Email #83 - Plenum of Mysteries Solved

Lots of you came forward to answer my stupid questions posed in the previous email #82:  "Plenum of Mysteries Up in the Attic," including Joel Loveland, Dean Heerwagen and Doug Zuberbuhler.

But first, the "windows" seen in the upper part of the attached photo are similar to the ones seen from inside the attic in the previous email.

However, these openings are for ventilating air, not for lighting the attic. Doug Zuberbuhler notes that they will be fitted with return air grills (500 cfm)  to exhaust air from the studios, passively.  That air will join the air rising from the breather walls, and together they will exit the building via the plenum to the cupola.

Concerning the horizontal HVAC ducts shown in the previous email #82, Dean Heerwagen says that these are part of the mechanical air ventilation of the first floor classroom, where there wasn't enough room for the ducts in the ceilings. So they ran them up to the attic, then down again.

John Stamets
March 25, 2007

See also #82