Built in place of an existing garage, the concrete slab was saved and reinforced for the new 2-story structure. Targa Homes was able to use an almost entirely FSC-certified framing package; wood harvested from the highest level of responsibly managed forests. The living unit is substantially airtight using a high-grade housewrap with taped seams as well as AeroBarrier air sealing process. Blower door testing showed the home to be under passive house (PHIUS) required air tightness of 0.05 CFM/SF of envelope. Triple pane windows and blown-in fiberglass insulation complete the above-code envelope.

Targa used a unique combined heating/cooling and ventilation device in this home called the Minotair Pentacare V12. This advanced machine brings in fresh air and exhausts stale air, much like an HRV/ERV, but with an internal heat pump it also heats and cools the living space. Appropriate for smaller, low load homes like this, it’s the only HVAC equipment needed. The Pentacare also features HEPA filtration. Airtight homes paired with fresh filtered outdoor air result in superior indoor air quality which is a focus for Targa Homes.

With an optimally pitched, unshaded South-facing roof, Targa was able to convince the homeowner to invest in a 5.85 kW solar PV array. Modeling and HERS rating by Evergreen Certified showed that this would be net-positive energy home, providing more than the total power needs for the all-electric home on an annual basis. That extra power is allowed by Seattle City Light to be put toward the main homes usage or can charge the new EV that the owners bought after construction was complete.

Interior finishes were chosen with an emphasis on sustainability and indoor air quality. Comfortable cork flooring runs throughout the home and sustainably manufactured Paperstone countertops were chosen for the kitchen. All paint and coatings are low or zero VOC.

Targa meticulously source-separates construction waste for recycling, including plastic film and styrofoam which are accepted for recycling at King County waste facilities.

Juanita Farmhouse cottages, built by John Buchan Homes, accomplished just that. Comprising nine new cottages and a common house/barn that includes a guest apartment, it achieved both Built Green 5-Star and Built Green Communities certifications in 2018.

Built Green Highlights

Site and Water

The cottage development wraps beautifully around a central garden court, with generous porches and the common house helping create a sense of community. Many existing trees were carefully maintained and included in the final landscape, which features walkways, benches, and a terrace in front of the common house.

The common house includes a barn-like garage, a community room, and a kitchen off the large porch. The shared guest apartment is available to all community owners.

The site is provided with infiltration swales for roof water drainage that are integrated with native and drought-tolerant landscaping, utilizing all pervious surfaces except for part of the shared driveway. Indoor water use is reduced by the use of low flow fixtures and WaterSense toilets.

Energy Efficiency

The cottage homes are conventionally framed with enhanced insulation and ground-source heat pumps for top tier energy efficiency. Other energy efficiency features include:

• Walls are blown-in blanket (BIBs) R 23
• Windows are double-pane low-e argon units with .27 u value
• Ground-source heating and cooling for best-in-class energy efficiency
• Duct system pressure tested for very low leakage
• Low-flow devices on sink and shower fixtures
• ENERGY STAR appliances and 80 percent LED lighting

Because of the trees, not all of the homes have good solar access. The two cottages at the south east corner of the site are wired as “solar ready.”