rooftop greenhouse

Apart from Vertical Farming, there are numerous hybrid cultivation initiatives taking place in and on buildings, also known as Urban Farming and Rooftop Farming. Even restaurants, supermarkets and offices are experimenting with growing fruit and vegetables in cities.

Vertical Farming is, of course, not suitable for crops that grow in an upwards direction, such as tomatoes and cucumbers. This problem was solved in Jackson (Wyoming) with the construction of an impressive building incorporating huge amounts of glass, designed by Larssen Ltd.: a very expensive building costing 3.7 million dollars, partly due to its earthquake-proof construction. Three stories of the building are dedicated to LED-illuminated Vertical Farming, with two stories reserved for herbs and leafy vegetables and the third for tomatoes. The 3,800 m² surface area is sufficient for a production of 45,000 kg a year. The building is intended to bridge the awareness gap between horticulture and the city’s inhabitants and also provides space for education. The vegetables can be seen growing from behind a glass wall. The project received financial support through crowdfunding and the municipality is the owner of the building.

Restaurants and supermarkets

InFarm is directed at growing vegetables in big cities; in and by restaurants and the retail industry. ‘We are the new farmers and the city is our company.’ In his mind’s eye, the founder of InFarm is seeing supermarkets with multi-tier cultivation for leafy vegetables above the shelves. You simply can’t buy fresher food with fewer food miles than this! InFarm developed the Kräutergarten for the Berlin-based Metro wholesaler, just as Mirai did in Japan: a multi-tier LED-illuminated greenhouse in the supermarket. The crops grown consists primarily of herbs (basil in particular) and leafy vegetables grown on a shallow layer of water (hydroponics).

You simply can’t buy fresher food with fewer food miles than this!

InFarm also operates the UFcontainerfarm in Berlin: a container with a small greenhouse on top. Tilapia fish are bred in the container. The water from the fish is pumped up to the greenhouse, where it is used to water the plants after it has been purified. This concept is also used in London, where it is called a GrowUp Box.

Above and below ground

An outsider in Urban Farming is SkyGreens. This Singapore-based initiative grows vegetables on trays suspended in gutters. These gutters circulate vertically by means of two A-shaped pillars nine metres tall. The circulatory movement enables each plant to obtain the same amount of sunlight. The company has 1,000 of these vertical towers with 20 gutters each and produces 800 kg of vegetables a day, including Chinese cabbage, spinach and other leafy vegetables.

The London-based Farmdrop initiative produces herbs underground, in former bomb shelters.

Another outsider, but of an entirely different calibre, is the Pasona office building in Tokyo, where a myriad of plants and vegetables are grown on and in the building, which also features a dedicated Vertical Farming division. The vegetables grown here are intended for the company restaurant. In conference rooms, workspaces - in fact, all over the building - you will see tomatoes growing all the way up to the ceiling, or sweet peppers and eggplants, broccoli, lemons and even passion fruit. A total of 200 varieties of vegetables, fruit and even rice are grown here! The staff is free to pick whatever they want. The company employs a permanent staff of ten people to keep the vegetables in tip-top condition. Not everything is grown efficiently, but the project was never intended to achieve a high production rate; the concept was developed to engender awareness for food provision.

The London-based Farmdrop initiative produces herbs underground, in former bomb shelters: 30 metres below the surface. It took Farmdrop two years to conquer all the challenges of underground cultivation.

Rooftop greenhouse

Where Vertical Farming appears to be booming, there is less interest among the inhabitants of big cities for rooftop cultivation - in greenhouses, at any rate. Few people practice greenhouse horticulture on rooftops, but when it is, this is mainly in the USA.

According to GothamGreens, urban farming is all about re-establishing the connection between people and the food they eat, educating young people and nurturing the soul.

A firm called GothamGreens operates a series of rooftop greenhouses, in which leafy vegetables are grown in gutters, in New York and Chicago. The first 1400 m² rooftop greenhouse was built in 2011, and the total surface area of GothamGreens has since risen to 16,000 m² distributed across four sites. The biggest measures 7,000 m² and is built on the roof of a bowling alley. According to GothamGreens, urban farming is all about re-establishing the connection between people and the food they eat, about educating young people and nurturing the soul. ‘Urban Farming will never become a primary source of food, but its impact is lasting.’ A head of lettuce grown here costs around $4 at Whole Foods, almost twice as much as conventional lettuce grown in the field and $1 more than organic lettuce.

Bright Farms also aimed to dedicate itself to rooftop cultivation, but it was forced to give up its plans due to the difficulties it encountered with permit applications and the costs, which were 20% higher in comparison to an 8.5 million dollar greenhouse built just outside of the city.

The Hague

The Swiss Urban Farms initiative in Basel built a 250 m² rooftop greenhouse as a pilot in 2013. Three years later, in May 2016, the UF De Schilde rooftop greenhouse opened its doors in The Hague, the Netherlands. As opposed to the rooftop greenhouses in the USA, which are all on one or two-storey buildings, this greenhouse is situated on top of building six storeys tall. Greenhouse builder Van der Valk Kleijn designed an extra-sturdy greenhouse with double glazing incorporated into the walls and roof. The project’s financiers are SVn (Stimulation Fund for Public Housing) and private investors. The greenhouse collaborates with Rijk Zwaan, Koppert Biological Systems and Priva.

UF hopes to cater to 900 families who can order fresh fish and vegetables via a subscription, as well as to restaurants.

The 1,200 m² greenhouse is the biggest rooftop greenhouse in Europe. The farm grows lettuce, micro-greens and tomatoes. The floor underneath the greenhouse is rented from the municipality of The Hague to farm fish, whose waste products are subsequently used as nutrients for the plants. Visitors can watch the cultivation process from behind a glass wall. UF hopes to cater to 900 families who can order fresh fish and vegetables via a subscription, as well as to restaurants: 500 tilapia fish a week and 50 tons of vegetables a year. UF expects the venture to be a success, mainly because consumers are enthusiastic about initiatives engaged in the local production of food.

Priva developed the necessary control technology for the project, which required an extraordinary degree of innovation taking into account all the regulations that apply to fish farming (e.g. temperature and oxygen content) and irrigation (including fertilising, temperature and electrical conductivity) for the various greenhouse sections in which lettuce, tomatoes and leafy vegetables are grown. On top of that, Priva also developed the systems for CO₂ and climate control.

Canada

Lufa Farms in operates a 3,000 m² rooftop greenhouse in Montreal (Canada) and one in Laval measuring 4,000 m². Both were built by the Montoni Group and Kubo. The greenhouses are capable of withstanding large amounts of snow.

Verticrop combines a rooftop greenhouse with Vertical Farming, with cultivation on horizontally circulating plates in twelve tiers in a greenhouse on top of a parking garage in Vancouver (Canada). As the plates rotate slowly, all plants obtain the same amount of light and are watered and harvested at a particular point. However, the company has since gone bankrupt. The investment in both the rooftop greenhouse and a complete new cultivation system was probably too high. Additionally, crops grown using this system tend not to grow as profusely due to the limited amount of daylight they receive.

Horticulture 3.0?

An interesting point for consideration is the extent to which the higher costs of a rooftop greenhouse are balanced against the presumed higher quality, freshness and local distribution. Or will the multi-tier cultivation of fruit, vegetables and fish under fully controlled conditions pave the way for Horticulture 3.0, with its smaller CO₂ footprint, retention of local employment and higher diversity in supply as its social driving forces? In the meantime, restaurants, supermarkets and offices are all experimenting with growing their own vegetables, and urban consumers have discovered the art of growing their own food as a meaningful and pleasurable pastime.

Locally grown, super-fresh and demonstrably sustainable could very well become the new standard of reference.

The consequences are, however, very limited for the Dutch horticulture industry, which has traditionally always focused on the export of primarily herbs and leafy vegetables to other European countries. This does not detract from the fact that the industry should consider expanding its focus area to feeding mega-cities rather than ‘shifting around’ products from one location to another, as the CEO of Hoogendoorn, Martin van Gogh, recently suggested during the Greenport Annual Event. Locally grown, super-fresh and demonstrably sustainable could very well become the new standard of reference.

Text: Tuinbouwteksten.nl/Theo Brakeboer. Photo: UrbanFarmers/Martijn Zegwaard.

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