I wish this were taken into account more often. Where I live there's been a major push for insulating older buildings where possible, and moving from single-gla

I wish this were taken into account more often. Where I live there's been a major push for insulating older buildings where possible, and moving from single-glaze to double-glaze windows and well-closing entry doors has converted these places to an almost air-tight box with close to no air replacement. These are compounded by the usual lack of any mechanical air extraction. I live in one such apartment, and even though it's reasonably big, if I sleep alone with the windows closed but all the doors open, CO2 will reach around 1000 PPM according to my Airgradient.