A builder from CA, TX & AZ is developing its first community in Raleigh, NC. They are using open cell spray foam insulation in the crawl space, attic, and exterior walls. In addition, they are running a duct line to the the crawl and attic spaces and advertising them as positive pressure "condition spaces". The crawl space foundation block and walls are insulated, but the underside of the house floor is not (the earth floor is lined with 10 mil plastic, sealed to the foundation block). Also, there are no vents for air circulation. The attic is insulated completely with no vents as well. The builder states that this is the latest building practice. Is anyone familiar with this technique? I am concerned about whether the high humidity in the Southeast would eventually cause mold without the air circulation.
An HVAC technique they are using is to install a 3x3 solar panel grid on the roof in a way that allows air to flow under the panels, and enter the return line of the air handling unit. The top row of panels is actually only used to preheat the air before it enters the duct (via an intake fan to a "heat transfer" module built into the duct line). This preheated air is used to maintain the water temperature of the hot water tank and to supplement the heating of the forced air heat pump system. My concern here also is the growth of mold due to the higher humidity levels in the Southeast. Is there a comparison that can be made of this method between the southwest and southeast?