Ventilation Control
All occupied buildings require a supply of outdoor air.
Depending on outdoor conditions, the air may need to be heated or cooled before
it is distributed into the occupied space. As outdoor air is drawn into the
building, indoor air is exhausted or allowed to escape (passive relief), thus
removing air contaminants. The term “HVAC system” is used to refer to the
equipment that can provide heating, cooling, filtered outdoor air, and humidity
control to maintain comfort conditions in a building. HVAC systems range
in complexity from stand-alone units that serve individual rooms to large,
centrally controlled systems serving multiple zones in a building.
Some buildings use only natural ventilation or exhaust fans to
remove odors and contaminants. In these buildings, thermal discomfort and
unacceptable indoor air quality are particularly likely when occupants keep the
windows closed because of extreme hot or cold temperatures.
In order to exhaust air from the building, make-up air from
outdoors must be brought into the HVAC system to keep the building from being
run under negative pressure. This make-up air is typically drawn in at the
mixed air plenum as described earlier and distributed within the building. For
exhaust systems to function properly, the control air must have a clear path to
the area that is being exhausted. To prevent operating the building under
negative pressures (and limit the amount of unconditioned air brought into the
building by infiltration), the amount of make-up air drawn in at the air
handler should always be slighter greater than the total amount of relief air,
exhaust air, and air exfiltration through the building shell. Excess makeup air
is generally relieved at an exhaust or relief outlet in the HVAC system, especially
in air economizer systems. In addition to reducing the effects of unwanted
infiltration, designing and operating a building at slightly positive or
neutral pressures will reduce the rate of entry of soil gases when the systems
are operating.
The selection of a specific ventilator should be based on the
following factors:
- Job details such as the atmospheric hazard, the size of the confined space, etc
- Airflow required
- Airflow volume required at the end of the duct to control the hazards present; and Breeze to ensure worker comfort in the space.
- Duct friction loss to ensure adequate air volume reaches the end of the duct.
Aims of HVAC Control Systems:
- HVAC Control
Systems are used for the following benfits:
- Lower energy
cost.
- Lower
operations cost.
- Increase
flexibility.
- Ensure
quality building environment.
Esaplling Pvt. Ltd.
Email:enquiry@esaplling.com
Contact no:020-65366661
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