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Birch House

Building Details

Building NameBirch House Construction / refurbishment date24/12/2017 Building Size182.27 sqm
Building Typeresidential single Address 2930 Birchwood Ave Bellingham Washington 98225 United States Region americas

Performance Details

Net Zero Operational Carbon

Buildings or developments that display best practice outcomes in energy efficiency, are powered by renewable energy, and as such have been verified and certified as "net zero energy and/or carbon" projects.

Qualification criteria: ILFI Zero Energy Certificate level: Net EUI: 33.7 kwh/m2/yr Net RPI: 49.4 kwh/m2/yr Net Offset Ren Energy Src: Net Offset Details: Net Verification Year: 2019

Additional Details

The house was rigorously designed to have identical floor plans between the first and second floors. This allows the house to change use over time from a 3 bed-2 bath family house to (2) 1 bedroom – 1 bath units when needing to downsize. Both floors were developed to take advantage of the expansive territorial views and used building elements to bring the landscape into the living space. On the first floor a large indoor solarium is used as a passive solar sink and bridges the gap between indoors and out. The second floor is surrounded by a green roof that adds insulation to the roof and brings the landscape to the face of the building visible from the floor to ceiling windows.

Solar Design

The house was designed with significant passive solar gain. The majority of the windows are facing south, with a few windows to the east and west to bring in morning and evening sun and cross ventilation. Only 2 windows are facing North to reduce heat loss. The site was cleared of trees to the south providing excellent solar access and the house, with its blank north façade pushed tight against the existing trees to the North. The simple shed roof was designed with a 7/12 pitch to provide ideal conditions for an active solar array. This move created an opportunity for sleeping lofts in the two upstairs bedrooms and a centrally located mechanical loft that houses the HRV, DHW tank and radiant floor mechanics.

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, from both the domestic hot water and air used for ventilation is mined for usable heat which is recycled back into the house. Other energy conservation strategies include CO2 heat pump for DHW and radiant heating, 100% LED lighting and induction range. The house was pre-plumbed for solar PV to reach Net Zero Energy. A 9.28 kW solar array was installed April 2016. The total energy use of the house for 2015-2016 was 5.6 kWh. The oversized solar array allows for increased energy usage over time as young children age and for the possible addition of car chargers and/or shop uses.

You can find out more about this case study from ILFI here.

Submitter's Details

OrganisationInternational Living Future Institution

The house was designed with significant passive solar gain. The majority of the windows are facing south, with a few windows to the east and west to bring in morning and evening sun and cross ventilation.