Urban planting revisited and the Adaptive Cities special interest group

New guidance on urban planting shows how innovative solutions and collaborative working can be effective in mitigating the effects of climate change in our cities.

CIBSE’s Immediate Past President, George Adams, discusses the Adaptive Cities special interest group which is currently being established and the latest guidance being issued by the Trees and Design Action Group.

CIBSE is establishing a new Adaptive Cities special interest group and as part of this action we are now a firmly established member of the Trees and Design Action Group (TDAG) and contributed to the TDAG's latest publication Trees in Hard Landscapes: A Guide for Delivery (freely available on their website).

"Hardly a street could not be improved, if someone would give thought to planting the right trees in the right places… (in) new development there will be a chance for growing trees in areas almost treeless until now. This book describes various ways whereby trees can be used, at relatively little cost, to make towns beautiful.”

The above is not a quote from TDAG guidance, but from a Ministry of Housing and Local Government book, Trees in Town and City, published in 1958. Much of what we are talking about today, and one of the reasons that TDAG was formed, was recognised in 1958 - but there is a difference. In 1958 the discussion was about the contribution that trees could make to beautify the urban area and to make pleasanter places for people. This remains an essential role of urban trees but we now have the much bigger challenge of climate change and the need to make our towns and cities more resilient.

In an earlier blog post I described the need to mitigate climate change by reducing CO₂ emissions and adapting our urban environment to respond to consequences such as flooding and overheating. The strategic planting of trees (as well as other elements of green infrastructure) can provide many benefits – conserving and reducing energy, cooling the external environment; reducing cold winter winds, improving air quality, reducing the rate of surface water runoff and reducing the urban heat island effect. The result is to make our cities more resilient.

Research at the University of Manchester showed that a 10% increase in canopy cover could help Manchester to ‘climate-proof’ the city to 2050. In London the canopy cover has been estimated at about 20% and the Mayor is committed to increasing it by 5% by 2025 and a further 5% by 2050. This is a positive start, but we need to go even further. It is vital to recognise that strategically applied tree canopy cover needs to be distributed more evenly across our urban areas- density is a critical criteria. There is also significant research in some American cities that demonstrates the potential benefit of urban strategic tree planting and that this holistic approach can be cost effective.

However the places that would most benefit from trees are those areas of hard landscape which are also the areas that present the greatest challenges because of the highly complex situation below ground. Utilities – water, gas, sewerage, electricity and communications - lie under the streets of our cities often without coordination for either mapping or access. This is given consideration in the new TDAG publication. CIBSE’s Adaptive Cities special interest group will be calling for a more sustainable integrated infrastructure where 'grey',‘blue’ and ‘green’ infrastructure together for joined up thinking and collaborative solutions. Engineering will be the common link between the inside and the outside of our buildings of which 80% will still be with us in 2050.

The built environment and the landscaping professions have a unique opportunity to work together for a sustainable future for our urban centres. Trees in Hard Landscapes was produced by TDAG in partnership with the Institution of Civil Engineers (ICE), the Chartered Institution of Highways and Transportation (CIHT), CIBSE and the Institute of Chartered Foresters (ICF) in recognition of the need for cross-disciplinary working. Indeed this guide is for all who work in the built environment – engineers, architects, landscape architects, urban designers, quantity surveyors and tree specialists - and it focuses on four areas for delivery:

·         collaborative working,

·         above-ground design issues,

·         technical solutions (particularly integrating trees below ground)

·         selecting the right tree species for the right place.

Taking an example, in the case of new trees, these can be planted in a rooting environment that also helps to manage surface water runoff; combines with the installation of a cycle route which will benefit from the shade the trees will provide over time.

The opportunities are there if everyone involved has the mindset to take them. The new Adaptive Cities group will adopt and embrace this exciting opportunity and will seek support from other CIBSE networks such as the Young Engineers Network (YEN) and Women in Building Services Engineering (WiBSE) to promote the need for inclusive thinking and joined up actions.

The key message here is that we will need all the practicable available solutions and collaborative working if we are to achieve the limitations on impact of climate change and reduce the urban heat build-up.

To not achieve this will surely be a failing of our professional and social responsibilities.

Thank you to everyone who has contributed to this blog, we have covered a number of vital issues and there has been such a positive response across social media. Thank you all for sharing your views and expertise and I trust you'll continue to do the same for Peter Kinsella during his presidential term.

CIBSE President George Adams