Absorption. The conversion of radiation impinging on a material's surface to
thermal energy within the material. All radiation incident on opaque
materials is either absorbed or reflected.
Bioclimatic chart. A diagram of temperature, humidity, radiation, and air
movement used to display the human comfort zone under a wide range of
Bodily cooling. Any means of using climate elements to cool the occupant
directly. Natural ventilation directed across the human body may cool it by
increasing convective and evaporative heat loss from the skin. Bodily cooling
is distinct from structural cooling.
British thermal unit (Btu). The amount of heat required to raise the
temperature of one pound of water by one degree F.
Building bioclimatic chart. An expansion of the bioclimatic chart in which
the limits for well-developed executions of climate control strategies are
plotted in addition to the comfort zone.
Clo. A unit of measurement used to describe clothing insulation level.
clo is equivalent to 0.155 m.2-(deg.C)/watts.
see Thermal comfort.
Conditioned and unconditioned spaces. The need for air treatment such as heat
addition, heat removal, moisture removal or pollution removal for a space, vs.
Conductivity. A measure of heat energy transfer through solids caused by a
difference in temperature.
Dewpoint temperature (DP). The temperature at which a given concentration of
moisture in the air begins to condense. The dewpoint temperature of any
temperature and humidity combination is found on the psychrometric chart at
the left end of the horizontal line passing through that temperature and
Solar heat liberated within the building after passing through
Direct radiation. Shortwave radiation that has travelled a straight path
(without refraction or reflection) from the sun to the earth's surface.
The difference between maximum day and minimum night
Dry-bulb temperature. A measure of sensible heat as read on a standard
thermometer and indicated on the psychrometric chart by vertical lines.