© University of York

Assessing the influence of green infrastructure on urban noise, heat and air quality

About half the world’s population now lives in urban areas, and the trend of migration to cities continues.  In such conditions, it is important to establish whether green infrastructure and urban ecosystems can support dense populations and provide sustainable services. Well-designed cities, including optimally located green infrastructure, should accommodate a large number of people in a relatively small amount of space, offering improved quality of life and allowing for greater resource efficiency and the preservation of larger intact natural areas. There is plethora of guidance on the identification, management and intervention of green infrastructure.

This research is a collaboration by Arup with the University of York and York City Council and is associated with the CAPACITIE project (Cutting-edge approaches for pollution assessment in cities), which aims to explore a wide range of technologies for air pollution monitoring.

The research team identified the existing approaches to measuring the benefits of green infrastructure and the availability of low-cost, high-performance environmental sensor technologies suitable for this application purpose. This information was used to design a pilot sensor programme in the city of York, in which data on air quality is being collected in real time. Information obtained through the city sensor programme will deepen our understanding of the role and impact that green infrastructure can have in positively influencing our city environments.

Through a literature review, we identified a variety of knowledge gaps. The majority of previous studies that identified and quantified the benefits of green infrastructure benefits were focused in North America and Europe, dominated by the USA and UK, respectively. A clear geographic knowledge gap exists from Australia, South and Latin America, Africa and Asia.

The available literature concentrated on generic urban elements such as buildings and urban green spaces, with a few studies focusing on specific building types, such as industrial and residential. Few prior studies considered the green infrastructure benefits of specific urban elements, such as street canyons, (non-canyon) roadsides, and residential buildings.  No studies were identified that examined quantitative benefits of green infrastructure associated with car parking structures, urban bridges, road walls and escarpments, monuments and cultural heritage materials, posts, walls and fences or indoor spaces.  Few studies examined cumulative or interacting effects of multiple air pollutants and how and to what extent green infrastructure mitigated these effects. The benefits of green infrastructure on mean and extreme peak pollutions remains poorly understood, with the exception of heat.

By addressing identified knowledge gaps, we are developing expertise that can be used in advising of the inclusion of green infrastructure in urban master plans.  Use of sensors to measure the performance of green infrastructure is a novel approach, especially when the sensors are deployed in the quantity and density adopted in the project in York.

This work builds upon and complements the research into green building envelopes recently carried out by Arup, combining insights derived from modelling results with the analysis of real-time sensor data to better understand the performance of green infrastructure.

This study contributes to the much needed evidence base of green infrastructure benefits, strengthening the business case for the incorporation of green infrastructure into urban development projects. With further research, the use of sensor technology and the smart city approach have the potential to inform and improve the way we design green infrastructure in order to maximise the benefits achieved. This type of information can be used to inform designers of the optimal location of green infrastructure. It can also be used in the preparation of business cases and to secure buy-in from the crucial stakeholders, and to justify the required investments.