Many farmers like the connection to the land that comes with growing plants, but Butler University’s Center for Urban Ecology Farm’s new cropland is on wheels. The GrOwING GREEN project, designed and constructed by a group of fourth-year architecture students at Ball State University, is the first fully automated mobile greenhouse.
Representing a collaboration of Butler and Ball State, the greenhouse is the fifth design-build project by students at the College of Architecture and Planning in support of urban farming in Indianapolis, says Tim Gray, associate professor of Architecture at Ball State, whose students previously designed and built the CUE Farm’s mobile classroom, made from a shipping container.
Funded by a Butler University Innovation Fund Grant, the $50,000 greenhouse prototype was created because of a building code issue. “The farm is in a flood plain, so we couldn’t build a permanent structure,” Gray explains. Realizing that many urban farms face land access challenges that could be appeased by a mobile growing platform, the college embraced the idea as an educational opportunity and a model for others.
“Urban farming is growing at a phenomenal rate,” Gray observes. “It’s becoming mainstream. Even Mayor Ballard supports it and encourages it on abandoned and vacant properties. But there’s not a lot of architecture typology.”
Gray and his team, which includes 14 Ball State students, Travis Ryan, chair of Butler’s Biology Department, which oversees the farm, and Tim Dorsey, farm manager, have now established a typology.
Over the course of two semesters, they designed a controlled environment to cultivate plant starts for the CUE farm. The plan began with a 32-foot flatbed trailer from I-69 Trailers that was custom-fabricated to their specifications. “It was hand-cut, welded and built by students in Muncie,” Gray recalls, noting that the electrical and irrigation systems were professionally installed.
The powder-coated steel tube frame is wrapped with a 2x2 fiberglass furring system. The skin a is double-wall polycarbonate panel. Windows are operational, connected to heat-sensitive sensors that require zero energy.
The unit does feature heating and air-conditioning. Fans operate on a thermostat. The greenhouse “plugs into an exterior port like an RV would,” Gray details, expressing measured concern about the power cost. “Butler provides the power, and because it’s an educational project, it’s not our primary concern. The requirement of growing year-round trumps efficiency.”
Besides, he adds, it’s a trade-off: passive ventilation should allow them to run without air conditioning or heat most of the year. However, Gray acknowledges that heating the greenhouse will be a challenge in the dead of winter.
Dorsey points out that winter temperatures will impact the greenhouse more significantly because it’s elevated, allowing cold air to circulate underneath the structure. However, they situated it to maximize the angle of the February sun in order to take advantage of as much passive solar heat as possible. Ultimately, though, he says the plan is to extend the growing season, but not use the greenhouse all winter.
Extended planting season
The intent is to start seeds in early spring and in June. “That was our primary need,” Dorsey says. “That drove the project. We used to use grow lights before or pay other farmers to grow starts for us. Now we’ll be able to manage that here.”
The CUE farm is about one acre in size. Dorsey hopes to plant in succession for continued harvesting. The ability to control the timing of starts and transplants will aid in reaching that goal.
Inside the greenhouse, the growing space is 8x32 feet, with bays of adjustable shelves for better use of the growing space. The design focused on placement on the farm where it will get the best sunlight and shelving to house the optimum number of plants.
Adding further flexibility is the four-zone misting and irrigation system that is customizable to different times of the year and different plant needs.
The interior structure is built of galvanized metal over recycled Trex composite wood decking. Siding and benches are constructed of cedar. “Because the farm uses no pesticides and no chemicals, we minimized the use of wood and chose cedar because it is decay-resistant,” Gray explains.
Goals and applications
What Gray describes as “our most ambitious student-built project” won a 2016 American Institute of Architects Indiana Design Award based on architectural excellence. The innovative and functional greenhouse on wheels, constructed with high-level craftsmanship, set the bar for future mobile designs. But now, it is “just” part of the farm, Gray indicates.
As such, it will play a role in academic internships, tours and classes on sustainable agriculture. Serving as a prototype for urban farming operations, it will inspire conversations, innovations and new projects in underutilized and abandoned urban areas, as well as locations compromised by restrictive building codes and problematic topography.
“A lot of urban farming happens in marginal areas that are challenged in different ways, like floodplains,” Ryan observes. “The idea of making something that’s mobile that might be able to exist and support facilities in these areas is interesting.”
Gray points out that with urban renewal, the city landscape can shift. Therefore, a mobile greenhouse offers a limitless future not subject to the changing face of urban planning. “It works on marginal properties subject to the whims of development.”
He reports that other communities have already expressed interest in the design, including cities as far away as Liverpool, England. “Bringing the farm to the community alleviates the problem of food deserts in the inner city.”
Gray towed the completed unit to the Butler campus with his F150 truck, proving the technical possibility of a truly mobile greenhouse. However, admitting that the initial conception of literally taking the farm to the community by driving it to various locations became unfeasible, he still believes the GrOwING GREEN project is useful.
“It’s a great tool for outreach, to support urban farming, promote education and generate community engagement.”
Someday, it also might be a money-maker for the college. “It could grow into other uses,” Dorsey imagines. “We could grow extra transplants for sale … flowers and other things for sale ̶ maybe later, greens to finish to sell to local restaurants. That would be a revenue source.”
He also expects this unique mobile growing contraption to drive more traffic to the farm, which will also increase revenue. “As a university-based project, it has a dual-track mission. We do our best to sell, but the educational opportunity is important. We don’t need to operate as a commercial enterprise.” But proving that they could be economically viable might secure the future for mobile greenhouses.