Most people have the mistaken idea that air temperature alone is what
governs comfort. Comfort is determined by the three main factors of air
temperature, mean radiant temperature and relative humidity (R.H.). Studies
by A.S.H.R.A.E. indicate that as R.H. approaches high or low extremes, the
range of air temperature considered comfortable narrows. This means heating and
cooling controls systems are constantly adjusted in a vain attempt to maintain
comfort. This translates into less efficient, and thus, more costly
operation.
The old idea that the moister the air, the warmer it feels is true
only to a limited extent. If air is extremely moist, then slightly warm air
will feel muggy and slightly cool air will feel clammy. If the air is
particularly dry, then discomfort and respiratory problems will occur. It has
been my experience that indoor air should, during the winter months, have a
R.H. in the range of 50 to 60%.
If a home is well caulked and weather-stripped, and all combustion
appliances are properly vented, the occupants will have little trouble in
maintaining this moisture level. The lore of the wood stove says that they
produce dry heat. The truth is, fireplaces that take their combustion air
from within the home will cause infiltration of large amounts of cold dry air
driving the R.H. down. A wood-burning appliance installed in accordance with
this report will not have that effect. Adding humidity, if needed, is much
easier and less costly than dehumidification. Unlike air temperature, that
tends to vary greatly throughout a structure, humidity tends to be very
uniform. It is somewhat analogous to the level of a swimming pool. No matter
where you add or take away water from the pool, the level of the pool is
equally effected over the entire surface. Therefore, putting a pot of water