2938 Madrona Street in Bellingham, WA, was the 100th home to enter into the Kulshan Community Land Trust, an organization that promotes beautifully-designed, energy-efficient homes. The home was developed in partnership with The Cascade Joinery, a design-build firm that specializes in green building and custom timber work. Located in Bellingham’s Birchwood neighborhood, this affordable, low carbon-footprint home is minutes from downtown and features close access to public transportation, trails, parks and schools.
|Net Zero Energy Building Certified on December 30th, 2015
|Bellingham Washington, USA
|Jeff Aslan and Anne Honrath
|Dean Fearing (Kulshan Community Land Trust)
|Ecotech energy (Solar)
01. LIMITS TO GROWTH IMPERATIVE
The Birchwood neighborhood is located three (3) miles from downtown Bellingham and is one of the city’s older neighborhoods, characterized by narrow streets and homes on large lots. Near as it is to a bustling downtown, Birchwood maintains a rural feel. The property is an infill project, wherein open land in an urban environment is dedicated to new construction. The site was initially granted to the Kulshan Community Land Trust to be developed into eco-friendly houses. Formerly part of another property, the land was subdivided in 2009 and construction on the Madrona house began in 2011.
NET ZERO ENERGY
As a home for the community land trust, another design strategy was to put a large portion of the project budget towards the building envelope, reasoning that envelope upgrades would likely be costly and difficult for future homeowners to upgrade. Cascade Joinery used advanced framing with 2 x 6 studs on 24″ centers to minimize the amount of lumber needed in construction and maximize available cavity space for insulation. The wall cavity utilizes 2” spray foam insulation, combined with 3.5” of blown-in cellulose, and on the exterior of the sheathing is 1″ of polyiso rigid foam to add R-value and serve as a thermal break, giving the walls an overall R-value of 35. In the attic blown-in cellulose provides R-60 insulation with raised heel trusses to ensure continuous insulation levels. The builders were also diligent about air sealing as well, achieving a very high level of air tightness. A blower door test revealed the CFM50 was 184.2938 Madrona Street was designed to be a home that balanced environmental performance, aesthetics and affordability. Kulshan Community Land Trust, which aims to preserve affordability for low to median income homebuyers, wanted to ensure a design that was simple yet elegant. One of the first overall design considerations was minimizing the building’s footprint and materials needs. It was designed with only an 880 sq. ft. footprint, including two porches on the east and west sides of the house. It’s also much smaller than the average house at 1150 square feet. Another initial design consideration was to maximize passive solar heating performance. The building orientation is lengthwise on an east-west axis and features large south facing windows which passively heat the solar slab and provide plenty of daylighting, while minimizing any north-facing glazing. A wooden overhang over the south facing windows provides shade in the summer months while allowing for full sunlight in the warmer months.
The windows are standard double-pane vinyl windows, used as a cost saving strategy. The current owners also installed thermal blinds with sidetracks on all of the windows and close them regularly at night during the heating season.
In terms of HVAC, a ductless minisplit system provides heating in the winter. The system utilizes two heads with the upstairs head ducted out into both bedrooms. The minisplit also provides cooling in the summer, but the occupants have not had to use it as the home stays cool using passive strategies. Ventilation is provided predominantly by an HRV. The HRV was a retrofit that was installed when the current owners took possession of the house. It features supply registers in the two bedrooms and one downstairs and one whole-house exhaust register. In the bathroom, a high-efficiency exhaust fan is used only when showering.
The owners also retrofitted the electric water heater and installed a heat pump hot water heater. Because the water heater is located in a storage room, a novel approach of exhausting both the intake and exhaust side ensures that the heat pump water heater is not cooling the home in the winter months. The shower and kitchen sink use low-flow fixtures.
The solar PV system is comprised of 4.95 kW Sanyo panels and a Power-One Inverter. During the performance year, the system supplied almost 2.5 times as much energy as the home consumed during that time.
In terms of lighting, the vast majority of the house is on LED lighting with a few CFLs used in closets. The lighting also features dimmers in many places for additional energy savings. The appliances of the home are all Energy Star-rated. They were donated to the project, helping keep costs down.
The owners are very diligent about managing plug loads around the house. Switchable strips are utilized on all of the electronics in the house. The owners used a watt meter to test all plugloads to determine draw and the presence of vampire loads. While being cognizant of plugloads and usage, the owners have not needed to impact comfort to attain net-zero usage.
19. BEAUTY & SPIRIT IMPERATIVE
The project development, design and construction team (Kulshan Community Land Trust, Cascade Joinery, and Greg Robinson Architecture) had a vision of house that would marry a classic look on the exterior with beautiful interior finishes, alongside low-impact environmental performance. Starting with the exterior, the home has a simple boxed look. Cascade Joinery is famous for their timber-framing and they incorporated some of their timber expertise in the porches on both sides of the house with exposed timber and natural woodwork. The current owners of the home began a large landscaping project in the front yard, removing all of the grass and designing and building a winding brick walkway that weaves through beds containing edible fruit trees, herbs and shrubs, and native shrubs on the perimeter. On the north side of the house, a chicken coop and run bordering the street invites neighbor’s children to come and have a look at the chickens.
19. INSPIRATION & EDUCATION IMPERATIVE
On the interior of the home, the first aesthetic feature that stands out is the trim. All of the trim was locally milled and was otherwise going to go to waste as a road was being cleared. The exposed slab of the house was stained a deep crimson color which attracts lots of compliments but also provides passive solar performance. The vibrant paint on the walls is all zero-VOC. Large windows on the south side of the house provide plenty of natural light and views of birds and blueberry plants. All of the windows feature attractive and high-performance insulating shades with side tracks. The kitchen features a full range of appliances alongside suave wooden cabinets. No detail was spared as even the platform holding up the washing machine features a beautiful wood trim.