Urban farming is becoming increasingly popular and there are many forms in which it can be seen. Community gardens, rooftop farms, even vertical farming projects can be found. These projects have of course advantages as well as disadvantages. The Netherlands is suffering from a large number of empty office buildings, and farming in it might seem like a good solution to it. Why is it then, that there are very few of these vertical farming projects? This article looks at the advantages and disadvantages of vertical farming and discusses whether vertical farming projects might be something for the future. It touches shortly upon the subject of rooftop farming and later it looks at an example of an urban farming project in the Netherlands.

A way to implement farming in urban areas is by ‘vertical farming’. Vertical farming is farming inside of buildings where crops are grown in layers on top of one another. The Netherlands has a problem with the high number of empty office buildings in the country. In 2013, almost 17 percent of the office spaces in the Netherlands were empty, as they were up for rent or sale. This covered a space of about 800 ha. Although it may seem obvious to use these empty offices and flats for vertical farming, there are still very few examples of this happening. A likely explanation for this is that this way of farming is more expensive than farming in glasshouses or on agricultural plots. To turn an office building or flat into an agricultural place, many adjustments need to be made and that can be very expensive. Additionally, the rent price of an urban office building is generally higher than a plot outside of the city and it costs more energy to grow plants in office buildings than in glasshouses or in the ground. Also, the building adjustments use energy, of course. Other examples of energy use in vertical farming are climate regulation in the buildings and lightning. All these aspects make it difficult for urban vertical farms to be more profitable than farms outside of the city with crops on open land.

Despite the disadvantages, vertical farming also has many positive aspects. It uses much less water than farming in open land and it can help create security of access to fresh vegetables since the growing conditions can be completely controlled and many crops can grow on a small surface. Given that crops are grown in a building, there is no weather dependency, which makes the harvest much more predictable. Additionally, as vertical farms can be located in the city, the production of crops is closer to the place of consumption, which reduces the transport distances. This is beneficial for the environment as well as for people’s health since it reduces air pollution. Less traffic can also contribute to the liveability of a place and to the well-being of the residents. Furthermore, the food seems for the consumer to expire slower when it is produced closer to the consumption location because it takes less time to go from harvest to plate. Next to this, fewer pesticides are needed in a vertical farm.

Another rising form of urban farming is by ‘rooftop farms’ or ‘rooftop gardens’, which are gardens situated on the roofs of buildings in urban areas. Rooftop farms are much more common than vertical farms and they have some of the same advantages. Advantages that rooftop farms have but vertical farms do not have are that rooftop farms use much less energy and that fewer building adjustments are needed, which makes them less expensive. A disadvantage of this method compared to vertical farming is that only one layer is used for farming, which makes them less efficient. Growing plants on roofs is a highly sustainable activity and contributes to combatting climate change. On urban roofs, it is generally quite warm, therefore it can be possible to grow plants on Dutch roofs that normally grow in Mediterranean regions. This can reduce transportation emissions greatly. Instead of transporting the crops for 2 days by truck, they can be harvested on a roof right around the corner.

Other than growing crops, urban areas have the potential for the fishing industry. An example can be seen in a building in Den Haag: Dakboerderij De Schilde. On top of the building is a glasshouse, and underneath it is a fish farm. It works in a very interesting way: The dirty water from the fish tanks is pumped to the plants. This water contains many nutrients and functions as a fertiliser. In doing so, the water is filtered by the plants and then pumped back to the fish tanks. Simultaneously, it cleans the water of the fish and provides the plants with nutrients. The building is a former factory building of the company Philips. When the farm opened in 2016, it was the largest urban farm in Europe. It produces around 20.000 kg of fish and 50.000 kg of vegetables per year. Next to this, it has space for tours and events. As mentioned before, it is difficult to make commercial urban farms more profitable than farms outside of the city. Secondary activities like this might contribute to the profitability of this urban farm.

Lights are needed to make vertical farming work. High-pressure sodium lamps (HPS lamps) are often used for growing plants in glasshouses. These lamps are used because they are cheaper to purchase than LED lights. However, LED lights have many advantages over HPS lamps. They use a lot less energy and work just as well for photosynthesis. Wageningen University and Research is researching the effect of different colours of LED light on the growth of plants. If this shows that not all colours are useful, yet more energy can be saved. When the energy usage is even lower, the energy costs of the farm will also become lower, which makes them more likely to use LED lighting. Another advantage of LED lights is that they do not get hot. This means that they can be placed between the plants, close to the fruit, which increases the vitamin C content of the fruits.

A vertical farm has many advantages, mainly being able to produce a lot of food on a small surface. It would be useful to do further research on how energy usage can be lowered to reduce the impact on the climate. When the energy usage is lowered, more vertical farms might arise and there will be benefits from the many advantages named earlier, hopefully with a positive impact on the environment.

It is difficult to say whether the switch from open land farming to urban vertical farming is good for the environment since it depends on a lot of factors. There are already some great vertical farming and rooftop farming initiatives. Nevertheless, there are still some obstacles to overcome in vertical farming. The problems are mainly the costs and the use of energy. More research about vertical farming will be useful since there is a lot to gain in this area with respect to climate change, food security and the liveability of urban areas.

This article was first published in the Girugten Lustrum Edition (Year 50 of Girugten – issue 02 –  May 2021).

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