Substitution between floor constructions in wood and natural stone: comparison of energy consumption, greenhouse gas emissions, and costs over the life cycle

Abstract

This paper compares two floor constructions used at the new airport outside Oslo, one made of solid oak and one made of natural stone, to (i) make an inventory of energy consumption and greenhouse gas (GHG) emissions over the life cycle of the two constructions, (ii) calculate the differences regarding GHG emissions and cost, and (iii) determine which factors have the strongest influence on the results. Manufacturing the wood floor required 1.6 times more energy and produced one-third of the GHG emissions compared with the natural stone floor. Over the life cycle, net GHG emissions can be avoided only if the wood is used as a biofuel after the replacement or demolition of the floor. The wooden floor must be competitive on price to be a cost-efficient action against global warming. Per cubic metre of wood floor, emissions of up to 1.263 t of CO2 equivalents can be avoided by a substitution between the two floor constructions. The factors that have the most influence on the result are carbon fixation on forest land, waste handling of wood, and discount rate, the latter reflecting the relative importance over time given to a unit of GHG emissions.