Assessing the environmental impact of using load-bearing reused wood and seaweed insulation in a building construction

Guimaraes De Campos, Renata

4. Term

Urban, Energy and Environmental Planning, Master

2022

2022-06-03

57

Produktion af nye byggematerialer står for omkring 11 % af verdens CO2-udledning, så byggebranchen søger materialer med lavere klimabelastning (GWP). Biobaserede materialer som træ og tang optager CO2, mens de vokser, og kan dermed sænke den samlede udledning. Dette studie sammenligner en 1 m² bærende konstruktion af træ og tang (WSW) med en konventionel løsning af beton og stenuld (CRW) for at hjælpe den danske byggebranche med at reducere sit miljøaftryk. Vi vurderede miljøpåvirkninger med en livscyklusvurdering (LCA), som ser på effekter fra produktion til slutningen af levetiden. Fordi WSW-løsningen er biobaseret, brugte vi en dynamisk LCA for at tage højde for timingen af optag og frigivelse af biogent kulstof. WSW-elementet havde 27,78 % lavere GWP end CRW-elementet, men 66,67 % højere påvirkning på arealanvendelse. Resultaterne ændrede sig markant afhængigt af den valgte LCA-tilgang, hvilket viser, at konklusioner om biobaserede materialers fordele er meget følsomme over for metodevalg. Med en tilgang for indirekte ændring i arealanvendelse (iLUC) havde WSW lavere påvirkning i 6 ud af 7 miljøkategorier og var kun højere i kategorier for arealanvendelse—hvilket indikerer, at mere brug af træ kræver mere land. Tang viste generelt lavere påvirkning i de fleste kategorier, men usikkerheder om end-of-life (bortskaffelse eller videre anvendelse) kan øge marin eutrofiering, især hvis proteinrigt fiskefoder indgår som biprodukt.

Producing new building materials accounts for about 11% of global CO2 emissions, so construction is seeking materials with lower Global Warming Potential (GWP). Bio-based materials such as wood and seaweed absorb CO2 while they grow, which can reduce net emissions. This study compares a 1 m² load-bearing structure made from wood and seaweed (WSW) with a conventional concrete and rock wool (CRW) solution to help the Danish construction sector lower its environmental impact. We assessed impacts with a Life Cycle Assessment (LCA), which examines effects from production through end of life. Because the WSW option is bio-based, we used a dynamic LCA to account for the timing of biogenic carbon uptake and release. The WSW element had 27.78% lower GWP than the CRW element, but a 66.67% higher impact on land use. Results varied significantly with the LCA approach, showing that conclusions about bio-based benefits are highly sensitive to methodological choices. Using an Indirect Land Use Change (iLUC) approach, WSW showed lower impacts in 6 of 7 environmental impact categories, with higher impacts only for land use—indicating that greater use of wood requires more land. Seaweed generally showed lower impacts in most categories, but uncertainties about end-of-life scenarios can increase marine eutrophication, especially when protein-rich fish feed is considered as a by-product.

[This summary has been rewritten with the help of AI based on the project's original abstract]

LCA ; wood ; seaweed ; load-bearing structure ; insulation ; environmental impact ; GWP ; Land-use ; water impact ; Dynamic LCA

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