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Wood Shingles and Shakes

Trailblazing Solar Home Made of Composite ICFs

Cannon Beach, OR

Feb 17 2009 By Miriam Landman | 4 comments

General Specs and Team

Location: Cannon Beach, OR
Bedrooms: 2
Bathrooms: 2.5
Living Space : 2268 sqf

Completed: March 2005

Builder: Rich Elstrom, Elstrom Construction, Gearhart, OR
Architect: Nathan Good, AIA, Nathan Good Architect, Salem, OR
Interior designer: Georgia Erdenberger, IIDA, Czopek & Erdenberger, Portland, OR
Landscape architect: George Erdenberger, Portland, OR
Associate architect: Leonard Lodder, Studio 3 Architecture
Mechanical engineer: Gene Johnson, SOLARC Architecture and Engineering
Energy consultant: Charlie Stephens, Adjuvant Consulting
Monitoring consultant: Bob Rogers, Oregon Institute of Technology
Solar energy consultant: Doug Boleyn, Cascade Solar Consulting

Construction

Foundation: semi-conditioned shortened concrete-slab basement; composite ICFs (R-21, Durisol)
Walls: composite ICFs (R-25 above grade; R-21 below, Durisol); timber framing at exposed framed openings
Roof: 2x14, 16 in. o.c.; between curving steel beams, two 1/2-in. layers of CDX plywood; triple-layer roof membrane; drainage mat; 4-in lightweight soil; 3-in. closed-cell spray foam insulation under roof deck; remaining roof cavity filled with formaldehyde-free fiberglass (R-58)
Windows: double-pane, low-E2, argon-filled wood frame(U-factor = <0.32; SHGC = 0.41)

Energy

Heating/cooling: Hydronic forced-air heat (evacuated-tube solar thermal collectors, two 120-gallon water storage tanks with 4500-W electric heat element, GSHP, ERV; no cooling system needed
HERS score: 94 (old scoring method)
Blower door test: 0.23 air changes per hour at 50 Pascals
Duct-blaster test: 80 cft. per minute at 25 Pascals
Annual energy use: 13.3MMBtu

  • Net use: 3,900 kWh
  • Gross use: 8,900 kWh
  • PV-generated: 5,000 kWh
  • Note: This estimate has not been revised since the new air handler was installed, so the actual energy usage could now be less.

    Photovoltaic: 5.9 kW STC DC grid-tied, roof-mounted system made up of 36 165-Watt modules and two 2,500 W inverters.
    Cost: approx. $29,000 State of Oregon tax incentives provided 55% savings on the total cost of the system; combined with incentives from the Energy Trust of Oregon, the payback period for the system was reduced from 28 years to less than 10 years

    • Multizone energy-recovery ventilation (ERV) system with in-line hydronic coils for supply air heating (subsequently replaced with a single air handler)
    • Passive solar heating; majority of interior receives functional daylighting; clerestory windows and light shelves used
    • Thermal mass moderates heating and cooling
    • Operable windows provide cooling and ventilation throughout
    • Roof overhangs for strategic shading
    • High-performance building envelope
    • CFL
    • Building automation control system

    Water Efficiency

    • On-demand circulator for instant hot water
    • Low-flow toilets and plumbing fixtures
    • Efficient, dual-drawer dishwasher
    • Native plants used in landscaping; no irrigation system required
    • Small bioswale to filter stormwater

    Indoor Air Quality

    • Window and interior layout facilitates natural ventilation
    • Multizone ERV system
    • Interior materials are zero-VOC and urea-formaldehyde-free
    • Rumford fireplace with glass doors and outside air source
    • Vapor-permeable exterior walls with external rainscreen

    Green Materials and Resource Efficiency

    • Pervious paving
    • Living (vegetated) roof
    • FSC-certified wood used throughout, including ICFs, framing, siding, exterior trim, and cabinetry
    • ICFs made of cement and wood fibers, lined with mineral wool insulation
    • Wind-fallen trees used for interior heavy-timber framing, flooring, and stairway
    • Doors made from reclaimed sinker logs
    • Windows made from sustainably harvested cedar
    • Structural steel beams and rebar of 90-100% recycled content
    • Foundation of 25% fly ash concrete; 35% fly ash concrete in ICFs
    • Recycled-content (windshields) tiles and beach pebbles used as bathroom tiles; locally salvaged bathtub
    • PVC-free materials (except for the underground electrical sleeves, electric wiring sleeves, and PVC in some appliances)
    • 95% of construction waste was diverted from landfill; wood waste was ground for boiler fuel; plastering backer board scrap was ground up and used as a soil amendment

    Certification

    Earth Advantage: platinum

    Efficient and durable coastal home blends site-sensitive design, traditional materials, and high-tech systems

    Lessons Learned

    The keys to this project’s successes were its integrated designBuilding design in which different components of design, such as the building envelope, window placement and glazings, and mechanical systems are considered together. High-performance buildings and renovations can be created cost-effectively using integrated design, since higher costs one place can often be paid for through savings elsewhere, for example by improving the performance of the building envelope, the heating and cooling systems can be downsized, or even eliminated. process and its post-occupancy evaluations and corrections. In order to familiarize all team members with the goals of the project and the use of new and unfamiliar equipment and systems, the team had many meetings before and during design and construction. The team included the architect, owners, interior designer, landscape architect, energy consultant, and contractor. They conducted five half-day eco-charrettes (brainstorming sessions on ideas for efficient use of energy and resources in a new building), which also included various content experts and neighbors.

    “Involving the contractor early in the design process was paramount,” Nathan Good notes. “His contribution to conducting abbreviated life-cycle cost assessments was critical to the selection of building systems and materials.” Nathan stresses that the support and involvement of the local building official was also critical to the success of the project: “Pre-design meetings with the building official paved the way for a number of local pioneering features, including the vegetative roof, the ICFs, the ERV(ERV). The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV. system, and the unvented and moderately conditioned ‘short basement.’”

    Simple is often best
    Charlie Stephens says that one of the main lessons learned from this project is, “Complexity breeds problems.” For example, “monitoring initially allowed us to spot a number of system problems, [but] a residential project doesn’t enjoy the continued technical support that a commercial building project does, so problems go undiagnosed, and the control functions ultimately failed to provide a reliable system for the owners.” The team ended up largely separating the monitoring and control functions to improve reliability and reduce overall energy consumption.

    The air-handling side of the HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. system has also been dramatically simplified. Charlie says, “While one can indeed use a properly controllable ERVEnergy-recovery ventilator. The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV. or HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. as an air handler, there are drawbacks. They impose a heating loadRate at which heat must be added to a space to maintain a desired temperature. See cooling load. due to efficiency well under 100% whenever they’re running as a space-heating air handler, and three of them use a lot more power than a single, larger one would. There were no larger ones with the necessary control features at the time, but a single, variable-speed air handler with an interlocked or built-in HRV would do the job better.” The owners have in fact had a new, simpler air handler installed to replace the ERVs.

    Charlie says that more fully packaged heat pump—based systems (mostly air-to-water) are now available in Europe and should soon be adapted for the U.S. market. “Building net-zero-energy homes will be a lot easier when we have more packaged systems to use,” Charlie says, “but, as always, attention to the shell first!”

    Energy equipment decisions can be tricky
    Another lesson, Charlie notes, was “the solar-thermal system isn’t contributing much when you really need it: during the winter, when there’s hardly any sun on the Oregon coast,” so it’s not particularly cost-effective in this case. He reports that the roof PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. system has operated well overall, though its output might be slightly compromised by salt spray from the ocean air.

    After a year of collecting data, the design team was unsatisfied with the performance of the geothermal heat pump. Components were replaced based on their findings, but the system still doesn’t appear to work as efficiently as anticipated.

    The home continues to be monitored and evaluated as part of the owners’ quest to get as near as possible to achieving a net-zero-energy home. It's clear that the location makes this a challenging goal, but each adjustment they make brings them a little bit closer.


    —Miriam Landman is a freelance writer and green building consultant in Marin County, Calif.

    Tags: , , , , , , , , , , , , , ,

    Image Credits:

    1. Dan Morrison/Fine Homebuilding
    2. Nathan Good
    3. Toshi Woudenberg

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