"As
evidence of the importance of radiant heat exchange to the
body’s thermal equilibrium, physiologists have discovered that
living human skin has extraordinarily high absorptivity and
emissivity (0.97), greater than almost any other known
substance, matte-black metals included. Consequently, we are
highly responsive to changes in mean radiant temperature."
Dr. A. Marsh
We have
roughly 166,000 thermal receptors in our skin with most of them
sensitive to heat loss.
We
don't inhale comfort, we feel it through our skin. Inhalation is
part of the respiratory process and relates to
indoor air quality not thermal comfort.
Forced
air system excel at condition the air, that is they are very
good at:
Facts About Your Skin - Temperatures in and on the human body (To turn off sound - click stop button on image below -
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The
human body's largest organ is the skin. Skin protects body
tissues against injuries and helps regulate body temperature by
making the pores larger or smaller. The
nerves in skin receive
the stimuli that are then interpreted by the brain as touch,
heat, and cold. Skin is composed of three layers: epidermis,
dermis, and subcutaneous fatty tissue.
The
interface between the epidermis and dermis is extremely
irregular and consists of a succession of papillae, or
fingerlike projections, which are smallest where the skin is
thin and longest in the skin of the palms and soles. The
papillae of the palms and soles are associated with elevations
of the epidermis, which produce ridges that are the basis for
fingerprint identification.
Subcutaneous fatty tissue is the deepest layer of the skin. It
is composed of connective tissue, blood vessels, and fat cells.
This layer binds the skin to underlying structures, insulates
the body from cold, and stores energy in the form of fat.
The
skin forms a protective barrier against the action of physical,
chemical, and bacterial agents on the deeper tissues and
contains the special end organs for the various sensations
commonly grouped as the sense of touch. Through the activity of
its sweat glands and blood vessels, it is important in
maintaining body temperature. One square inch
(6.5 square centimeters) of skin contains up to 4.5 m of blood
vessels, which have as one of their functions the regulation of
body temperature. The skin varies in thickness from 0.5 mm on
the eyelids to 4 mm or more on the palms and soles.
More about your skin:
The
typical body has between 20 ft2 to 22 ft2
of surface area which serves as a radiator for releasing heat
via radiation to lower the body temperature or as an absorber to
take in radiant energy to raise the body temperature. The skins
emissivity is around 0.97 which makes it almost perfect as a
radiator and absorber.
Quotes
"There is no normal temperature but a range over which
temperature fluctuates and changes." Dr. Tim Lowenstein
"...your skin
temperature varies parabolically from 83 deg F. (28.2 C) at an
ambient temperature of 49 deg F. (9.5 C) to 98 deg F. (37.2 C)
at an ambient temperature of 95 deg F (35 C)."
Dr. K.R. Koehler College Physics for Students of Biology and
Chemistry, University of Cincinnati
More
about core body temperatures:
"When
summarizing studies with strong or fairly strong evidence the
range for oral temperature was 33.2–38.2°C, rectal:
34.4–37.8°C, tympanic: 35.4– 37.8°C and axillary:
35.5–37.0°C. The range in oral temperature for men and women,
respectively, was 35.7–37.7°C and 33.2–38.1°C, in rectal
36.7–37.5°C and 36.8–37.1°C, and in tympanic 35.5–37.5°C and
35.7–37.5°C." Sund-Levander,
Märtha; Christina Forsberg and Lis Karin Wahren. Normal oral,
rectal, tympanic and axillary body temperature in adult men and
women: a systematic literature review. Scandinavian Journal of
Caring Sciences. Vol. 16 No. 2 (June 2002): 122.
"Skin
is the principal organ for dissipating heat: the human body
dissipates
approximately 85% of its heat loss through the skin under normal
environmental
conditions (Zhang 2003)." Holopainen, R.,
A human thermal model for improved thermal comfort, Doctor of
Science in Technology Thesis, Aalto University, VTT, December
2012
Bibliography/endnotes
1. Copyright (c) 2005, Arizona
State University, All Rights Reserved, Republished by www.healthyheating.com with restricted permission from ASU.
