]

I may have understated the reflectivity of titanium paints- while rutile process TiO2 is fairly absorptive in the blue & UV, a super-bright-white shiny anatase TiO2 pigments  it about 90% reflectivity in the visible & infrared, even though they're still absorbing half the UV, so it's at least remotely possible that a titanum paint would exceed 75% reflectance of whatever initally passed through the low-E coating.  See figure 5.  It's fair to say that materials used in shades are nowhere near that reflective.

Dana1-

Have you perhaps redefined reflectance of the surface from:

Standard definition: The amount of energy reflected off a surface divided by the amount of energy incident on the surface.
to
Dana1 definition: The amount of energy reflected off a surface and back through the glazings divided by the amount of energy incident on the surface (or incident on the outside of the glazings).

The standard definition is the one used by Mills and McCluney and in use by me.

We share the definition.

The definition you've mis-attributed to me is not what I've used here.