BRIGHT-MINDED HOME – August 2013
By Melissa Coleman

Q+A with Justin McIver of Main Eco Homes

We asked designer and general contractor Justin McIver what he’s learned from building and living in his first net-zero model home in Sweden, Maine.  

Q:Howdoyoubuild a home that uses less energy than it produces?
A:   Build only what you need.  Create a tight, well-insulated building envelope with controlled ventilation.  Site for passive solar, and put living areas in southern exposure and bedrooms in northern.  Reduce electric loads with an efficient electric heating system, LED lights, and Energy Star appliances.  Include alternative energy sources such as photovoltaic solar.  Live a low-impact lifestyle.

Q:Which energy-efficient products performed best?
A:We were amazed by the Mitsubishi Mr. Slim mini-split heat pump’s ability to heat a 2,000-square-foot home located on a windy mountain, while using a third of the electricity of a normal baseboard. We were able to save $10,000 on less expensive R5 triple-glazed windows by adding insulated honeycomb blinds to get to R10.

Q: Anything you’d do differently next time?
A:  Instead of the backup baseboard heater I’d like to try connecting an inline electric heater and thermostat to the heat recovery ventilator (HRV). We’ve also found a double wall with recycled cellulose insulation to be a better, cleaner, and less expensive alternative to foam board and spray-foam layers. Lastly, the three floors provide more space than two people need, so the resources for the third floor could be used for a garage instead.

Q: What’s next?
A: We’ll find out this year if the 6.8-kilowatt solar array is enough to get us to net zero. Our total energy bill in January was $149 and by May had gone down to $9. We expect to come out even with solar credit over the summer, but if needed, we’ll simply add more panels.