Today I spent some time looking into automatic windows. Could windows be automatically be opened when the indoor and outdoor temperatures are at the right place? There are some windows we plan to put in the lofted area that will be too high to easily reach. These could also benefit from automatic window opening.

It seems that most solutions are pretty expensive. The cheapest/easiest solution seems to be using linear actuators. There are also window openers specifically made for this, but they tend to be even more expensive ($170) .

It seems that a lot of cost could be saved if regular DC motors could be fashioned to be used instead of pricey linear actuators. The actuators don’t get much cheaper than $110. DC motors would require more complex arrangement with chain or string and likely one for opening and one for closing the windows. These could probably be done, but would require quite a bit of experimentation first. It would cost significantly less, probably closer to $75 complete instead of $150 complete. These could be added later to double hung windows. One problem with these is that they can’t lock the window closed, also if the window is opened manually, the string will get messed up. Some kind of geared belt system might work better, but that gets way more complex …

One down side to the linear actuators is that due to the large cylinder, they might not be easy to fit in between a window and its screen. They make sense for casement windows and awning windows, but are more difficult for double hung windows. We have the benefit of 2’ deep walls, so it should be relatively easy to install a large 12” linear actuator in between our awning windows and their screen.

I also found these that seem to be reasonably priced and could fit in a much smaller space (it is 7 cm wide). They run on 24V. The actuator itself costs just around $100 + UK VAT? + shipping. They also come with lots of options for building a system with their accessories (power supply, remotes, etc.) One problem with these is that they are much less powerful than the general purpose linear actuators and only extend to 15cm (5.9 inches). You could mount them closer to the hinge to make the 5.9 inch opening act like more but I wouldn’t be confident that they would be strong enough to open the window with that kind of leverage.

One thing to consider before building, is that we might be able to run any necessary wiring through the walls, which I think would be preferable. Especially for above greenhouse windows. Another possibility is for double hung windows to have linear actuator built up into the wall, like in a lintel or something … The problem is that if we want the window to open 30 inches, there needs to be a 30 inch actuator inside …

Yet another possibility is making the linear actuators themselves out of a DC motor or servomotor. There are lots of designs, and they are really quite simple. The hardest part would be calculating the size of motor necessary to get the amount of force desired.

After all of this, I’ve decided that automatic windows are definitely not worth it at this point. I will still need to come up with a method for opening the windows that will be too high to open in a typical fashion, but will likely just use a simple manual pulley or push bar system. To be determined …