Environmental Impacts of Multi-Storey Buildings Using Different ...

- 126 -• How does the choice of finishing materials affect the life-cycle energy use andGHG emissions?Comparing the Timber with the TimberPlus building shows that a significant reduction inembodied energy and embodied GHG emissions can be achieved by increasing the amount ofwood and wood products in the building envelope. The largest benefit comes from replacingaluminium with wood in the window frames and the sun louvres.A similar benefit would accrue if a large amount of timber finishing materials were used inthe Concrete and Steel buildings.Further increasing the use of timber throughout any of the buildings, for example in ceilingsand interior walls, as insulation and floors, would reduce embodied energy and GHGemissions even more.• What impact does the end-of-life disposal of materials have on energyconsumption and GWP?The end-of-life disposal of materials (with a number of feasible scenarios) has a significantimpact on full life cycle energy consumption and GWP.Scion proposed two end-of-life scenarios; landfilling (creating carbon storage) and materialreutilisation, the latter combusting wood for energy recovery, and recycling concrete andsteel. The Discussion in Section 9.5 proposes a different end-of-life scenario, where theassumption is that all carbon sequestered in wood products is retained in perpetuity.The Scion results show a variation in end-of-life impact between landfilling and materialreutilisation. Reutilisation resulted in a reduction in total energy consumption in all buildingswhen compared to the landfill scenario. The reutilisation scenario showed similar benefits forGWP for the Concrete and Steel buildings; however, the Timber and TimberPlus buildingsshowed a slight increase in total GWP (results for the two scenarios were very close, so thatno firm conclusion can be made, other than that both scenarios result in a negative end-of-lifeGWP figure, which reduces the total life cycle GWP).Material reutilisation enabled a significant recovery of energy and reduction in GWP for allbuilding types. Material reutilisation recovered a proportion of the embodied energy of thewood that would otherwise be wasted if the wood was landfilled.The building with the largest energy recovery and GWP reduction was the TimberPlusbuilding, as this building is composed largely from wooden materials that can be combustedfor energy recovery. The Steel building also had a significant reduction when the structuralsteel was recycled, as production of primary steel is avoided; however, the reduction is stillless than recovering energy from combusting wood in the TimberPlus building.Recycling the steel and concrete in the reutilisation scenario would be more beneficial thansimply landfilling these materials because this displaces the need to use new primarymaterials with high initial embodied energy and GWP.