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What Humidity Level Should I Have In My Home? - Part 2

New Homes Versus Older Homes

What Humidity Level Should I Have In My Home?

The correct amount of humidity in the home is relative to the outdoor temperature. If the indoor temperature is maintained at 70° F. Table 1 is a reasonable guide to the humidity level you should maintain in your home.

Table 1 - Humidity Levels Based on 70° F Indoor Temperature

Outside Air Temperature

Indoor Relative Humidity

-20° F or Colder

15% Maximum

-20° F

20% Maximum

-10° F

25% Maximum

0° F

30% Maximum

10° F

35% Maximum

20° F

40% Maximum

Keeping the humidity levels above these amounts will result in condensation forming on windows and other surfaces.

New Homes Versus Older Homes:

Condensation problems in homes are on the increase because we continually improve the energy efficiency by design homes that prevent outdoor air from entering and indoor air from escaping. Older homes could breathe, basically exchanging the drier outdoor air with the moist indoor air and creating a balance. Insulation, weather stripping, thermal windows and heat exchangers have all but eliminated the mixing of indoor and outdoor air.

The economics of energy efficiency have placed a higher burden on homeowners to manage their indoor humidity levels with a greater degree of care and accuracy.

In order to reduce condensation you must reduce the humidity in your home.