Exploring the climate impact effects of increased use of bio-based materials in buildings

Published Date
30 October 2016, Vol.125:219–226, doi:10.1016/j.conbuildmat.2016.08.041

Author 

Diego Peñaloza ^a,b,,

Martin Erlandsson ^b,c,

Andreas Falk ^b,

aSP Technical Research Institute of Sweden, Drottning Kristinas väg 67, 114 86 Stockholm, Sweden

bKTH Royal Institute of Technology, Brinellvägen 23, 114 86 Stockholm, Sweden

cIVL Swedish Environmental Research Institute, Valhallavägen 81, 100 31 Stockholm, Sweden

Received 4 November 2015. Revised 15 July 2016. Accepted 10 August 2016. Available online 17 August 2016.

Highlights

• Three building designs with increasing biobased material content were modelled and analysed using LCA.
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  Dynamic LCA was applied to account for biogenic carbon sequestration, storage and emissions.
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  Increasing biobased content reduces climate impact even if biogenic exchanges are assessed.
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  Time horizon, timing of forest growth and end-of-life recycling are key assumptions.
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  Time horizons lower than 100 years are not enough to capture properly climate impacts from buildings.

Abstract 

Whenever Life Cycle Assessment (LCA) is used to assess the climate impact of buildings, those with high content of biobased materials result with the lowest impact. Traditional approaches to LCA fail to capture aspects such as biogenic carbon exchanges, their timing and the effects from carbon storage. This paper explores a prospective increase of biobased materials in Swedish buildings, using traditional and dynamic LCA to assess the climate impact effects of this increase. Three alternative designs are analysed; one without biobased material content, a CLT building and an alternative timber design with “increased bio”. Different scenario setups explore the sensitivity to key assumptions such as the building’s service life, end-of-life scenario, setting of forest sequestration before (growth) or after (regrowth) harvesting and time horizon of the dynamic LCA. Results show that increasing the biobased material content in a building reduces its climate impact when biogenic sequestration and emissions are accounted for using traditional or dynamic LCA in all the scenarios explored. The extent of these reductions is significantly sensitive to the end-of-life scenario assumed, the timing of the forest growth or regrowth and the time horizon of the integrated global warming impact in a dynamic LCA. A time horizon longer than one hundred years is necessary if biogenic flows from forest carbon sequestration and the building’s life cycle are accounted for. Further climate impact reductions can be obtained by keeping the biogenic carbon dioxide stored after end-of-life or by extending the building’s service life, but the time horizon and impact allocation among different life cycles must be properly addressed.

Abbreviations

IPCC, intergovernmental panel for climate change

LCA, Life Cycle Assessment

EPS, expanded polystyrene

CLT, cross-laminated timber

GWP, global warming potential

EoL, end of life

EPD, environmental product declaration

Keywords

• Life Cycle Assessment
• Dynamic LCA
• Wood construction
• Biogenic carbon dioxide
• Climate impact assessment

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• DOC (868K)

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  Corresponding author at: SP Technical Research Institute of Sweden, Drottning Kristinas väg 67, 114 86 Stockholm, Sweden.

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