Mitigating Solar Gain with Motorized Shades

The shades from outside the house. Only the uppers are down in this shot.

Given that the house faces Puget Sound to the southwest and the view side is almost completely glass, it was of utmost importance to engineer a sun management strategy that allowed the house to stay as cool as possible in the summer and as warm as possible in the winter.

For sun control in this situation, there are a few things you can use: long eaves which help shade your windows when the sun is high in the sky, interior shades which block solar rays from hitting your interior surfaces, or exterior shades which block the solar rays before they even hit your windows. The eaves were a given as they fit with the style of the house, but the shades were a very long project in investigation and implementation. The great thing about interior shades is that many different brands are available and you can use them year-round no matter what the conditions are like outside. The downside, however, is that your glass still gets very hot, so they are less effective at keeping rooms cool. The great thing about exterior shades is that they block upwards of 90% of the sun’s energy before it even hits your glass so they are excellent at keeping things cool. However, since they are exposed to the elements, they must be retracted during high winds (of which we get plenty).

Since eliminating heat in the summer was our top priority, we chose exterior shades from Somfy. Somfy is the only company that makes motorized exterior shades that tie nicely into most home automation systems. It would have been nice to have our pick of brands since there is a lot about Somfy I don’t particularly care for (like the fact that they use an old school serial interface), but since they were the only game in town, we went forward with them.

The most difficult part, however, was picking which Somfy system to use. They have a system called RTS which uses easy wireless controls, but the blind motors are “dumb” and can’t give the system status on their position. They are also either “fully up” or “fully down”. You can’t send a command to a blind telling it to move to 10% up at 10am and then 20% up at 11am, etc etc.

The other, newer system is called ILT. These blinds report their positions to the automation system and also can respond to the sort of incremental commands mentioned above. The downside of the ILT system, however, is that it uses a wired serial interface. Somfy just released a wireless Z-Wave interface but it came out too late for us to use it. The Z-Wave interface was supposed to come out last January and we had planned our project around it, but Somfy kept stringing us along on the release date and it didn’t end up coming out until our blinds were already being fabricated. This was extremely maddening as it caused us to run more wire through the house, purchase more equipment from Somfy, and end up with a system that was not Z-Wave aware.

Another maddening thing about the system is that while older Somfy motors like the RTS have an integrated sun and wind sensor that can automatically retract blinds during periods of high wind, the ILT offers no such sensor. Instead I’m in the process of rigging up a Davis Weather Station on my roof that can report weather conditions back to the home automation system, which will then in turn raise and lower the blinds automatically. Yes I know, it sounds like total overkill.

Even though I’m generally very happy with the blinds now, I will admit that I probably overthought the situation a bit. I was under the impression that when the blinds were down, you would barely be able to see out the windows. For this reason, I wanted to do things like incrementally raise and lower the blinds throughout the day according to sun angle. I basically wanted to only lower the blinds as much as necessary at any given time.

As soon as I lowered them for the first time, however, I was shocked at how little they obstructed the view. They are so transparent that sometimes you can’t even tell they are down. Had I known this from the outset, I might have just gone with the RTS setup and not worried about precise blind positions. Long term, I’ll probably be happier with these as I can do things like detect when a window is open and only lower the blinds to the top of that window, but still, the many hours of research and work to get this system into place were not as necessary as I originally thought.

As you can see, there’s virtually no reduction in view when the blinds are down.

While Somfy has been extremely spotty in providing support for my project, my other two partners on this project were great: Atrium Shade fabricated and installed the shades and my buddy Danny Mavromatis of Myro did all the ridiculously cool and complicated home automation tie-ins. Atrium provided the shades (as well as other interior shades throughout the house) at a very reasonable price and Danny expertly enabled me to do things like raise and lower them from my iPhone or any other IP-connected location.

Costs accrued during this stage:

Shades - Interior and Motorized Exterior (Atrium Shade Company)$24,080.00

11 Responses to “Mitigating Solar Gain with Motorized Shades”

  1. Aseem Says:

    Pretty amazing to see shades taken to this level, but the cost is greater than the entire lumber and steel package for the framing of our 2500 sq ft 3-story modern house in Seattle. Wow.

  2. Mike D. Says:

    Aseem: Worth every penny. A cheaper, but still effective motorized shade package would have only been a couple grand less. By the way, if you paid under $25,000 for your entire framing package (steel, lumber, labor, etc.), that is pretty dirt cheap. I think the framing stage for me was about $46,000. House is two stories at 3200 square feet plus a 1500 square foot basement but I didn’t use steel in the framing either. Steel is usually pretty pricey.

  3. Aseem Says:

    I wasn’t including labor, just steel & lumber (I think labor is another $12k). So maybe our numbers aren’t too far off. Steel is pricey, but necessary for our cantilever (you can see progress and a rendering at

    We haven’t even budgeted for shades. I’m certainly hoping to spend less, but I imagine we’ll stick with hand-actuated internal shades (probably rollers). BTW, your blog has been a great help in our project.

  4. Toronto Modern Says:


    I wanted to respond to you on the shades point on your blog, but I didn’t meet any of the profile criteria on your blog, so I am posting a reply to you on Mike’s blog. (Which I hope is not a breach of etiquette.) You may wish to talk about shades with your architect at this early stage. The cleanest shade solutions are those where the housing is hidden, but this requires planning well in advance. You can add blinds above the windows after wards, but this doesn’t look as good. It does add to the cost, but if you have big windows, electric blinds should definitely be considered as you will want to be able to put them up and down easily to control sun and privacy. (If you want to go electric, the wiring will have to be done early as well) We found in our previous house (with hand operated shades) that the shades just stayed in one position as we couldn’t be bothered to raise and lower them. With electric blinds, we raise and lower them at will, and it is such a great convenience. (The kids love demonstrating them to visitors as well!) We went with interior blinds rather than the exterior kind that Mike used. We got a couple of quotes, but even with searching the motors were surprisingly expensive. We justified it by telling ourselves that even traditional drapes can cost a lot of money. Window coverings that are easy to use will make a huge difference in your enjoyment of the house.

  5. Mike D. Says:

    Agreed about getting window coverings in the budget asap. Keep in mind also, Aseem, that I had a LOT of glass to cover. There are 7 blind motors in total (powering 9 blinds) and several of them are gigantic (like 10 feet tall by 12 feet wide). If you only end up needing motorized shades on a couple of your windows, it’s going to be a lot cheaper. Figure on maybe $2000 per fairly large window… less for normal sized windows.

  6. Aseem Says:

    Hi Toronto Modern, thanks for the comments. I changed my blog’s commenting policy, I wasn’t aware it was so restrictive.

    I did a bit of poking around, and we have discussed the issue of shades with our architects. Honestly, there’s no way we have budget for electrically-operated shades. However, putting the canister of the roller shades into the ceiling is a possibility and not too expensive. Part of the problem is that we’re not sure where we need shades; definitely the bedrooms, but we’re hoping the low-E windows will make shades unnecessary in the living areas. This is something we’ll have to decide before drywall goes up.

  7. Mike D. Says:

    Aseem: The visual impact of low-E glass will be next to zero. It will not cut down glare at all. Will only reduce heat a tad. We have low-E glass as well. By the way, $2000-$3000 a window would be for exterior motorized. Interior can be cheaper. What I would do if I were you is just run the wires for every single window you’d ever want a motorized shade on. Running wires is cheap during framing. The whole thing will cost you probably $500. Then, when you’re ready to put shades in, you’ll already be wired and ready to go. Pushing the shades up into the drywall is nice but you can also just get nice aluminum covers which will be plenty subtle.

  8. Toronto Modern Says:


    Hi. We did as Mike suggested – we put in wiring and then made the final decisions once we were in the home stretch as to where we would go with the blinds. We also tried living without blinds in some of the rooms where privacy was not a concern (living areas, including kitchen are pretty private) to see if we really needed blinds, but we found that even with efficient windows, because of the size and number of the windows, it got incredibly hot and bright and downright uncomfortable, even with the AC cranked up. So it became pretty clear that good blinds were a must. (Glass houses are beautiful, but architectural magazines never talk about these sorts of comfort issues…)

    Building a custom house involves a lot of decisions and trade-offs and it’s probably downright presumptuous of me to say this, but I would seriously recommend saving in other areas (like tiles or flooring) to create room in the budget for electric blinds in the rooms where you will want to raise them up and down on a regular basis. The interior motors were about $400 each (Canadian), as I recall. Some of the bigger windows required 2 motors. If you go with shades, you have to pay for the material anyway, so the motors would be the only cost savings if you went manual rather than electric. Ultimately, we did go manual in a couple of rooms where we thought that the blinds would be down most of the time (and they are, because we can’t be bothered to raise them by hand), but everyday when I raise the blinds in the other rooms, I am so glad we went electric in those areas.

    Whatever you decide to do, make sure you can access the mechanism (be it manual or electric) easily as you don’t want to be ruining and then fixing drywall if repairs or changes are indicated.

    Good luck! I look forward to checking out your progress.

  9. Aseem Says:

    Thanks for the tips, guys. We certainly have a lot of floor-to-ceiling windows, and most are south or west facing. Good stuff to ponder, and I’ll think about the solution and get some price quotes.

  10. Sam Says:

    What a beautiful home design; I love how energy efficiency and sustainability is seamlessly integrated.

  11. Greg Fox Says:

    Sometimes you have to spend money to save it in the end. I love windows and in the process of designing a home that we break construction next summer. Thnx for the info, this might change my plans a bit.