The Birch Case Study House was developed using the Living Building Challenge as a guide. The primary goal of this project was to implement numerous sustainable strategies highlighting the successes and failures when designing, permitting and constructing Living Buildings.
To help realize the project, [bundle] design studio partnered with non-profits and building product manufacturers. Through the course of construction [bundle] hosted a workshop series with Sustainable Connections to present green materials and strategies to the local building community. [bundle] also partnered with Northwest Energy Efficiency Alliance (NEEA) for the NextStep Homes program. Lastly [bundle] partnered with WSU to field test a CO2 heat pump, used for domestic hot water and radiant floor heating.
The Birch Case Study house has proved successful at demonstrating a number of pathways towards living buildings:
NET ZERO WATER: The Birch Case Study house is the first within the Bellingham,WA City limits to choose not to hook up city water and sewer. Instead the project is completely Net Zero Water through the use of onsite Rainwater catchment, composting toilets and greywater site infiltration.
NET ZERO ENERGY: As the major energy savings strategy the building envelope was designed to eliminate nearly all thermal bridges and air infiltration(.4 ACH50), reduce framing lumber, cost effectively increase insulation values and integrate high quality south facing windows. Heating that is used to condition the house was treated as a valuable commodity. Heat recovery, both the DHW and air used for ventilation is mined for usable heat which is recycled back into the house. Other energy conservation strategies include CO2 air to water heat pump for DHW and radiant heating, LED lighting and an induction range. The house was preplumbed for solar PV to reach Net Zero Energy, to be installed fall 2015.
MATERIALS: The use of FSC certified lumber proved to be prohibitively expensive and difficult to source. Alternatively [bundle] salvaged joists from the demolition of the 1920’s Birchwood Elementary School located less than 1/8 mile from the site. All exposed joists, rafters, cabinet faces, shelving, handrails, decking, and stairs were built from the salvaged lumber lending a character to the project that would have been lost with conventional framing. Beyond salvaged wood the house employs FSC countertops, no-VOC paints and sealers, metal siding and insulation with high recycled content and an overall reduction in finish materials.
SITE: Outside of the house attention was given to controlling storm water through a permeable driveway, rain gardens and a green roof. The site was divided north to south by the house segregating the property into distinct areas of habitat, habitation and urban agriculture, including extensive gardens and an orchard up the driveway.
HEALTH: Every space both inside and out were evaluated for access to light and air. Within the house a heat recovery ventilator is used to supply the all spaces with fresh air while properly placed windows heat the space and provide views to the exterior.
BEAUTY: The goal was to create a simple form using familiar materials. Natural materials were used exclusively throughout the project with minimal finishing or processing allowing them to take on a patina as the structure ages. A pealing back of the finished surfaces exposed the raw construction of the house providing a contrast in material that helps delineate the internal and external spaces.
Builder: Chris Tretwold, Tretwold Construction, LLC Architect: Dan Welch, [bundle] design studio
Alternative Building Systems: CO2 Heat Pump, HRV, Roxul Exterior Insulation, Prosoco Wetflash System, no clothes dryer, more.
Appliances: All electric Energy Star including induction range. No dryer(drying room using HRV exhaust)
Cabinets, Shelves, Millwork: Custom cabinets from Renew Wood-salvaged lumber_ 1920's school demolition 1/8 mile from site
Building Envelope: Prosoco Cat5 air & water barrier, Roxul comfortboard (exterior) & Comfortbatt (wall cavity) insulation, Rainscreened metal & open joint rainscreen cedar siding.
Automotive: No Garage. Remote Parking. Truegrid Permeable Paving (structured fire lane/driveway)
Countertops: Paperstone- FSC certified
Decks: Burnt wood
Door/Hardware: Codel fiberglass entry doors
Exterior Finishes: Metal Sales-LBC compliant metal panels, Cedar fence boards
Fire Protection: Darley (pump and control panel), Reliable (sprinkler heads), Pex distribution
Flooring: Concrete- radiant
HVAC/Ducts: Sanden SanCO2 air-to-water CO2 heat pump(energy factor = 3.35), Taco- radiant floor controls and distribution
Insulation: Roxul comfortboard IS (2" exteriorR-8), Roxul Comfortbatt (5.5" wall cavity R-23) (14.5" floor cavity R-60), Polyiso (3-3" layers continuous above roof sheathing R-63)
Landscaping: Etera-(green roof sedium tiles), Sumas GroMedia (green roof soil), 40 year old Plant/tree Salvage from other clients
Lighting: Phillips LED bulbs
Plumbing/Plumbing Fixtures: Composting toilets, Greywater onsite infilltration, Rainwater Catchment for potable, all low flow fixtures & appliances
Renewable Energy Systems (solar, wind, etc.): Solar PV (preplumbed, fall 2015 install)
Roof: LBC compliant Metal Sales steel roofing. Rain catchment on metal sloped roof. Green roof on flat TPO (Esary Roofing). Etera-(green roof sedium tiles), Sumas GroMedia (green roof soil)
Specialty Products: PowerPipe- drainwater heat recovery
Structural Components: Salvaged wood joists/rafters, No rebar in concrete- Helix rebar replacement
Ventilation: Zehnder ComfoAir 550- whole house HRV
Water Filtration: Sterilite spv-410 UV sterilization, sediment & carbon block filtration
Water Heating: Sanden SanCO2 air-to-water CO2 heat pump(energy factor = 3.35), Powerpipe Drainwater Heat Recovery(65% efficiency)
Waste Management: Onsite greywater irrigation, dry-composting toilets
Window Coverings: External rolling screens, interior drapes
Windows/Skylights/Patio Doors: Cascadia 300 & 400 series Triplepane tilt turn windows & patio door, Crystalite skylights(quad glazed)
Other: Interior Planter for greywater treatment and food production.