The American Institute of Architects (AIA) Tennessee chapter brought their 2014 convention attendees to see the Little Green House, Nashville, Tennessee. As they said, the home “serves as a model for right-sized sustainable residential development.” The visitors to the Little Green House admired its aesthetic and small size (at just over 1,100 square feet). They also studied the home’s angled tin roof, cantilevered second floor and charred oak siding. These details, as well as the rain garden out front and a glass garage door in back, are more than aesthetics; they are what make the Little Green House so green. These details also played a role in the home becoming one of the area’s first passive solar houses.
Challenge: To install an HVAC system that would support sustainable building.
The lot that the house now sits on was passed over by many builders before one took interest. That builder was Ryan Nichols, co-founder, Green Home, Nashville. Nichols uses green technology and progressive design concepts to build custom homes. “This space was tricky to build on,” Nichols said. “The topography is steep and the lot is small, so more conventional builders passed it up.” Nichols was ready for the challenge and partnered with local energy consultants, designers and contractors.
The team used the lot’s limited square footage as inspiration for a design that would complement passivity. The team chose the orientation that best furthered their energy goals, and explored how a roof overhang would control incoming sunlight.
Another big consideration in achieving passivity was the HVAC system. “We wanted this house to be on the cutting edge technologically,” Nichols said with his eye on dual-zone technology. “I used to live in Japan. These types of systems are quite common there.”
In the U.S., Nichols said that for “the last several years, there’s been a push for geothermal. But it’s quite invasive and there’s a lifespan on it.” Beyond this concern of sustainability, Nichols also considered the serviceability of the chosen system. He said, “[A dual-zone system] just makes a lot more sense to me in that you can service the parts. It’s a huge advancement from a technological perspective.”
Nichols brought in Kevin Allen, founder, Complete Comfort Solutions, Nashville (at the time an employee with South Nashville Heating & Cooling), to specify the system and conduct the installation. Allen said, “I fell in love with this technology years ago. It has a high SEER rating and you can individually control each room. You can cool one-sixth of your house, for example, instead of having to cool the entire thing.” This is especially crucial in a passive house where energy expenditures must remain as small as possible.
Solution: A dual-zone system from Mitsubishi Electric provided an easy installation and bolstered a sustainable design.
Allen was particularly impressed by the offerings of Mitsubishi Electric US, Inc. Cooling & Heating Division (Mitsubishi Electric). “They have a great infrastructure, there’s product availability and they know what the U.S. customer wants. Ultimately, the Mitsubishi Electric equipment and what it can do is second to none.”
The team selected a Mitsubishi Electric M-Series dual-zone heat pump system. “This was a smaller house; it’s under half the size of the average American home. When you have a smaller house, air ducts become a problem. You don’t have a lot of room the way big houses do with spare closets or attics. This technology eliminates a lot of that extra ductwork. So the installation was easy,” Nichols said. “The installation was flawless,” Allen added.
Life post-installation in the Little Green House has involved much happiness, too. Hana Elliott, who owns the Little Green House with her husband, Jake Elliott, said, “the unit is discreet and unobtrusive, which we love. When people do notice it, or notice that it’s ‘cool’ to control settings via remote, it ends up being a great conversation starter.” Hana was also pleased that the look of the ductless HVAC system “fits into our modern home.”
Dual-zone systems are also known for quiet operation, a feature the Elliotts value greatly. When Hana said the system is “very quiet,” she was not exaggerating: the systems run at no louder than a human whisper. The Elliotts also appreciate the greenness of the Little Green House and their Mitsubishi Electric equipment. “We feel like we are using something with lower environmental impact,” Hana said. Hana noted that they pay on average $75/month for electricity. The U.S. Green Building Council took note of the home’s high sustainability and granted it LEED® Platinum status.
Nichols recognized the success of the iconic Little Green House and said Mitsubishi Electric will continue to play a role as his team sets out to complete more sustainable projects in the area. “It’s a good technology,” Nichols said, “I’m hoping to use more of it.”