I just left a very disheartening situation where a homeowner has faithfully sought the advice of "putative professionals" to solve her problem with high bills and overwhelming discomfort. I say putative because in every case, the "professional" who visited her home seemed more intent on selling their product and/or service than diagnosing and solving her problems.
The list is voluminous from a meaningless blower door test, foam encapsulated attic where an 80% gas furnace resides, closed crawl space, new Pella windows, air sealing including plugging the combustion air supply in two furnace closets adding insulation and air barrier via foam board on the back of knee walls as well as increasing the insulation levels on the floor of the attic. Yes, the attic is also encapsulated with foam. Supposedly the bills went up and their comfort has suffered.
After seeing that no adults seemed to be present during sales pitches, I simply told the homeowner that someone needed to call a time out on the "let's try this" plan and put some diagnostic scholarship in its place.
Contrary to the implication of events, the homeowner is extremely intelligent, which I absolutely love. I just think she trusted to wrong people.
One issue I am trying to get my head around that I know will require explanation is why the attic is still substantially hotter in the summer than they expected. To review, spray foam was applied to the underside of the roof deck at about R-19. BUT they left the R-19 or so of rock wool on the attic floor. After feeling they weren't getting the full benefit of the spray foam, the owner took the advice of another insulation contractor who installed even more insulation on the attic floor using R-19 fiberglass batts.
I realize the attic space temp is now going to be somewhere between the outdoor and indoor temperatures (Plus a few degrees for radiant) ---- with the % of R-value determining which side of 50/50 it will fall. And to be honest, I am not really interested in explaining energy balance equations. Moreover, I don't want to measure the roof surface area to do them.
I dont see this set up being a determinitve energy penalty. But it does present the perception that the foam ain't working. Then I had a second thought. Since the attic will be hotter in the summer, how are duct loads affected? I am musing its a moot point. But at this stage, I am throwing the question to you folks because I am too lazy to think about. it.