1. John Shillito John Shillito United States says:

    With all due respect to the authors, the assumption of 65% indoor relative humidity in sub-freezing climates is far too high, at least for residential buildings. At that level water would be literally dripping down the insides of windows. A look at the Psychrometric chart show at a temperature of 68 degrees (20 c) and 65% RH that the dew point is 55/13 degrees. If outside temperature is, say, 20f/-7c most any windows and even other exterior surfaces would be below this dew point.
    In my climate zone of 6 in the norther U.S. we find that indoor humidity in winter should be under 40%.  

    Also, your recommendations f and g seem to be contradictory. Perhaps you mean to say indoor air circulation should have a high degree of filtration?

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