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

- 86 -This shows that if a building is well designed and constructed, even if embodied energy isrelatively high, maintenance impacts will be much lower over time which decreases theoverall life cycle impact.6.5.4 Comparison Between Landfilling and MaterialReutilisationThe results show a variation in end-of-life impact between landfilling (creating carbonstorage) and material reutilisation (combusting wood for energy recovery, and recyclingstructural concrete and steel). These results showed that the reutilisation scenario resulted in areduction in total energy consumption in all buildings of 0.5% (Concrete) to 4% (TimberPlus)when compared with the landfill scenario. The reutilisation scenario also showed similarbenefits for GWP for the concrete and steel buildings, with 0.2% (Concrete) and 5% (Steel)reductions respectively. Conversely, in this scenario, the Timber and TimberPlus buildingsshowed an increase in total GWP of 0.5 and 1% respectively, when compared with the landfillscenario.The GWP of the Steel and Concrete buildings decreased in the reutilisation scenario due toavoidance of production of primary materials (aggregate and primary steel). In the Timberand TimberPlus buildings, landfilling showed a carbon storage benefit, while combusting thewood for energy displaced the use of fossil fuels. Overall the GWP results for Timber andTimberPlus buildings in the two scenarios showed a slight favour to landfilling, though theresults are so similar that no real conclusion can be made other than that both options result ina negative end of life GWP figure, which reduces the total life cycle GWP.Material reutilisation enabled a recovery of energy for all building types. Reutilisationrecovered a proportion of the embodied energy of the wood that would otherwise be wasted ifthe wood was landfilled. Therefore the buildings with the largest energy recoveries were theTimberPlus and Timber buildings, as these buildings were composed largely from renewablewooden materials that could be combusted for energy recovery. The Steel building also had areduction in energy use when the structural steel was recycled, as production of primary steelis avoided.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 – in the case of steel these materials have a high initial embodied energy and GWP.For the Concrete building the differences are not as pronounced, however there are still slightGWP and energy reductions as a result of material reutilisation.In summary, reutilisation shows clear benefits for the Steel building. The Concrete buildinghas energy and GWP benefits from reutilisation, though they are small enough to be affectedby changes in transport distances. Both scenarios result in end of life GWP reductions for theTimber and TimberPlus buildings. However, the reutilisation scenario shows the additionalbenefit of energy recovery and displacement of fossil fuels.The comparison between the two end-of-life scenarios shows that conclusions based on asingle indicator could lead to unintended outcomes. Using the TimberPlus building as anexample, the results of the landfilling scenario would be slightly better in terms of climatechange. However, looking at the energy results alongside the global warming potential