Bedroom ventilation is the binding constraint, not insulation
Evidence
- CO₂ reaches 1,860 ppm at 06:10 on both logged nights with the door closed
- Trickle vents present but painted shut on both windows
- Surface temperature at the north reveal runs 3.1 °C below room air
- Relative humidity peaks at 68% overnight — within 2 °C of dew point at the reveal
Recommended actions
- FreeSleep with the bedroom door ajar; retest yourself with the loaned meter.
- ~$40Free off both trickle vents and clean the seals. This alone should take the peak below 1,300 ppm.
- ProjectIf you are already replacing the north window, specify a larger vent area. Do not do it on its own — the payback is not there.
What not to do
Do not add insulation to that reveal before the ventilation is fixed. Warmer, wetter air against a cold surface makes condensation more likely, not less.