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

- 75 -8,0007,0006,0005,000GWP (t CO2 eq.)4,0003,0002,0001,0000-1,000Concrete Steel Timber Timber+Initial Embodied Maintenance Transport Operation End-of-Life CO2 RetainedFigure 6.15: Percentage of GWP of each unit process, compared between building types in thereutilisation scenario.Table 6.11: Total GWP (tonnes CO 2 equivalent) of each stage of the life cycle including the CO 2 retainedthrough displacing the use of traditional energy sourcesInitialembodied[t CO 2 eq.]CO 2 eqretained[t CO 2 eq .]BuildingtypeMaintenance[t CO 2 eq.]Transport[t CO 2 eq.]Operation[t CO 2 eq.]End-of-life[t CO 2 eq.][t CO 2 eq.]Concrete 1,576 131 42 4,910 135 -12 6,782Steel 1,615 166 39 5,000 -241 -11 6,567Timber 971 139 29 5,161 11 -302 6,010Timber + 566 99 30 5,038 12 -414 5,330The total primary energy consumed and GWP of each stage of the life cycle for thereutilisation scenario are presented in Table 6.10 and Table 6.11 respectively (presentedgraphically in Figure 6.14Figure 6.14Figure 6.14 and Figure 6.15). The negative figure in theEnd-of-life column for Steel includes a credit for the displacement of virgin steel. Thesetables also present the quantity of energy recovered from combusting the wood componentsand the CO 2 retained through displacing the use of traditional energy sources with theirassociated CO 2 emissions. These figures can be seen in the ‘Energy retained’ (Table 6.10) and‘CO 2 eq.retained’ (Table 6.11) columns, and the larger figures represent the larger quantitiesof wood available for energy recovery in the Timber and TimberPlus buildings.Total6.3.5.2 Transport DistancesIt is important to note that the transport contribution to total impact is minimal at around 0.3%and 0.5% for primary energy use and GWP respectively. However, for the purpose of thestudy it was interesting to test the relevance of the assumptions made. A sensitivity test wastherefore carried out to test the difference in environmental impact when the location of eachtype of building was changed (Base scenario assumed Christchurch). The change in location