Page 26 - Green Builder Magazine Sept-Oct 2021

Key Features

WALLS: Double wall, R-44 total: 2-by-4 stud
24-inch on center (o.c.), 1/2-inch gap, 2-by-6
stud 24-inch o.c., 7.5-inch blown fiberglass, 2-inch
closed-cell spray foam, 1/2-half coated OSB
sheathing, 1-inch EPS foam under stucco,
3/8-inch rainscreen behind stone and wood siding.

ROOF: Shed truss roof: 3/4-inch roof sheathing,
standing seam metal roof, 24-inch raised heel.

ATTIC: Vented: 23-inch R-70 fiberglass; Vaulted:
R-70 fiberglass; 8-inch closed-cell spray foam
and R-19 batt.

FOUNDATION: Unvented crawlspace: 8-inch
poured-in-place concrete, 2-inch EPS on interior and
on exterior, liquid-applied crystalline waterproofing.

WINDOWS: Triple-pane, low-e2, aluminum-clad
wood casement frames, U=0.19, SHGC=0.50;
automated interior motorized blinds.

AIR SEALING: 1.25 ACH 50; all foam-sealed top
plate, wall and floor penetrations.
Hot property. Radiant floor heat and a highly
VENTILATION: HRV ducted to each room; insulated, draft-free building envelope keep
switch-activated boost mode; 12 MERV filter. the owners wrapped in warmth throughout
the Colorado winters.
HVAC: Radiant floor heat from a 95 AFUE boiler; COURTESY OF MANTELL-HECATHORN BUILDERS AND MARONA PHOTOGRAPHY
16 SEER AC.

HOT WATER: Combi uses HVAC boiler to heat
50-gallon tank, 0.88 energy factor; cross-linked system is included, the HERS score drops coated oriented strand board (OSB) prod-
polyethylene (PEX) piping; recirculating pump. to 14, and projected annual energy costs uct that is topped with one inch of EPS
are cut by more than two-thirds—to $595 rigid foam under portions of the house.
LIGHTING: 100 percent LED; lighting controls; per year, or almost $50 every month. Even Stucco and a 3/8-inch rainscreen run
automated window blinds; daylighting. without the PV, the annual energy costs behind stone and wood siding.
are expected to be $1,980, a savings of The vented attic has 23 inches (R-60)
APPLIANCES: ENERGY STAR dishwasher, more than $1,000 per year compared to of blown fiberglass. Over the living room,
clothes washer and refrigerator. a home built to the 2015 International the vaulted ceiling trusses are filled with
Energy Conservation Code (IECC). 8 inches of closed-cell spray foam, plus
SOLAR: 7.3 kW; 24 305-W rooftop panels; R-19 fiberglass batts for an R-value of
central inverter. TOOLS OF POWER R-70. The foundation is an unvented
PERFORMANCE crawlspace, insulated on the interior and
WATER CONSERVATION: EPA WaterSense The home has double walls consisting exterior with 2 inches of EPS.
fixtures and toilets; drought-resistant landscaping. of an interior 2-by-4, 24-inch on-center Mantell-Hecathorn used expanding
stud-framed wall, a half-inch gap, and a foam to seal every penetration through the
ENERGY MANAGEMENT SYSTEM: Smart 2-by-6, 24-inch on-center stud framed floors, walls, and top and bottom plates.
thermostats; cell to lighting; windows; security wall. These two walls form a 9.5-inch deep The builder used tape on any stacked
equipment; sound; HVAC. cavity that is insulated with 2 inches of studs to seal the gap between the studs. He
closed-cell spray foam plus 7.5 inches of also used tape along the top plate on the
OTHER: Electric vehicle charging; accessibility blown fiberglass, then wrapped in another outside from the top of the wall sheath-
features; reclaimed redwood; no- or low-VOC inch of rigid expanded polystyrene (EPS) ing to the top plate. Fire-rated can covers
formaldehyde cabinets, sheathing, floor finishes, foam beneath the stucco, stone and wood were installed over every can light, and
mastics, paints, caulks and carpet. siding. The walls are sheathed with a spray foamed to air seal around them to

24 GREEN BUILDER September/October 2021 www.greenbuildermedia.com