Expert article
Edit 05 December 2023
by Daniela Patti

The Macrolotto Zero Urban Jungle!

Macrolotto Zero pilot area. Photo by Eutropian
The Prato Urban Jungle project tested nature based solutions (NBS) in different pilot sites of the city in order to carry out innovative strategies to create urban forestation, urban jungles, that could improve the environmental and social impacts on cities. One of the pilot sites is developed in the Macrolotto Zero, an area characterised by underutilised spaces at the heart of the Chinese neighbourhood, one of the biggest in Europe, where the reconversion of the former industrial warehouse becomes a model for the reuse of Prato's disused industrial heritage. The building identified for this experimentation was planned for the city’s new metropolitan market. This intervention was part of a larger renewal plan in the neighbourhood, led by the municipality, through the implementation of services and the creation of new buildings and public spaces for working, community engagement and open-air activities. The renewal plan in Macrolotto Zero aimed to convert the nature of the neighbourhood, from a transition area into a place to be and stay. 

The project for the Macrolotto Zero was that the façades would be covered with plants and whose air would be purified by the largest Air Factory ever built. It would have been possible to consume local products and enjoy the benefits of a space regenerated by plants. 

Within the Macrolotto Zero site, the design was carried out by PNAT, PUJ partner, making this a testbed for innovative nature and plant- based solutions. 

In fact, within the PUJ project , PNAT was also responsible for drafting guidelines for the use of Nature and Plant-Based Solutions (PBS) in architecture. The Guidelines collect and classify PBS applications at the scale of the building and its pertinences and identify the criteria for evaluating the benefits generated. They also define a performance index, the Urban Jungle Factor, which is a fundamental operational tool for assessing the social, environmental, and economic impact of each solution, allowing to measure the soundness and sustainability of projects.

The term Plant-Based Solutions (PBS) identifies all the solutions, strategies, and interventions based on plants, capable of amplifying the sustainability and resilience of urban systems to climate change, of protecting and restoring biodiversity, and of bringing benefits in terms of health, well-being, air, water, and soil quality. Plant-Based Solutions provide for the use of plants in all dimensions of the built space, without limiting them to canonical, albeit fundamental, places such as parks, avenues, gardens, and flower beds. Used innovatively and efficiently, plants can cover the facades of buildings by reducing energy consumption, produce food on horizontal surfaces, purify the air of indoor environments, provide for the phytoremediation or renaturalization of abandoned and degraded areas, regiment and purify waste water, capture CO2 and filter atmospheric contaminants, responding effectively to the needs of sustainable development of cities.

Therefore within the Macrolotto Zero the first action to be carried out, was the creation of a measurement system to evaluate the effectiveness of natural solutions applied to the scale of the building and its appurtenances. This experimental system relies on pioneering studies carried out by some European and North American cities, to assign a score to green interventions in the city. The score is calculated with a formula that takes into account the green area compared to the total area of the building, and a factor that estimates the quality of the intervention with respect to the criteria of air, water, soil, food, health and well-being, comfort and biodiversity, as well as with respect to the use of resources. The Urban Jungle Factor was used as a guideline for carrying out an initial enhancement intervention on the new building of the City Market. Greenery is an element present both on the outside of the building volume, covering both the main facade and inside, making the vegetation and the building itself a biological machine capable of purifying polluted air, mitigating the impact of the building in the surrounding environment, combating the urban heat island effect.