JoyWood was a project that took part to the Greemta Challenge in 2020.
The name comes from the so called Bosco di Gioia, a urban park in central Milan that was closed in 2006 and subsequently destroyed in order for the Palazzo Lombardia, composed by two skyscrapers, to be built upon.
This event has caused popular upheaval and also a song was written about it by italian prog group Elio e le Storie Tese. Lately the importance of urban green hass been reevaluated, and we are convinced that analytical and quantitative tools may help to understand how to manage urban greenery and study its effects on our quality of life.
In fact urban greenery reduces the anthropic impact on the environment from various point of views: not only it absorbs CO2 and hence reduces carbon emissions, but it also creates shade from direct sunlight and absorbs radiation.
Furhtermore, it helps to mitigate climate changes not only in hot seasons but also in winter: in particular urban bushes can block cold winds and improve thermal retention of buildings.
Our work has been focused on datasets on trees and meteorological informations gathered by the Ayuntamiento de Madrid. In particular, our aim was to visually represent different dimensions of human wellbeing, in order to understand the positive effect of urban green on our health and psyche.
Urban Heat Islands
An Urban Heat Island (UHI) is an urban area significantly warmer than its rural surroundings due to human activities, it is a common phenomenon especially among big cities. Building materials are generally insulants, so the absence of green areas can aggravate the situation. People need energy to live and they disperse a lot of it in the form of heat, that is why densely populated areas tend to be generally hotter. Other than the temperature itself UHIs have bad repercussions on air and water quality.
High temperature are linked to a number of diseases and are responsible for the death of many people every year. Furthermore, to defend themselves from heat people use air conditioners and other types of electrical machines to cool the rooms , but this ends up in heating even more the area. To fight this vicious circle cities need green areas.
Thermal comfort indices
Air temperature isn't the only important index of UHIs, there are several indexes developed to determine the perceived temperature, holding in account for many factors. We chose to focus on two of these indices PET and UTCI. Monitoring thermal comfort indices is key to a better management of urban green. For example there is evidence of bigger impact on the temperature by trees west and east of buildings.
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PET ( stands for 'Physiological Equivalent temperature') based on the heat balance equation for the human body, it is a representative index of perceived temperature. The PET depends on air temperature, relative humidity, solar radiation, human metabolism, clothing and other factors .
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UTCI ( stands for 'Universal Thermal Climate Index') is a useful index to estimate how people perceive temperature. This index is designed to describe outdoor environments.
In UHIs this indices are significantly higher than air temperature measured, meaning that other than being hotter than the near zones UHIs make humans feel even more hot!
We show how green areas affect this two indices, linking the presence of vegetation to a more liveable urban environment. Not only the presence of grass and trees makes perceived temperature go down, they also absorb many polluting substances. Moreover green spaces, especially trees are linked to a lower level of psychological stress, suggesting that citizen would benefit a lot from a greener setting. A smart way to reduce the urban heat is the construction of plantable roofs, in one move we achieve both a lower temperature and absorbtion of greenhouse and polluting gases.
Tools
Python has been used to develop the script. The dashboard was made with use of Streamlit, hosted on Heroku. Pandas and Scipy libraries have been used for computations, whereas Deck.gl by Uber has been used for the visualization.