For installers

Tightened a house? Leave the homeowner a way to check the bedrooms.

Air sealing and insulation keep heat in. They also keep in the air people breathe out overnight. Hand the homeowner a HouseExhale card: a CO₂ monitor by the bed for three nights shows how each bedroom does, which free fixes to try first, and whether the house needs fresh-air ventilation.

For insulation, air-sealing and window contractors, energy auditors, weatherization programs and builders. Free, and unpaid both ways. HVAC and ventilation companies join as installers instead.