Annexure 2.5 EHS Guidelines
Rev.76, 202517
Guidelines for Ventilation Survey
1.0 Scope:
Scope of this document is to provide guidance on measurement and verification of ventilation in
various areas in ITC factories and hotels. The document covers,
- Natural ventilation
- Mechanical ventilation
o In non air- conditioned areas
o In air- conditioned areas
Cooling and heating of air is not covered in this document.
2.0 Brief on ventilation:
As per National Building Code 200165, ventilation is defined as the process of changing air in an
enclosed space. A proportion of the air in the enclosed space should be continuously withdrawn and
replaced by fresh air drawn from outside to maintain the required level of air purity. Ventilation is
required to control the following:
- Oxygen content: Prevent depletion of the oxygen content of the air;
- Carbon dioxide and moisture: To prevent undue accumulation;
- Contaminants: To prevent undue rise in concentration of body odors and other contaminants;
- Bacteria: To oxidize colonies of bacteria and fungus to prevent their proliferation;
- Heat: To remove body heat and heat dissipated by electrical or mechanical equipment or solar
heat gains.
Ventilation is broadly divided into two categories:
Natural ventilation: Supply of outside air into a building through windows or other openings due to
wind outside and convection effects arising from temperature or vapor pressure differences (or both)
between inside and outside of the building.
Mechanical ventilation: Supply of outside air either by positive ventilation * or by infiltration due to
reduction of pressure inside caused by exhaustion of air, or by a combination of positive ventilation
and exhaust of air.
3.0 Required ventilation rate:
3.1 Natural Ventilation:
Since it is difficult to measure the volume of air through natural ventilation as it varies from time to
time and depends on speed & direction of wind, estimation is done by a default method based on size
of ventilation openings. State Factories Rules stipulate that aggregated area of ventilation openings
*
Positive ventilation: The supply of outside air by means of a mechanical device, such as a fan.
Page 1 of 6
, Annexure 2.5 EHS Guidelines
Rev.76, 202517
(window, ventilators, etc.) should be more than 15% of the floor area of space/ portion of space
under consideration. (See illustrative example at figure 1)
Where,
O1, O2 , O3 & O4 - Areas of ventilation openings in m2.
A - Floor area in m2.
So, Aggregated area of ventilation openings
O = (O1 + O2 + O3 + O4) m2
O should be greater than 15% A
Figure 1 – Ventilation openings for natural ventilation
Spaces/ portions of spaces, to be naturally ventilated shall be permanently open to wall openings
directly to the outdoors. Where interior rooms or portions of rooms, without direct openings to the
outdoors are ventilated through adjoining rooms, the openings between rooms shall be permanently
unobstructed.
Inlet openings in the buildings should be well distributed and should be preferably located on the
windward side at a low level, and outlet openings should be located on the leeward side. (Inlet and
outlet openings at high levels may only clear the top air at that level without producing air movement
at the level of occupancy.)
As per ASHRAE Standard 62.1-202210 on ‘Ventilation and Acceptable Indoor Air
QualityVentilation for Acceptable Indoor Air Quality’, spaces or portion of spaces to be naturally
ventilated should be located within a distance based on the ceiling height (as explained below):
- Single side opening: For spaces with openings on one side of the space, the maximum distance
from the openings is 2H, where H is the ceiling height. (See illustrative example at figure 2)
- Double side opening: For spaces with openings on two opposite sides of the space, the
maximum distance from the openings is 5H, where H is the ceiling height. (See illustrative
example at figure 2)
For ceilings that are increasing in height as distance from the openings is increased, the ceiling
height shall be determined as the average height of the ceiling within 6 m from the openings.
Page 2 of 6
Rev.76, 202517
Guidelines for Ventilation Survey
1.0 Scope:
Scope of this document is to provide guidance on measurement and verification of ventilation in
various areas in ITC factories and hotels. The document covers,
- Natural ventilation
- Mechanical ventilation
o In non air- conditioned areas
o In air- conditioned areas
Cooling and heating of air is not covered in this document.
2.0 Brief on ventilation:
As per National Building Code 200165, ventilation is defined as the process of changing air in an
enclosed space. A proportion of the air in the enclosed space should be continuously withdrawn and
replaced by fresh air drawn from outside to maintain the required level of air purity. Ventilation is
required to control the following:
- Oxygen content: Prevent depletion of the oxygen content of the air;
- Carbon dioxide and moisture: To prevent undue accumulation;
- Contaminants: To prevent undue rise in concentration of body odors and other contaminants;
- Bacteria: To oxidize colonies of bacteria and fungus to prevent their proliferation;
- Heat: To remove body heat and heat dissipated by electrical or mechanical equipment or solar
heat gains.
Ventilation is broadly divided into two categories:
Natural ventilation: Supply of outside air into a building through windows or other openings due to
wind outside and convection effects arising from temperature or vapor pressure differences (or both)
between inside and outside of the building.
Mechanical ventilation: Supply of outside air either by positive ventilation * or by infiltration due to
reduction of pressure inside caused by exhaustion of air, or by a combination of positive ventilation
and exhaust of air.
3.0 Required ventilation rate:
3.1 Natural Ventilation:
Since it is difficult to measure the volume of air through natural ventilation as it varies from time to
time and depends on speed & direction of wind, estimation is done by a default method based on size
of ventilation openings. State Factories Rules stipulate that aggregated area of ventilation openings
*
Positive ventilation: The supply of outside air by means of a mechanical device, such as a fan.
Page 1 of 6
, Annexure 2.5 EHS Guidelines
Rev.76, 202517
(window, ventilators, etc.) should be more than 15% of the floor area of space/ portion of space
under consideration. (See illustrative example at figure 1)
Where,
O1, O2 , O3 & O4 - Areas of ventilation openings in m2.
A - Floor area in m2.
So, Aggregated area of ventilation openings
O = (O1 + O2 + O3 + O4) m2
O should be greater than 15% A
Figure 1 – Ventilation openings for natural ventilation
Spaces/ portions of spaces, to be naturally ventilated shall be permanently open to wall openings
directly to the outdoors. Where interior rooms or portions of rooms, without direct openings to the
outdoors are ventilated through adjoining rooms, the openings between rooms shall be permanently
unobstructed.
Inlet openings in the buildings should be well distributed and should be preferably located on the
windward side at a low level, and outlet openings should be located on the leeward side. (Inlet and
outlet openings at high levels may only clear the top air at that level without producing air movement
at the level of occupancy.)
As per ASHRAE Standard 62.1-202210 on ‘Ventilation and Acceptable Indoor Air
QualityVentilation for Acceptable Indoor Air Quality’, spaces or portion of spaces to be naturally
ventilated should be located within a distance based on the ceiling height (as explained below):
- Single side opening: For spaces with openings on one side of the space, the maximum distance
from the openings is 2H, where H is the ceiling height. (See illustrative example at figure 2)
- Double side opening: For spaces with openings on two opposite sides of the space, the
maximum distance from the openings is 5H, where H is the ceiling height. (See illustrative
example at figure 2)
For ceilings that are increasing in height as distance from the openings is increased, the ceiling
height shall be determined as the average height of the ceiling within 6 m from the openings.
Page 2 of 6
