What would it be like to never pay a power bill again? Mark Kuntz, chief operating officer, Mitsubishi Electric Trane HVAC US, is well on his way to finding out. With a passion for high-performance building, Kuntz decided to put his knowledge to the test after buying an 11-acre property in Monroe, Georgia. Looking to build a home that would consume zero energy, incur no debt and utilize long-lasting materials, Kuntz set his sights on designing a DOE Zero Energy Ready Home.
Harbin customer, custom home builder and energy rater, Imery Group, was selected for the job. Imery Group has been installing Mitsubishi Electric HVAC equipment since 2011 and is dedicated to the green building movement.
“Everything we do as a company focuses on value and quality. Not only the economic value of a high-performance building but the social and environmental values to the greater community as well,” said Luis Imery, owner, Imery Group. After assessing Kuntz’s goals and the property, the team set their sights on building a DOE Zero Energy Ready Home. “This home recognition essentially means that we maximized our efforts and did everything we could to make the house as healthy and energy efficient as possible, prior to the incorporation of renewable energy,” explained Imery.
With these criteria in mind, the project team planned the thermal envelope and mechanical system design for the 1,863-square-foot, two-story home.
“For a home like this, you always start with the building envelope: the exterior walls, the roof and the foundation assembly,” noted Imery. “For Mark’s house, we wanted to have a continuous and air tight thermal envelope. That means insulation that goes around the foundation, the walls and the ceiling, all in a continuous form.”
Imery Group installed below-grade slab insulation to accommodate the horizontal plane of the house. As for the walls, they’re covered in ZIP System® R-Sheathing from Huber Engineered Woods and the studs are staggered in a zig-zag pattern. The home was further insulated with spray cellulose, a recycled paper product. The combination of these materials effectively prevents air leakage, allowing the mechanicals to perform optimally.
“The less wood you have touch the exterior of the home, the more efficient it will be, which is why we used the insulated sheathing and staggered stud walls,” noted Imery. “On a conventional 2×4 wall, you typically place studs 16 inches on center. In this case, we did 2×6 walls (allowing us more insulation) and staggered the studs 24 inches on center for the exterior and 24 inches on center for the interior, off set 12 inches apart.”
Since the home’s completion in December 2018 and review by a third-party green verifier, Home Performance Solutions, the residence has exceeded the entire project team’s expectations. “With the solar panels, the home has a confirmed HERS score of -13. For a conventional, new build home, RESNET references a HERS score of 100 and the Georgia Building Code goes even further, requiring a HERS index of 90. This is a terrific result for Mark,” said Imery. The home also officially meets DOE Zero Energy Ready Home, ENERGY STAR®, EPA Indoor airPLUS and EarthCraft™ certifications and exceeds the 2009 and 2012 International Energy Conservation Code® (IECC). In addition, with the solar panels, Kuntz’s projected energy costs per year total $120. That’s an annual savings of $2,837 compared to the average, new U.S. home.
In a note to the suppliers of this build, Luis wrote, “I’d like to recognize every single one of you for your individual and collective efforts on making the residential home building industry better. As many of you know, Imery Group started getting involved in the green building advisory and sustainable construction world as early as 2009. Through the years we have been blessed with participating on meaningful construction projects which have created the opportunity to increase public awareness for better ways of building homes that are healthy, durable, efficient and comfortable. Without your support in each of your capacities, whether you are a green building organization, a manufacturer or a trade partner we would have not been able to succeed and get were we are now. Thanks you for your efforts on further the high performance industry, and I am convinced that by 2025 what we do will become the new normal.”