- Project plans
- Project activities
- Legislation and standards
- Industry context
- Specialist wikis
Last edited 25 Sep 2020
Plenum ventilation in buildings
Plenums are air compartments or chambers that are sometimes found in buildings, either above suspended ceilings, in the gap between the ceiling and the floor slab, or below raised floors in the gap between the raised floor and the floor slab. They form part of the ventilation system for the building.
They may be supply or return plenum, and may serve either an entire building, or a specific zone in a building. Supply plenum supply ventilation air to the occupied space, whilst return air is generally extracted through ductwork. Conversely, in return plenum the air is generally ducted to the space, whilst the return air is extracted through the plenum.
Underfloor air distribution (UFAD) uses the underfloor plenum beneath a raised floor to provide ventilation air through floor diffusers directly to the occupied zone. The air spreads across the floor forming a reservoir of fresh, cool air. Any sources of heat (such as people or computers) generate a thermal plume lifting contaminated air to high level where it can be removed from the space. See Underfloor air distribution for more information.
Plenum can give good flexibility for the layout of buildings. However, they can provide a space within which fire can spread, particularly because of the air supply they offer, and so they may be required to include fire and smoke detection, and potentially combustible material (such as cables) may be controlled. They can also create a pathway for the transmission of sound between separate spaces.
 Find out more
 Related articles on Designing Buildings Wiki
- Active thermal mass.
- Air handling unit.
- Chilled beam.
- CIBSE Case Study Olympic Velodrome.
- CIBSE Case Study Ortus Learning and Events Centre.
- Ground preconditioning of supply air.
- Herringbone strut.
- Floating floor.
- Floor plenum airtightness.
- Mechanical ventilation.
- Night time purging.
- Raised floor.
- Sprung floor.
- Suspended ceiling.
- Thermal labyrinth.
- Thermal mass.
- Underfloor air distribution
Featured articles and news
Two new research reports published by APM.
50% off APM Associate membership for Designing Buildings users.
A commentary from the insurance perspective.
In brief with further links.
A definitive book on a pioneer of green architecture.
Using heritage as a catalyst for reviving historic centres.
Declaration prioritising sustainable urbanisation adopted.
Some brief words about the actuator.
After 34 years at the Institute.
To support the next generation of engineers.
CIAT reporting from the Competition and Markets Authority.
Making sustainable construction number one priority.
Interview with ECA CEO.
Many provisions came into force on June 28, 2022.
With room to expand.
Refurbishment, Energy Efficiency, Indoor air and process.
Why building acoustic considerations must be non-negotiable.
Aluminium Composite Panels (ACP) is one example.
Inventors and innovators at ICE.
Life, death and art at the Stuart court. Book review.
Real estate, place adaptation and innovation.
Review and comment on the revised draft before July 11.
Write about something you know, help us build and grow !
A blended event and triumphant return.
Mark Reynolds succeeds Andy Mitchell as Co-Chair of CLC