Venting and pressure in encapsulated crawl space
I'm considering the purchase of a renovated house with an encapsulated crawl space. The HVAC system is brand new, sealed ducts running in the crawl to the single story above. The furnace has PVC intake "snorkel" pipe and high efficiency PVC out vent. My question is how to create ventilation for getting rid of any buildup of any future odors and/or radon buildup, since studies indicate the logical buildup of radon in encapsulations.
Is it better to provide positive ventilation by adding a fresh air supply duct or two to the crawl (900 sf area) or is it better to install a Bdry style exhaust vent that gets its air from the upstairs through a passive vent in the door?
Positive may suck air from under the door that provides access via stairs leading to the kitchen (has a partial basement/cellar space). Negative pressure may suck conditioned air from the living space and result in higher utilities. Seems like an issue here since radon is probable, and so are recalcitrant odors over the years.
Ongoing debate perhaps, but I'd tend to favor the positive feed of air from the system and allow some of it to push under the access door into the house since it would be "fresher" than not doing it.