[en-us]

I'm not the OP, but I use this one with similar results: https://www.amazon.com/gp/aw/d/B01FYWU2IS

One of these days I'm going to have to rig up something to start the house fan when the CO2 goes above 800 ppm and I think you'd need a different sensor with a realtime output port for something like that.

[ip26]

Direct feedback is cool, but a simple schedule is really easy & reliable. Even occupancy detection isn't all that critical- nobody wants to come home to a stuffy house, and most people's schedules are very predictable.

These days IoT is so widespread that something like a $25 WeMo smart outlet is hard to beat. Hard wired is "best" but a million times more hassle and more expensive.

[bumby]

If you want a reference on setting this up to meet industry standards on demand controlled ventilation practices see ASHRAE 62.1 and 62.2 standards