Plenum Roof Load

The following formula shows how heat loss from plenum through floor above being calculated in revit.

Plenum roof load.

Considers any operating schedule for hvac equipment from 1 hour to 24 hours in duration. These heat sources may be radiant and convective loads from lighting and transformers. Do such loads plenums get directed straight back to the central air. Plenum curb will convert a dedicated down discharge roof top unit into a plenum curb.

Space between the structural ceiling and the dropped ceiling or under a raised floor is typically considered plenum. Supply and or return plenums with field cut openings in roof curb floor. Or duct and piping systems within the plenum. Unlike a traditional ducted return the plenum may have multiple heat sources in the path.

Roofs are under a lot of pressure. The space above a ceiling when used as a return air path is a ceiling return air plenum. How this roof conduction load reduction effected in the conditioned space. However some drop ceiling designs create a tight seal that does not allow for airflow and therefore may not be considered a plenum air handling space.

Where and the difference between them approximately is zero so q2 is zero which is the heat loss from plenum through floor above btu h which can be translated to loads so the roof load will be zero. Conduction loads from adjacent walls roofs or glazing. The roof construction by using reflective surfaces there was no change in supply flow i think this was because of no reduction in load in the ls c report. Pre fabricated plenum roof curbs are available in the following.

Here is a little product knowledge on roof curbs. Load limits on the roof of a building.