The poor air quality in our cities is currently at the centre of public debates on health living conditions and at the pinnacle of innovative urban planning and mobility policies. Especially, so-called 'street canyons' represent the most problematic arteries of our cities: these are narrow inner-city roads that are flanked on both sides by a continuous row of (high) buildings. In these street canyons, the air quality is often below the European standards and those of the World Health Organization. Both urban design and technological solutions, such as photocatalyst, have proven to be a powerful tools for improving the air quality and overall health. However, this research is often restricted to a single domain, sector or discipline (either bioengineering or urban design) and is often limited to the analysis of the impact of a single parameter on air quality. Secondly, the most well-known measures focus on the reduction of emissions of pollutants and are situated on a larger scale planning and policy level. At the local scale level of traffic intensive locations and the so-called street canyons, systematic research on the possible contribution of urban design and technological interventions to improve the air quality is lacking. Moreover, a group of pollutants under less public scrutiny, volatile organic carbon (VOC), are less susceptible to traffic regulations. The treatment of paving, walls and facades with a photocatalyst have proven to contribute to improve the air quality. However, in street canyons the airflow rates are often low for an optimal performance of these photocatalysts. Alterations of the urban design (that improve the air circulation and the integration of UV lightning) can seek VOC abatement in urban street canyons with minimized environmental burden. In conclusion, in terms of air quality on the level of street canyons, there exists a fundamental disciplinary schism between environmental and urban design sciences.
Dealing with the spatial distribution of air pollution and high threshold to bridge technological innovation with urban planning, this research project aims to combine environmental and design sciences. Therefore, the Research group for Urban Development (Design Sciences), DuEL and BioGEM (Engineering Sciences) decided to team up to tackle together this pregnant challenge.
The scientific challenge grasped in this project is threefold: (1) Understand the spatial and molecular distribution of VOC in urban environment, with focus on street canyons, (2) Maximize the effect of urban design changes to improve the health effects of street canyons by incorporating photocatalytic abatement technologies; (3) Formulate design guidelines for improvement of air quality in street canyons based on LCA metrics, and extrapolate the methodology to future technological improvements. Together these challenges constitute an opportunity to significantly lower the threshold for future developments to improve the health conditions in street canyons.
Divided over four Work Packages and four years, this multidisciplinary approach of this challenge calls for a combination of methodologies, ranging from literature review, to research by design, over modelling and case study research. The Turnhoutsebaan in Antwerp is selected as case study, being representative for typical Flemish street canyons in terms of structural characteristics (length, height over width ratio), traffic density, demonstrated high air pollution levels and the availability (or lack) of green infrastructure.