[agsnu]

Presumably, an unexpected increase in CO2 would be a proxy for intruders.

[twothamendment]

Yes, what is kinda fun is I can tell what time my kids are out of bed (really it if their room) just by the changes in co2.

Everyone was gone today at the same time (rare with WFH and home school). I can see within about a minute when we arrived home.

[defrost]

Or houseplants dying.

[twothamendment]

Ha, if only it were that sensitize. I have an air exchanger, so I don't think the plants will change it enough to matter. I expect that normal air infiltration would cycle more air than plants.