Buildings don’t work they way they used to.1 Folks are always
saying stuff like this. But let me make the case regarding just
one factor and you decide. There are other factors of course,
but I want to focus on only one for the moment. This one over-
arching factor is the amount of energy exchange across the
building enclosure. I think that higher levels of thermal
resistance and reduced heat gain across building enclosures has
forever changed the performance of buildings—and not necessarily
in a good way. And things are going to get worse before they get
better. Sound familiar? The lens I am going to use to look at
this factor is moisture. Why? It is one of the principal damage
functions acting on materials along with heat and ultra-violet
radiation.2 I think moisture is the key to understanding the
performance of buildings in general—and in this particular
case—in specific. The consequence of this reduced energy
exchange is beginning to be seen all over the place: mold, part
load humidity problems, rot, and