Carbon Calculations

As a recently certified B Corp we have joined a community of leaders, committed to using our business as a force for good. We consequently consider the environment in every decision we make. Our aim is to further show our commitment to the environment in all aspects of work we undertake.

We therefore started to produce documents detailing the social and environmental benefits for different features of our project designs. This has extended to include carbon calculations, where we are able to work out the amount of carbon associated with these features. On occasions where more than one design option is being considered, tables compare the carbon impact of each design. This was key to the Aire Park work, given Leeds City Council’s mission to becoming a net-zero carbon city by 2030, which forms part of the Government’s 2050 net-zero commitment for the entire UK.

A net-zero carbon city is one that will be carbon neutral, meaning that it will achieve an overall balance between the amount of emissions produced, and the amount of emissions taken out of the atmosphere. For cities this will mean reducing the carbon emissions where possible, and offsetting any remaining emissions. It is a step forward in slowing down climate change and reducing environmental impact. The calculations act a helpful quantifier for how landscape design can support attainment of CO2 reduction and climate change targets, beyond ‘X number of trees have been planted’.

The design features that we have developed calculations for, as well researched other environmental impacts, include:


  • A young tree absorbs on average 5.9kg of CO2 per year, whilst a 10 year old tree absorbs at an average rate of 22kg CO2 per year. Trees are also highly effective at absorbing gas and particulate pollutant, and the most effective when compared to other city surfaces.
  • Hedges, however, are better at absorbing pollutants among tall buildings due to their height acting as a barrier. Being lower to the ground, they can trap toxins at exhaust pipe level, reducing citizen’s direct exposure to harmful pollutants.
  • The cooling effect of trees can also reduce the need for air con in buildings, decrease energy demand, whilst ameliorating the felt impact of climate change on human health by reducing the temperature in many cities.
  • Trees can also help to reduce and intercept stormwater, improving the quality of run off water which contains fewer pollutants.

Amenity Lawns

  • Grass lawns also soak up CO2, which is then stored in the soil when the grass rots. One acre of managed lawn will hold on average 0.38kg of CO2 per m2 per year.
  • Problems associated with grass lawns, that increases their environmental footprint, include the use of fertiliser and overwatering.

Water Features and Planting

  • Ponds accumulate organic matter in their sediment and therefore sequester carbon. Water plants also absorb carbon as part of the photosynthesis process, and will create sediment that sequesters the carbon. Should a body of water be void of this sediment and planting, they will not sequester carbon.

FSC Certified Timber Benches

  • Using timber that is Forest Stewardship Council (FSC) certified means that the wood is sourced from a forest that is managed in an environmentally appropriate, socially beneficial and economically viable manner.
  • Using timber for furniture, in place of concrete, can save on average 1000kg of CO2e per m3 used.

Cement Free Paving

  • Using cement-free paving can reduce CO2e by up to 70% over normal cement products.

Electric Maintenance Equipment

  • Using electric landscape maintenance equipment, in place of diesel or petrol powered equipment will reduce carbon emissions.
  • A petrol based mower produces double CO2e per hour of operation than electric lawn mowers.

LED Lights VS Incandescent

  • LED lights are 80% more efficient than traditional lighting, such as fluorescent and incandescent lights, as they use less electricity for the same light output.
  • If LED lights were to be left on for 4 hours per day, 100kg of CO2e would be saved per annum, when compared to traditional lighting.

Drinking Water Points

  •  Encouraging the use of drinking water fountains will reduce the demand for bottled water. This will reduce the CO2e that are released through the plastic production process, as well as preventing plastic pollution.
  •  6000kg of CO2e are saved for every tonne of plastic that is not used.

The above is just an example of some of the calculations we have developed through a couple of recent projects. Our capabilities continue to expand with each commission, as we look to better support the communities within which we work and the environment.

Written by Marigold Melton, Sustainability and Research Assistant