Question-and-Answer Resource for the Building Energy Modeling Community
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The Gowri approach (PNNL) is a wind only model and so clearly suspect especially in colder climates where stack effect is important. NIST has published an approach, AN IMPROVED METHOD OF MODELING INFILTRATION IN COMMERCIAL BUILDING ENERGY MODELS by Ng et. al. that purports to improve assuming E+ defaults and on the Gowri approach. It looks interesting but their method 2 which would be the practical way to implement the method is not totally convincing. I was looking for conversation on this approach and found this thread.
One issue with pressurization and infiltration reduction is that the pressure differential at the floor, when the building is warmer, is what matters. If the floor pressure is zero on all four sides of the building then infiltration is indeed zero. Substantial pressurization air can be added to a building without reaching this condition. In residential buildings, zero infiltration was found to occur only after fan flows were twice the infiltration flow that would occur without the fan. http://aceee.org/files/proceedings/1992/data/papers/SS92_Panel2_Paper25.pdf
