Human thermal comfort describes the state of mind that expresses satisfaction
with the surrounding environment. It is affected by six factors:
- Air temperature is the most common measure of thermal comfort and
can easily be influenced with passive and mechanical heating and cooling.
- Mean radiant temperature
is the weighted average temperature of all exposed surfaces in a room.
The greater the difference between air temperature and exposed surfaces,
the greater the wind chill factor.
- Wind chill factor (relative
air velocity) is the apparent temperature felt on exposed skin due to
wind. For example, if cold air is leaking in from a window, the air
temperature feels lower than the actual air temperature, hence the increased
likelihood of feeling cold, even when the heater is on.
- Humidity or relative humidity
is the moisture content of the air. If the humidity is above 70% or
below 30% it may cause discomfort.
- Activity levels can reduce the heating needs, as lower air temperature
is acceptable when occupants have higher activity levels.
- Thermal resistance of clothing or warm blankets in a bedroom can reduce
the need of heating.