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

- 128 -For the TimberPlus building, there is an even more noticeable impact - net storage of carbon,over 630 tonnes of CO 2 equivalent. The storage of carbon more than cancels out all thegreenhouse gases emitted in the manufacturing process of all the other building materials.As shown in Figure 10.2, under this permanent carbon storage scenario, the Timber andTimberPlus buildings have significantly lower net emissions over the full 60 year life-cycle ofthe buildings (data from Table 6.9 and Table 9.3) compared to either conventional, presentdaylandfilling or material reutilisation and recycling.This storage of carbon would allow the TimberPlus building to operate for the first 12 yearsas a ‘carbon neutral’ building with no net emission of CO 2 .Net storage of carbon in wood products is consistent with the idea of ‘regenerative building’where the built environment positively repairs the damage of previous generations.GWP (t CO2 eq.)8,0007,0006,0005,0004,0003,0002,0001,0000Concrete Steel Timber TimberPlusLandfill scenario w ith decomposition of 14% of timber after 46 yearsReutilisation / recycling scenarioLandfill w ith 100% permanent carbon storage in timber productsFigure 10.2. Net lifecycle GWP emissions for the four buildings showing comparison of different end-oflifescenarios.• How important is the choice of indicators for an assessment?The comparison between the two end-of-life scenarios in Chapter 6 shows that conclusionsbased on a single indicator could lead to unintended outcomes. Using the TimberPlus buildingas an example, the results of the landfilling scenario would be slightly better in terms ofclimate change. However, looking at the energy results alongside the global warmingpotential results, the reutilisation scenario shows an energy reutilisation benefit, as well asstill being beneficial to climate change. Therefore, the use of multiple indicators is necessaryto inform the environmental decision-making processes.