Indoor humidity levels-summer and winter

[ron3637]

What should the range of humidity levels be for the summer and winter months, and should there be a difference between the humidity levels according to the seasons. Is a higher indoor humidity level perferable in the summer? I keep my indoor humidity levels around 40% year round. I live in Washington DC and its hot and humid during the summers. . Thanks

[Daltex]

Lower humidity in the summer is more comfortable unless you grew up in the amazon jungle. 40% is good for summer heat. Low humidity in the winter can cause dry skin, static etc. I'd want it higher than 40% in the winter myself ~50%.

[adrianf]

This may help: http://www.gasairconditioning.org/relative_humidity_chart.htm

[HpDude]

Idealy 40-50 RH is perfect, ultimately if you can maintain
45% year round life is good...

Unless you are one of the few lucky folks who had it built right,
be sure to clean the humidifier often !!!

[beenthere]

Becarefull of 45% RH in the winter. When its 20 or less outside. It can cause mold at some outside wall areas. An inside wall with a hydrometer may read 45%, but a cold outside wall could be at 70%.

[addamsmasher]

There is no "right" humidity level, it really comes down to what's comfortable for you provided some of the conditions that others have mentioned are met (too much humidity in winter months [condensation on windows, wood warping, etc.]). Now if you live in Arlington, Alex, Silver Spring, Bethesda area that will probably never be a problem considering how loosely most of those older homes are/ I live out in Loudoun County so I know how keeping humidity under control in the summer can be challenging.

[cem-bsee]

35- 55% for indoor RH per respitory therpists -- [for my ex who had emphysema]

[Carnak]

If you have quality windows I would say when the weather is below freezing 35%, when it is above freezing 50%

[motoguy128]

I'll post this here as well. http://www.cottagestocastles.biz/pdf/misc/Humidity.pdf Its' summarizes the issue and touches on what Beenthere mentioned. There is a risk to you building structure with high indoor humidity. Thermal Pane windows might have a insulation value or R2 or 3. Some poinst inside the wall might be lower.

The key measure value is dewpoint... not RH.

At 70F indoors and 40%RH, any surface under 44F will condense the water vapor in the air. Lower that to 25% and now it's 32F. With windows, even if you get low-E argon filled jobs, you'll find that air leaks and the frames themselves have a lower R value than the glass, plus the aluminum reenforcment has a lot of mass.


I appreceiate all the recommendations comming from folks in Alabama, Texas, Forida... you know, places that don't have winter and probably don't need a humidifier if the home is 1/2 way tight. :) hte glass probably only condenses in florida on the inside if you breathe on it. Condensation on glass is more of a summer problem there.