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

- 54 -6.3 Life Cycle Assessment of the Four Building Designs6.3.1 GoalThe goal of this study is to calculate the environmental impacts (energy consumption andGlobal Warming Potential) of four alternative designs of a theoretical office building locatedon the University of Canterbury campus.The four designs are composed of three different structural materials; Concrete, Steel andTimber. In addition a variant called TimberPlus has been examined, in which the use of woodhas been maximised to the highest practical level.The study includes the initial production of the required materials to construct the building, amaintenance schedule where some building materials are replaced over the lifetime of thebuilding, impacts related to the operational energy, and the end-of-life of the four buildings.In addition to the overall goal, scenario analysis and sensitivity tests were carried out. Thescenario analysis examined different end-of-life scenarios, as well as the impact of differentlocations of the buildings with regard to changes in transport distances.The end-of-life scenarios include a base scenario where all waste is landfilled compared witha scenario in which the building materials are reused. This includes combustion of all woodmaterials and recycling of structural concrete and steel. Scenarios for transport distances lookat the location of the building in Christchurch (base scenario), Wellington, and Auckland.The end-of-life and transport scenarios are described in more detail in sections 6.3.3.3 and6.3.3.4.Finally, the results of the study are analysed and compared with an assessment of thebuildings using the current Green Star NZ assessment tool introduced by the New ZealandGreen Building Council (NZGBC). Green Star NZ is an environmental rating system forbuildings. Green Star for office buildings was released in April 2007 and evaluates buildingprojects against eight environmental impact categories, plus innovation. The goal of thisanalysis is to show how the same commercial building would rate using Green Star comparedto a life cycle based approach, as it is applied in Life Cycle Assessment.6.3.2 ScopeThe scope of the study includes a clear description of the system under analysis, thefunctional unit, system boundaries and data quality as well as the intended audience andapplication of the results.6.3.2.1 Functional UnitThe results of the study are related to an office building with gross area 4,247 m 2 on sixfloors, located in Christchurch and used over a period of 60 years. Four designs of thebuilding have been considered.