When a new building smells moldy, the owner's first phone call is often to the building's HVAC designer. To most people, moldy odors suggest HVAC problems. But while the air system may indeed spread fungal odors, the HVAC system in new buildings is seldom responsible for generating them. In new construction, mold infestations usually are caused by moisture in building materials. That moisture can come from rain or snow before the building is closed in, or from leaking water pipes, wet concrete or condensation on surfaces like cold floor slabs during springtime.