I think this is overlooked far too often. Through various programs, my mom went crazy on the insulation and energy efficiency in her old ranch style house but

I think this is overlooked far too often. Through various programs, my mom went crazy on the insulation and energy efficiency in her old ranch style house but didn’t add an air exchanger. We realized we felt like crap there and measured the CO2 and it was hitting over 3000 ppm! https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms https://www.kane.co.uk/knowledge-centre/what-are-safe-levels... I’m horrified to think of all the poor people in these programs that are probably feeling bad but have slightly better energy bills. Good health is the most important quality we have. There need to be energy conserving air exchangers put in with each tight house made. That’s the best of both worlds.