Because Radon actually causes cancer and ventilation is expensive. I’ve read many articles about people going nuts trying to manage CO2, but I think it’s useful to know if I’m being exposed to something that would actually result in early death as I’m more likely to take immediate action on that.
Modern well insulated buildings need active ventilation. Passive just doesn’t cut it anymore.
I installed a HRV system in my (well insulated) house, and I love it - air quality indoors is noticeably improved.
Only downside is that there’s lots of wood burning in my particular (and densely populated) area of Europe, so I was quickly drawn into the rabbit hole of particulate matter sensors and how to automatically shut the ventilation system off when the neighbors turn on their fireplace.
And when it comes to mold, our bathroom used to have black spots on the walls after a while, but with improved ventilation it stays amazingly clean and everything dries much more quickly. Almost no condensation on surfaces like mirrors and walls anymore either.
You missed out - they’re giving away the batteries for almost nothing now to get rid of the lease. Mine was manufactured in 2011 (!) and is still at 93% of its original 22 kWh rated capacity after doing 90.000km, which is amazing compared to a Leaf.
The logic being that whenever you bring in fresh air, you decrease radon concentration.
And a high CO2 level means you need to bring in fresh air anyway, and you incidentally also reduce radon concentration.
I could be way off here though, happy to learn more on the topic as I don’t have experience with (dealing with) radon.