The ANR (French National Research Agency) project COOLTREES

Urban vegetation professionals are in demand of information and tools to complete and support their planning decisions, notably in order to deal with upcoming climate changes.

COOLTREES has constructed and evaluated on the construction and evaluation of a modelisation and 3D simulation software and collected new information regarding urban vegetation. The results provide lines of thought for professionals as well as perspectives for the development of 3D modeling tools for the planning of trees. The goal is to be able to test the impacts of a planning before its implementation in order to optimize the services provided, notably in terms of urban heat island effect mitigation.

Two principal results are emerging !

1 : A global, substantial and researched database

This database gathers 5 years of field measurements taken in the botanical garden of Strasbourg’s University.

This database gathers global meteorological measurements as well as physiological measurements taken on lime trees 'Tillia tomentosa' during this work period. It will be available for all in 2023. In the meantime, a Data Paper describing the database will be published following the work of the researchers in 2022.

2 : A modelisation and 3D simulation software : LASER.T (LAtent SEnsible Radiation & Trees) 

LASER. T merges the software LASER/F, on which the research team TRIO from the Icube laboratory of Strasbourg is working since 2009, and the software RATP developed par the INRAE of Clermont-Ferrand, which allows to model and simulate with an accuracy of within one centimeter the interactions between trees and their environment.

It operates on the basis of the meteorological measurements corresponding to the present microclimate, the materials’ characteristics, and the trees’ physiological information. You can choose to perform a model at a given time, or in a day or more provided that the computer is given sufficient time to perform the calculations.

What happens in the software ?

Based on the different data, the software simulates and calculates all the existing interactions between the elements composing the scene as well as their physiological and physical responses. It then concludes an energy balance and provides different data, such as the elements’ surface temperature.

Once the modeling is done, a window presents the 3D scene and different filters allow to choose the information highlighted.

In addition to these information, it is possible to perform comfort index calculations, based on all the data, in order to know the scene temperature as well as calculate the evapotranspiration of one or more trees. Examples are presented in the synthesis of the project available for free download.

But what does these modelisation look like?

Let’s start from the beginning of the project; the botanical garden of Strasbourg’s University where the measures presented in the database were taken. Here is the modelisation that was done with LASER/F:

Everything is possible with this software. For example, it is possible to create a canyon street and let the software simulate an entire day. You will find in the project’s synthesis this same scene with a few alterations in order to highlight the impact of trees on the microclimate of the street at 9 am, 1pm and 6pm.