In future, it will be possible to assess the environmental impact of different types of climate protection solutions in urban areas.
Considerable resources are currently being invested in solutions designed to collect and manage increased volumes of precipitation to prevent flooding and other types of damage. Existing underground drainage systems are being expanded, and green infrastructure is being established in the form of planting along roads, rainwater reservoirs, etc.
“The general feeling has probably been that green solutions are best for the environment, but so far this has not been supported by data. It therefore made sense to find a way of analysing different climate adaptation solutions,” says Sarah Brudler, postdoc at DTU Environment, who has been the driving force behind a recently completed three-year research project between DTU and water utilities in Copenhagen, Aarhus and Odense.
The purpose of the project was to establish a basis for conducting lifecycle analyses—or LCAs—of different solutions employed to manage extreme rainfall. (An LCA is a standardized tool for evaluating the environmental sustainability of a product or service from cradle to grave).
The evaluation of a climate protection solution is thus based on data covering the whole process—from the manufacture of elements like drainage pipes and transporting them to site, to any excavation work required on site, daily operations, and finally the recycling or reuse of disused pipes. The researchers have looked at a total of 30 different elements that may form part of various climate adaptation solutions.
Large data volumes collected
“It’s the first time that data of this kind has been collected with a focus on the entire process. It has therefore taken a lot of work to find out about all the elements forming part of different climate protection solutions, and also to find and add data about their environmental footprints. The researchers have looked both at the impact of point source emissions of toxic substances on the natural world, and at the resources going into constructing the climate protection solutions under investigation,” explains Sarah Brudler.
Having collected the data, Sarah Brudler performed LCAs on climate solutions in two places in Denmark. The overall conclusion confirmed previous assumptions that the greatest environmental impact is caused by climate protection systems based on the laying of underground pipes. This is due to the fact that the environment is impacted especially by the production and subsequent disposal of the necessary elements in the form of, e.g., plastic pipes.
Looking at the impact on ecosystems, all the various types of solutions—underground pipes and green infrastructure—were, slightly surprisingly, found to have the same impact.
Damage is primarily caused by point source discharges of contaminated rainwater. The main sources of pollution of the natural world are the metals copper and zinc which are used on the facades of buildings.
The considerable data volumes were initially entered in a large spreadsheet, which Sarah Brudler is currently transforming into a simple tool for use by the employees of water utilities who are involved in planning climate protection solutions.
“The idea is that users should be able to select the elements used in existing or future climate protection solutions and then calculate their environmental impact. The tool will also be able to suggest ways of optimizing a solution, e.g. by choosing drain pipes made from alternative materials. The solution has already attracted quite a lot of attention, and it may end up as a web-based tool which can be made available to a wider circle of users, like consultants and municipal town planners,” says Sarah Brudler.