Impact of end-of-life stage in cradle-to-cradle LCA analysis of timber and timber-hybrid buildings

Timber and hybrid timber buildings are very-well known for their properties of optimizing structural performances through a forward-looking combination of timber with other materials. These types of structures are also more sustainable from environmental perspective if compared to traditional RC buildings, especially considering the End-Of-Life stage (stage C) and Beyond System Boundary Stage (stage D) of Life Cycle Assessment (LCA) analysis where timber members contribute to the reduction of e.g., Global Warming Potential, given their very low – or even negative – values in terms of released kg CO2 eq. Two main issues have been identified by the authors concerning assessment of that topic, as first of all no standard methods are available for stage D impact evaluation; this problem is exacerbated by data shortage, given that this stage is currently not compulsory in the development of LCA analysis. In order to standardize this phase with the goal of spreading its importance, the authors investigated different case studies. Analysed previous studies are also needed for the second issue development, as a point of primary importance is the building structural scheme, with particular focus on fastening technology. Considering re-use, recovery or recycling potential of a building part or member, a key issue is the disassembling simplicity: this characteristic should be definitely taken into account in a cradle-to-cradle LCA analysis as this is the unique way to design the building in sustainable terms. Reducing number of steps from building dismantling to the new building construction and minimizing amount of materials destined for disposal become measures of the building ability to reverse CO2 emissions to zero or negative values with stages C and D detailed assessment.