My normal territory is in Northern California, where it's hot and dry. Recently, however, I helped with an evaluation in the tropics, where the temperature was regularly in the mid-80s, as was the relative humidity. It was their winter. One of the chief goals is to reduce electrical usage, which in turn means reducing the use of air conditioning. Much of the load on the AC is to remove moisture, so it strikes me that one strategy is to limit moisture intrusion.
But how do you determine how the moisture is entering? Let's assume:
1. We've performed blower door tests and know how much air leakage there is.
2. There is no bulk water to deal with.
3. Wherever possible, capillary breaks have been added.
One of the buildings I looked at is two story, slab-on-grade (with no moisture barrier and a high water table); walls are styrofoam blocks with concrete cores (essentially like our ICFs) and stucco cladding (no rain screen). How do we determine what percentage of the moisture is due to infiltration; due to diffusion through the walls; diffusion through the slab?
And a follow-up question: if we were to treat the slab to block diffusion through the floor, would that increase the rate of diffusion in inaccessible areas, i.e. beneath the sole plates of the walls (several of the other buildings are slab-on-grade with wood frame construction)?
Thanks. I look forward to hearing how you would go about analyzing this.