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

- 109 -9.4.3 Data Sets9.4.3.1 GeneralThe embodied energy and GWP of the various building materials is calculated by multiplyingthe quantities of materials in each building by an appropriate embodied energy or GWPcoefficient. Thus, the coefficient data set used in these calculations quite obviously makes asignificant difference to the results.LCA is a fairly recent research technique and much of its ‘evolution’ has been based inEurope, where a number of important data sets have been developed. Due to the lack oflocally produced and specific data for building materials, a number of studies in New Zealandhave been based on European industry and energy data sets. Until recently, the best ‘local’data set was produced by Alcorn (see Alcorn, A. (1995), (1998) and (2003)) but this workacknowledges that the data set is now out-of-date and has some significant deficiencies.A recent study undertaken by Scion in collaboration with Alcorn for the NZ Ministry ofAgriculture and Forestry (Nebel et al., 2009) presents a dataset for key NZ building materials;the dataset was developed using LCA studies of timber and other building materials bycombining, updating and extending overseas data and NZ information. This project identifieda problem in the significant variation between NZ and European manufacturing and theresulting data differences. Whilst this latest dataset is recommended for use with NZbuildings, greater accuracy will only be achieved by the rigorous collection and analysis ofNZ specific data and the development of a comprehensive NZ Life Cycle Inventory database(which would include data from other sectors such as transport and energy).9.4.3.2 The importance of a NZ-specific GWP coefficient for LaminatedVeneer LumberThe recent study “Life Cycle Assessment: Adopting and adapting overseas LCA data andmethodologies for building materials in New Zealand” (Nebel et al., 2009) has addressedsome of the issues and produced a limited data set for the major building materials in NZ (seealso Section 6.3.2.3.) However, a notable omission from this new data set is a globalwarming potential (GWP) coefficient for laminated veneer lumber (LVL). This product isproposed to be used extensively in new pre-fabricated, multi-storey timber building, such asthe Timber and TimberPlus buildings in this report.For the LCA presented in Chapter 6, Scion have used a GWP coefficient of 0.377 (Kg CO 2equivalent per Kg of material) for LVL based on Glulam (a somewhat similar laminatedtimber product) derived from European industry, with some significant adaptions made torecognise;(i) that NZ LVL is produced using a significant component of renewable energy and(ii) that the bioenergy (solar energy) captured by timber products during the growing ofthe wood should not be included in the coefficient (Scion have made similarallowances for all other timber products in the new data set, as well, which is asignificant departure from some of the European data sets which incorporate thisbioenergy to complete an energy balance).