The envelope design is based on continuity of the insulation layer and air barrier from footing to eave to ridge to eave to footing. Great effort was made to eliminate thermal bridging. For instance, all roof overhangs (used to harvest rainwater) are independently framed outboard of the insulation layer and air barrier. The actual R-value is not remarkable - R39 - but the designers believe continuity makes up for that. For instance, our recent blower door test shows an extremely tight building meeting Passive House standards.
4-inches of expanded polystyrene, continuous under slab, and around foundation wall
Slab edge assembly
Slab edge is isolated from grade our out door air by 4 inches of expanded polystyrene insulation.
Slab edge R-value
Foundation wall assembly
Conventional poured in place concrete foundation wall wrapped with 4 inches of expanded polystyrene insulation.
Foundation wall R-value
Above grade wall assembly
siding over plywood sheathing, over 6 inches polyisocyanurate insulation (2 layers of 3 inch, joints staggered), over air and vapor barrier, over 3/8 inch plywood sheathing, over 1.25 inches tongue and groove sheathing
Above grade wall R-value
Flat attic assembly
Flat attic R-value
Cathedral ceiling assembly
roofing over plywood sheathing, over 6 inches polyisocyanurate insulation (2 layers of 3 inch, joints staggered), over air and vapor barrier, over 3/8 inch plywood sheathing, over 1.25 inches tongue and groove sheathing
Cathedral ceiling R-value
See cathedral ceiling assembly.
Windows and Doors
Alpen 725 Series WIndows
Hollow metal door with polyurethane core. Ceco Door, Assa Abloy 1-3/4" Trio-E Door.