Sliding window opener

I am trying to keep my garage as cool as possible in summer. I have an automated extraction fan. It helps, but not as much as I would like it to. The next step is to open a window while the fan is running. It is a sliding window, by the way.

So, I made a prototype window opener. Here’s what I wanted:

  • Easy to install, easy to remove
  • No drilling holes (new windows!)
  • Reasonably low force (none of these finger-cutting, arm-breaking, leg-bruising 6kN actuators!)
  • 100mm/4" travel - that’s how far I can open my window while keeping the anti burglary lock engaged

Here’s what I ended up with:

Basically, a small linear actuator, attached to window glass with suction cups. Logic is provided by ESP32 running EPSHome, and muscle by a L298N motor driver module.

Shopping list:
ESP32 ($10.99):
Motor drivers ($8.69 for two):
Actuator, ($33.05):
Suction cups ($18.89 for four) :

Also needed are jumper wires and 12V power supply - I had these. Oh, and a small piece of silicone tubing to keep the actuator centered in the scution cups.

Yeah, the electronics I ended up with are quite similar to what @DrZzs and @Mahko_Mahko used. Great minds, etc., etc.

The actuator has some sort of overload protection built in. This makes open loop control possible - I just drive it for a predetermined period of time and then stop. If it hits the limit earlier (as it usually does), it will just turn off by itself.

The next step will be to design a small motor controller board with a socket for the ESP32. What I have now looks too much like a science fair project for my liking.

If anyone wants to play with a similar project, I’ll be happy to share my code and wiring diagram.


Love it!

For version two of my Cranky I went with the mini L298N and a wemos d1 mini to help keep overall size down…

Are the suction caps holding on ok?

To let more warm air in?

Too bulky in my opinion.

Yeah but it is a garage. I agree I wouldn’t have it in a living area.

Well I would, my wife wouldn’t.

The suction caps seem to be doing their job. As a matter of fact, they are pretty difficult to detach, even with the latches off.
Of course, I have only installed them two days ago. Who knows what happens after several months in sunlight.

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To let cooler air in. The whole thing - fans and window - is controlled by HA based on the temperature difference between my garage and outdoors. In the morning, when it gets warm, the window will close and fans will turn off.

In a living area I would have a very different set of criteria. Yes, aesthetics would be pretty high on the list. But I would also want to be able to open the full width of the window, and some means of opening the window - quickly! - manually would be needed. Emergency egress and all that…
Honestly, I am not sure how I would approach this.

I’ve been working on a whole bunch of rules for whether the windows should be open or not. They are “kind of working”…

Internal/external absolute thresholds and differences in temp/humidity, forecasted high for the day, whether external temp is rising quickly, a rain sensor, a dev pollen sensor, I’ve got a CO2 sensor on the way. I tinkered with “feels like” temps too.

By default I want the windows open and I get an announcement when my rules close them and why.

Bit out of control but it’s getting there.

OK, you got me interested. Why do you care about rate of change and forecast?

Yeah still figuring that out myself:)

In my mind it’s a “conservation mode” that banks thermal mass for use later…

If it’s cold(ish) inside, but going to be hot, I’d prob want to keep windows closed to “bank” that cooling mass to offset later heat, rather than open the place and warm it now, and for it to heat up even more later.

Similarly if outside heat is really starting to ramp up, I’d prob keep windows closed even if it’s cold inside - be “outside of range now” to help passively control temperature “later”.

Seems like reasonable logic to me but happy to have it explained otherwise:).

OK, I think I get it. It is basically an optimization exercise with several contradictory goals. Something like “I want the windows to be open as much as possible, but I do not want the home to get warmer than XYZ.” A weather forecast can help with decision making here.

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Yep. And rules change depending on whether I’m home or not.

If I’m away I’d still like to aerate the place and don’t really care so much about temp. But I do still care about making the place damp if it’s too humid outside etc . And prob don’t want pollen coming in.

How is your suction cup setup holding up?

Thinking of doing something similar

Funny you should ask. At this very moment my 3D printer is working on a replacement for the suction cup. It will be something very similar in shape, but instead of suction, it will be attached to glass with hot glue.

The suction cup I have works fine - for a couple of weeks. Then it falls off. Then I reattach it and get another couple of weeks, and so on. I guess I lost patience and decided to try an alternative.

How is hot glue working out so far?

So far so good, but it has not even been two weeks since I installed it.