Heat: Ways the Human Body Gains or Loses Heat to its Environment

Heat 1
ASSIGNMENT 2 – HEAT
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Heat 2
With diagrams describe the ways that the human body gains or loses heat to its
environment. Explain how these mechanisms work.
Every alive human being is continuously producing heat through the body’s metabolic processes.
The general output of this heat is 100W but it will easily fluctuate from 70W (when one is
asleep) to 700W (during an intense work out). This heat should therefor be constantly released
into the environment otherwise the body will continue increasing temperature to a point of death.
The body’s thermal-regulation in very important (Houdas & Ring, 2013).
E – Evaporation
Rd – radiation
Cd – Condensation

Heat 3
Cv - convection
The human body losses or gains heat through the following main processes; evaporation,
radiation, convention and conduction.
Heat lost through evaporation
When a person is exposed to high temperatures, for instance during the summer, or after an
energy intensive activity, he or she will sweat to reduce heat in the body (Houdas & Ring, 2013).
The cells of the skin pumps water up to the surface so that the body heat can evaporates it, and
transfers that heat into our immediate surroundings.
Heat Gained or lost through Conduction
Conduction is heat transfer when two solid bodies with different temperatures come into contact.
This means, when one touches a warm object, heat is conducted from the warm object to your
body. The inverse is also true, when one touches a cold door handle, heat is transferred from the
body to the handle.
Heat lost or gained through Radiation
Radiation heat transfer does not require a medium for heat to transfer. Heat transfer occurs
through electromagnetic waves. A good example is the warmth we feel from the heat of the sun
Heat lost through Convection
Convection is the heat transfer through fluids (liquids and gases)

Heat 4
The human body generally radiates heat that forms a protective ‘blanket’ all round our bodies.
When one wears clothes, this heat is trapped next to the skin keeping us warm (Sherwood, 2015).
In a case where the wind blows, the air next to the skin is replaced with colder air due to the
temperature differences thus heat loss through convection occurs.
This forms the basis of thermal comfort of a human being at any particular environment.
However, comfort is very subjective as it is well-defined as the state of mind which will convey
satisfaction with the surrounding thermal environment. One’s comfort level may not be the same
as the other person. Thermal Comfort is not only affected by our surroundings but by other
physical elements such as clothing. In spite of this, there is always a perfect range of comfort for
a given region or climate
2. For an uninsulated brick veneer house in Sydney in winter describe the main paths of
heat loss to the outside air