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A Company in Midtown Manhattan Brings Fresh, Locally Grown Produce to Underserved Urban Areas by Engineering Green Gardening on a Commerical Scale

[+] Author Notes

Tom Gibson is a consulting mechanical engineer in Milton, Pa., specializing in green building and a freelance writer specializing in engineering, technology, and sustainability. He publishes Progressive Engineer, an online magazine, www.ProgressiveEngineer.com.

Mechanical Engineering 135(04), 38-42 (Apr 01, 2013) (5 pages) Paper No: ME-13-APR2; doi: 10.1115/1.2013-APR-2

Abstract

This article is a case study on BrightFarms, which is a company in Midtown Manhattan that brings fresh, locally grown produce to underserved urban areas by engineering green gardening on a commercial scale. Based in Midtown Manhattan, BrightFarms builds and operates hydroponics greenhouse farms across the United States, mostly at supermarkets. The company tries to use renewable energy sources and waste energy from a host building. BrightFarms now focuses on commercial clients that can handle the high volumes of produce that come out of the greenhouses. The BrightFarms team has expertise spanning horticultural sciences, engineering, ecology, energy analysis, environmental education, and produce marketing. While much of BrightFarms’ work has focused on New York City till date, it is trying to build facilities not only wherever it makes economic sense, but also where it makes sense in the food system.

Article

If you go up to the third floor of the Manhattan School for Children in New York’s Upper West Side and walk out onto the roof, you’ll find a greenhouse. At first glance, it might look like any other, but this one’s unusual because it was created to grow fruits and vegetables using hydroponics in an urban environment. It is part of an effort to grow produce with a reduced carbon footprint by reducing energy use, both in the growing and in transportation to market. Designed by a nonprofit, New York Sun Works, it is called The Sun Works Center for Environmental Studies.

The developer of the greenhouse, BrightFarms Inc., says that this kind of gardening is green indeed.

According to Zak Adams, director of engineering at BrightFarms, “We’re marrying greenhouses with environmental technologies like rainwater capture and renewable energy production. These controlled-environment agriculture facilities can produce ten times the amount of food in a given area compared to conventional soil agriculture.”

Talia Calnek-Sugin of New York Sun Works tends nasturtiums, a favorite in the rooftop greenhouse because both leaves and flowers are edible.

Photo: Tom Gibson

Grahic Jump LocationTalia Calnek-Sugin of New York Sun Works tends nasturtiums, a favorite in the rooftop greenhouse because both leaves and flowers are edible.Photo: Tom Gibson

Based in Midtown Manhattan, BrightFarms builds and operates hydroponic greenhouse farms across the United States, mostly at supermarkets. The greenhouses typically produce lettuce and other salad greens; leafy greens such as chard, kale, and mustard greens; herbs; tomatoes; peppers; and cucumbers.

Extensive engineering goes into a typical BrightFarms greenhouse project. “Structural considerations are always a big challenge when we start an initial design,” Adams said. “We want to make sure the building underneath us can not only handle our load but also has the proper membrane on the roof so we don’t disturb any aspect of our host building’s operations.”

He described the existing roof structure at the school as “beefy,” adding that greenhouse structures are not relatively heavy. Most roofs in the Northeast, for example, are already built to support a snow load of 40 pounds per square foot, roughly equivalent to that of a greenhouse. The school has an aggregate roof with multiple epoxy membrane layers, so BrightFarms peeled off and removed the membrane, leaving enough to overlap onto the greenhouse.

BrightFarm’s rooftop greenhouses are carefully designed to provide water and steady temperatures without overloading the building’s structure..

Photos: courtesy of BrightFarms

Grahic Jump LocationBrightFarm’s rooftop greenhouses are carefully designed to provide water and steady temperatures without overloading the building’s structure..Photos: courtesy of BrightFarms

With the roof providing adequate overall structure, the concern shifts to point loading. The roof has girders, or I-beams, every 15 to 20 feet, but these didn’t match the spacing of the loads, mainly water tanks, in the greenhouse. So the company put in dunnage I-beams perpendicular to the girders for additional support and placed the loads over the girders as much as possible.

’Because we use rainwater catchment in our facilities, we want to store as much water as possible. That can be diffi cult,” Adams said. “You might need to come up with schemes for how to store the water. Store it at ground level and maybe pump up to a smaller tank at night when electricity’s cheaper and less in demand, for example. Or, as you can see with this facility, position your water tanks directly over very strong points in the roof, where girders intersect or where there’s a dunnage stage or an elevator bulkhead.”

A 50,000-square-foot greenhouse will grow about 500,000 pounds of produce a year.

Grahic Jump LocationA 50,000-square-foot greenhouse will grow about 500,000 pounds of produce a year.

The school greenhouse has single-pane glass around the sides and double-layer polycarbonate on the roof, which is actually the opposite of how it would normally be done. Normal greenhouse construction uses glass in the roof to get the most sun exposure. You want the roof as clear as possible because that’s critical to plant growth. However, school rules would’ve required safety glass with wire in it to provide extra protection for students, and this would’ve been extremely expensive. BrightFarms used glass for the walls mainly so the students could see out better.

Adams said that the BrightFarms greenhouse grows food using a fraction of the land and water of conventional methods and produces no agricultural runoff.

The company tries to use renewable energy sources and waste energy from a host building. If an adjacent building generates waste heat from a process, that too can be piped into a greenhouse.

The founder of BrightFarms, Ted Caplow, recalls how he got started. “I visited a large-scale hydroponic vegetable greenhouse in 2005, and I was immediately hooked,” Caplow said. “To me, hydroponics represented a fusion of engineering efficiency and grassroots food production, and the challenge of applying these ideas to the congested urban environment was immediately appealing.”

Born in New York City, Caplow has a B.A. in sociology from Harvard, an M.S. in mechanical and aerospace engineering from Princeton, and a Ph.D. in environmental engineering from Columbia. His expertise lies mainly in the area of integrated system design, with specialties in renewable energy, water contaminant dynamics, and technology assessment.

In 2006, Caplow founded New York Sun Works to promote the use of hydroponic greenhouses for sustainable urban agriculture. In 2007, NYSW launched the Science Barge, a prototype urban farm. Constructed on a steel deck barge and moored on the Hudson River, the Science Barge serves as a public demonstration of renewable energy supporting sustainable food production. Its greenhouse electrical systems are powered by sun, wind, and biodiesel. The Science Barge also acts as an environmental education facility.

“Hydroponics Represented a Fusion of Engineering Efficiency and Grass-Roots Food Production, and the Challenge of Applying these Ideas to the Congested Urban Environment was Immediately Appealing.”

Visitors explore the hydroponic gardens aboard the Science Barge, a floating food production facility powered by wind, solar, and biodiesel.

The Science Barge, moored in the Hudson River in Yonkers, New York, also serves as an environmental education facility.

Photos: courtesy of BrightFarms

Grahic Jump LocationVisitors explore the hydroponic gardens aboard the Science Barge, a floating food production facility powered by wind, solar, and biodiesel.The Science Barge, moored in the Hudson River in Yonkers, New York, also serves as an environmental education facility.Photos: courtesy of BrightFarms

Ted Caplow, Founder, BrightFarms.

Photo: courtesy Ted Caplow

Grahic Jump LocationTed Caplow, Founder, BrightFarms.Photo: courtesy Ted Caplow

Caplow founded BrightFarm Systems in 2008 as a consulting firm providing technical services for rooftop greenhouses and building-integrated agriculture. Then, in January 2011, the company took its present form.

The initial mission of BrightFarms has been to establish sustainable urban agriculture and educate people. The greenhouse at the Manhattan School for Children opened in 2010 as a project of NYSW. It serves over 700 students from kindergarten through eighth grade in addition to training educators from around the world.

BrightFarms now focuses on commercial clients that can handle the high volumes of produce that come out of the greenhouses. BrightFarms signed what may be the first long-term produce purchase agreement under which it will deliver local produce year-round to McCaffrey’s, an independent chain with grocery stores in Pennsylvania and New Jersey. A 50,000-square- foot greenhouse in Yardley, Pa., will grow about 500,000 pounds of produce a year.

The BrightFarms team has expertise spanning horticultural sciences, engineering, ecology, energy analysis, environmental education, and produce marketing. The 32-year-old Adams has been with BrightFarms since it started and is responsible for overseeing all design and engineering duties. He has played a role in the design and building of all the firm’s greenhouses to date.

Adams has a B.S. in human ecology and agroecology from Rutgers University and an M.S. in ecological design from the University of Vermont, and he’s LEED AP certified. According to Adams, “If anyone asks me what my real profession or trade is, I always say ecological engineering because it’s a mix of taking the built environment and mixing it with the natural environment and marrying them to create a functioning system that serves a purpose for humanity. I’m definitely a student of biomimicry.”

While Adams does the in-house engineering, he said BrightFarms also shops out much of its engineering work. On any given project, it will have a structural engineer, an MEP engineer, and depending on the project, perhaps a civil engineer. “Those are really key partners on the design project team,” Adams said. Teams change from state to state, because of licensing requirements.

Besides structure, an important facet of a roof-mounted greenhouse is heating and cooling. Typical of greenhouses, the school’s facility has a hierarchy of HVAC systems. The first stage of temperature control is a side guillotine vent with panels that slide up and down like windows for natural ventilation. Fans are the second stage; two big ones loom at one end of the greenhouse. The third stage is an evaporative cooling system in the wall at the other end of the building.

The final stage is aluminized plastic curtains, polypropylene with aluminum strips threaded through them; the aluminum reflects heat, like a space blanket. They cover the roof most commonly but can also be used on the walls. A motor and push rail system controlled by a computer opens and closes them. It generally extends the curtains at night when the interior air temperature falls below 60 °F. They will be drawn back just after sunrise, unless it is cloudy. An air-source heat pump is available mainly for heating.

The greenhouse’s rainwater harvesting system gathers water in gutters along the lower edges of the roof, as on a house. From there it flows to two 350-gallon HDPE tanks that are connected to act as one. A small flotation tank on one of the tanks siphons off the first 40 gallons to catch dirt and debris, which are flushed out. The system, which provides most of the water the greenhouse needs, operates at 40 psi and has a UV lamp filtration system to sterilize the water. All the growing systems have reservoirs with a float valve and pump.

The greenhouse is controlled by a PC-based system, which most commercial greenhouses have. The computer monitors data such as indoor and outdoor temperature and tries to keep it 75 degrees indoors during the day and 65 at night, for optimal plant growth. The computer also controls lights, pumps, nutrient levels, and water levels. Technicians can log operational and environmental data to see how systems are performing and what technologies are working well.

At the core of the plant production process, rows of small plants growing out of tubes mount on sawhorses. The tubes have a thin layer of water in them. The plants actually start life in trays, where they stay for about two weeks before moving to the tubes in a process known as succession planting. Constant rotation of the plants assures a consistent harvest. In another area, vines grow out of a tub on the floor, yielding tomatoes, cucumbers, and peppers.

Photos Courtesy Tom Gibson & Bright Farms

Grahic Jump LocationPhotos Courtesy Tom Gibson & Bright Farms

While much of BrightFarms’ work has focused on New York City, Adams reveals, “We defi nitely have a desire to spread the model on a global scale. We are trying to build our facilities wherever it makes economic sense but also where it makes sense in the food system: in semi-urban to urban areas underserved by the conventional food system and with a need for fresh local produce. Anywhere where there’s a seasonal lack of fresh produce our model makes sense.”

Copyright © 2013 by ASME
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