Is the exposed commercial ductwork insulated?
I'm trying to understand the issues as to when and where ductwork needs to be insulated. It is my understanding that ductwork should be insulated even in conditioned space in a home. How does it work with the aesthetic round commercial metal ductwork that you see exposed in some buildings. Does that always have insulation inside it? If it doesn't always have insulation, can you help me understand in what situations it is not necessary?
It's usually insulated for 2 reasons:
1) To prevent heat loss/gain of the air inside (and make the system lose efficiency)
2) To prevent condensation
Any supply duct should be insulated. Return/make up/exhaust ducts are usually not, depending on their location. A return duct that runs in an "unconditioned" space should be. Insulation can be inside the duct, or outside.
I'd say that depends a lot on the area too...
Around here I'd venture to say that 90% of the exposed duct isn't insulated (square or round), and if it is, odds are only the 1st 10' of it is, and that's mostly done for sound.
Course, it's pretty dry around here, so condensation isn't usually a major issue in this situation
"If you call that hard work, a koalas life would look heroic."
I'd say Houston is pretty humid. But duct in the conditioned area does not have to be insulated. Joints sealed, yes. Unless the code has changed in the last year.