The CO2 gizmo arrived a few days ago. Useful tool & highly recommended. Thank you again, Chattanooga Dave!
Preliminary findings: In my house, indoor air worsens dramatically without ventilation! If 420ppm (uncalibrated) is the outdoor reading, empty indoor rooms read 540. In the room I am working at my desk: 675. Working out: 800+. This is *with* fans moving air and doors open to other areas of the house!!!
Sleeping in my corner bedroom with no fan, levels reached 800 with the door open! Holy frijoles! Indoor air is freakin' TERRIBLE. I don't even have any pets, kids, etc... it's just me in this 2500+ sqft house from 1925 which is hardly airtight... geez.
No wonder so many people working from home are falling asleep during meetings, etc. This has been a real eye-opener.
I'm very pleased with the results at the museum. Very, very pleased. Front desk remains around 480ppm due to the constant inflow. Inside, the levels never exceed 530 at multiple test points even with as many as 20 people present with masks. I wonder how many more I'd need to move the needle?
I know it is working because it is sensitive as heck. If I blow at it from six feet away, once, it'll temporarily spike the levels by 40ppm.
Key takeaway: Pay attention to the ppm level -->>with respect to how many people are inside<<--.
Lotta people + large room + 550ppm reading = good ventilation.
Few people + large room + 550ppm reading = not good.
It's all about how well the space is maintaining its CO2 count -->>relative to total attendance<<--.
More importantly, MY HOUSE NEEDS REMEDIATION for my own well-being! To fix this, I'm getting an Air King QuFresh mechanical ventilator installed. At $300-ish, it is far less expensive than a full-on ERV (Energy Recovery Ventilator).
The QuFresh basically turns your house into a positive pressure system, unlike running your bathroom fan 24x7 with negative pressure. It can be programmed to only pump air indoors when the air "falls within favorable criteria" which you can set yourself.
Too humid? Not humid enough? Too hot? Too cold? It'll basically stop running during those times. Otherwise... whoosh! It's a basic low-tech way to get more fresh air indoors without the expense and maintenance costs of an ERV (runs all the time).
Learning is fun!