Provide Effective
Ventilation Air Distribution
Introduce ventilation
air supplies, with a high proportion of outdoor air, directly to
the occupied volumes of spaces, and place return air intakes as
high in the spaces as possible. This has several advantages:
- Occupants
breathe cleaner air.
- Smaller supply
air quantities reduce energy consumption.
This strategy,
known as “displacement ventilation”, can use conventional
supply registers located low in the occupied zone, or supply air
distributed via a raised floor plenum. To ensure comfort and avoid
drafts, the cool supply air must be carefully distributed with low
velocities, and supply grilles provided with volume controllers
for use by occupants. Return air temperatures are typically higher,
due to lower supply air volumes.
Another method
of concentrating fresh supply air in the occupied zone is the use
of “personal environmental modules” at each workstation.
Typically used only for offices, these have a small supply register
in a desktop module complete with a lamp. Airflow is controlled
by each user, and the registers are connected to a plenum or ductwork
located below a raised floor.
Cautions
- Careful placement
and selection of supply air diffusers and temperatures is critical
to ensure comfort.
- Provision
must be made to periodically clean raised-floor supply air plenums,
considering that the plenum is also used for wire and cables.
