House in the Hollow Case Study

House in the Hollow Case Study

This just in and hot off the press – the House in the Hollow Case Study! TC Legend built this net-zero house through the winter of 2020/ 2021.

The house-in-a-hollow isn’t really in a hollow, it’s on a knoll, above protected wetlands, northeast of Bellingham. The hollow is formed by the trees, which were preserved to shield the house from overheating, and to conserve the flora of the native wetlands.

Measuring 1950 square feet, this Department-of-Energy certified Net Zero clerestory design has a central kitchen and a 1st floor aging-in-place floorplan. Designed for an Alaskan couple whose love of the outdoors demanded a house that fully engaged with the landscape, plenty of daylight is admitted & access to outdoor living is easy.

“Builder TC Legend Homes of Bellingham, Washington, aims for quality and sustainability in every home it constructs and company founder Ted Clifton Jr. has found the U.S. Department of Energy’s Zero Energy Ready Home program is an ideal way to achieve that goal.”

“The DOE Zero Energy Ready Home program is a great benchmark not only for ourselves, but for all those looking to build or purchase a home that is eco-friendly. Since the program incorporates ENERGY STAR and Indoor airPLUS, holds high standards for energy efficiency, and is nationwide, it is an easy way to compare homes across the board and that reduces confusion for purchasers,” said Clifton.

“It’s also great that the DOE program has a very low cost barrier. There are many other certification programs that charge large fees, making it difficult for small builders to participate. Or, the cost of the fees gets passed along in higher home prices, increasing the barrier to purchase for many people,” Clifton added.

Since 2015, TC Legend Homes has built all of its homes to the DOE program criteria. The builder typically constructs one spec home and five or six custom homes for buyers each year and currently has nine homes under construction. In 2022, the builder was recognized by DOE for its efforts with a Housing Innovation Grand Award in the category “Custom for Buyer under 2,500 ft2.”

Modeled Performance Data of House in the Hollow:

• HERS INDEX: without PV: 33 with PV: -23

• Annual Energy Costs: without PV: $600; with PV: $-280

• Annual Energy Cost Savings: without PV: $1,200; with PV: $2,150

• Annual Energy Savings: without PV: 8,400 kWh; with PV: 20,350 kWh

• Savings in the First 30 Years: without PV: $48,930; with PV: $86,550

Read & download the full case study HERE.

Learn more about the house build & see the the full gallery of pictures HERE.

TC Legend Homes ‘House-in-a-Hollow’ Home Wins 2022 Housing Innovation Award!

TC Legend Homes ‘House-in-a-Hollow’ Home Wins 2022 Housing Innovation Award!

Written by: Nicole Miller

For TC Legend Home’s 9th time, we are thrilled to announce another Department of Energy Housing Innovation Award (HIA) winning home!

House-in-a-Hollow has won the grand prize for the ‘Custom for Buyer less than 2500 Square Feet’ category. We could not have achieved this award without the amazing homeowners who helped us push the envelope and our extremely skilled field crew who nailed the execution (pun-intended). 🙂

Our very own Talia receiving TC Legend Home’s Department of Energy 2022 Housing Innovation Award!!
Talia had a blast at the EEBA conference last week in Scottsdale, AZ and loved seeing The House in the Hollow showcased!

Each year the HIA updates their application pushing companies to innovate more and change with the times, and this year was no exception.

Along with the house performance, design and materials/sustainability information required, the award also requires the builder to submit information on their business metrics and how they create quality construction.

This year, they added the “Advances Home Concepts” section which consists of written portions on the company’s advanced building practices, smart building techniques and environmental impact.

Much like the Seattle based Built Green program, they have also added a portion to evaluate the company’s sustainable business practices which includes their diversity, equity and inclusion practices, and workforce training.

These latter additions are very valuable as the industry recognizes the interconnection between sustainable housing and equitable housing. Sustainable housing should not just be for the wealthy and, in fact, those of lower incomes are far more likely to live in homes or areas that negatively impact their health.

This is due to the homes being less desirable to the wealthy and therefore cheaper, creating a market where the only homes that are financially available to folks with lower income, are the ones that are unhealthy. It should go without saying that this is unfair and unjust. Making it that much more important the sustainable housing be available for everyone.


Award Winning Features of House-in-a-Hollow

House Description:

  • Size: 1935 sf
  • Bedrooms: 3
  • Bathrooms: 2.5
  • Lot Size: 9.88 acres
  • Garage: separated and unconditioned
  • HERS Index (With PV): -23
  • Annual Utility Costs: -$278.00
  • Energy Savings: 20,354 kWh
  • Net-Zero: Yes
  • Aging-in-Place Design: Yes
  • Clerestory Design: Yes


  • Zero Energy Ready Home
  • EPA Indoor airPLUS
  • Built Green 5 Star


  • Walls: 6.5 inch Neopor SIP panel (R-29) with Hardie plank lap siding
  • Roof: 10.25” and 12.25” Neopor SIP panel (R-49 and R-59), IKO Armourshake asphalt roofing, foam splines in place of wood splines
  • Air Sealing: Aerobarrier sealed to 0.54 air changes per hour (ACH)
  • Foundation: Slab on grade with R-20 underslab insulation and insulated concrete form (ICF) stemwalls
  • Windows: Vinyl, Triple-pane, Low-e3 coating, Argon-filled, Fixed U-value of 0.15, Casement U-value of 0.18
  • Additional: Extended roofs/eaves and clerestory windows for summer shading and passive winter gain


  • Ventilation: Zehnder Comfoair 550 whole-house HRV, Fantech HEPA filter, whole house CO2 & humidity sensors
  • Heating/Cooling: Chilltrix CX-34 air-to-water heatpump with Comfopost, radiant in-floor heating on first floor, and fan coil unit heating on second floor
  • Hot Water: Domestic hot water is heated by the Chilltrix heatpump
  • Photovoltaics: 10.56kW rooftop array with microinverters on each panel
  • Electric Vehicle Charging Station: Yes
  • Additional: Awair Indoor Air Monitor that tracks the internal humidity, temperature, chemical pollution (VOCs), PM2.5, and CO2


  • Low Emission Finishes: GreenGuard certified flooring, GreenGuard certified Neopor SIPs, hardwood trim, solid maple cabinets, no-VOC paint, low-VOC sealants, waterbased caulk
  • Additional: 100% LED lighting, Energy Star appliances, WaterSense and low-flow plumbing fixtures, low-emission finishes

Land Development

  • Undisturbed Land: 98%
  • Tree Retainage: 74%
  • Wetland Buffer Mitigation: Installation of 630 native trees & shrubs
  • Landscaping:  Installation of only native plants that require no potable irrigation
  • Grass: No
  • Additional: Large rocks placed along perimeter to deter human impact on wetlands, a few trees removed on the immediate South side of house for passive solar gain & PV array, trees to East & West retained to shade house

Learn more about other innovative builders and award winners here:…/buil…/housing-innovation-awards

Read Our 2016 Housing Innovation Award-Winner Case Study

Read Our 2016 Housing Innovation Award-Winner Case Study

TC Legend Homes built this 2,463-ft2 home in Seattle, Washington, to the performance criteria of the DOE Zero Energy Ready Home (ZERH) program. The two-story home has SIP walls and triple-pane windows for draft-free construction and high insulation values.

Project Data

  • Name: 19th Avenue
  • Location: Seattle, WA
  • Layout: 4 bdrm, 2.5 bath, 2 fl, 2,463 ft2
  • Climate Zone: IECC 4C, marine
  • Completion: May 2016
  • Category: custom for buyer

Modeled Performance Data

  • HERS Index: without PV 44, with PV -2
  • Projected Annual Energy Costs: without PV $1,053, with PV $25
  • Projected Annual Energy Cost Savings (vs home built to 2012 IECC): without PV $811, with PV $1,889
  • Projected Annual Energy Savings: without PV 9,453 kWh, with PV 20,993 kWh
  • Added Construction Cost: without PV $0

When a net-zero-energy home can be built at a cost on par with traditional construction, everyone wins. TC Legend Homes is helping to usher in a new era of green construction in which home owners don’t have to choose between cutting-edge efficiency and staying on budget.

“Over the last decade, we’ve developed practices that allow us to build net-zeroenergy homes for the same price as traditionally constructed homes. Sometimes,
we are able to build them for even less,” said TC Legend Homes’ owner and lead Ted W. Clifton, Jr.

“We know we are doing something right because our services are in high demand,” said Clifton, who is headquartered in Bellingham, Washington, but also builds in the Seattle area.

One way TC Legend Homes is achieving net zero is by building to the high performance criteria of the U.S. Department of Energy’s Zero Energy Ready Home program. DOE has honored the builder with four Housing Innovation Awards since 2013, including a grand award in 2014 in the affordable category
and a 2016 award in the custom home category. The 2016 award-winner is a two-story, 2,463-ft² home located next to another TC Legend Home on an urban
infill lot in Seattle.

The high-performance features of this home, combined with the 9.5-kW PV system
and solar water heating, help the home achieve a Home Energy Rating System
(HERS) score of minus 2. That equates to calculated annual utility costs of $25
(counting service charges) or enough electricity to power the all-electric home. If
the home performs better than calculated, it will cover the power for the electric
car charging station in the garage as well. Even without the PV, the home would
achieve a HERS score of 44, far better than the HERS 80 to 100 of typical homes.

Clifton is used to getting such scores. He has been certifying homes to the DOE
Zero Energy Ready Home program since 2013. His previous winning homes have
HERS scores ranging from -12 to 13 with PV or 34 to 43 without PV. Clifton has
committed to building all of his future homes to the program.

The DOE Zero Energy Ready Home program requires homes to meet all of the
requirements of ENERGY STAR Certified Homes Version 3.0 and the U.S.
Environmental Protection Agency’s Indoor airPLUS program as well as the
hot water distribution requirements of the EPA’s WaterSense program and the
insulation requirements of the 2012 International Energy Conservation Code.
In addition, homes are required to have solar electric panels installed or have
the conduit and electrical panel space in place for future photovoltaic panel

The 2016 award-winning home was situated on the northern edge of the lot to maximize southern exposure. “Our houses are designed from the ground up to take advantage of the sun. A passive solar layout like the one in this house means lots of windows facing south and few facing north,” said Clifton. The long axis of the house is east to west to allow for maximized solar exposure for the PV and solar hot water systems and for passive solar heating. High-quality triple-paned, vinyl-framed windows were located on the south side of the house to maximize
solar heat gain. The builder polishes and stains the concrete floor slab to use as the finished flooring; its thermal mass absorbs heat from the sun during the day and slowly releases it at night to provide beneficial passive solar heating.

Structural insulated panels (SIPs) were used for the walls and roofs. “We chose SIPs for their excellent insulation values, airtightness, and ease of construction,” said Clifton. SIPs consist of two layers of OSB sandwiching a layer of rigid expanded polystyrene foam. They arrive from the factory as 4×8-foot sheets or precut for doors and windows as required for each wall. Clifton uses locally made panels that come precisely cut, allowing for fast construction, a strong, airtight
shell, and practically zero jobsite waste. The TC Legend Homes crew is trained in
SIPs construction, which helps assembly go smoothly. Clifton has used SIPs ever
since he began constructing homes with his father, Whidbey Island builder and
designer Ted L. Clifton, while in high school. Ted Clifton Jr. is on site daily to
oversee every step of the TC Legend home construction process, allowing for any
problems to be quickly fixed.

For the winning home’s walls, Clifton specified R-29, 6-inch SIPs that are glued
and taped at all interior and exterior joints. The panels are covered with house
wrap that is overlapped and taped to serve as a drainage plane under the fiber
cement siding. The roof decking consists of R-42, 10-inch SIPs, also taped at all
interior and exterior joints. The whole roof deck is covered with self-adhering
ice-and-water shield, which provides a weather-resistant layer under the asphalt
shingles. There is no attic in the home. Because the SIP panels provide the
insulation and roof decking in one layer, all of the home’s upper-floor rooms
can have vaulted ceilings.

The home has a slab-on-grade foundation with stem walls made of insulated
concrete forms (ICFs) that wrap the sides of the slab in R-23 of insulation while
an R-20 layer of rigid foam covers the ground under the entire slab. Seams are
taped and the rigid foam layer serves as the vapor barrier between the ground and
the home.

The concrete floor slab contains radiant floor loops. Water for the radiant floor
heating is provided by the roof-mounted evacuated tube solar hot water system
and by an ultra-efficient air-to-water heat pump with a coefficient of performance
(COP) of 4.5. These systems also provide domestic hot water. The heat pump’s
indoor unit is centrally located on the main floor. Low-flow fixtures help cut
water usage.

ENERGY STAR-rated appliances also reduce water and energy usage. All of the
home’s lighting is provided by LEDs, adding to energy savings.
The home was assessed by a home energy rater per DOE Zero Energy Ready
Home requirements and showed air leakage of only 0.60 air changes per hour
at 50 Pascals. That’s equivalent to the Passive House Institute U.S. Standards
and three times tighter than required by the newest energy code. (The 2015
International Energy Conservation Code requires 3 ACH 50 or less.)

To provide good ventilation for the home, the builder installed timered exhaust
fans to provide spot ventilation in the four-bedroom home’s 2.5 bathrooms. The
range hood fan is timer controlled with a 200-cfm fan that pulls fresh air into the
home through a vent located downstairs on the north side of the home. Both fans
can be set to come on for balanced ventilation during the day and for night-time
cooling in the summer. 

Use of low- and no-VOC paints, finishes, and flooring and good moisture
management practices like site grading and drainage were among the measures
the builder installed to comply with the requirements of the EPA’s Indoor
airPLUS checklist.

Home Certifications

  • DOE Zero Energy Ready Home Program, 100% commitment
  • ENERGY STAR Certified Homes Version 3.1
  • EPA Indoor airPLUS

In a “green” market like the Pacific Northwest, marketing DOE Zero Energy
Ready Homes is easy. TC Legends has found it gets more than enough
customers through these avenues: 1) referrals from other customers; 2) TC
Legends’ website; 3) TC Legends’ presence on other websites, for example the
DOE Tour of Zero and Housing Innovation Awards sites; and 4) participation
in the annual Northwest EcoBuilding Guild’s Green Home Tour.

“Because TC Legend Homes builds custom homes, most of our potential
customers approach us already wanting an energy-efficient home. We educate our
customers about how our homes are different from most houses and about how we
achieve net-zero energy and positive energy in the homes we build,” said Clifton.
“By conserving as much energy as possible, these homes will be able to offset
more than 100% of their electricity usage with the roof-sized solar electric
systems.” said Clifton.

By value engineering and fine-tuning their processes, TC Legends is able to achieve zero energy at surprisingly low cost. “We only do net zero energy construction, and for less than most builders in the area do regular construction. We average $200/ft² including solar,” said Clifton.

Key Features

  • DOE Zero Energy Ready Home Path: Performance.
  • Walls: R-29, 6″ SIP taped at all interior and exterior joints, fiber cement siding.
  • Roof: R-42, 10″ SIP taped at all interior and exterior joints. Ice-and-water shield, asphalt shingles.
  • Attic: None.
  • Foundation: R-23 ICF stem walls, R-20 rigid foam under slab.
  • Windows: Triple-pane, vinyl-framed, low-e windows, U=0.21.
  • Air Sealing: 0.60 ACH 50.
  • Ventilation: Timered exhaust fans.
  • HVAC: Evacuated tube solar hot water and 4.5 COP air-to-water heat pump for in-floor radiant hydronic heat.
  • Hot Water: Air-to-water heat pump, COP 4.5.
  • Lighting: 100% LED.
  • Appliances: ENERGY STAR refrigerator, clothes washer, range hood; induction cooktop.
  • Solar: 9.5-kW PV, evacuated tube solar hot water.
  • Water Conservation: Low-flow fixtures; centrally located water heater.
  • Other: Low-VOC paints and finishes.
  • Electric vehicle charging stati

The U.S. Department of Energy invites home builders across the country to meet the extraordinary levels of excellence and quality specified in DOE’s Zero Energy Ready Home program (formerly known as Challenge Home). Every DOE Zero Energy Ready Home starts with ENERGY STAR Certified Homes Version 3.0 for an energy-efficient home built on a solid foundation of building science research. Advanced technologies are designed in to give you superior construction, durability, and comfort; healthy indoor air; high-performance HVAC, lighting, and appliances; and solar-ready components for low or no utility bills in a quality home that will last for generations to come. 

For more information on the DOE Zero Energy Ready Home program
go to

Download the case study in PDF.

Take a Virtual Tour of Our Zero-Energy Homes

Take a Virtual Tour of Our Zero-Energy Homes

Through its Zero Energy Ready Homes initiative, the U.S. Department of Energy has been busy documenting homes that live, work, and last better. They’ve put together a great web resource with such homes all over the country. TC Legend Homes is well represented, with four such “homes of the future” in the Marine climate zone, three of which were Housing Innovation Award winners.

Check out the full tour or click on the links below to take a virtual tour of homes that are so energy efficient a renewable energy system can offset all or most of their annual energy consumption. These award-winning homes are independently certified to meet DOE Zero Energy Ready Home guidelines. Zero Energy Ready Home is part of the U.S. Department of Energy’s Better Buildings initiative. Better Buildings aims to make commercial, industrial, public, and residential buildings 20 percent more energy efficient over the next decade.

Department of Energy Case Studies

Ballard Zero-Energy Home
Cedarwood Zero-Energy Home
Montlake Modern
Bellingham Power House