Carbon Footprint in Landscape Architecture

The objective of landscape architecture should be climate positivity. This will most likely manifest when landscape carbon positivity becomes a sales argument or a general policy, and amendments to legislation are made.

Landscape architecture projects have a surprisingly large carbon footprint due to hard surface cover and artificial materials used in the plans. The main ‘bad boy’ here is the production of cement and steel. Even if during the planning process intuition seems to imply that there are plenty of various greens, rain water is absorbed by the soil, etc., it might still happen that carbon neutrality in that area remains centuries away. That means the location will have been rebuilt several times. Even if vegetation were not replanted, the part that will definitely get upgraded is the biggest contributor to the footprint—the hard surface cover and small built objects—which will further increase the footprint. For vegetation to neutralise the effect of hard surface covers, we would be needing it in very, very large quantities.

What is behind the carbon footprint in landscape projects?

As with architecture projects, the main ingredient to consider in landscape projects is the footprint of material production and the following maintenance costs. The Atelier Ten environmental consultancy claims in one of their studies that transportation of materials, and building of exterior areas only makes up about 15% of carbon emissions. Obviously, different materials have very different factors, which have to be evaluated for each project separately. Transportation costs depend on distances: whether it is national, inter-continental, etc. Granite is a well-known low-impact material, but importing it from China makes its footprint skyrocket compared to the effects of mining it in Nordic countries.

The rest of the footprint is caused by manufacturing of materials. Where use of timber may be the magic wand in building construction, in external conditions this option is limited in our climate zone. A huge efficiency factor is the use of existing materials, avoiding transportation of artificial materials or even processed soil. The best results in landscaping are achieved by using local soil to the maximum. Other regions in the world crush gravel from local rock, etc.

Complexity of assessment. How to calculate?

The sustainability evaluation of landscape projects is made complex by constant change caused by succession. Climate neutrality increases alongside tree growth and when habitats reach their full vitality, it may start to decrease after a certain point. When large, old trees that have lived their life are replaced by new ones, carbon gets partially emitted in the process.

Calculations of the climate neutrality of landscape architecture projects has been globally practiced for about a decade and so far has been mainly done by counting on fingers, i.e., performing complicated computations manually. A considerable number of case studies are open access that can be used to make certain choices.1

For example, an application called iTree2 can be used to assess the effect of trees on the environment, including their carbon sequestration. Pathfinder,3 which was launched in 2019, should be the first and so far the only application that enables calculating the carbon footprint of landscaping projects as a whole, and the time when the project will become climate positive.

The application enables estimating solutions designed thus far, or alternatively using it throughout the planning process to retrieve feedback on the impact level of certain project alterations on carbon amounts. There is ongoing debate about climate neutrality being a below the bar objective for landscaping projects: the aim should be climate positivity, and formulating calculations around that from the beginning makes the goal more achievable and less painful.4

Complex with one of the smallest CO2 footprints globally: Center for Sustainable Landscapes in the US (The Design Alliance Architects, 2013). The building and the exterior areas have highest level LEED and SITES certificates.

Carbon footprint in landscaping projects in Estonia

Currently, there are no demands placed on the landscape architect to calculate carbon footprint. Our office has only received one privately commissioned request that desired as much carbon sequestration as possible in a project. When we added the carbon calculations to the price proposal, so as to not merely offer an as-much-grassland-and-park-area-as-possible solution, our price turned out to be non-competitive.

A change may appear on the horizon when landscape carbon positivity becomes a sales argument for the (private) commissioner, or, a general policy, and amendments to legislation are made. Calculations are extra work and extra money which have global significance but remain inconspicuous at local level.

These calculations are currently neither required by the so-called imported LEED and BREEAM certification systems. So far, we have come across one of them in our practice and based on our initial experience, practitioners may remain critical of the efficiency factor these systems have on landscapes. The considerable amount of extra work inherent in the process does not really provide the kind of substantial benefit that a good specialist would not think of himself. By inconsiderately applying requirements what can result are ecological traps which offer no useful solutions for either the fauna or the flora. At the same time, systems like these are comprehensible and will hopefully prove themselves as stepping stones towards increasingly substantiated certificates. We must also bear in mind that climate neutrality might not always go hand-in-hand with biodiversity or ecological tools, since attaining those two can come at the cost of high energy expenditure. Similarly to the aforementioned systems, the US has implemented the SITES certification programme to measure landscapes, which seems more substantial by the look of its description, however, I have no direct experience with it.5

Should a landscape architect consider climate neutrality?

Until a respective policy regarding landscapes comes into force, landscape architects should acknowledge that the mere absorption of rainwater, use of local species and solar parks will not suffice to influence the course of climate change. The former tools are so-called base solutions. A new type of material aesthetic needs to be rooted as well. The client must arrive at an understanding why using asphalt or concrete as surface cover is not beneficial and why bonded bulk material should be considered as an alternative. A general consensus should be reached at public level: at least until we learn to make highly bespoke artificial materials in a climate-neutral way.

We should also pay more attention to different types of soil whose biota is actually the stronger carbon sequestering agent than the plants. Carbon is released as soil becomes impoverished. Soil quality can be naturally supported by lush, free-growing, native plant-life with deeper roots and an efficiency factor times bigger than that of regular lawn plants; the use of bio-coal as fertiliser would also be beneficial. That would enable sequestering additional carbon in the soil for centuries to come. In a similar mindset, local low-fertile soil should not be removed and relocated to some place out of sight, but should be made more fertile with the skilful use of planting instead.6

Example of a conscious effort to create an exterior project aiming at climate positivity: general view of the environmental house (design 2019–2021). Principal designer and architecture by KavaKava; exterior space by Kino.

Square vs park

Clearly, we need squares and streets where the footprint can not just be reduced by replacing the hard surface cover for a soft one. For example, Pathfinder recommends setting a five-year goal to attain climate positivity in park projects, and a twenty-year goal for squares. Sometimes a hard surface cover is necessary. This is where it becomes crucial to make better choices in material and try to keep the average sum result of projects climate positive. Built square and street projects can be neutralised with park projects, etc.

Graphs indicating carbon ratio are being drawn up constantly and they have been calculated from all angles. A common thread runs through each, revealing that Europe is not the world’s largest cause of carbon footprint. Across disciplines, landscape architecture does not seem to have a big effect either. However, this generates a comfortable illusion because in reality, we are all interconnected through a global network. Landscape architecture is one part of a simple local remedy: as we reduce the use of energy-demanding materials in our solutions, the need to manufacture those materials somewhere far away decreases and less fossils have to end up in furnaces here in Estonia. As we use local species, there is no need to grow and transport demanding cultivars from abroad that are alien to our habitats. The need for artificial fertilisers disappears as well, etc. This type of approach actually enables influencing all factors that would normally increase the carbon footprint, from transportation to industry. In addition, landscape architecture impressively holds the reins over problems originating from other disciplines, having the ability to solve them by sequestering as much carbon from other sources as possible.7 That is why the purpose of landscape architecture should be climate positivity.

MIRKO TRAKS is a landscape architect and CEO of Kino Landscape Architects.

HEADER photo by Markus Spiske / Unsplash

PUBLISHED: Maja 105 (summer 2021) with main topic Landscape Architecture!

4  Green, Jared. To Stop Adding to the Problem, Use Climate Positive Design. – The Dirt, 10.03.2019.
5  SITES Rating System.
6  Landscape Design for Carbon Sequestration.
7  Holmes, Damian. Landscape Architects Leading the Charge for Climate Action. – WLA, 14.11.2017.