Microscale urban climate modelling

The UrbClim model provides local policy maker with a city wide view and a tool to identify intra-city hot spots and investigate city-scale climate adaptation scenario's for urban development. Many of the more concrete measures such as green roofs, building whitening, water ponds etc impact the microscale environment, for which the UrbClim model is too coarse. Hence, our team is working together with the department of Urban Physics of the Technical University of Eindhoven (TU/e) to develop a computational fluid dynamics (CFD) tool for urban climate assessement at the microscale. 

A multi-scale analysis of the urban heat island effect: From city averaged temperatures to the energy demand of individual buildings. Global warming and the related urban heat island effect are environmental problems of growing concern. A joint effort between VITO and TU/e (group of Prof. Dr. ir. Bert Blocken) where both partners have agreed to bear 50% of the cost of the project, aims to develop and apply modelling tools that investigate these problems on scales ranging from the urban scale down to the scale of individual buildings.

 

Project goals

  • Developing a CFD model for simulating the UHI effect on the micro-scale. CFD models are primarily developed for simulating air flows. In this project, we aim to extend an existing CFD model with all functionalities required to properly simulate the urban heat island effect. We will use the open-source CFD model OpenFOAM as base for all our developments.
  • Coupling the UHI-CFD model with meso-scale models. Decreasing the scale from the urban scale to the micro-scale requires a proper coupling between urban scale (meso-scale) models and the CFD model. We will specifically focus on how the results of meso-scale models can serve as boundary conditions for the CFD based micro-scale UHI model.
  • Validation and case study of the UHI-CFD model. Validation is an essential step in the development and use of a CFD model. In this project, we aim to dedicate time to both a numerical study as well as a measurement campaign of a carefully selected case study in order to properly validate the UHI-CFD model. An in-depth analysis of the case study is also planned.
  • Effect of building characteristics on the UHI effect. Generic values of building characteristics are often assumed for UHI studies. We aim to assess the influence of taking into account the individual building specific characteristics in a neighbourhood for studying the UHI effect. As such, building scale information serves as input for the micro-scale UHI-CFD model. Also here, measurements are foreseen to validate the model.
  • Building energy performance and indoor thermal comfort. The results of the UHI-CFD model can also serve as input for building energy performance models and indoor thermal comfort models. This allows us to assess the effect of the climate change on the future energy demand and personal thermal comfort in cities.