Indoor air often feels very dry in winter because cold outdoor air contains little absolute moisture and its relative humidity drops when heated indoors. Ventilation, air leakage, and heating intensify the effect; measure with a reliable hygrometer before adding a humidifier.
Measure relative humidity instead of relying only on feel
Dry skin and static electricity are clues, but they do not reveal the actual percentage. Place a hygrometer away from cooking, showers, and direct supply air and compare readings at different times.
Cold outdoor air becomes relatively drier when heated
Each time cold outdoor air enters through ventilation or leakage and is warmed, its relative humidity falls. Sealing obvious leaks and avoiding excessive ventilation can help without adding moisture.
Use a humidifier to a moderate target
Raising humidity too far encourages condensation on windows and cold surfaces. Adjust for climate, building, and equipment guidance; if condensation appears, lower the target even if the number seems comfortable.
Localized dryness can come from airflow
A bed or desk next to a register that blows constantly can feel drier than the rest of the home. Change position or air direction without blocking registers the system needs.
Sources
- U.S. Department of Energy — Energy Saver — Residential energy efficiency, heating and cooling, and equipment use.