In 2014, the homeowners learned of net zero energy at the Minneapolis Building Show. Shortly thereafter, they purchased their retirement home and interviewed five different sets of architects and builders to compose the core of the design team. They settled on the one with the most “green” building experience and connections, Marc Sloot of SALA Architects, who also recommended a builder with green experience, Sean Morrissey of Morrissey Builders in St. Paul. The design and permitting took more than a year, (beginning in August 2014 through the end of 2015), proceeding through the usual architectural steps of conceptual design to detailed CAD drawings. Permitting was obstructed for a few months due to a proposal to extend the home’s walls by one foot to accommodate insulation. Since the owners are in their late 60s and hope to live in the house for as long as they are able, the house incorporates many design features from the National Association of Homebuilders, which enables occupants to live in a house throughout old age. An accessible rear entry to incorporate a ramp, 36″ wide doorways to accommodate wheel chairs on one level, wide turning radiuses throughout, a 4-foot wide stairway between floors, soft close cabinets in kitchen, base cabinets with pullout shelving, easily manipulable faucets, wall-mounted toilets (for easy cleaning), bright LED lighting throughout, sensor lighting on the exterior, lever door handles on exterior doors, low-maintenance exteriors including porch decking, washing and drying machines raised 12″ above floor, side-by-side refrigerator, laundry chute, grab bars in bathrooms including shower and tub, brightly-lit closets, and etc. have been incorporated into the home.
Efficient insulation and energy conservation were the biggest drivers for the design and energy outcome of the home. Foam is expanded polystyrene (EPS), with 1000 times less environmental impact than extruded polystyrene (XPS). Four linked Geothermal wells, 250’ deep, in a diamond pattern 10 feet on a side, exist within the 30×40’ backyard. A ground-source heat pump was sized accordingly with a reduced load made possible by thick insulation. A solar PV system is used to power geothermal systems and other technologies within the home. This system was sized accordingly through modeling which initially projected an annual consumption of 19,000 kWh. The actual output ended up yielding around 17,000 kWh, more than enough to cover 12,000 kWh consumption in the first year.
You can find out more about this case study from ILFI here.