Extract

It is often believed that green infrastructure assets are net carbon sinks and this may have contributed to the lack of consideration of embodied greenhouse gas emissions by landscape architects. However, these embodied emissions cannot be ignored. This paper aims to demonstrate the significance of life cycle greenhouse gas emissions in park design and the need for landscape architects to address them. We use a hybrid life cycle inventory approach to quantify the life cycle embodied greenhouse gas emissions of the 26 000 m² Willowdale park, a greenfield development near Sydney, Australia. We take into account operational emissions associated with lighting, operating barbecues and mowing, as well as carbon sequestration in soils and trees. All original quantities are sourced from primary data. Results show that life cycle embodied greenhouse gas emissions are significant, at 1 419 tCO2e over 50 years (55 kgCO2e/m²). Initial embodied greenhouse emissions from the day the park opened represent almost 73% of life cycle emissions. It takes 47-48 years for the trees and the soil to sequestrate enough carbon to offset embodied and operational emissions. In other terms, for almost the first five decades, this park remains a net carbon emitter. These results demonstrate the need for landscape architects to understand embodied emissions in construction materials. Equally, they need to plant as many climate-resilient trees that sequestrate enough carbon to offset embodied greenhouse gas emissions in shorter timeframes. Using a detailed and comprehensive life cycle assessment model is critical to achieving climate positive outcomes.

Keywords: Embodied carbon; Carbon Sequestration; Life Cycle Assessment; Landscape Architecture

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