This edition of the Phius Project Spotlight Series highlights the Iowa City Nest home in Iowa City, Iowa.
Our monthly Project Spotlights highlight the cutting-edge work being done by Phius professionals and provide examples of successful design and construction strategies. We feature projects of various sizes, typologies, and climate zones, offering you a peek behind the curtain of each.
Our June Project Spotlight is: Iowa City Nest in Iowa City, Iowa! Iowa City Nest was chosen as the winner in the Single-Family category of the 2023 Phius Passive Projects Design Competition.
The Iowa City Nest is a new construction Phius Certified home on an infill lot in Iowa City. It was designed to be a cost-effective, contemporary home, and was largely shaped by the constraints of site context and passive design strategies.
The home is carefully sited to preserve existing trees, and presents a low profile to the street to fit in with the scale of neighboring homes. A second story is tucked to the rear, and a tandem garage takes advantage of rear alley access. Large windows to the south take advantage of passive solar gains, and its simple, compact form achieves excellent performance on a budget.
The existing trees proved a particular challenge, as their shading was detrimental from a passive standpoint. The team developed a methodology for more accurately modeling deciduous trees in WUFI Passive, which allowed us to both preserve the trees and achieve Phius targets.
The home uses thick layers of cellulose for insulation, with 12” TJIs on the walls and 24” of cellulose in the roof. MEP systems include a Zehnder ERV, heat pump water heater, and ductless mini-splits. Plumbing and ventilation systems were laid out early in design, which kept the systems compact and efficient. The use of conventional materials and straightforward, off-the-shelf systems kept both material and installation costs low. A6.2 kW solar array provides 100% of the home’s net site energy needs on an annual basis.
In addition to the home’s energy efficiency goals, the team sought to reduce the embodied carbon of the home’s materials. The choice of cellulose insulation and engineered wood cladding reduced embodied carbon significantly compared to a conventional assembly. On the interior, the light, Scandinavian-inspired finishes were selected both to reduce embodied carbon and promote good indoor air quality.
The design utilizes passive building details as opportunities for architectural expression. The 12-inch insulation blanket peels away at the garage, creating aesthetic interest without added cost.
The home was designed between 2018 and 2020; constructed from 2020 to 2021; and received Phius Certification in 2023.
The result is a light-filled, low-carbon, contemporary home that provides exceptional energy efficiency on a budget.
All photos courtesy of Sol design + consulting