6 minute read
Climate Positive Design – Exploring the Pathfinder Carbon Calculator
The Pathfinder app was launched in 2019 – Gillespies has been evaluating its UK application.
Kara Heald
Gillespies
This is set in the context of the Landscape Institute’s (LI) 2019 recognition of the climate and biodiversity emergency and subsequent publication of their Climate and Biodiversity Action Plan in May 2020. The Action Plan sets out objectives and actions about how the LI will respond to the emergency and help equip practitioners to do the same. Two such objectives of the Action Plan, focusing on the carbon impacts of our work, are highly practical and tangible: – Develop and/or signpost towards tools to measure the carbon impacts of different design decisions at a landscape scale. – Work with partner organisations, suppliers and their supply chains to accelerate clearer information on embodied carbon/sequestration potential for hard and soft landscape materials, and provide sustainable specification guidance for practitioners. One such carbon calculation tool which the LI can promote or work with to measure the carbon impacts of design decisions is Pathfinder (https://app. climatepositivedesign.com/). This is part of Climate Positive Design launched by Pamela Conrad, Principal at CMG Landscape Architecture, in 2019. Pathfinder is North Americabased but can be used for projects around the world.
Gillespies began using Pathfinder on our projects in 2021, most recently on our shortlisted competition entry for Leeds City Square.
Speaking at the Landscape Architecture Foundation Innovation and Leadership Symposium in 2019 to launch Pathfinder, Pamela Conrad recognised that “as landscape architects and designers of the built environment, we have the tools in our everyday toolkit to sequester carbon, to take it out of the atmosphere.”
She is right; it comes down to the simple actions of more shrub and tree planting, less paving and hard materials, careful selection of hard materials, consideration of sources, and sustainably-minded specifications and operation and maintenance regimes. Not only do we have the tools to sequester carbon, but we also have the opportunity to make our projects carbon positive, meaning that they sequester more carbon than they emit. Pathfinder is a valuable resource to help practitioners achieve this.
Pathfinder is free for anyone to use, allows practitioners to measure the carbon footprint of their projects, and actively encourages users to achieve carbon positive projects in recommended timeframes. In essence, Pathfinder works out how much carbon is emitted by the use of materials and construction, how much is sequestered by planting, and how long it would take for a project to start sequestering more carbon than it has generated, offsetting its carbon footprint. Pathfinder accounts for the embodied carbon of materials used in the project (comprising the extraction, manufacture, transportation, installation, use/maintenance and replacement of construction materials), emissions generated from demolition prior to construction, and emissions from the installation of planting and soils.
The Pathfinder platform is intuitive to use, allowing practitioners to consider both the baseline site condition and test options for design proposals. A site location can be selected internationally, and the extent of the site drawn out so that a total site area is calculated.
Project works are divided into ‘Materials’, ‘Plants’, and ‘Operations’, and preprogrammed items, such as stone paving or trees, are available as standard with carbon data pre-set – so it is as simple as measuring a project design and quantifying areas/ items for all hard and soft materials and operations that will be undertaken during use.
It is important to recognise that some materials in Pathfinder are suited to a North American context, and materials will differ in some cases for a UK environment. In order to make the tool more specific and accurate for a UK or European context, there is an option to create custom elements. As such, availability of UK specific data is key to making Pathfinder more accurate and will continue to expand among suppliers if the LI seeks to work with them to accelerate more precise information on carbon. Vestre has plans to integrate their products into the tool so that they can be selected from a preprogrammed set of furniture. Marshalls are already providing the carbon footprint of their natural stone paving on datasheets, so the carbon footprint of Yorkstone quarried in the UK can be compared to a granite quarried in China. Barcham tree specialists are now providing the sequestration rates for all their trees, so again a custom element can be added to Pathfinder for a specific tree species.
Information on the data and metrics on which Pathfinder is based is available to download through the website. Practitioners should be aware that emissions for transport, construction and end of life process are assumed as 30% of the emissions from production, so it should be recognised that, depending on project location and material sources, this will in reality vary project to project. It is also worth noting that supplier data is unlikely to include emissions for transport, construction and end of life process, given this can vary so much, so it should be checked and recognised if the data is not available.
Carbon emission considerations for the Leeds City square design competition.
© Gillespies LLP
The pre-set data provided by Pathfinder combined with sourcing data for custom elements relevant to the UK makes clear the benefit, in carbon terms, of tree planting in our projects, and also helps us understand the nuances of carbon emissions. For example, a highly maintained lawn emits carbon overall due to the use of mowing equipment, irrigation, and fertiliser. In comparison, a ‘no mow’ lawn, or perhaps low maintenance wildflower meadow in the UK context, sequesters carbon.
We have the data to consider the carbon benefits of reusing materials onsite, sourcing products more locally, and selecting low carbon product options. In essence, Pathfinder gives practitioners data to back up the simple design actions we are already taking to make our projects more sustainable.
For a project to become carbon positive, Pathfinder relies on the sequestration of carbon by planting and trees, outweighing the embodied carbon from the use of materials for construction. It is also worth considering how forms of renewable energy generation might be accounted for in Pathfinder (balancing the embodied carbon for fabrication with clean energy produced over their lifetime). While not sequestering carbon, they are providing clean energy without directly emitting carbon, so a project that uses energy for elements such as lighting or a water feature can consider how clean energy could be used to reduce carbon emissions.
Pathfinder is a very helpful tool for practitioners to understand the carbon footprint and climate impact of their work. With UK and European-specific Environmental Product Declaration data starting to be provided by suppliers, it can be more focused on our local context. Considering the climate impact of our work should begin from the outset of any project, starting with initial client discussions, to make clients aware that as landscape architects, we have the tools to inform better decisions concerning carbon emissions. This must still sit in the context of how we as practitioners continue to consider the longevity of materials, suitability of materials specific to a project, and client cost considerations, taking a balanced approach and utilising Pathfinder as a tool to inform our decisions for more climate-positive design.
Kara Heald is a Principal Landscape Architect at Gillespies, the UK’s largest independent landscape architecture and urban design consultancy. She is committed to advocating and helping all landscape professionals take responsibility for protecting and enhancing the environments we work and live in.
