Folks - I'm a total rookie on the topic so all thoughts are welcome. Please specify if your recommendations would be cost neutral or significant upfront investments. Also, if you think I'm wasting funds on part of the design - don't hesitate to say so.

SETUP: We are using a GC in Cincinnati to build a 4500sq ft home. It will be 2x6 construction with advanced framing techniques and brick veneer. This is a 20 year home, and my goal is the make wise investments that will pay off with monthly savings on energy bills. Also, we've lived in drafty homes (old and new) and want a tight, warm and healthy home.

I'm driving the thermal envelope specs with little help which I guess is common. From my reading, I've learned that while true R value is critical, air leaks are often the real enemy. But then better R and tighter homes require greater moisture/vapor strategies (colder sheathing). And I have 'mastered' the difference between air, water, and vapor barriers (thanks to Dana1!)

Also - we plan to do a blower test pre insulation to tighten up leaks prior to insulating.

With that in mind, here's the solution:

BASEMENT (Finished (900sq ft): continuous 1" XPS interior with a thermal break between walls and foundation (R5 with thermal break); fill 2x4 studs with batts or cellulose; mold and moisture resistant drywall. Nothing on the floor.

BASEMENT (Unfinished): unsure

RIM JOISTS: o.c. foam (block air flow)

1st and 2nd FLOOR WALLS: Zip system (Air barrier) with good permeance - dense pack cellulose (good moisture properties and R20 in the cavities) - no plans to stagger the studs with 2x4s or an exterior thermal bridge; builder is concerned about the wall width, and I'm concerned with cost

ATTIC: Zip system for the roof and 6" of oc foam with a vapor retarder applied in the ceiling joists (R 22, but tight) - this will make for a semi-conditioned space for some ductwork. I also like pulling the thermal load off of the ceilings of the bedrooms on the second floor.

HVAC: It may be possible to go to one HVAC system with two zones (or three) with the house being fairly tight (with an HRV). In this case, I could insulate the attic floor instead with no ducts in the attic.

Thanks and look forward to all feedback.

On the brick veneer/2x6 A-F walls you'll still need some vapor retarder between the brick and the ZIP sheathing on the 2x6 or that cellulose could take up a lot of water from exterior moisture drives, particularly on sun-exposed surfaces. But without foam to the exterior of the sheathing a class-II or stronger interior vapor retarder would be necessary to keep the sheathing from loading up with moisture in the winter, so it a setup for building in a moisture trap.

Putting 1" XPS on the exterior of the ZIP, facing the cavity to the masonry would slow it down, but 1" foil-faced iso would block it completely. Cincinnatti is on the edge between zone 5 & zone 4, and 1" of either XPS iso would be sufficient exterior-R to prevent wintertime moisture accumulation in the sheathing, removing any need for an interior vapor retarders other than plain-vanilla grades of latex paint. It does mean longer masonry ties though, which is an added expense.

If the extra inch makes the wall too thick to fit on the foundation, note that standard-framing 2x4 16" o.c. cellulose-filled walls with 1" of exterior iso runs about R16- which is slightly better than the R15 whole-wall performance of a 2x6 AF cellulose wall with no exterior foam that you've sketched in. (At the same thickness of a 2x6 wall, 2" of exterior iso over standard 2x4 construction, for an R22 whole wall, but the the masonry tie issue may complicate it.)

Below grade with approach using 1" XPS + R13 batts you'll also have about R15, but the heat loss per square foot would be less than that of the above-grade walls.

You get better bang for buck framing out the upper floor a foot or so taller to be able to bring all ducts and electrical runs inside of conditioned utility-chase above the gypsum ceiling, with an OSB attic floor above detailed as an air barrier to support R50+ cellulose, with vented attic rather than a sub-code-min R22 foamed rafter job. (R30 min is required for cathedralized ceilings in OH, R38 if attic-floor.) The added cost to the framing & attic floor but with cheaper (yet 2x deeper) insulation could be about a wash, but the thermal performance would be 2x better.

See: http://www.greenbuildingadvisor.com/blogs/dept/musings/service-cavities-wiring-and-plumbing

Thanks - a few follow-up questions - if we go to one HVAC for the whole house the ducts and returns would all run from the basement up and take the attic out of play. I would assume you would support this idea, but any thoughts on one system with 2 or 3 zones for a house of this size? With a tight house, it seems doable.

Any thoughts on using cellulose or batts in the basement finished space, and what would you recommend for the unfinished space of the basement? Most insulators want to run 4ft of thermax down the wall and that's it.

I am really intrigued by the 2x4 with 2" of XPS. Just to confirm, I would keep the rim and top plates at 6" and studs drop to 4". The ZIP would attach to the studs and the XPS on top of the studs for an effective 2x6 will. Jambs stay the same.

Two questions: Any thoughts on cost for that much XPS (2 stories, 2000 ft on each floor)?

Also, the floors are 10 ft for the first and 9 ft for the second. Is 2x4 ok for the 10ft first structurally?

For insulation deals look to http://www.insulationdepot.com/ or http://www.insulationfactoryseconds.com/. Besides those places Menards has pretty good pricing on about all building materials.