Ventilation and heat control are necessary to provide fresh air, remove contaminants and maintain comfortable temperatures for human health and safety. Good ventilation supplies oxygen, removes carbon dioxide and pollutants from processes, and regulates air temperature. It decreases heat stress and improves worker productivity, health, safety and satisfaction. Poor ventilation has opposite effects, including insufficient fresh air and increased discomfort, stress and accident risks.

1. PURPOSE & EFFECTS OF VENTILATION AND
HEAT CONTROL
Clean, fresh and uncontaminated air is a
basic need of life. Industry has many
pollutants which contaminate air and heat
stress is generated due to hot processes.
Well designed and effective ventilation
provides solution to these problems.

2. Purpose of Ventilation and Heat Control:
1. Air is life and fresh air is the first need for survival of living creatures.
Absence of air brings death within a few minutes. Life without breathing
is not possible and the clean air is needed for the whole life- for breathing
and functioning of human body. Therefore good ventilation giving
sufficient fresh air is the permanent requirement.
2. Human body cannot tolerate excessive temperature. Heat stresses produced
by very hot or cold exposures cause adverse effects on health and safety of
work people. Therefore environmental temperature control is also
permanently needed for well functioning of human body. Ventilation helps
in removing excessive temperature
3. Heavy physical work or heavy work load causes heat stress and strain and
increase metabolic heat, body temperature, sweating, heart rate etc. To
maintain (control) body temperature, ventilation is necessary.

3. Purpose of Ventilation and Heat Control(Cont)
4. Carbon dioxide is continuously exhausted by all human beings. Much more
contaminants are added by manufacturing processes to pollute air.
Therefore cleaning of air and supply of fresh air with sufficient oxygen are
also necessary. This is possible by good ventilation and pollution control
techniques only.
5. Where due to weather or atmospheric conditions or process parameters,
excessive temperature is unbearable or uncomfortable, air conditioning or
HVAC systems are also necessary. Conversely where air heating is
necessary as in case of excessive cold climate, it must be provided.
6. Basic functions of ventilation are to (a) maintain the oxygen content of the
air and to prevent CO, concentrations from rising (b) prevent or removal of
body odours (c) prevent harmful concentration of aerosols and air-borne
contaminants and (d) maintain reasonable conditions of thermal limits for
comfort and efficiency which result in decreased heat stress, increased
productivity, reduced accident rates (hot conditions induce unsafe acts)
and adverse health effects (interaction with other hazards), higher level of
job satisfaction, reduced absenteeism, improved attitudes, reduced
downtime for hot vessels and compliance of required standards.

4. Cont…
7. While designing industrial buildings care must be taken to-
1.provide good ventilation for dilution of inside air to prevent
vitiation by causes, such as body odours,
2. remove process released contaminants and heat exposures
3.maintain satisfactory thermal environments,
4. maintain heat balance of body and
5. prevent acute discomfort and injury to the health of the workers.
If natural ventilation is not sufficient for these purposes, mechanical
ventilation, cooling system or other techniques must be employed to
achieve satisfactory results.
Thus main purpose of ventilation is to remove heat 'and
contaminants from air in residential or industrial building and to
supply or regulate fresh and cool (or hot) air for the comfort of the
occupants or workers.

5. The quantity and quality of air required
for ventilation depend upon
1.Rates of heat generation in the room.
2. Rates of contaminants (gas, vapour, dust) generation
in the room.
3. Rates of dispersion of heat & contaminant.
4. Rates of dilution and removal that may be achieved
by ventilation.
5. Electric fittings for ventilation system in
flammable/explosive area should be flameproof and
of the approved type.

6. Effects of Good and Bad Ventilation:
• Effects of good ventilation are:
1. Availability of sufficient fresh air for breathing or life.
2. Removing oxygen deficiency from a confined space.
3. Removal or dilution of carbon dioxide and other air
pollutions.
4. Decrease in environmental heat or temperature.
5. Increase in air changes per hour as per statutory
requirement.
6. Maintaining metabolic body temperature or heat
balance.
7. Removal of air contaminants (dust, gas, fumes, mist etc)
from work room.
8. Maintaining room temperature for comfort.

7. Cont…
9. Providing desired air conditioning (cooling or heating).
10. Removal of body odour and bad smell from the room.
11. After heavy physical work, evaporating body sweating and
making the body cool.
12. Decreasing discomfort and distress.13. Maintaining
efficiency of work.
14. Decreasing chances of accidents and maintaining safety
and productivity.
15. Providing better job satisfaction and good attitudes.
16. Increasing cooling rate of hot vessels or hot substances.
17. To maintain overall comfortable working conditions and
18. To help compliance of statutory provisions and standards.

8. Effects of bad ventilation
• Effects of bad ventilation are opposite to above
• non availability of fresh air for life,
• insufficient air changes
• no cooling effect
• discomfort, body stress and strain
• no removal of air contaminants, body odour, bad smell etc,
• increasing chances of accidents, lowering efficiency and
productivity
• no job satisfaction
• more time for cooling of hot vessel and substances and
violation of statutory provisions etc.