GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Audio Play Icon Headphones Icon Plus Icon Minus Icon Check Icon Print Icon Picture icon Single Arrow Icon Double Arrow Icon Hamburger Icon TV Icon Close Icon Sorted Hamburger/Search Icon
Green Homes

Trailblazing Solar Home Made of Composite ICFs

DESIGNING AROUND THE SUN. Mounting the evacuated-tube hot-water collectors on the hillside instead of the roof gave more freedom to angle them precisely for the best sun exposure. The roof over the southern patio was matched to the angle of the sun as well: in summer it blocks unwanted solar gain but in winter lets the sun's rays directly warm the home.
Image Credit: Dan Morrison/Fine Homebuilding
View Gallery 9 images
WORKING WITH NATURE. Mature conifers shield the house year-round from the strong coastal winds. The wildflower-filled living roof absorbs stormwater and could help avert damage from forest fires. Sustainably harvested, FSC-certified cedar siding and trim, sourced for this project by The Audubon Society, holds up well against the elements too.
Image Credit: Nathan Good
**Beautiful inside and out** Fortunately, orienting the house for good sun exposure also aligned it with the striking coastline to the south. With all of the rooms flanking this central great room, every corner of the home enjoys excellent views. The above clerestory windows bring light all the way to the kitchen on the north side of the house in addition to augmenting the views. Even without the views, the broad selection of warm, natural materials creates a beautiful indoor environment.
Image Credit: Dan Morrison/Fine Homebuilding
FSC-CERTIFIED WOOD was used throughout the interior of the home. Some of the larger structural pieces were taken from windfallen trees. The homeowners and designers all felt that environmental responsibility, durability, and healthfulness were important requirements when choosing materials.
Image Credit: Dan Morrison/Fine Homebuilding
PV PANELS MAKE MORE THAN 50% OF THIS HOME'S POWER, a respectable percentage in this frequently cloudy environment. The 5.9kW grid-tied system consists of 36 individual modules. The varying angles of the panels allow each third of the array to get direct sun at different times of the day.
Image Credit: Dan Morrison/Fine Homebuilding
KEEPING TRACK OF IT ALL. Dozens of sensors around the house connect to a computer that graphs energy production and consumption. Understanding how all of the systems work together has allowed the design team to make changes that increased the energy efficiency of the home. It will be an ongoing process that could continue to inspire future improvements. The system is also being accessed by the Oregon Department of Energy and the Oregon Institute of Technology so that others can learn from a real-world example.
Image Credit: Dan Morrison/Fine Homebuilding
CHOOSING THE RIGHT MATERIAL FOR THE JOB. After a detailed analysis, composite ICFs made of cement and wood and filled with rockwool insulation were deemed the best choice for a balance of cost, durability, and resource efficiency. Fly ash substitutes 35% of the Portland cement in the concrete that was poured into the ICFs. All of the framing lumber is FSC certified, and the structural steel contains more than 90% recycled content.
Image Credit: Nathan Good
MASONRY UNIT OR INSULATED FORM? The Durisol blocks don't quite fit the standard description of either material. The insulation (rockwool) is on the inside, unlike most ICFs. But they are installed much the same; concrete is poured into cavities, tying the blocks together and giving them compressive strength. Because they are made of mineralized wood fibers, they are relatively lightweight, but the portland cement that binds everything together makes them sturdy and rot-resistant.
Image Credit: Nathan Good
STRIKING A BALANCE. In a nutshell, the goal was: create a home that equally embraces and withstands nature. Materials were chosen for environmental responsibility, durability and healthfulness. 80% recycled wood content means The Durisol ICFs are resource efficient; their portand cement binder protects them from fire, rot, and insect damage. All of the wood used in the home - from concrete forms to framing to flooring - is FSC certified. Most of the surfaces are unfinished or at least covered in natural or no-VOC coatings.
Image Credit: Toshi Woudenberg
A CHALLENGING PLACE TO SHOOT FOR NET-ZERO. Even though temperatures are relatively mild, the often cloudy and windy Oregon coast proves to be a tough place to build a net-zero-energy home. A 5.9kW PV array produces more than half the required power for this home; a well insulated envelope, plenty of thermal mass, active and passive solar heating, and very effective natural daylighting keep the demand fairly low. Overall the home imports 13.3 MMBtu (3,900 kWh) of electricity, but continuous energy monitoring and upgrades to the home's systems are inching it toward the initial goal. (In fact, a new air handler replaced the original ERVs, so the total energy consumption may already be lower than the number stated here.)

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

Located in Cannon Beach, on the Oregon coast, this home has breathtaking views and is also conveniently located within a short walk of the town center and the beach. The home’s owners have a strong commitment to environmental sustainability, and they were actively involved in the design and building process. From the outset, they asked their architect, Nathan Good, to design “a small home that is healthy to live in, using materials and systems with a dramatically reduced impact on the environment.”

The house has a modest footprint, and its interior spaces are efficiently designed for multiple uses; a window seat also serves as a twin-size guest bed, and the study doubles as a guest bedroom. The L-shaped home is also carefully designed to wrap around a majestic, 200-year-old Sitka spruce that shelters the site.

Disaster-resistant, bioclimatic design

Building in such an exposed, hilly location means that the home could have a potentially big impact on the site, and vice versa. In this cool, damp climate, a long-lasting home requires extremely durable materials and carefully thought-out building assemblies. Gale-force winter winds and dense local forests make fires another big risk. In fact, a previous home on this site, as well as the owners’ prior home in another part in Cannon Beach, had both burned down in a fire.

A detailed site assessment, including sun-path diagrams and a microclimate study, enabled a comprehensive design approach. The team tucked the home into a south-facing hillside and positioned it for ideal passive warming and good daylighting. The passive solar design, good insulation, and high-thermal-mass materials keep the home comfortable even during extended power outages. A Rumford-style wood-burning fireplace supplies back-up heating, if needed.

The home’s vegetated upper roof reduces the burden on the municipal stormwater system by absorbing rainwater and reducing runoff. It is also fire resistant, helps insulate the home, and has a life span of at least 50 years. Although it had a higher initial cost compared to some more traditional types of roofs, its durability should pay off over the life of the home. People seem to think it looks better, too. Nathan Good reports, “The roof has become a delight for the owners and neighbors and those who walk through the neighborhood.”

With a well-rounded list of durable materials, the home should stand the test of time and require little maintenance. Some are natural, local, traditional materials, like cedar and stone. Others are more modern. Curved steel beams make up part of the home’s structure, and the home was one of the first in the Pacific Northwest to use Durisol insulated concrete forms (ICFs). These composite ICFs are made of recycled wood chips and cement with mineral rockwool insulating cores. Aside from being resistant to rot, termites, and fire, they add thermal mass, have an above-ground R-value of 25 and are rated for Zone 4 seismic performance.

Comprehensive energy strategies

Extensive research and modeling in the design phase put the home’s projected energy use at 58% less than what is required by Oregon Energy Code. Daylighting studies and DOE-2 energy modeling were crucial in creating the most efficient thermal envelope and fine-tuning the mechanical systems and passive solar design.

The home’s primary energy source is the 5.9-kW photovoltaic (PV) array on the roof. A combination of solar-thermal collector tubes and a ground-source heat-pump system heats both the living space and domestic hot water. Excess summertime thermal energy is stored in the bedrock beneath the house for later extraction by the heat pump. A “short basement” — a conditioned, unvented crawl space that contains the heating ducts and adds to the home’s thermal mass — also helps minimize temperature swings.

The home’s innovative energy system was also originally equipped with multizone energy recovery ventilators (ERVs), which warm incoming fresh air with heat from outgoing stale air; these were subsequently replaced with a single air handler.

High-tech monitoring and evaluation

Engineers on the project and staff at the Oregon Department of Energy (ODOE) led an extensive commissioning process of the home’s systems. More than 60 sensors installed in the house allow the ODOE and Oregon Institute of Technology (OIT) to track the house’s energy usage remotely, providing valuable data for this and future projects. Early identification of design and installation glitches allowed them to quickly correct problems, including excessive noise from the heating and ventilation systems. One of the most significant discoveries resulting from the measurement and verification was that the heat pump performed at about half the manufacturer’s stated level. When representatives from the heat-pump manufacturer were presented with monitoring data, they agreed to replace the 1.5-ton heat pump with a more energy-efficient 2-ton unit.

The team originally set an ambitious goal of getting the home energy use as close as possible to net-zero (generating as much energy as it consumes annually), a challenging if not impossible goal for such a cloudy locale. Energy consultant Charlie Stephens estimates that the home is currently generating about 56% of its energy use through its on-site solar PV system. The systems are still being fine-tuned to get closer to the net-zero goal.

Lessons Learned

The keys to this project’s successes were its integrated design 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 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 system has also been dramatically simplified. Charlie says, “While one can indeed use a properly controllable ERV or HRV as an air handler, there are drawbacks. They impose a heating 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 PV 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.

General Specs and Team

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

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

  • 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

Energy Specs

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.

    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

    Alternate Energy Utilization

    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

    Certification

    Earth Advantage: platinum

    4 Comments

    1. Richard Medlock | | #1

      Cannon Beach OR
      Superlative design, engineering, and execution. Loved it when I first saw it in FINE HOME BUILDING - still love it.

    2. Robin | | #2

      Cannon Beach OR house
      I remember reading about this house years ago. Saved the article, but lost it, but never my fascination with the house or the possibilities of building one of my own. It is an absolutely beautiful home.

    3. James Widder | | #3

      What a beautiful design. Very
      What a beautiful design. Very well done!

    4. Deniz Bilge | | #4

      Nice House
      Very nice house. I do have a couple questions about the roof. Firstly, how long is the bitumen roof good for? The house I am building will have a living roof, and while I am leaning on an EPDM membrane, I will pour a thin slab on top of it to help prolong its life. I am also a curious about the potential toxicity of the water after it drains from the roof. While a bitumen roof layer is watertight, it is toxic enough that one shouldn't ever use this water as potable, even after filtering. ...some food for thought. Thank you.

    Log in or create an account to post a comment.

    Community

    Recent Questions and Replies

    • |
    • |
    • |
    • |