State of the Planet

News from the Columbia Climate School


How Sustainable is Vertical Farming? Students Try to Answer the Question

Sky Vegetables in the Bronx
Sky Vegetables in the Bronx

The world’s food system is beginning to strain under a global population expected to reach nine billion by 2050, by which time the planet’s arable land is projected to be half of what it was in the 1970s. And as climate change threatens long-term food security, agriculture will need to produce 70 percent more food to feed an increasingly crowded world.

Today’s agricultural systems are not as efficient or sustainable as they should or could be: Agriculture uses 80 percent of freshwater and produces approximately 24 percent of the world’s greenhouse gas emissions; pesticide use causes runoff that pollutes rivers, lakes and oceans.

At the Capstone presentation
At the Capstone presentation

Moreover, the average item of food travels approximately 1,500 miles before it reaches our plates, resulting in wasted food and more greenhouse gas emissions.

Vertical farming—the growing of crops (up rather than out) in a closed stacked system— is one promising solution to the drawbacks of traditional agriculture. Compared to traditional agriculture, vertical farming uses 70 to 95 percent less water and over 90 percent less land, while harvesting 80 percent more per unit of area. The Association for Vertical Farming, a two-year-old nonprofit focused on advancing the industry, says that vertical farming allows farmers to produce crops all year round because all environmental factors are controlled. It produces healthier and higher yields faster than traditional agriculture, and is resilient to climate change. Moreover as the global population becomes more urbanized, vertical farms can help meet the rising demand for fresh local produce.

There are many kinds of vertical farms, differing in the type and square footage of buildings or rooftops they occupy and the mode of light used (daylight or LEDs). Crops can be grown using hydroponics, in water or a growing medium with nutrients delivered directly to their roots; aeroponics, where a mist delivers nutrients to plant roots; aquaponics, when fish are raised concurrently and their waste is used as nutrients for crops; or even in soil if the building is designed accordingly.

Edenworks uses aquaponics technology
Edenworks uses aquaponics technology

The 109-member, Munich, Germany-headquartered Association for Vertical Farming challenged a group of students in Columbia University’s Master of Science in Sustainability Management program, who must work in teams with real clients for their final capstone projects, to come up with a certification system to assess the sustainability of vertical farms. Ideally, the certification system would be able to define the criteria for a credits-based sustainability rating of farms, recognize farms operating sustainably, and provide a best practices guide for existing and new farms to become more sustainable.

“The challenge The Association for Vertical Farming is facing is how do you manage the growing industry of vertical farming,” said Kiley Miller, one of the project’s student managers. “As that growth continues, you need to make sure that these operations are sustainable, and not impacting water resources and energy use. There’s a lot of focus on food as a sustainable piece, but not as much on entire farming systems, and operations and management structures. So The Association for Vertical Farming is trying to figure out a way to standardize systems performance across the industry and within the farms, and to identify best practices and benchmarking baselines so it can engage with these farms and ask how can we improve, how can the industry improve as a whole.”

Students, from left: Michelle Bostwick (team member), Kiley Miller and Katie MacDonald (managers)
Students, from left: Michelle Bostwick (team member), Kiley Miller and Katie MacDonald (managers)

Henry Gordon-Smith, vice chair of The Association for Vertical Farming and an alumnus of the Master of Science in Sustainability Management program, said that because vertical farming is a rapidly growing and young industry, it is important to develop a strategy capable of defining its impacts early on. While the benefits of vertical farming seem obvious, its real effects are complex and need to be quantified since they might be subject to greenwashing. For example, “They might be growing a big yield in a small space, but be using a lot of energy to do it and not talking about that,” he said. “Or they might be using less water, but it might have nutrients in it that could cause problems for the urban water system.”

Susanne DesRoches, the capstone’s instructor, divided her 14 students into two teams. One team was tasked with investigating other certification systems such as LEED, Energy Star and USDA Organic to figure out how established systems do their benchmarking. The other team researched vertical farms in the New York and New Jersey area, visiting nine farms and conducting 17 interviews with growers.

One farm that particularly impressed the students was Sky Vegetables in the Bronx, which is building sustainable, commercial-scale hydroponic farms on urban rooftops across the country.

Sky Vegetables
Sky Vegetables

Based in a LEED building, the Bronx farm grows fresh, chemical-free produce, which it provides to local residents and restaurants, and creates jobs and educational opportunities.

After researching other certification systems to understand the types of systems and frameworks that exist, the students broke them down into various principles and criteria. They considered the feedback from the vertical farms and the main indicators the farms said were important to measure for systems performance. They also looked at what the Food and Agricultural Organization of the United Nations determined were key indicators for a sustainability assessment of food and agriculture systems. Finally, the students settled on nine key principles by which to assess the sustainability of vertical farms.

  • Health and safety
  • Food safety and quality assurance
  • Pest management and pesticide use
  • Nutrient management and fertilizer use
  • Water conservation and management
  • Community relations
  • Waste management
  • Energy and climate
  • Site and facility characteristics.

Within these nine principles are 50 more specific metrics to be measured. The students then tried to figure out how to relate these to the certification systems they had studied to determine what kind of system would work best for the farms.

The big challenge they faced was gathering the systems performance data necessary to establish a baseline of best practices and benchmarking numbers. Several farms had data to offer, but the majority did not. There is not yet enough data available to be able to determine what metrics can or should be considered sustainable—for example, to say definitively that X number of kilowatt-hours of electricity use is considered sustainable for a farm of a particular type or size. And without data and benchmarks, it’s impossible to create a certification system.

“Most of the farms are new. Their average age is 6 years old, and they’ve previously had no incentive to collect this data and track it and record it,” said Katie Macdonald, the second student manager. “It’s resource intensive, and at these farms there are not many on staff, so it would be costly to do.”

Gordon-Smith knew beforehand that there were gaps in the data. “Farms don’t want to reveal their costs because it is a competitive business,” he said. But he felt it would be valuable to have the students dive in and do the research from scratch, taking a fresh look at what the association might do.

Glen Halperin presenting the team's recommendation
Glen Halperin presenting the team’s recommendation

On Dec. 8, Glen Halperin presented the team’s findings to The Association for Vertical Farming at the final briefing of the Capstone Workshop.

The students’ final recommendation is that the association set up its own certification system, phasing in a framework based on the 50 metrics related to the nine key principles.

Phase 1 would collect data for 24 metrics, for example on energy use intensity, total growing area and growing medium. Phase 2 would introduce more metrics measuring total annual waste, pesticide usage and packaging. Phase 3 would include the remaining metrics on annual water use, average food miles and community education.

Farms would be scored based on the total number of metrics for which they submit data, starting immediately with a simple score derived from data some farms can provide now.

The capstone team envisioned how the system would evolve over the next number of years: Phases 1 to 3 involving data disclosure might take up to three years; in year four, benchmarks could be established; in year five, the benchmarks could be reviewed and refined to ensure that they truly represent the desired standards; and the performance credit system could be launched in year six. In a few years, with data collection ongoing, The Association for Vertical Farming will be able to analyze industry trends and establish minimum performance standards for vertical farms.

Harlem Grown
Harlem Grown

The $2.36 billion invested into the AgTech sector in 2014 is an indication that agriculture is undergoing a transformation as new technologies are being integrated. Vertical farming is a fast-growing sector of AgTech. In 2014, “indoor agriculture” received $175 million in investment, including $36 million for Aerofarms, the world’s largest indoor vertical farm for leafy greens, being built in Newark, N.J., and $8 million for Gotham Greens in New York City and Chicago.

With the fast growth of these new technologies, Gordon-Smith is pondering a larger question: “How do we set standards for emerging technologies to balance business and sustainability? Vertical farming embodies this question. When do we need a certification scheme? When is the market big enough?” He believes it’s essential to find answers so that the people investing money and resources into these new technologies are motivated to develop them in socially and environmentally sustainable ways.

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Congratulations to our Columbia Climate School MA in Climate & Society Class of 2024! Learn about our May 10 Class Day celebration. #ColumbiaClimate2024

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7 years ago

More people should be using hydroponics to grown fresh vegetables at home. Hydroponics doesn’t take up much space and the plants grow fast. Many people in rural areas have gardens and people in urban areas should use hydroponics to have their own as well.

Gupta S P
Gupta S P
5 years ago

2G + 3G L1 + 4G LC greenhouse technology

Dear Sir

Kindly spare a moment to have a look at the attached presentation and circulate the same among your Honorable members and advise your interest.

I have built a 500 m2 prototype greenhouse the images of which together with standing crop would be uploaded on Facebook in the coming 3 to 4 weeks and on our following website :

It is respectfully suggested that you may kindly approach your government with a request to finance or subsidize the outright purchase of this technology , for all the greenhouse growers and greenhouse manufacturers on the premise that this technology considerably reduces global warming

Kindly also advise the existing greenhouse acreage in your country

2G greenhouse comprises multiple inventions :
3G L1 greenhouse inventions comprises improvements over 2G greenhouse inventions and
4G LC greenhouse inventions comprise improvements over 3G L1 greenhouse inventions comprise :
1) A method for almost free of cost greenhouse supplementary heating and almost free of cost hot air for numerous needs in cold locations which obviates burning fossil fuel and saving very substantial cost of fossil fuel leading to reducing global warming.
2) A method for almost free of cost heating residential , commercial , office and industrial units etc (Premises)
3) A method for almost free of cost greenhouse supplementary cooling saving substantial cost of electric energy which is mostly a product of burning fossil fuel and reducing global warming.
4) A method for almost free of cost conditioning the premises saving substantial cost of electric energy
5) A method for reducing global warming by preventing the greenhouse carbon dioxide comprising carbon dioxide released by the plants during dark hours or residual carbon dioxide available after carbon dioxide enrichment events of sun light hours ,
from being released into the atmosphere. and instead capturing , compressing , dehumidifying , storing and utilizing the greenhouse carbon dioxide during sun light hours for carbon dioxide enrichment for optimizing the productivity leading to achieving a more economically viable greenhouse by selling the carbon credits which are not used because the greenhouse carbon dioxide is not released into the atmosphere.
In this regard kindly be apprised that the aforesaid two innovations substantially reduce global warming and are likely to be mandatory.
6) A method for mechanizing and optimizing air circulation around the plants facilitating at least four fold plant density.
7) An unique method for maintaining greenhouse air relative humidity at a predetermined set point by capturing greenhouse humid air which is compressed , maintained almost dry in the dehumidifying tanks , stored into the earth tube heat exchanger and released into the greenhouse for mixing in the greenhouse humid air for maintaining greenhouse air relative humidity at a predetermined relative humidity set point without traditional manipulating the greenhouse air temperature.
8) Almost similar method for maintaining greenhouse air temperature at a predetermined set point in hot locations wherein there is no option to evaporative cooling which increases the greenhouse air relative humidity resulting in minimal evaporative cooling
9) A method for substantially reducing input cost of nutrients by using activated nutrient solutions of very low cost nutrients such as Urea, raw Calcium sulphate, and raw Magnesium sulphate. Using a method to dissolve raw Calcium sulphate, and raw Magnesium sulphate into water and activating there solutions and converting urea into an activated solution of nitrate, apart from saving cost , So4 ions without chloride ions which is very beneficial
Nutrients comprise a substantial portion of the total cost of food production and as such using the aforesaid very low cost nutrients, leading to a substantial reduction in the cost of food production.
10) A method for aerating the roots of the crop and for maintaining the temperature of the roots of the crop at a predetermined temperature set point which optimizes uptake of nutrients by the plants leading to maximizing the productivity
11) A method for switching-off an irrigation or a fertigation event on first few drops of drained off leach ate which is very beneficial in hydroponics in particular and in other systems in general. Plants receive optimal watering and nutrition without any danger of plants collapsing due to water logging.
12) A method for obviating gutters in multi span structured greenhouses together with all gutters’ related problems , leading to at least 10 % reduction in the cost of the multi span structured greenhouse and saving replacement cost of gutters
13) A method for conditioning relatively cooler greenhouse air to relatively warmer greenhouse air in cold locations and for conditioning relatively warmer greenhouse air to relatively cooler greenhouse air in hot location
wherein an earth tube heat exchanger comprises L1 cost reinforced concrete pipes of a predetermined diameter and of a predetermined volume based upon the greenhouse area to be serviced which may comprise a plurity of greenhouses. The earth tube heat exchanger comprises four separate compartments for respectively storing carbon dioxide rich dehumidified greenhouse air , oxygen rich dehumidified greenhouse air , carbon dioxide rich lowest humidity almost dry greenhouse air and oxygen rich lowest humidity almost dry greenhouse air
Earth Tube Heat Exchanger Fundamental
soil strata between 2 – 3 mtr depth
temp regime is constant (thermal constant)
temp in this strata displays no diurnal fluctuation
it does display annual fluctuation but amplitude is small
at Ahemdabad (india) 23. 03 n lat
average thermal constant 27° c
14) A method for measuring the average thermal constant temperature of a location which is essential for installation of the earth tube heat exchanger
15) Providing a bio thermal energy harnessing automated equipment comprising of a single bio thermal energy harnessing tank with the facility of partially loading fresh material
from the top end and unloading compost from the bottom end facilitating 24 hours and 7 days harnessing of thermal energy for greenhouse supplementary heating and hot air for numerous needs in cold locations wherein harnessed bio thermal carbon dioxide is used for carbon dioxide enrichment events during sun light hours for optimizing the productivity. When carbon dioxide is not needed for enrichment during dark hours or cloudy environment , the bio thermal carbon dioxide is stored into the earth tube heat exchanger’s compartments which respectively already store carbon dioxide rich dehumidified and lowest humidity almost dry greenhouse air.
16) A method to provide oxygen rich environment during dark hours which plants are in dire of to respirator and rejuvenate , plants’ health vigor and strong immune system maximizing plants’ tolerance to disease organisms, bacteria, pathogens, fungi, viral infection, harmful insect, pests
17) A method for obviating horizontal and , or vertical non uniformity by controlling and maintaining at all the vertical and horizontal location in the greenhouse, an uniform air relative humidity at a predetermined relative humidity set point and an uniform air temperature at a predetermined temperature set point.
18) A method for magnifying and intensifying the artificial light and , or sun light to the predetermined level producing red , blue, and white light, in predetermined proportions. In cold locations natural light is deficient and has to be supplemented with artificial lighting and is accompanied by cold air incurring substantial heating cost whereas in hot location natural light is accompanied with hot air and has to be cooled incurring substantial cooling cost.
Furthermore quality of light comprising red, blue and white light or combination of aforesaid color lights can be achieved by just replacing the lamp with a lamp emitting , the light in the color or combination of colors for various growth stages of the plants. The operating cost of artificial lighting is only a small component of greenhouse supplementary heating and supplementary cooling cost in the respective cold or hot weather locations. Furthermore the light of requisite intensity and of requisite quality in predetermined colors or combination of colors is available 24 hours and 7 days of a week.
So far in India light emitting diode lamps in wattage higher than 50 watt and emitting red , blue , green and ultra violet light are not available. When these lamps are available the intensity of light would be almost double because now the magnifying mirrors , lamp mirrored shades are provided coloring
19) A method for fully insulating the greenhouse from the atmospheric environment, covering the exterior surfaces of the greenhouse roof and the four external sides with thermal shading film of a predetermined thickness based upon the climate of the location
20) A method based upon climate pattern of a location for covering predetermined area and locations of the external surfaces of the greenhouse roof and to the exterior surface of at least one of the four sides with diffused white film and the external surfaces which do not comprise diffused white film , comprise thermal shading film and each side which does not comprise diffused white film comprise a thermal shading film fixed thereto so that benefit of natural light can be realized together with admitting into the greenhouse only predetermined deficient solar radiation for minimizing needless heat gain , reducing greenhouse air temperature and minimizing the supplementary cooling cost.
21) A method comprises fixing diffused white film to the greenhouse roof and to at least one side of the greenhouse and each side which do not comprise diffused white film comprise fixing a thermal shading film to also avail the benefit of natural light.
22) A method for maintaining exterior surfaces of greenhouse cover film free from dust / dirt
23) A method for efficient fire fighting
24) A method to facilitate carbon dioxide enrichment during sunlight hours in hot locations.
25) A method for melting snow on the exterior surfaces of the greenhouse cover film.
26) A method for heating water for circulation into the radiators in residential , offices , industrial and malls and all kinds of premises wherein heating is required. As of now the heating of the premises is performed by burning fossil fuel
27) A method for preventing escape into the atmosphere of the stored carbon dioxide and / or bio thermal carbon dioxide and or additional carbon dioxide released at the cultivation level for enrichment during sunlight hours, which is readily taken up by the plants. This reduces the cost of carbon dioxide which could have escaped into the atmosphere and could have also increased global warming.
28) A mechanized module for adjusting the height of artificial light source which provides substantial benefits because as of now the artificial lighting fixtures are mostly provided at about 15-30 centimeter distance from the level of a fully grown plant the level which the grown plants would achieve after a long duration so that the plants at various growth stages does not receive enough lighting from artificial light source leading to substantial reduction in the productivity.
29) A method for sos melting snow on exterior surfaces of greenhouse and also for melting snow anywhere : Runways of Airports Highways , Railway Tracks and the like
30) A method for obviating need of repeated greenhouse warm or cool atmosphere exchange with outside atmospheric hot or cold air up two full air exchanges every hour for maintaining carbon dioxide and oxygen balance in the greenhouse during winters, rain and snow storms when the greenhouses are maintained closed leading to substantial reducing in the associated thermal energy cost for heating the exchanged atmospheric cold air in cold locations and the associated cooling cost of the exchanged atmospheric hot air in hot location.
31) A method for obviating the problem of maintaining air tight the two layers of the double polythene film covering the greenhouse roof and four sides.
32) A method for obviating need of horizontal air fans and thereby saving their capital and operating cost.
33) A method for using smaller wall thickness cheaper galvanized iron pipes filled with sand (ends sealed to ensure no escape of sand) in place of costly large wall thickness C-class galvanized iron pipes both serve same objective.
34) A method food production in greenhouse in cold locations by increasing deficient sunlight energy together with artificial lighting energy, using earth tube heat exchanger together with bio thermal energy harnessing equipment.
35) A method to maintain optimal insulation between two layers of inflated double layer polyethylene for covering the greenhouse wherein leaking segments can be visually identified and easily repaired
36) Achieving all the benefits of a tall greenhouse in a shorter greenhouse leading to a much more economically viable greenhouse with greater energy efficiency and reduced capital and operating cost.
37) Efficient photoperiod control :
38) So for no method exists to control daily light photoperiod, which is vital factor Influencing plants’ growth. Plants grown in conditions of varying daily light photoperiod pattern can’t settle in regular life cycle and grow poorly.
39) In the prototype greenhouse the light intensity increasing and magnifying facility comprise smaller diameter magnifying mirrors and smaller size lamp mirrored shades. Depending upon the requirements the aforesaid components can be of much higher sizes.
40) Also the bio thermal energy harnessing automated equipment comprise a bio thermal energy harnessing single tank of one meter diameter and three meter height. Depending upon the requirements the bio thermal energy harnessing tank can be of much higher diameter and of much higher height.
i) Obviating gutters in multi span structures and installations for numerous needs which saves about 10% cost of the structure and obviates all the problems related to the gutters together with the replacement cost
ii) Earth tube heat exchanger comprises low cost reinforced concrete pipes which is very beneficial in environment controlled or non environment controlled structures and installations for numerous applications and needs, cold storages multiplexes, hotels, malls, commercial and residential complexes, zoological parks’, stud farms cows or buffalos sheds etc (premises)
iii) Bio thermal energy harnessing automated equipment which is very beneficial in environment controlled or non environment controlled structures and installations for numerous applications and needs, multiplexes, hotels, malls, commercial and residential complexes, zoological parks, stud farms cows or buffalos sheds etc (premises)
A 500 m2 prototype greenhouse has been constructed wherein all the facilities has been installed wherein a cucumber crop is being seeded so that the interested parties may realize the real time benefits. Video with standing crop would be uploaded on Facebook and You Tube within next 3 to 4 weeks.
Kindly advise your comments and interest.
S P Gupta, Chandigarh, (INDIA