CoolingMinisplits At Center Of Zero-Net Energy Home

A builder makes homes heated and cooled with just two minisplits.

Given the greater swings in temperature throughout the year in Massachusetts, the feat of Carter Scott is all the more impressive to those of us in Bellevue and Redmond. The builder has put up 18 homes heated and cooled entirely with just two ductless minisplits.

Just Two Minisplits Heat and Cool an Entire Home

How did he do it? Builder Carter Scott defeated the critics in 2009 by building homes with two minisplits – one in the downstairs living room and one in the upstairs hallway. Using high-R walls, triple-glaze windows and minimizing air leakage, he managed to make these homes comfortable, without the cost of ductwork and with low-energy heating and cooling sources.

Other Design Features

By adding a 5.7-kW roof-mounted photovoltaic array, he managed to make the home self-sufficient on energy, making it a zero-net energy house. The most enthusiastic responses from homeowners marveled at the even temperatures obtained with this system and the total lack of a utility bill.
The units heated an area of 1,232 square feet, admittedly making these homes a little small. Scott insulated basements with 3″ of closed cell spray foam and R-30 fiberglass batting for a total R-value of 50. The basements were not conditioned, further saving energy.
Walls were made with 12-inch-thick double-studs, offering wide insulation pockets to fill with 3” closed-cell spray foam and 9″ cellulose, again R-50 value. The sloped ceilings were sprayed with 5″ closed-cell spray foam and 13″ cellulose, giving them an R-value of 64. The siding was vinyl.
Mechanical ventilation was required to accomplish the feat as well. Water was heated using a solar thermal drum system with electrical resistance backup.
The design won Scott second prize in the Zero Energy Challenge, sponsored by the area utility companies. The winner, Bick Corsa Construction, built a 1,152-sq.-ft. home, which produced more energy than it used.
Scott has managed to build larger homes with just two minisplits, including one measuring 2,000 square feet. In one case, he built a house using just one downstairs unit. Although the home was adequately heated, the upstairs became too hot in summer and he decided to stick with his original design. He continues to weak things with the goal of minimizing cost to the homeowner while maximizing efficiency.

Seattle’s First Net-Zero Energy Home

Massachusetts may have beat us to the punch, but we know of one Washington net-zero energy home in Ballard. Homeowner Eric Thompson built a home that uses more energy than it produces, just trying to own a budget-friendly home. With rebates and incentives, he and his wife spent $178,000 on construction for a total cost with land of almost $400,000, but they got back $9,000 in cash rebates in 2011 and will get $1,000 a year in energy incentives until 2020. That home also uses heat pump technology like that in a minisplit.

Talk to MM Comfort Systems about Affordable Minisplit Systems

If you’re looking into building a net-zero energy home, minisplits and heat pumps are both excellent options for heating and cooling. Call us at 425.533.9058, or use our online contact form to set up a free energy efficient heating and cooling consultation.


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