Attic Space Vs Plemum Space

The energy savings touted by unvented attics can be as high as 20.

Attic space vs plemum space. It will increase your load and contaminate your house air if it has been converted from a ventilated attic to a sealed attic. That space typically has about a 10 12 degree difference than the conditioned space below it. Rarely will a sealed foam insulated attic deviate more than 15 degrees from the living space temperatures below it. Space between the structural ceiling and the dropped ceiling or under a raised floor is typically considered plenum.

The velocity of the overall air movement within the two spaces would be substantially different at the same cfm. Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings. Plenum trusses create a reverse bulkhead in the center of the attic space where ducting can be housed in an insulated area. However if moisture is able to enter the unvented attic space it may lead to roofing panel issues.

A basement is below and an attic is above the main part of the house. I wonder if the nec definition of the word plenum would actually apply to the entire attic space. Compare that with the daily 140 degree temperatures found in vented attics. It s easy to see your point about eliminating ductwork from the attic.

However some drop ceiling designs create a. Think about the volume of space normally associated with return air ducts vs the volume of space involved in an attic space. Cabling between the many devices and to the users runs through this open floor space. A two room addition on the 1st floor has limited attic space and a 4 crawl space.

So when we have a choice we prefer hvac systems located under the house. This allows intensive cooling to be pumped through the space under the floor to cool the servers switches routers etc. That dead air space is designed to be a buffer between the roof. The plenum truss bulkhead adds only the amount of inside conditioned space required to house the ductwork by modifying the roof framing to create a boxed in area in the otherwise unconditioned attic.

A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems by providing pathways for either heated conditioned or return airflows usually at greater than atmospheric pressure.