Saint Claire Powerhouse

Saint Claire Powerhouse

This 1,900 square-foot 3 bedroom clerestory home, with an additional 672-square-foot attached garage located outside the SIPs shell, was built in 2016 in western Washington.

Because the master bedroom and bathroom were required to be located on the first floor, the clerestory design allowed us to locate two additional bedrooms and a bath on a minimal second floor, while leaving the glorious and spacious SIPs vaulted ceiling within the main living & kitchen spaces.

The play of light from the second-floor clerestory windows penetrates deeply into the main living spaces, eliminating glare at the large south windows and providing unusually even and dynamic day-lighting within the kitchen and living room. The occupants feel connected to the sweep of the sun, clouds, and weather patterns outside.

This is a near-perfect lot for a solar-panel net-zero home, identified by the clear solar exposure to the south, with no trees or buildings between the building and the sun.

 

SPECS/FEATURES

  • Department of Energy Net-Zero certified
  • Chilltrix CX34 air-to-water heat pump
  • 100% on-site storm water infiltration via 30-foot dispersion trench
  • 10.8 kW of solar panel installed
  • 6.5” R-29 SIPs walls
  • 10.25” R-49 SIPs roof
  • 4” R-20 foam under 4” concrete slab-on-grade for thermal mass
  • 5.5” foam (total) R-23.8 insulated concrete form (ICF) perimeter stem walls
  • Vinyltek Boreal series triple-pane windows (U values from 0.14 to 0.16)
  • 1:1.6 aspect ratio floor plan, with the long side facing south
  • Minimal east and west glazing

Worrell

Worrell

This 1,340 square-foot single-story, south-facing rural home was built for a professional couple in western Washington in 2018. It features an additional 576-square-foot attached garage to the north. The unheated garage, which sits outside the SIPs shell, is stick framed to reduce building and energy costs.

The home’s two offices are permitted as legal bedrooms, so it’s really a three-bedroom, two-bath net-zero rambler with a huge south-facing roof that has space for enough solar panels to power two electric cars and run the house.

Specifications

  • Department of Energy Net-Zero certified
  • Fujistu 9RL minisplit heat pump
  • 100% on-site storm water infiltration via 40-foot dispersion trench
  • 70 trees and 160 shrubs were planted that will grow a forest on site
  • 10.8 kW of solar panels installed
  • 6.5” R-29 SIPs walls
  • 10.25” R-49 SIPs roof
  • 4” R-20 foam under 4” concrete slab-on-grade for thermal mass
  • 5.5” foam (total) R-23.8 insulated concrete form perimeter stem walls
  • Vinylek Boreal series triple-pane windows (U values of 0.14 to 0.16)
  • 1:1.6 aspect ratio floor plan, with the long side facing south
  • Minimal east and west glazing

 

Chappell

Chappell

This 1,950 square-foot, two-story, 3-bedroom family house was completed in Seattle in 2018. It has a two-wall carport adjacent to the back door.

The project presented a challenging permit process for the TC Legend office and a complex dig: The undeveloped lot was located atop a known landslide area, requiring deep pin piles and extensive geotech involvement. A heavily protected 6-foot-diameter seqouia tree stands beside the only site entrance and was successfully cared for during the extensive dig, with drain lines threaded through the roots, dug by hand.

With the main hilltop vista facing west, the challenge was to have the house embrace the view without overheating in the afternoon sun. Retaining the deciduous western tree cover was essential, as was ordering the western windows with low solar-gain coatings.

The storm-water system was not allowed to point-discharge onto the steep slope. The extensive use of permeable pavement ensured the trees and shrubs remain watered, stabilizing the slide-prone slopes.

Specifications

  • U.S. Department of Energy Net-Zero certified
  • Chilltrix CX34 air-to-water heat pump
  • Zehnder 350 HRV
  • 10.8 kW of solar panels installed
  • 6.5” R-29 SIPs walls
  • 10.25” R-49 SIPs roof
  • 4” R-20 foam under 4” concrete slab-on-grade for thermal mass
  • 5.5” foam (total) R-23.8 insulated concrete forms perimeter stem-walls
  • Euroclime triple-pane windows (U values between 0.14 and 0.18)
  • 100% rainwater-permeable driveways and walks
Massey

Massey

This 1,200 square-foot two-bedroom clerestory riverside home was built in 2020 in Ferry County, WA. TC Legend designed and permitted the home, and it was built by a Ferry County contractor.

The greater temperature swings associated with the continental climate led us to do a cost-efficiency study to choose the best SIPs panel thicknesses. Walls were bumped to 8 inches, yet the roof remained 10.25 inches. The exposed concrete stem wall footing stands high above the finished grade to keep the snow away from the panel toe, assisted by generous eaves and covered walks & porches, which also provide necessary shade during the hot summers.

An entry mudroom/utility room airlocks the house to minimize the entry of smoke during the fire season. Fresh, filtered air is delivered throughout the house via heat recovery ventilator (HRV), scavenging the heat from the waste air and imparting that heat into the incoming fresh air.

The circular windows are very easy to cut into SIPs panels; the trim-out is a bit more tricky.

 

Specifications

  • Fujitsu 9RL heat pump
  • Zehnder 220 HRV
  • Ground-mounted solar array for easy snow removal
  • 8.25” R-38 SIPs walls
  • 10.25” R-49 SIPs roof
  • 4” R-20 foam under 4” concrete slab-on-grade for thermal mass
  • 5.5” foam (total) R-23.8 insulated concrete forms perimeter stem walls
  • Vinylek Boreal series triple-pane windows (U values between 0.14 and 0.16)
Bellingham Affordable Net-Positive Home

Bellingham Affordable Net-Positive Home

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.

Key Features:

  • 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.)