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

- 130 -also Section 6.3.2.3.) This new NZ-specific data set shows that in comparison with one of themost widely used data sets in Europe (Gabi 4.3), there are major differences in coefficients foraluminium, steel and engineered wood products, such as LVL and plywood.The new data set now derives a GWP coefficient for LVL produced in NZ of 0.377 kg CO 2eq., which is significantly less than in previous studies. However, this figure is still based onGlulam (a similar laminated timber product) derived from European industry data, with somesignificant adaptions made to recognise NZ conditions.Nelson Pine Industries Limited, a NZ-based producer of LVL, has undertaken extensive workto calculate a GWP coefficient for its LVL. Nelson Pine use a significant amount of biomassenergy. When this biomass is recognised as a renewable energy source, they have calculateda GWP coefficient for LVL of 0.206 kg CO 2 eq. This is finished LVL product out-the-gate.Furthermore, Nelson Pine believe that planned improvements in the production process coulddrop this figure to under 0.174 kg CO 2 eq.• Does the NZ Green Building Council Green Star Office rating tool capture thefull environmental impacts of energy consumption and GWP and does the ratingtool recognise the benefits of reutilising all materials?There are clear differences in the results of environmental impacts for both energy usage andGWP between assessments based on the Green Star rating tool and the LCA methodology.The results of both tools were not consistent and it is obvious that the recycling content ofsteel and concrete drive the material related results in Green Star. The reutilisation scenarioin the LCA study showed that there are environmental benefits related to the energy use ofpost-consumer timber, especially through thermal treatment (burning to recover energy anddisplace other carbon based fossil fuels). This can not be accommodated for in the Green Starassessment tool.The Green Star Office rating tool does not take the amount of timber used in a building intoaccount. The LCA process showed a clear difference between the Timber and the TimberPlusbuilding; however, both have the same results in the Green Star assessment.The higher weighting of energy (25 %) than materials (10 %) for the single score of the GreenStar rating is consistent with the LCA study which showed that operational energy usedominates the results over the whole life cycle.• Is it possible to construct a multi-storey building in Timber?A considerable and growing volume of research and expertise in the design of timberstructures and buildings, aided by advances in engineered timber products and associatedindustry developments, supports the proposal that the Timber building designs in this reportcould be built right now.The performance-based NZ Building codes should not provide any ‘roadblocks’. Designfeatures of the Timber buildings can address and allay all concerns over seismic, fire andnoise constraints and research is on-going.