James Cridland · 14w Window (actually, a door) open. Ceiling fan on. But even then, overnight in the bedroom hits 1,000 ppm of CO₂. This doesn’t seem great. Unsure of how to reduce it. Any ideas? https://assets.bne.s... Bryan Haskin @Bryan Haskin 1773109963 @nprofile1q... do you own the home or rent? If you own you can install a HRV or a ERV 1