Choose carefully when indicating if those leaky ducts are in conditioned or unconditioned space.
If the duct work is located in an intentionally conditioned space, the modeling will not show an improvement for sealing the duct work. If conditioned air is leaking into a conditioned space, it is not considered a loss of conditioned air.
An intentionally conditioned space is an open space that is conditioned by intentionally putting a register or a vent or heating/cooling supply into that room or open space. Or if the room is open to the rest of the house where the ducts are supplying it (no door to the basement, for example) that is considered an "intentionally conditioned" space.
A "conditioned" crawlspace that is sealed and insulated, is not "intentionally conditioned" meaning that it does not have a heat register or vent to heat the crawl space.
If the home is losing conditioned air from the ducts, the location is usually an Unconditioned Space. See the drop down menu for a selection and types of spaces.
References:
Building America / NREL -
Better Duct Systems for Home Heating and Cooling
Energy.gov -
Tips: Air Ducts
