Net Zero Energy Co-Housing

Net Zero Energy Co-Housing

Net Zero Energy Co-Housing

Written by: Nicole Miller

We are excited to announce our Net Zero Energy Co-Housing spec project that’s currently
under construction!

Titled “Woburn House” on our social media, this 5-bedroom home is
intended to house multiple family units and has an accessible first-floor bedroom and bathroom.
Our hope is for this to be a multigeneration home creating a small, tight-knit community.


As always, this home will create its own power, leaving the residents with zero electric bills. We
also anticipate it will receive Built Green 5-Star, Indoor AirPlus, EnergyStar, and Zero Energy
Ready Home certifications.


Once completed, this home will be open for lease or purchase!

6 Frequently Asked Questions About SIPs

6 Frequently Asked Questions About SIPs

by Nicole Miller | Mar 1, 2024

SIPs FAQ
A photo of a man applying a liquid mastic to the edge of a SIP during the installation process.

There seems to be a lot of confusion around Structural Insulated Panels (SIPs) in home building. In this article, we will run through the most common questions we’ve seen!

Are SIPs panels non-combustible? / Are SIPs panels fire resistant?

While SIPs can still catch fire, they are less combustible than traditional stick-framed homes. That’s, in part, due to less wood being used and because of the flame retardants used on the foam. In combination with the gypsum drywall, the whole assembly has a 1-hour fire rating. SIPs construction also does not require an attic space, which can be a fire hazard, thereby eliminating a major threat.

How are SIPs panels made?

SIPs are manufactured off-site to the exact specs of the house. Each panel is made up of two OSB panels sandwiching an EPS or GPS foam core. During the manufacturing process, workers cut out each window and door opening and cut all of the pieces perfectly to size, so that when they are installed on site, they will fit together perfectly like Legos. This also means that the panel off-cuts can be recycled and reused at the manufacturing plant, reducing the overall waste!

Are SIPs panels load bearing? / Are SIPs panels structural?

Yes! SIPs can be used for the entire exterior shell of a house. According to Insulspan, “SIPs have structural properties similar to that of a steel I-beam.” In fact, SIPs are actually considered more structurally sound than traditional stick-framed homes.

Are SIPs panels environmentally friendly?

Yes! SIPs are generally considered to be more environmentally friendly than traditional stick-framed homes. That being said, SIPs can use either EPS or GPS foam cores and EPS is not a very eco-friendly option. So, it’s best to use GPS SIPs in order to lessen the home’s overall carbon footprint. Also, since SIPs are manufactured off-site, they are made to the specific dimensions of a home which reduces the waste. Any scraps produced during manufacturing are also reused. Furthermore, when shipped, the panels are tightly flat-packed together reducing fuel needed for transportation.

Can SIPs panels get wet?

Yes! SIPs are built to dry out and can withstand exposure to the elements for many months. The foam core doesn’t absorb water unless it’s physically submerged or constantly wet for a long time. In all the years we’ve built using SIPs in the rainy Pacific Northwest, we have never had an issue with the SIPs compromising due to moisture.

How long will a SIPs house last?

SIPs are a super sturdy and hardy building material. Assuming you are properly maintaining your house (i.e. replacing your roof every 30-50 years, fixing any broken siding or trim, fixing leaks as soon as they happen, etc.), then a SIPs house will last 100+ years.

Still have questions? Shoot us an email! We’d be more than happy to answer any questions you have!

If you’re interested in learning more about our net zero energy homes or want to get started designing your very own net zero energy homecontact us today! We also offer pre-made net zero energy home plans!

Featured in the Northern Lights: Point Whitehorn net-zero home constructed with efficient features

Featured in the Northern Lights: Point Whitehorn net-zero home constructed with efficient features

Written by: Senna Scott

Our Point Whitehorn net-zero home was featured in @TheNorthernLight Blaine & Birch Bay’s Community Newspaper!

“Nestled adjacent to wetlands and with views of Birch Bay State Park, TC Legend Homes’ Point Whitehorn house is not your average house. The home has a 7.2kW photovoltaic system – the conversion of light into electrical energy – and is built in a highly efficient envelope, setting it up to be a net-zero energy house in Birch Bay.”

You can learn about our cost-saving measures and design challenges by reading the full article online >> HERE <<

TC Legend has been recognized by U.S. EPA as a 2023 Indoor airPLUS Leader Award winner

TC Legend has been recognized by U.S. EPA as a 2023 Indoor airPLUS Leader Award winner

TC Legend Homes has been recognized by the U.S. Environmental Protection Agency as a 2023 Indoor airPLUS Leader Award winner for our ongoing commitment to building homes with improved indoor air quality through participation in the Indoor airPLUS program.


“Congratulations to all 14 2023 Indoor airPLUS Leader Award winners!” said David Rowson, Director of EPA’s Indoor Environments Division.

“It is always inspiring to have the opportunity to recognize the incredible work that our partners do every day, from expanding the use of Indoor airPLUS on a national scale, to maintaining strong leadership within their local communities. On behalf of EPA and the Indoor airPLUS team, we would like to congratulate and thank the 2023 Indoor airPLUS Leader Award winners for all of their work in constructing healthier homes for the American consumer”.


This annual award recognizes market-leading organizations who promote safer, healthier, and more comfortable indoor environments by participating in the Inoor airPLUS program.

To learn more about the 2023 Indoor airPLUS Awards and the Indoor airPLUS Program, visit www.epa.gov/indoorairplus

Net zero development: Which way to run the streets

Net zero development: Which way to run the streets

Written by: Jake Evans

Which way do you run the streets to maximize solar exposure for dense Net Zero development?

A street view of a row of colorful houses. The center blue house is a Net Zero house designed by Powerhouse Designs and built by TC Legend Homes.

Common wisdom states that the optimal streets run east west, which makes sense if you’re the house on the north side of the street, because there’s nothing shading your house, garden or solar panels. However, living on the south side of the street, you suffer from north facing gardens and probably some shading unless the lots are 5000sf or greater.

Critically, 10 dwelling units (du) per acre is the density with enough inhabitants to support a bus service (*1), a key part of the sustainable urbanist vision for transit, pedestrian & bike use, rather than private cars. An acre is 43500sf.

My conclusion is that the common wisdom is wrong for dense, Net Zero development, that the streets should run north-south.

A Net-Zero house has most of the windows on the south side of the house because south facing windows can be effectively shaded from summertime overheating, and can harvest wintertime solar energy.

Because all the windows are on the south walls, we can’t have another 2-story house immediately to the south as shown in ‘East-West 3700’ below, or the valuable direct wintertime sunlight will be prevented from entering & you’ll have a house that is gloomy all winter.

Sure, if the lots are big, we can keep the southern house away, as shown in ‘East-West 4500’ below, but then we end up with less than 10 du/ acre (du/a) and there’s no bus & everyone’s driving cars.

The ‘North-South 3800’ drawing below shows a 1-story neighbor garage to the south, avoiding shade. Bingo! That’s a 3800sf lot, and offers 11.34 du/a. Additionally the frontage length is reduced which lowers roadway & utility development costs.

Street Orientation Option 1 North-South 3800. A drawing showing a block of houses on streets oriented north to south and situated on their lots with garages on the north side and the long side of the house on the north and south side, allowing solar gain on the south side while not being blocked by the roofline of the neighboring house. Text says "2000 sf house with dbl garage. 3835 sf lot. 59' frontage / du = 11.34, du/a = density supports bus OK. Winter light = 100%. Equal solar exposure for all houses."
Street Orientation Option 2 East-West 3700. A drawing showing a block of houses on streets oriented east to west and situated on their lots with garages to one side of the house and the long side of the house on the north and south side. The two houses to the north of the block have garages on the west side and the southern two houses have garages on the east side mimicking the layout. The orientation allows solar gain on the south side but the diagram shows that 40% of the northern houses will be blocked by the roofline of the neighboring southern house. Text says "2000 sf house with dbl garage. 3700 sf lot. 74' frontage / du = 11.76, du/a = density supports bus OK. Winter light = 60% @ northern houses."
Street Orientation Option 3 East-West 4500. A drawing showing a block of houses on streets oriented east to west and situated on their lots with garages to one side of the house and the long side of the house on the north and south side. The two houses to the north of the block have garages on the west side and the southern two houses have garages on the east side mimicking the layout. The orientation allows solar gain on the south side while not being blocked by the roofline of the neighboring southern house. However the houses are visibly farther apart. Text says "2000 sf house with dbl garage. 4505 sf lot. 74' frontage / du = 9.66, du/a = density ~ supports bus OK. Winter light = 100%."

(*1) Transit modes related to residential density (Boris Pushkarev & Jeffry M Zupan)