Cooling performance of urban trees in software and orgware
Cities must adapt to cope with climate change impacts such as higher temperatures and periods of heat stress. Trees are widely accepted as natural 'aircon' for our cities, but precise data on how much they cool - and in particular over their life cycle - is lacking. In the project i-Tree 2.0-NL, accurate metrics for urban trees in Dutch cities will be developed and translated into databases, application software and 'orgware'. “With this project, we intend to quantify one of the most important benefits of trees in the urban space - cooling. And armed with the scientific evidence, we will be working with planners and design practitioners to integrate this knowledge for cooling cities with urban forestry”, says project leader Rene van der Velde.
Greenspace, and urban trees in particular, are one of the most effective ways to make cities climate-adaptive. Trees are able to effectively reduce extremes of urban heat cycles. But more than this: the urban forest (the entire mosaic of trees in urban public spaces) provides benefits for urban water management, air quality, biodiversity, and the health and well-being of residents. The fact that trees can be integrated in most places in the city means that they can also play a central role in the resilience of urban communities to climate change. But despite these opportunities, and the long tradition of urban forestry in Dutch cities, the role of urban trees in climate adaptation remains limited.
Greenspace managers, policy makers and designers need accurate data and tools to monitor and model the benefits of urban trees in relation to heat cycles and urban microclimates. This applies to both baseline performances of different tree species, as well as performance over the life of a tree. A central concept in understanding this performance is tree architecture - a knowledge domain in the Urban Forestry research fellowship at the Faculty of Architecture and the Built Environment. Physical characteristics of a tree such as crown morphology, wood anatomy and leaf characteristics determine how and to what extent a tree cools its environment, and how this helps thermal comfort. These metrics can be supplemented by data on the transpiration rate of different tree species, which further help a tree’s cooling capacity through evaporative cooling. If this performance is then calculated over the life cycle of the tree, we can finally get a full picture of the thermal benefits of the urban forest.
The i-Tree 2.0-NL project will develop accurate metrics on the optimal cooling performance of hundreds of tree species grown in Dutch cities. This will facilitate estimates of a tree’s performance over its life cycle. The data will be integrated into an existing tool: i-Tree. This project aims to develop i-Tree so that it is capable of making assertions about the degree to which urban trees can help reduce heat in Dutch cities.
The development of accurate data within the i-Tree tool means that planners, designers and greenspace professionals will be better able to shape and manage urban green spaces for climate adaptation. But the success of the tool does not rest solely on the data, it must also be usable and applicable. A next step is to have one of the most important benefits of urban trees better integrated into planning and design practice. To do this the project develops the i-Tree tool further so that planners, designers and greenspace professionals can better utilise the potential of urban trees. New applications of i-Tree will be developed via design simulations and co-design with stakeholders. The ultimate goal is to develop climate-adaptive and sustainable urban green spaces for climate resilient urban communities.
The project consists of a consortium of 28 partners, including 5 research institutes, 8 municipalities, 7 tree consultancies, 5 tree nurseries, 3 engineering, spatial planning & architecture offices and 4 societal partners. The project will run for three years.
Project leader: dr. René van der Velde, Associate Professor Urban Forestry Department of Urbanism, Faculty of Architecture and the Built Environment, TU Delft
Project co-lead: dr. Rebecca Price, Assistant Professor of Transition Design, Faculty of Industrial Design Engineering, TU Delft