Dear Tom,
When we have mild winter days, say around 60 degrees, and I keep my house thermostat set at 68, I am comfortable inside. But when the outdoor temperature is around zero degrees and I keep the thermostat at 68, I have to bundle up like an Eskimo inside. Why?
— Ken Mueller
?
Dear Ken,
It has to do with the relative humidity. A higher indoor relative humidity makes the 68 degree temperature feel more comfortable; a low relative humidity makes it feel chilly. An outdoor temperature of 60 degrees is often accompanied by a dew point reading of 50 degrees, sometimes higher. Outdoor temperature/dew points of 60/50, when brought inside and heated to 68 degrees, yields a relative humidity of 52 percent; outdoor readings of 0/-5, for example, when heated to 68 degrees indoors gives a low 5 percent relative humidity.
