This LEED Platinum-certified home is a model of sustainability on a community level
This small house on reclaimed institutional grounds in Salem, Oregon, is just the first of many to come in a project that puts equal importance on energy efficiency, environmental conservation, and quality of life. Though the Pringle Creek cottage uses some cutting-edge technology to produce its heat and electricity, the essential principle of its design is an efficient use of space and resources.
Part of a whole
Many elements—from the ground-source geothermal loop to 12 acres of open space—are shared at Pringle Creek, thus weaving a fabric of experience and intent for people living here. There really is a Pringle Creek, too. As part of the original master plan for some 275 acres, the creek was cleaned and restored; the aquifer that underlies the property was protected through multiple swales, percolation beds, roads with permeable surfaces, and much more. This house may not exist apart from the community it’s in.
A large ground-source heat pump (GSHP) satisfies the space heating load of more than half the homes in the complex. The heat pump system is around 50% more efficient than standard forced-air heating. The heat is delivered through pipes that loop through the community in an underground right-of-way. A two-well system supplies the GSHP with nonpotable water; it also supplies water for irrigation of common areas. More than 90% of stormwater remains on-site due to an all-porous street system and network of rain gardens.
The very tightly built house pulls fresh air through an energy recovery ventilation unit (ERV) to further conserve energy.
The city provides water for domestic use, which flows through all the low-flow fixtures and low-usage appliances. Nonpotable rainwater is harvested from roof runoff and stored underground in a 1,500-gal. concrete tank. This supplies occasional irrigation needs (plantings around the house are native and drought-tolerant) and exterior uses, such as washing the car.
The scale of experience
It’s not common for a house this small to be equipped with a sprinkler system, but this high measure of safety was the serendipitous trade-off with the fire marshal for granting the planners narrower streets at better human scale. This scale ties in to the house, which was designed with large windows that provide “eyes on the street.” The open flow of the plan blends the living energies of back and front and makes the house feel larger than its 1,350 square feet.
Oriented for passive solar benefit, the house is equipped with solar screens and generous eaves to optimize light in winter and manage it gently in summer. A grid-tied 2.0-kWh photovoltaic (PV) array feeds any excess electricity back to the utility grid, and a visually subtle evacuated-tube solar collector on the roof provides domestic hot water. On cloudy days, an electric water heater backs up the solar thermal system.
Crafted with the exterior proportions of an evolving “traditional” Northwest architecture, fiber-cement siding and roofing contribute to durability, as does modest detailing. Low-VOC paints, adhesives, and finishes are employed throughout, as are locally sourced structural FSC lumber, exterior paints, and Pacific madrone wood flooring. The very high indoor air quality is further protected through a detached garage, which keeps away auto pollutants.
Structure addresses conditions
A rainscreen works to keep the building dry. Essentially, such an arrangement divides the function of weather resistance into two parts. The exterior protective cladding of fiber-cement clapboards, usually nailed to housewrap and sheathing, is held away from these by polypropylene battens, which provide a ventilation space—a layer of air over the entire inner wall. Water may get under the siding through gravity, capillary action, or the force of winds, but it never condenses on the housewrap (in this case, also polypropylene) or enters the structure beneath it. In the rainy Northwest, this strategy eliminates problem leaks and the unhealthy molds that can grow as a result.
Architect and community master planner James Meyer intended to dispel myths that thoughtful design and technology were not compatible or doable. This house came together in about four months using local contractors. Meyer says, “The technology needed for a green house already exists—all that’s needed is the will.” He feels that “the new paradigm has arrived” and that builders are willing, but they need a helping hand—they tend to stay with what they’re used to and may confuse this with responding to what the market demands. Current home buyers are alert as never before to sustainability but have tremendous confidence in what builders say, so it’s important that builders “embrace green technologies.”
The benefits of integrated design
Addressing the community's various priorities, such as aesthetics and indoor air quality, holistically rather than independently was an important design strategy. Not only did this contribute to the overall efficiency of the project, it ensured that the cottage (and the whole Pringle Creek community) would be a pleasant, durable, and healthy place to live.
General Specs and Team
|Additional Notes:||Completed: June 2007|
Architect: James Meyer, AIA LEED,
Foundation: short basement; 4-in. concrete slab; 6-in. poured concrete wall; 2-in. XPS insulation on inside (R-15)
Walls: 2x6 studs at 24 in. o.c.; vented rainscreen: housewrap (Tyvek), vertical XPS battens 12 in. o.c.; dense-packed blown cellulose; 1-in. R-5 foil-faced polyisocyanurate over sheathing (R-28 total)
Windows: cedar-frame, double-pane, low-E2, argon-filled (U-factor < 0.32, SHGC 0.41, Jeld-Wen)
Roof: cool-color standing-seam metal roof (Taylor Metals); 3/4-in. ply sheathing, waterproofing membrane; 9 1/2-in. I-joists at 24 in. o.c., open-cell spray foam (R-36, Sealection 500)
Garage: one-car detached
- Passive solar orientation
- Building-integrated shade
- Short, semi-conditioned basement
- High-performance insulation
- Reflective metal roofing
- Energy Star kitchen appliances
- CFLs throughout
- Sealed ducts, ERVs, and whole-house fan
Heating/cooling: vertical-loop ground-source heat-pump system, neighborhood-shared, with 2-ton heat pump (WaterFurnace), forced-air heat, and (initially) three-zone ERVs; no cooling system
Water heating: Two evacuated-tube solar collectors, two 120-gal. storage tanks, 4,500-W backup electric heating element
Annual energy use: 13.3 MMBtu/yr.
(8,900 kWh gross-5,000 kWh PV production). Note: Air handler was upgraded, so current energy use could now be less.
- Low-flow fixtures
- Dual-flush toilets
- Rainwater harvesting (1,500-gal. underground tank)
- Drought-tolerant landscaping
- Drip irrigation
Indoor Air Quality
- Energy-recovery ventilator (ERV)
- Operable windows (natural ventilation)
- Formaldehyde-free sheet goods
- Low-VOC interior finishes, sealants, and adhesives
- 100% wool carpeting
Green Materials and Resource Efficiency
- Minimal site disturbance
- All stormwater remains on-site
- Concrete contains 35% fly ash
- Advanced framing
- 95% of construction waste recycled
- Fiber-cement siding
- 100%FSC-certified construction-grade lumber & plywood sheathing
- Locally sourced hardwood flooring, paint, and windows
- Biodegradable foundation form-release oil
- Community-wide measures:
- landscape irrigation integrated into GSHP system
- biofiltration swales
- permeable-surface roads, sidewalks, paths
Alternate Energy Utilization
Photovoltaic: 2-kW, grid-tied
LEED for Homes: Platinum (101 points)
Earth Advantage: platinum