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

- 110 -This figure (0.377 Kg CO 2 eq./Kg) is significantly different to the figure which would havebeen used in earlier studies.However, as noted above, this new LVL coefficient is still a ‘best-estimate’ and has not beendeveloped by a thorough investigation, analysis and understanding of LVL production in NewZealand.There are a limited number of LVL producers in NZ, at least two of which have undertakenrecent work to determine a NZ-specific coefficient for LVL. Nelson Pine Industries Limitedhas undertaken a detailed assessment through analysis of the production and extraction of themain raw material in the production process (logs) from Nelson Forests’ domestic log supplychain and considering major inputs in processing operations within their own factoryincluding assessment of the electrical energy, boiler fuel, mobile plant fuel and PF resin (notethat for the wood residues used for heat generation the assessment has included the fuel andother CO 2 emissions associated with collection, processing and transport).Nelson Pine uses a significant amount of biomass energy. When this biomass is recognised asa renewable energy source (excluded), the emissions profile of Nelson Pine LVL is 118 kgCO 2 eq./m 3 . This is finished LVL product out-the-gate. (Note that stored carbon is notincluded in the assessment).The density of Nelson Pine LVL at 12% moisture content is 574 kg/m3 and this gives acoefficient for Nelson Pine LVL of 0.206 kg CO 2 eq./kg.Nelson Pine believe that planned improvements in the production process could drop thisfigure to under 100 kg CO 2 eq./m 3 . Using the same density conversion after plannedimprovements could reduce the coefficient to 0.174 Kg CO 2 eq./kg.If a coefficient of 0.206 kg CO 2 eq./kg or less was used for LVL in the LCA study inChapter 6, there would be a reduction in embodied GWP emissions associated with theTimber and TimberPlus building, both of which use a significant amount of LVL in theirstructure.The work undertaken by Nelson Pine has not been independently reviewed at this stage andcompatibility with other datasets used in this study, with regard to system boundaries andother methodological issues, could not be established. Therefore, the dataset was not appliedin this study9.5 Permanent Carbon Storage in Wood Products; anAlternative End-of-Life Scenario.The LCA conducted by Scion and detailed in Chapter 6 covers the full life cycle of thebuildings – often referred to as a ‘cradle to grave’ assessment. All life cycle assessmentsrequire assumptions about the end-of-life of the building. Chapter 6 has used two end-of-lifescenarios, one being landfilling with emissions of some of the decomposition gases and thesecond being “reutilisation” with the wood products being burned for energy recovery. Thesescenarios are difficult to predict because many things may be different in 60 years time (orlonger) when the buildings reach the end of their useful lives.