Net-Positive-Energy

Bellingham Affordable Net-Positive Home

Lembo Toomes 6.13.18-634.jpg

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).

West Seattle 2018 Award Winner

Photos by Yuriy Manchik

Photos by Yuriy Manchik

This is a Built Green Emerald Star home in West Seattle. It was the first Emerald Star home for TC Legend and the second of its kind built in Seattle! It is also a Department of Energy 2018 Housing Innovation Award Winner and Built Green’s “Green Hammer” Project of the Year!

This floorplan is flexible into the future, with two extra bedrooms already in the program, fitted with egress windows & minimum floor area to meet code; One will partition behind the utility, the 2nd can partition from the recreation room upstairs. So this 3 bedroom main house can grow to 5 bedrooms in a day!

The energy-shell is a simple rectangle, conforming to and ideal 1:1.6 established ratio for temperate environments. SIPs shell construction is post & beam type of load-bearing construction that means internal walls can be moved easily during the life of the building as they carry no load. The post & beam structure is visible as both architecture and a celebration of the woodcraft of the Pacific Northwest.

Specs

  • 3,160 Square feet

  • 4 Bedrooms

  • 4 Baths

  • 9.9-kW Solar

  • Triple-pane windows

  • 10,000-gallon rainwater storage

  • Air-to-water heat pump

  • 2 electric car charging stations

  • Low- or no-VOC products sourced throughout. No PVC.

Bellingham Power House

Bellingham Power House Exterior

There's nothing we love more than building overachieving homes. This remarkable home not only produces enough solar electricity to meet its own energy needs, but it produces surplus power to charge two electric cars.

Nicknamed the Power House, it is the first of its kind in Whatcom County. The home sends power to the city’s electrical grid when the sun is out and draws it during the night or on cloudy days. (Contrary to popular belief, the Pacific Northwest is an excellent place for solar). Averaged over the entire year, the panels will produce more power than the house uses, with enough of a surplus to power two electric cars through on-site charging stations.

The house qualifies for a one-time federal tax credit of approximately $10,500 and Washington State solar production credits of approximately $5,000 a year until 2020.

Perhaps more remarkable than the home’s efficiency is its modest price tag. Shared by two couples and three children, the 2,700-square-foot custom home cost under $150 per square foot to build, significantly less than most other residential construction projects in Bellingham. 

With its airtight shell, structural insulated panel (SIP) construction, numerous south-facing windows and passive solar design, highly efficient heat pump, solar hot water, and a solar PV array using Bellingham-built ITEK modules, this one-of-a-kind house has no electrical bills (other than the monthly service charge for this  grid-tied system) and costs nothing to heat. No oil, natural gas, or other fuels are used. 

This home shows that cutting-edge energy efficiency technology can actually be made affordable by eliminating entire categories of expenses, like heating and gasoline bills. And if one house can be shared by two families, expenses are decreased for both.

Specs

2,700 square feet, co-housing duplex for 2 families, 2 stories, 3 bedrooms, 3 bathrooms, 3 multi-purpose rooms: loft, rec room and sunroom, semi-covered deck, covered parking, acid-stained concrete slab foundation, radiant-heat floors, exposed beams, Hardie plank & milled cedar siding, metal roof, solar hot water, 9.9 kW solar array, 2 electric car charging stations.
 

  • Powers itself and two electric cars, for net-zero emissions, over the course of a year
  • Uses a 9.9kW photovoltaic system (half power goes to the house, other half powers two cars)
  • Envelope includes structural insulated panels, insulated concrete forms, and 4” foam under slab
  • Heat and hot water provided by a solar hot water collector with an air-to-water heat pump backup
  • South-facing high solar gain triple-pane windows and solar absorbing concrete floors
  • Utilizes the most energy-efficient appliances and lighting available on a budget
  • Collects rainwater for all outdoor water usage and utilizes low-flow fixtures indoors
  • Provides housing for four adults and three kids with enough garden space to feed both families
  • Budget under $150/SF includes all development costs except land (built on an infill lot in the city)
  • Northwest Energy Efficiency Alliance is monitoring home for US Department of Energy pilot program
  • Fresh air provided by heat recovery ventilator and earth tube combo system
  • HERS rating is -15

Montlake Modern

After more than two years of looking at dozens of houses, putting down multiple offers on several properties, and just not being able to find exactly what they wanted, Relja and Yoojin decided to build their own house. With two architects in the family, it probably wasn't very surprising.

The modern, positive-energy home they designed meets all its own energy needs while also powering an electric car. 

Both Relja and Yoojin work in the technology sector, and building their home with the most advanced materials was important to them. However, after receiving bids from other builders, they weren't sure their dream home would be within their price range. After teaming up with TC Legend Homes, they found that building with advanced materials, such as structural insulated panels (SIPs) and insulated concrete forms (ICFs), could actually fit their budget.

In keeping with the high-tech concept, the house includes the latest in home automation to further reduce energy requirements. Heating, cooling, and the LED lights are all controllable through wifi. Even the master shower has a feature that prevents the water from turning on until the desired temperature is reached. The owners are looking forward to writing their own apps to help automate the house.

Features

  • Fresh air system utilizing HEPA filtration

  • Storm water managed with pervious concrete

  • Triple-pane windows

  • Zoned radiant heat powered by an electric heat pump

  • All-electric heat and appliances, including an induction cooktop

  • Car charging station in the garage

Press

Energy.gov
DOE Tour of Zero: Montlake Modern by TC Legend Homes

Green Building Advisor
Modern Dream Home is Energy-Positive

Curbed.com
Modern Marvels: Net-Zero Montlake Modern House Keeps It in the Family

Case Study

Download the Department of Energy Case Study

Back to Portfolio

Family photos courtesy of the homeowners and Katie Blanch Photography.