Urban Gardens

The practice of urban agriculture is a new trend among citizens who want to take a role in homegrown vegetable production. Although urban gardens can be installed directly on the terrace’s surface, they are usually installed on cultivation tables raised or level the ground. These tables help contain the substrate and make practice easier.

Urban gardens contribute to making cities more sustainable if ecological agriculture is practiced without fertilizers or chemicals and if it benefits from organic waste. Its practice is an activity that could be educational, rewarding, and strengthening to the social fabric. It should be clear, though, that the production achieved in an urban garden is not large-scale and should be seen as a plantation with different vegetables with staggered harvesting.

The vegetable gardens can be communal if they are implemented in empty spaces managed by the City Council and distributed among interested citizens. Eixverd proposes semi-community or private gardens. They are semi-communal if they are installed on the roof of a residential building. Access would only be for neighbors and would be self-managed by them. The urban garden could also be for personal use if installed on a private terrace or balcony, in this case with inexistant benefits of the social fabric.

Urban gardens are also related to the food sovereignty movement where small producers provide consumers with nutritious, ecological, km0 and low cost products, giving an alternative to industrial agriculture and its associated problems of price wars, import of vegetables, and production of vegetables of a different season.

If you are excited about gardening and you have the space, what’s holding you back?

Profits

A type of green roof is an agricultural roof to promote food sovereignty and local food production. It also has benefits for citizens and the environment. We summarize some of them here:

Thermal insulation

  • Innumerable studies show that a well-functioning green roof provides excellent thermal insulation. In our own experimental green roof we have observed that, in contrast with the temperatures of up to 60 and 70 ° C prior of it’s installation, 28 and 35 ° C are reached under the green roof’s soil.

Acoustic insulation

  • Households below the green roof can see noise reflection reduced by up to 3dB and sound insulation improved by up to 8dB.

Heat island effect:

  • The heat island effect, an effect that makes the city center 2 or 3 degrees warmer than it’s outskirts, would be palliated. This could lead to a reduction in air conditioner use and further reduction in carbon emissions.

Reduction of CO2 emission:

  • CO2 emissions would wane because:
    • Plants absorb it
    • The heat island effect would be palliated
    • Other CO2 emitting forms of insulation would be discontinued.

Water runoff:

  • The plants of a green roof naturally accumulate water for their future use, entailing a slower drainage, thus resulting in a smaller dimension of the sewage.

Urban biodiversity:

  • Increases urban biodiversity by maintaining the green corridors that range from Collserola to the Mediterranean Sea.
  • Increases the m2 of green / inhabitant ratio

Pollutant particle absorption:

  • Absorption of polluting particles such as NOx and PM10

Albedo increase:

  • Albedo, which is the degree to which light is reflected by a surface, will increase. This is a benefit because unreflected sunlight will be absorbed and thus increase the temperature of the atmosphere.

Social aspects:

  • Enjoyable area for the residents of the building
  • Urban agriculture km0 and the possibility of having a self-sufficient area of production.
  • Accessible private space to use in times of confinement.

Circular economy:

  • Possible installation of a rainwater-collecting tank to use for irrigation
  • A composter can be installed to convert debris into compost.
  • Any lights or pumps installed can be run by renewable energy.

Economic aspects:

  • More durable roof as the substrate protects it’s waterproof layer
  • Increase of the value of the estate
  • Possible decrease in sewer rate due to reduced water runoff when it rains
  • Possible decrease in taxes of real estate
  • If solar panels are installed, reduction of the electricity bill

Frequently asked questions about Urban Gardens

Do green roofs promote water leaks or moisture in ceiling?

On the contrary, the waterproof layer is protected from thermal influences. Green roofs must be installed on an irrefutably waterproof site: it must pass a watertightness test .

How are green roofs installed?

We prefer to install vegetable gardens directly on the ground on top of the technical layers. After the waterproof layer, which has to be resistant to roots (if you don't have one, you must install one specifically for that purpose), there is a protective and water-retaining blanket. The drainage layer provides a reservoir for rainwater and air that favors root development. On top of the drainage layer there is another layer that filters the particles so as not to saturate the drainage layer. And the finishing layer is the substrate, which should be more organic and be, at least, 20 - 40 cm deep.

Is insurance provided for green roofs?

When the green roof and the waterproof layer are installed together, an insurance of 10 years is given.

What type of vegetable gardens can be installed?

We can install kits or urban cultivation tables, which are very appropriate for small spaces and require little maintenance. These types of vegetable gardens do not require a building license, but they might require structural advice. On the other hand, if you are looking for a garden that has sufficient productivity to supply a group of neighbors, the cultivation tables aren’t enough; we will install it on the ground on the multilayer system.

My terrace is communal, how could I convince the rest of the neighbors to install a green roof?

We can attend the owners meeting; as well as present a preliminary proposal and budget to facilitate the conversation with the neighbors and be able to find suitable solutions for all doubts anyone may have.

Does the government offer any subsidies?

Depending on the City Council of each municipality, through the Consorci d'Habitatge (Housing Consortium), a financial aid of 30% of the costs could be given for the rehabilitation of a building, but if there is an action that improves energy efficiency such as a green roof or solar panels, the subsidy could amount to up to 50% of total costs. L’Institut Municipal de Paisatge Urbà de l’Ajuntament de Barcelona (the Municipal Institute of Urban Landscape of the City of Barcelona) has also launched a competition that rewards the winning green roofs with a 75% subsidy.

What is the approximate cost of a vegetable garden?

Roughly, one made with boards will cost around € 100 / m2. But if the vegetable garden is done with the multilayer system and includes the installation of automatic irrigation and waterproofing it can be around 200 EUR / m2.

Can my building have an agricultural roof? Should we make structural reinforcements?

Not all buildings can have an agricultural roof due to the weight of the 25-40cm of substrate. We will take care of the structural analysis, the landscape design, the project, the building permit, the execution and, if desired, the maintenance. In the structural analysis phase we will avoid unnecessary structural reinforcement. However, we may need the building to be reinforced in specific situations due to a previous anomaly or because we want to put more substrate than is necessary to increase the variety of crops.

What does the vegetable garden maintenance include?

In principle, the vegetable gardens are made so that the neighbors take care of the garden. However, we can offer advice, occasional maintenance and even capsules and guided tours.

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