TC Legend Homes – Bellevue Net Positive Energy Home
Located on a portion of a subdivided, family property, this 2,614 SqFt Bellevue, WA home is a beautifully built house that helps to foster multigenerational ties and community. With a 5-Star Built Green rating, EPA IndoorAir Plus certification, and a Net Zero Energy certification, this award-winning TC Legend home is an example of the influence and success of the Build Green program. With a specific focus on indoor air quality, this home employs a new ventilation and air filtration system, helping to make it a safe and comfortable environment for its occupants.
Built with passive and active solar needs in mind, the two-storey house faces south. Numerous triple glazed Vinvltek windows on the south side provide passive heating and light within the home. These windows and others throughout the house are coupled with white interior paint to help provide significant daylighting and reduce energy demand from the 100% LED home lighting. The home also employs a 12.87kW photovoltaic system, producing enough power to make the home net positive and power an electric vehicle. With a shell system constructed from 6.5” SIPs walls, 10.25” SIPs roof, 4” foam under the slab-on-grade, ICF form slab-edge stemwalls & U 0.18 average triple pane windows, this house has a tight envelope, helping to reduce energy consumption.
The three-bedroom, two bath house is meant to allow the occupants to age in place with the kitchen, main living space, a bedroom and bathroom, and ADA compliant doorways on the first floor. The state-of-the-art fresh air system includes a Zehnder 350 HRV, Zehnder Comfopost inline heating/ cooling coil, and HEPA air filtration system. This system allows for fresh, filtered air to enter the home throughout the day and to be increased when needed, such as when the kitchen hood fan is drawing smoke out of the kitchen during cooking. This fresh air system keeps the indoor air clean, reducing particulates in the air, even when the outdoor air quality is particularly poor such as during a summer forest fire.
Overall, this home is a comfortable, clean, and net positive building, allowing the homeowners to be happy, healthy, and confident in the knowledge that their home is serving their needs and protecting the environment in the process. The BuiltGreen Certificate of Merit and 5-Star rating this home received help to reinforce this knowledge due to the standard of excellence required of BuiltGreen certified homes.
Built Green highlights:
SITE & WATER
Long term erosion reduction strategies in place
Over 70% of building site left undisturbed with preservation of trees and native vegetation
Stormwater infiltration system catches all stormwater from the site and the uphill grandparents house, mitigating flow
Approx. 50% of the lot is turf grass
Watersense certified fixtures and low flow fixtures and toilets
Rainwater collection ready
Net-Positive Home with a HERS score of -22 and extra power to serve an electric vehicle
12.87 kW roof PV array
Substantial envelope insulation lowers heating requirement: R-30 walls, R-49 roof, R-20 under slab, R-24 slab-edge, average U-0.18 windows
Triple-paned Vinyltek Windows with u-values from 0.15-0.22
Passive Heating Design strategies utilized
Chiltrix Air-to-Water Heat Pump for heating and domestic hot water with COP of 3.92
AeroBarrier air sealing and blower door results of 0.47 ACH50
100% LED lighting
All Energy Star certified appliances
Energy Star certified
DOE Zero-Energy Ready certified
HEALTH & INDOOR AIR QUALITY
Indoor AirPLUS certified
Solid wood cabinets with Low-VOC finish
All Low-VOC paints, adhesives, and sealants
No gas-burning appliances in house
HEPA Air Filtration System
Zehnder HRV with ComfoPost
Graphite SIPS for exterior walls and ceilings
ICF foundation walls
85%+ of waste recycled
Locally produced lumber, SIPs, concrete, cabinets, doors, and siding
Exterior cedar posts constructed form telephone pole MFG waste
Leftover materials moved to next job
Solid wood, domestically grown interior doors and trim
Locally produced Vinlytek windows
Location: Bellevue, WA Star Level: 5-Star, Net Zero Energy Label Checklist: Single Family/Townhome New Construction Verifier: Ecoe Company
Site and Water: 109 Energy Efficiency: 239 Health and Indoor Air Quality: 126 Materials Efficiency: 109 Total Score: 629
The TC Legend Family is growing! We have hired two new Carpenters and two new Draftsman trainees! Big welcome to Miles, Lee, Talia & Amber! Check out ‘Our Team’ to learn more about them.
We are always excited to grow our team and hire on other passionate individuals who aim to create a carbon neutral future and affordable housing!
The Bellingham Barn House is coming to an exciting end, and it was a great opportunity to get Senna and Talia out of the office and on-site! (And finally get some headshots of our new crew!)
Talia, our first TC Draftsman Intern, got to get her hands on the house plans and review her first TC Legend Home in action.
Here’s what Talia learned and noticed about this exquisite home:
“Visiting the Bellingham Barn House site was a great way to see the paper plans come to life in a real home. It was fascinating to see HVAC and water heating setup in person as well as all the design details that the on site crew carefully constructed.
I was particularly excited to see the positioning of the stairs in the middle of the house, serving as a visual and physical separation of the upstairs while keeping a cohesive design and smooth flow of traffic throughout the house.
It was also great to meet the crew and chat about the solar system with Jeff. I walked away having learned and seen a number of new things and I am really excited to be a member of this team!”
Talia has always been interested in building design, architecture, the environment, and renewable energy. When she had the opportunity to combine those interests in the form of an undergraduate course called Energy Efficient and Carbon Neutral Design, she jumped at the chance. After that course, she caught the net zero building bug.
Talia will be graduating in June, 2021 from Western Washington University. One of the incredible things that she did in her undergraduate studies that impressed the TC owners was her participation in an extracurricular competition, the DOE Solar Decathlon, where she designed a functional Net Zero Home for the Tri-cities.
“I’m excited to be making an impact on people’s lives and our environment through designing comfortable, affordable, and efficient homes as a member of the TC Legend Homes team!”
Ted & Jake did some virtual conference speaking last summer.
The subject was how to build an affordable Net Zero home. The Built Green footage is here: Videos | TC Legend Homes, and the NW Eco Build footage should be along shortly.
The principles are simple. Here are the notes:
Simple, rectangular footprint, Conforming to the formula for the Pacific Northwest the rectangular footprint is; 1.6 units long on south wall, 1 unit deep east and west walls. No wiggles or bump-outs as they increase cost and reduce energy efficiency. The long side faces south to harvest winter passive solar heat. Short east and west sides are minimized to reduce exposure to hot, low angle sun.
Formula for glazing. To avoid overheating during summer, large east and west facing widows are avoided. South-side glazing is heavily preferred as there we can shade the hot, high summertime sun with eaves and shades, yet allow the low wintertime solar heat to enter.
Daylighting. Rooms needing great daylight: kitchen, dining room, etc. are located on the south side behind the plentiful south windows.
The low-light-requirement rooms: mechanical rooms, bathrooms, staircases etc. are to the north.
Correctly sized clerestory windows can bring daylight deep within the interior of the house.
Pitched roof. A huge south roof, pitching to the south collects solar power from roof-mounted PV panels. Often the south roof is asymmetrically large, to create space for the maximum number of PV panels, achieving Net Positive and powering an electric car. This is a new aesthetic – Environmental Modernism!
Right sized rooms: Interior spaces and rooms that are exactly big enough to thrive within, but no bigger. Well placed exterior doors access the outside when you need more space.
Energy modeling. Modeling the building during the design process ensures it’s on-track to meet Net Zero, and allows precise evaluation of the cost/ energy advantages of the various construction components, including the HRV.
We use the WSU component performance worksheet. It’s a free excel spreadsheet, specific to WA state.
Detail: Post & beam structure. Fine-finished structural posts and beams enrich the interior at low cost, and allow easy remodel as no interior walls are loadbearing.
Detail: Slab-on grade. Fine finishing the concrete slab-on-grade floor gives a modern, durable interior at low cost. Not compulsory though, the slab can be covered with engineered floating floors.
Flat lot: Lower construction costs by avoiding steep lots with expensive retaining walls, excavation, soils trucking and geotechnical involvement.
Utilities: Power, water, sanitary drainage/ septic, driveways. Utilities can cost over $80K to install on remote rural lots. The ideal lot has all the utilities stubbed-out in the street or on-site.
Solar exposure: An ideal site would have a clear sky to the south, down to the horizon so the building can harvest low, wintertime passive solar heat. If there were deciduous trees to the east and west, those trees could shade the east and west walls / windows in summertime but allow valuable winter light to penetrate once the leaves have all fallen off!
Critical Areas: Water in all forms is heavily protected in Washington State. The presence of wetlands, streams, lakes and ocean all add to the complexity and cost to build.
SIPs panel construction: Highly insulated R29 walls, R49 roof are fast to build and are inherently very air-tight. The thick roof panels span far and make vaulted roof space as standard.
ICF formed stemwalls: Insulating the stem-walls adds R24 below grade, preventing the building from leaking heat at the slab edge.
4” under-slab foam: R20 foam below the slab as standard.
Triple Pane windows: Standard.
Heat recovery ventilator (HRV): Delivering fresh air is essential in super-sealed modern buildings. HRV ventilators recover over 90% of outgoing heat, whist providing constant fresh exterior air, filtered to HEPA standards with particulates removed.
Heat pump. Electric air-to-air (Fujitsu), or air-to-water (Chilltrix) heatpumps are highly efficient and provide cold air conditioning in addition to heating.
Concrete floor: The slab-on grade is inside the energy shell (above the 4” R20 foam) and serves as a thermal heatsink; storing the house’s warmth, or cool, within the concrete. Protecting the heatpump from short-cycling and preventing temperature swings, even during a multi-day power-outage.
Energy star appliances: As standard.
Solar panels: As standard to achieve net zero, or net positive if an electric car will be driven.
How $200/ square foot?
The economics are made possible because the house is explicitly designed to achieve net zero and to cost $200/sf. The shell, mechanicals and living quality are best-of-breed, the finishes are durable, solid materials, and modest.
There is an economical point (~1200sf) where the house has to become two story to remain in this cost bracket.
Small houses below 1500sf cost closer to $250/ sf as the basic elements (heating, kitchen, bathroom, etc.) all still have to be present and are not reduced as the floorplan reduces.
$200/ sf is possible (for a NetZero house with solar installed) with a 2,000sf house.
If you want a small (e.g. 800sf) NetZero house for $200/ sf: Think about duplexing with your friends, triplex, multiplex! Co-housing……..
We are excited to announce that the TC Legend Homes Everson Farmhouse has been awarded the 2020 Built Green Hammer Award winner in the category of Built Green Project of the Year!
The Built Green Hammer Awards recognize Built Green members in King and Snohomish counties for their outstanding projects and participation from the previous year.
Ted & Jake received the award virtually at the 2020 Virtual Built Green Conference on September 17, after giving a stellar presentation on “The theory, practice and details TC Legend Homes uses to design and build affordable Net Zero housing for the Pacific Northwest.”
“We’re really very happy to have been granted this prestigious award. Thank you all at BuiltGreen for the recognition. You guys at BuiltGreen work hard & we work hard at TC Legend Homes and we feel that together we can make a real difference to the future built environment.” – Jake Evans
Great job TC Legend Homes team!
Built Green 5 star certified,
HER rating of -19 (with P.V.)
Department of Energy certified Zero Energy Ready Home.