Passive Solar Design | TC Legend Homes

Fox Net Zero House

by Senna | Nov 28, 2023

Fox Net Zero Home

Started in the winter, building the Fox Home was not without its challenges, but the challenges ended up working in our favor in the end and producing this beautiful and unique home. Right off the bat, after we poured the concrete slab, the weather turned and frosted. As we saved the slab from freezing using plastic sheets and hay, the wind kicked up and caused the hay to come into direct contact with the slab as it was curing. The hay interacted with the concrete and caused what turned out to be really cool color undulations which add to the home’s character. Now we are intentionally adding this option for future clients who want some extra pizzaz in their concrete floors!

We always love when clients add their personal touches to a home as well, and in this case that personal touch was in the form of a repurposed trash receptacle laundry chute!

Specs

Overview:
- 1978sf SFR & 876sf garage
- 4 bedroom, 2.5 bath SFR
- Net Zero Energy
- 1st floor aging-in-place
- Passive solar heating/cooling design
- Insulation: R-29 walls & R-59 ceiling
- Air Sealing: 0.18 ACH50
- HERS Index: -2
- Annual Energy Cost Savings: $2,800
- Certifications: DOE Zero Energy Ready Home certified, ENERGY STAR certified, EPA Indoor airPLUS certified, anticipated Built Green 5-star certified
Mechanical:
- Ventiliation: Fantech Hero 250 with built in HEPA filter. Built-in humidity, temperature, and CO2
- Heating/Cooling: Chilltrix CX-34; hydronic radiant floor heating downstairs and fan coil unit
- PV: 9kW solar array with Enphase microinverters and battery ready
Selections:
- Thermatru exterior doors
- Certified Cool Roof metal roofing
- Birch doors and hemlock trim
- Floor Score certified vinyl flooring & zero-VOC, anti-microbial underlayment
- Quartz countertops
- Thrifted plumbing fixtures
- Europly maple cabinets
- LED lighting
- WaterSense plumbing fixtures
- ENERGY STAR appliances
- No/Low-VOC finishes
- Triple pane, Low-E coated, argon-filled vinyl windows

Point Whitehorn Net Zero

by Senna | Nov 15, 2023

Point Whitehorn Net Zero

Point Whitehorn Net Zero home is a modern, space-efficient, and economical home for the couple to spend quality family time in with their kids and eventually grow old in. The entire first floor is accessible for aging-in-place, leaving the second floor for family to stay over.

The stacked design and minimal undulations in the envelope helped make the most use out of every inch and get the best cost per square foot.

On the North side of the property is a wetland mitigation area that has been smartly sectioned off and adds an extra beautifully landscaped view with native trees, shrubs and wildflowers.

Specs

Overview:
- 1802sf SFR & 300sf carport
- 3 bedroom, 2.5 bath SFR
- Net Zero Energy
- 1st floor aging-in-place
- Passive solar heating/cooling design
- Insulation: R-29 walls & R-59 ceiling
- Air Sealing: 0.31ACH
- HERS Index: -2
- Annual Energy Cost Savings: $2,141
- Certifications: DOE Zero Energy Ready Home certified, ENERGY STAR certified, EPA Indoor airPLUS certified, anticipated Built Green 5-star certified
Mechanical:
- Ventiliation: Fantech Hero 250 with built in HEPA filter. Built-in humidity, temperature, and CO2
- Heating/Cooling: Chilltrix CX-34; hydronic radiant floor heating downstairs and fan coil unit
- PV: 7.2kW solar array with Enphase microinverters and battery ready
Selections:
- Thermatru exterior doors
- Lifetime warrantied asphalt roofing
- Birch doors and hemlock trim
- Floor Score certified laminate flooring
- Quartz countertops
- LED lighting
- WaterSense plumbing fixtures
- ENERGY STAR appliances
- No/Low-VOC finishes
- Triple pane, Low-E coated, argon-filled vinyl windows

Lynden Powerhouse

by Senna | Nov 15, 2023

Lynden Powerhouse

Lynden Powerhouse is a highly efficient, net-positive home with an additional ADU and stick-framed garage/shop. This home will receive the DOE Zero Energy Ready Home, ENERGY STAR, EPA Indoor airPLUS certifications, and Built Green 5-star certification.

Lynden Powerhouse will provide full-time and temporary housing for up to four separate family groups. This level of complexity required a greater attention to climate and ventilation zoning, which necessitated the installation of three separate Fantech Hero 250 HRV units and one extra-large Chiltrix CX50 heat pump. These devices allowed the home to be compartmentalized into three separately conditioned spaces – the main living space downstairs, living space upstairs, and ADU. Breaking up the air spaces ensures that the fresh air circulation can independently adapt to the measured CO2 levels and temperatures of each air volume. Given that hazardous airborne viruses are a normal part of life for the foreseeable future, having three separated air spaces allows those infected to quarantine without infecting others. Further measures to make the home as energy efficient as possible with the best indoor air quality included hydronic radiant floor heating, HRVs with integrated HEPA filtration, all ENERGY STAR rated appliances, LED lighting, triple pane windows, and Aerobarrier air sealing.

One of the owners, who works in the tech industry, used his knowledge to create innovative automation systems for the ventilation and hot water circulation systems using motion detectors and CO2 sensors to minimize wasted energy, water, and time. Each air space has a motion sensor that will stop the HRV unit if no motion is detected for 24hrs to conserve energy. Additional automation uses custom algorithms to vary the HRV air velocity to balance CO2 extraction with ventilation-induced heat energy loss. Motion sensors placed near each plumbing fixture trigger the hot water circulators only when need is anticipated. By the time the person turns on the fixture, hot water is available, minimizing both water, time, and energy waste.

Lynden Powerhouse features a 17.01 kW solar array with six 48v 100AH LFP batteries for backup storage. The system was designed to be oversized, knowing that the combination of PV with storage allows for disaster resiliency and for the house to operate completely off-grid for weeks if needed. It also supports three EV charging ports, two for occupants and one outside for guests. Moreover, having an oversized solar array on an already super-efficient house, means the owner can eliminate the entire energy bill which makes retirement budgeting more predictable and effectively making the cost of living cheaper in the future. By over-sizing the system, the house can fully power the AC units of four less efficient homes in the cul-de-sac, thereby minimizing peak energy loads for the entire block. The reduction in peak-energy loads helps reduce the stress on the grid caused by extreme weather events. And is the key to eliminating petroleum powered peaker plants, thereby reducing CO2 production for the entire street.

Specs

Overview:
- 1549sf SFR & 842sf ADU
- 1123sf unconditioned garage & shop
- 4 bedroom, 3.5 bath SFR & 1 bedroom, 1 bath ADU
- Net Zero Energy
- 1st floor aging-in-place
- Passive solar heating/cooling design
- Insulation: R-29 walls & R-59 ceiling
- Air Sealing: 0.45ACH
- HERS Index: -24
- Annual Energy Cost Savings: $3,717
- Certifications: DOE Zero Energy Ready Home certified, ENERGY STAR certified, EPA Indoor airPLUS certified, anticipated Built Green 5-star certified
Mechanical:
- Ventilation: (3) Fantech Hero 250 with built in HEPA filter. Built-in humidity, temperature, and CO2
- Heating/Cooling: Chilltrix CX-50; hydronic radiant floor heating downstairs and (3) fan coil units
- PV: 17.01kW solar array with whole home battery back-up
Selections:
- Timber framed entry
- Metal roof
- Locally made walnut and maple cabinets
- Bamboo Floor Score certified flooring
- Vanair vented interior doors
- Locally made solid fir front door
- Silestone and Corian countertops
- ENERGYSTAR appliances
- LED lighting
- WaterSense plumbing fixtures
- No/Low-VOC finishes
- Triple pane, Low-E coated, argon-filled vinyl windows

Download Case Study Here!

Neos House

by Senna | Aug 26, 2021

The Neos house is a 4 bedroom family house. 2614 square feet. Completed in spring 2021.

Designed as a multi-generational home with one full bathroom & one full bedroom on the 1^st floor, if the piano-room & the rec-room were enclosed with walls we’d have a 7-bedroom home. Enough for a substantial family to live together.

Pointing south, the view looks towards the huge garden.

The garden spills into the dining area through sliding doors. The folks who commissioned this home are gardeners, with kids, who will be drawn towards the natural world as a way to thrive.

The weather briefly nips at you as you walk from the front door to the garage under the covered walkway, creating a connection with the day’s weather and the world outside the energy-shell.

The SIPs installation was subcontracted because this is a Bellevue job & the TC crew have northern families & want to be home at night if possible. Issac taught a Peruvian framing crew how to sling the SIPs and the job ran fast & smoothly using advanced SIPs details required by the Bellevue jurisdiction.

Despite one design mistake (the mechanicals are in the unheated garage), this house is an exercise in textbook design for cost & energy performance.

The client did a stellar job of following design advice & the crew lovingly built the house, sealing the envelope to 0.6 air changes per hour, Passivehaus standard. The result is an economical house that has won a Department of Energy Grand Prize, attained 5-star Build Green certification and is certified Net Zero.

The envelope & mechanical systems are all drawn from the 2020 TC system: 6.5” walls, 10.25” SIP roof, 4” R20 foam under the slab, R24 ICF’s, Chilltrix CX34 heatpump with (1) fancoil upstairs, Zehnder 350 HRV with comfopost heat/ cool delivery. Vinyltek triple pane windows & Thermatru front door.

All the stormwater from the roof is infiltrated back into the onsite soils via a huge infiltration trench. Additionally, the excavation soils all remained onsite to reduce soils trucking. The clients took responsibility for seeding the exposed construction soils, choosing to plant a complex cover crop in place of the usual grass. The cover crop can be tilled back into the soils to impart nitrogen & other nutrients when a new planting regime is decided upon.

The house in a garden is a traditional family way of life and TC is proud to have built a modern, dense & flexible version of this ideal, updated to make all its own power to address the demands of the climate-change world.

Download Case Study

Trax

by Senna | Apr 16, 2020

This 2,540 square-foot clerestory (one-and-a-half story) family house has an integrated, differently heat-zoned 1,040-square-foot garage and woodshop sitting within the SIPs shell. It was built in 2020 in western Washington.

A rigorous passive-solar window design uses the majority south-facing glazing for wintertime heating, shaded in summer by a shallow south porch and accurate south clerestory overhang. Multi-direction daylight penetrates and reflects deep into the connected main living space and second-floor balcony via the high second-floor clerestory glazing.

Multiple cutting-edge HVAC and home-automation systems integrate to deliver low-cost air-to-water heat pump-based central heating, cooling, and fresh-air delivery, triggered via automatic carbon-dioxide and humidity sensors. Alexa-driven automated lighting and blinds are installed, a home-automation system that will expand in its capabilities as more options become available.

The clients’ requirement for a spacious first-floor master suite led us to design a smaller second floor in relation to the first. The clerestory design accommodates this layout by producing a daylight-rich one-and-a-half-story house.

Specifications

U.S. Department of Energy Net-Zero certified
Chilltrix CX34 air-to-water heat pump
Zehnder 550Q heat recovery ventilator (HRV), with in-line fan coil from Chilltrix
Development dedicated 1 acre of pastureland to a perpetual conservation easement, ensuring growth of native species
12.4 kW of solar panels installed
6.5” R-29 SIPs walls
12.25” R-59 SIPs roof
4” R-20 foam under 4” concrete slab-on-grade for excellent thermal mass
5.5” foam (total) R-23.8 insulated concrete forms (ICF) perimeter stem-walls
Vinylek Boreal series triple-pane windows (U values between 0.14 and 0.16)
1:1.6 aspect ratio floor plan, with long side facing south
Minimal east and west glazing