Carbon sequestration through urban ecosystem services: A case study from Finland

- The CO2 emissions of buildings may be regulated by the uptake of carbon in plants.
- The sequestration compensates for less than 10% of emissions over the full life cycle.
- Up to 85% of emissions may be compensated for in the production phase.
- Site efficiency and the number of trees set the potential for emission compensation.
- Several knowledge gaps were found in the quantification of the compensation potential.

Plants and soil are natural regulators of atmospheric CO2. Whereas plants sequester atmospheric carbon, soils deposit it for decades. As cities become increasingly more densely built, the available land area for such ecosystem services may decrease. We studied seven different housing areas in the Finnish city of Espoo to ascertain the extent to which site efficiency affects to the ecosystem services if the full life-cycle GHG emissions of these areas are taken into account. The results show that the impact of CO2 uptake through carbon sinks in growing plants and the uptake of soil organic carbon vary greatly. Its share of all emissions varied from a marginal value of 1.2% to a more considerable value of 11.9%. The highest potential was calculated for a detached house located on a large site, while the weakest was calculated for compact apartment blocks. The study revealed that in order to quantify this potential more accurately, several knowledge gaps must first be addressed. These include impartial growth algorithms for Nordic wood species, missing accumulation factors for soil organic carbon in cold climates and statistical maintenance scenarios for gardens.

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