This Built Green 5-Star zero-energy home defines the Seattle eco-lifestyle. It features an open floor plan, heated hardwood floors, 9-foot ceilings, and exposed beams. On the roof, a 9.5kW net-metered solar array provides all the home’s power needs, and an electric car charging station is built into the garage. Triple-pane windows and SIPs construction offer plenty of insulation, and a whole-house filtration system keeps the air pure. Designer touches include Hinkley lighting, custom cabinetry, Carrara marble countertops, stainless steel appliances, an induction cooktop, and a 9-foot kitchen island.
TC Legend Homes demolished an existing one-car garage and re-purposed the available space with a cozy, high-performance, 775 square foot, detached accessory dwelling unit (DADU) that includes an attached single-car garage. The RE Store handled the structure demolition to maximize recycling opportunities and minimize waste.
The DADU was designed from the ground up to be net-positive-energy, meaning it will produce more energy on an annual basis than it requires. TC Legend Homes applied the same approach and many of the same building techniques to this DADU as it does to any of its other homes.
A simple design to minimize exposed surface area
Orientation and window placement to optimize active and passive solar
Slab on grade with 4” under-slab insulation & Insulated concrete forms
Structural Insulated Panel construction (vice traditional framing) to reduce possibility of thermal bridging
High-efficiency mini-split heat pump for heating & cooling and high-efficiency heat pump for water heating
HEPA High Efficiency Whole House Insulated Filtration System
5.4kw photovoltaic solar system
Energy Star, EPA Indoor airPLUS, and 5-Star Built Green Certified
Home Energy Rating System (HERS) Index is negative 16! (A typical new home has a rating of + 62).
Built by the TC Legend Homes/Powerhouse Designs team. We design and build. With a standard palette of materials & details that have been chosen, tested & refined over many houses, there is no confusion for the crew. The draftsman, engineer, and crew are consistent through all our projects, so everyone has done this system before.
Positive Energy – produces enough electricity to also power an electric car.
Energy Star, EPA Indoor airPLUS, and 5-Star Built Green Certified.
Honorable Mention in the Affordable Category of the 2018 US Department of Energy Housing Innovation Awards.
The home is oriented for both passive & active solar performance by facing south, as a rectangle with the long side (26’) running from east to west. The home is outfitted with an 8.1kw photovoltaic system.
Energy envelope includes structural insulated panels (SIPs). The 6.5″ Neopor R29 SIPs panel walls are locally made in Washington. Designed & engineered to reduce cold bridging by minimizing structural lumber & maximizing use of foam splines to connect panels. Shell is air sealed with triple beads of mastic at all joints and panels additionally taped at all joints. RIM joist insulated with R30 spray-foam at floor systems. Perfect rectangle box adds simplicity to construction & reduces corners & thus cost & air leakage.
4″ Extruded Polystyrene (EPS), a low VOC foam (R20), is used under-slab. The concrete slab-on-grade is exposed and is effectively a free finished-floor and a functioning thermal mass.
The heat recovery ventilator (HRV) is a Zehnder Comfo-air 200 which can scavenge 95% of the heat from the outgoing dirty air. Running through a class 4 filter (merv7/8) at between 29 and 118 cubic feet/ minute (cfm), the unit ventilates the whole house, extracting moist air from bathrooms/utility spaces, bringing fresh air into living spaces.
Energy Star appliances including a Geospring 50-gallon heat pump-powered hot water heater.
Stormwater from the roofs is infiltrated on-site using splash blocks below the gutter downspouts.
Home Energy Rating System (HERS) Index is negative 25! (A typical new home has a rating of + 62.)
Owners: Eric Thomas and Alexandra Salmon
Designer: Zero-Energy Plans, LLC (zero-energyplans.com)
Builder: TC Legend Homes (tclegendhomes.com)
Site Address: 612 NW 60th St., Seattle, WA 98107 (Ballard)
1,915 square feet, single-family, 2 stories, 3 bedrooms + work loft, 2 bathrooms, concrete slab foundation, radiant heat floors, Hardie plank siding.
Structural Insulated Panel construction, air-to-water heat pump, 6kw solar electric (photovoltaic) system, triple-pane windows, passive solar design, rain garden, stained concrete floors, reclaimed fir floors, recycled fixtures, zero-VOC paint, low-waste engineering, low-energy LED and CFL lighting, capacity for additional solar panels to power an electric car 5,000 miles per year.