Cost: One 1976 Morris Mini Minor
A walk around the house reveals a shed that houses a water heater and biodiesel burner system for the home’s latest addition. In 2007, after the home’s diesel furnace gave out, Candace was faced with the decision of how best to provide heating for the house. She wanted to use a renewable energy source for heating, but she wasn’t exactly sure how to go about it and whether she could afford to do it. Short on funds, she got creative. She ended up contacting Juaning Higgins from Portland Green Heat to help create a heating system that would use biodiesel as the heat source, but keep the combustion unit separate from the living space. Candace bartered an even exchange—her 1976 Morris Mini Minor (a precursor to BMW’s Mini Cooper) for a new furnace.
The blower remained in the utility room, and a hydronic radiator coil with 130,000 Btu capacity was installed in the old furnace cavity above the blower. The biodiesel burner was located outside in the shed, along with an expansion tank, biodiesel pump, and pump control box that was modified for B99—99% biodiesel fuel.
The furnace’s relay and transformer are managed by a New Vision Pro 8000 touch-screen programmable thermostat, with a remote for upstairs. Two 110-gallon storage tanks in the laundry room hold the B99 fuel. Initially the furnace was burning 3 to 5 gallons of biodiesel fuel per day, but once Candace insulated the shed and wrapped the tank and pipes with insulation, usage dropped to 0.5 to 1 gallon per day. With new insulation added between the floor joists, and blown-in cellulose in the walls, the furnace and hydronic baseboard heaters (which are connected to the solar hot water system) keep the house comfortable.
Using a 240-gallon cedar hot tub that she found on Craigslist, Candace and several of her students installed a solar hot tub in the backyard. Mr. Sun Solar handled the technical aspects of the installation.
The finished system relies on a used, 32-square-foot solar thermal collector. The hot glycol from the collector runs through cross-linked polyethylene (PEX) tubing underground into a coil of copper at the bottom of the tub.
The controller from Independent Energies allows the hot tub to reach temperatures up to 109°F before the pump shuts off. Polystyrene spray-foam insulation (R-7 per inch) in the tub’s lid, walls, and bottom help keep the tub hot for days in sunny weather. The cost to run the system’s pump and supplemental electric heater is about $176 per year.
Candace also designed a simple rain collection system—nine 60-gallon barrels along the north side of the house and six 30-gallon barrels along the straw bale structure—to collect rainwater from the roofs. When the first barrel fills, overflow goes into the second barrel. The barrels can store 740 gallons of water for most of the summer garden’s needs.