denim insulation

Energy Comes from the Sun, Wind, and Earth in This Vermont LEED Platinum Home

Charlotte, VT

Mar 23 2009 By Jesa Damora | 17 comments

General Specs and Team

Location: Charlotte, VT
Bedrooms: 4
Bathrooms: 3
Living Space : 2700 sqf
Cost (USD/sq. ft.): $196/sqf

Cost does not include septic and well
Completed: August 2007

Architect: David Pill, Pill–Maharam Architects
Builder/contractor: Jim Huntington, New England House Wrights
Energy consultant: Andy Shapiro, Energy Balance, Inc.

Construction

Foundation: 4-in. concrete slab over 4-in. EPS foam on gravel (R-16); poured 8-in. concrete walls lined with 2-in. EPS; 2x4 studs at 24-in. o.c. filled with dense-packed cellulose contained by reinforced netting (R-21 total)
Floors: I-joists at 24-in. o.c.; OSB subfloor, then 4-in. poured concrete floor, ground and polished, enclosing radiant heating system (denim batting under first floor radiant slab, R-21)
Walls: 2x6 studs at 24-in. o.c. insulated to full depth with closed-cell polyurethane spray foam; 1-in. polyisocyanurate foam board over exterior sheathing; house wrap; cedar breather mesh; painted cedar clapboard/corrugated metal exterior cladding (R-40)
Windows: triple-glazed fiberglass (U-value, .17; R-15 to R-17, Thermotech)
Roof: 2x10 rafters at 24-in o.c. filled to 9 in. with closed-cell polyurethane spray foam (R-58); 3/4-in. OSB sheathing; waterproof membrane; standing seam metal roof (Engler)

Energy

Heating/cooling: GSHP (Econoair) with variable-speed drive (Hitachi) connected to well
Water heating: same as above plus 100-gallon storage tank (Marathon)
HERS index: 0
Annual energy use: 0 MMBtu/year Energy production and use from January 9, 2008, to January 9, 2009:

  • Total electricity usage: 6,094 kWh
  • Total produced by wind turbine: 6,286 kWh
  • Net electrical gain: 192 kWh

  • Building envelope sealed to NACH .08 for heating 600 cfm @ 50 Pascals
  • Fluorescent lighting throughout
  • Open plan oriented for daylighting and maximum solar gain in winter
  • Highest-rated Energy Star appliances
  • GFX waste hot water heat recovery

Water Efficiency

  • Low-flow plumbing fixtures

Indoor Air Quality

  • Low-/no-VOC paints, finishes, and most adhesives
  • Natural materials

Green Materials and Resource Efficiency

  • Most of existing 14,000-square-foot riding arena building relocated and reused locally
  • Created access to community open space and trails
  • Innovative septic system by Presby Enviroseptic: filtration tubing contains coarse fabric with ridges and perforations laid out over leaching field
  • FSC-certified decking (Cumaru)
  • Most materials locally sourced
  • Reclaimed fir columns
  • Recycled materials (denim) in insulation
  • Certification

    LEED for Homes: platinum (90 points)
    Energy Star score: 5+ stars

    Multiple renewable-energy sources help a Vermont home built with more or less conventional methods reach net-zero-energy use

    To build a house with no carbon emissions and zero-net-energy use, the owners of this rural home in Vermont employed a strategy embracing alternative energy sources, unusually high insulation values, and conscientious fabrication.

    Lessons Learned

    David wanted to push the economy of building the structure, so they used two-stud corners (with nailers), minimal framing for window headers, and a two-foot module for all dimensions. He thought of using a single plate and skipping the exterior sheathing, using lateral bracing instead, But Jim advised strongly against these last two, even though they are increasingly recognized as advanced framing techniques. David’s glad he listened, as winds can plow down the valley with vigor.
    Because the owners went for all the bells and whistles in the GSHP assembly, installation took a lot of time, as did programming the drive that manages it. They’ll probably never use the extra lines in the radiant heat manifold that stub to the second floor — the house stays comfy from what’s in the first floor slab alone. They'll also never use the blocking in the walls for brises-soleil — it stays cool without it.

    Heating system choices offer challenges and opportunites
    They also want prospective alternative energy users to carefully assess the apparent cost of new technologies in context: For instance, “If you already have a well you can use [for the GSHP] and are already doing a radiant floor, the cost of it might be not much more than a standard boiler," David advises. "The benefit of a boiler is that you can put in relatively inexpensive baseboard, which itself is less costly than radiant.”

    These trade-offs can get complex because the sizing of the heating system also depends on how tightly the house is sealed, among many other things. Can a non-architect manage all this? “Yes,” says David, ”but they’ll need the help of experts.” He adds, “It can be a fun learning experience.”


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    Image Credits:

    1. Jim Westphalen
    2. David Pill
    3. Toshi Woudenberg

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