Bathroom Fans. “That’s a weird thing to measure”

Making a home more energy efficient means both insulation AND air sealing, or tightening of the homes boundary. Contractors are getting very good at this and when they finish, the home may require a special solution for providing fresh air to avoid having a “sick” home. In extreme cases, a biofilm can build on the basement walls. I’ve seen this and fixed. This is done by installing a robust bath fan, typically the Panasonic Whispergreen, that has the ability to slowly move the air when not in use during a shower and uses only $12 in electricity if left running all year.