In 2014, green|spaces, a nonprofit that works to advance the sustainability of living, working and building in Chattanooga, Tennessee, hosted a competition challenging participants to design a zero-energy, affordable home. The winning design was a 1,700-square-foot home featuring Hyper-Heating INVERTER® (H2i®) technology from Mitsubishi Electric Cooling & Heating (Mitsubishi Electric) Zoned Comfort Solutions™. The neighborhood is complete with four homes now featuring this design.
Michael Walton, AIA, LEED AP, executive director, green|spaces, worked with Chattanooga-based firm Workshop: Architecture and other consultants to bring the houses to life. He said, “Chattanooga really saw what happens when you forget about environmental sustainability and do what’s expedient and cheap. The problem is…builders say no one is asking for sustainability while homeowners say no one is providing it. So this project is meant to say, ‘no, look, you can build it and you can ask for it.’”
The HVAC engineering team had quite the challenge with Chattanooga’s short but significant heating season, a very significant cooling season and high humidity most of the year.
Kim Ray, vice president, Conditionaire Company, Inc., Chattanooga, designed the HVAC system on the winning entry and eventual build. He said, “The houses’ biggest need was energy efficiency to achieve net-zero. We promoted ductless because of the INVERTER technology and zoning applications, and also to hold the costs down with the limited amount of space to do ductwork.”
Walton agreed with the selection of zoned technology. “The biggest drivers for the mechanical systems were efficiency and resilience. We considered several options – as we did with each element going into the homes – and we knew electric heat pumps were the answer. Ground-source, for example, would have been too expensive, killing our budget. We needed not just the most efficient system, but the most efficient for the money.”
With the houses completed and on the market, the project team now looks forward to learning who the lucky homeowners will be. Why lucky? “Between the solar array and other efficiency strategies, the homeowners won’t have a utility bill,” said Walton.
To read more about the NextGen Homes project, check out the full case study here.