Environmental and economic impacts of substitution between wood products and alternative materials: a review of micro-level analyses from Norway and Sweden

Abstract

This article gives a state of the art overview on quantitative analyses from Norway and Sweden of Life cycle analyses (LCA), which compare the environmental impacts of substitution between wood and alternative materials, with emphasis on greenhouse gas (GHG) emissions, economics and methodological issues. In all studies referred to this overview, wood is a better alternative than other materials with regard to GHG emissions. Furthermore, wood is causing less emissions of SO2 and generates less waste compared to the alternative materials. Preservative treated wood, on the other hand, might have toxicological impacts on human health and ecosystems. Impacts on acidification, eutrofication and creation of photochemical ozone vary in different comparisons. Amount of greenhouse gases avoided due to substitution between wood and steel is in the range of 36–530 kg CO2-equivalents per m3 input of timber with 4% discount rate; depending on waste management of the materials, and how carbon fixation on forest land is included. This amount is 93–1062 kg CO2-equivalents for substitution between wood and concrete, if the wood is not landfilled after use. Many of the LCAs could be considerably improved, if the analyses were done with several alternative assumptions regarding boundaries of the system used in the LCA. This is important, not least to map what are the main assumptions for the results obtained and to compare with other studies. It is also important to consider the time-profile of the GHG emissions and other impacts over the life-cycle—it is surprising that this is not taken more seriously. Wood as a building material is competitive on price in those studies that include costs. It is a weak point of many LCAs that costs as well as other economic aspects influencing product substitution are not included, and a major research challenge is to combine traditional LCA with economic analysis in order to make both more policy relevant. In particular, one should develop dynamic input/output models where price and income substitutions as well as technological changes and cost components are included endogenously.