Objective of the lecture
:
- Human Comfort
HUMAN COMFORT
Thermal comfort, also
termed as neutral comfort, may be defined as “that condition of mind which
expresses satisfaction with the thermal environment”.
As we all know that, the
chemical energy of our food get converted into heat and work which is then
utilised for the proper functioning of our body organs including heart, brain,
lungs, liver and other parts of body organ and then ultimately, the energy is
rejected into the environment in the form of the waste and urea.
Such process of
conversion of conversion of chemical energy present in the food to heat and
work is termed as “metabolism”. The rate at which the process of conversion of
the chemical energy presented in the food into heat and work happens is termed
as “metabolic rate”. The knowledge of
metabolic rate and other factors including humidity, air temperature and air
velocity etc. are very necessary so as to know the cooling load of the air conditioned building.
To define thermal efficiency of a human being, one can termed it as “the ratio
of the useful work output to the energy input”. The thermal efficiency of a
human being can vary from 0% to as high as 15-20% for a short duration of time.
For the efficient
working condition of human body, the internal organs require the temperature
close to 35o C and this is achieve by rejecting appropriate amount
of heat in the surroundings.
Core
temperature = 36.8o C
Skin
Temperature = 33.7o C
If the temperature of
the human body rises above this temperature, then human body tries to achieve
this temperature range which is achieved by perspiration process of the body.
Human beings do not feel comfortable if the body require some extra effort to
reject this energy to the environment, which results in major loss in
efficiency.
LECTURE RELATED QUESTIONS :
1. Define the term "Human Comfort".
2. Define "Metabolism".
3. Define "Metabolic Rate".
4. Write down the factors affecting the human comfort.
5. Define "thermal efficiency" of a human being.
6. What is the core and skin temperature of a human body?
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