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

- 115 -Figure 9.2 shows that the net GWP emissions from the materials in the Timber building arejust 5% of those from the Concrete and Steel buildings. This is because the carbon stored inthe wood-based building materials balances out nearly all of the greenhouse gases emitted inthe manufacturing of all the other materials in the building.For the TimberPlus building, the net total CO 2 emissions for the materials in the TimberPlusbuilding are negative because the carbon stored in the wood-based building materials morethan cancels out all the greenhouse gases emitted in the manufacture of all the other materialsin the building. The net negative figure - or long-term carbon storage - is over 630 tonnes ofCO 2 equivalent.9.5.2 Materials only – using data from LCA assessment inChapter 6Another method of analysing the data in Chapter 6 is to take the results of the LCAassessment presented in Chapter 6. The top line in Table 9.4 is the initial embodied GWP(tonnes CO 2 equiv.) for all materials in each of the four buildings from Table 6.7. The secondline in Table 9.4 is the equivalent CO 2 sequestered in the wood materials, derived from thewood quantities in Table 6.2. The quantity of carbon in that table has been converted to CO 2equivalent by multiplying by 3.67 (the conversion factor for changing tonnes of carbon totonnes of CO 2 equivalent).Table 9.4: GWP (tonnes CO 2 equiv.) for all materials in each of the four buildingsConcrete Steel Timber TimberPlusEmbodied (CO 2 eq.) 1,576 1,615 971 566Sequestered (CO 2 eq.) -32 -31 -846 -1,162Total 1,544 1,584 125 -596The figures in Table 9.4 are plotted in Figure 9.3 (as separate figures) and Figure 9.4 (netfigures). These graphs show similar trends to Figure 9.1Figure 9.1Figure 9.1 and Figure 9.2.The actual numbers are a little different from the coefficients method - the reason for this isnot known precisely. The difference may be due to the unknown assumptions used to obtainthe coefficients presented in Table 9.1.However, the over-riding conclusion from using both methods, is that the carbon stored in thewood-based building materials of the TimberPlus building more than cancels out all of thegreenhouse gases emitted in the manufacture of all the other materials in the building.