| dc.description.abstract | The building sector is responsible for more than one-third of the global GHG emissions and consequently, climate change. As the result of the Paris agreement and the initiatives for reducing GHG emissions, the building sector has massive potential to reduce its GHG emission and energy use. Concepts such as Zero Emission Neighbourhoods or Zero Emission Buildings can play a crucial role in reaching GHG reduction goals. Embodied Emission (EE) has been the area of concern in recent years for more ambitious levels. Life Cycle Assessment is a commonly used standard methodology for assessing the potential impact of building materials. This study analyses the uncertainty in building materials that cause the uncertainty of the embodied emission results from the production stage (A1-A3). There are two main aspects of material considerations in buildings. Firstly, material saving in quantities or efficiency strategies and secondly emission intensity reduction in upstream processes. The focus of this study is to find recommendations on where the design should be done differently in early-stage planning.
A literature review has been done to understand the theory and uncertainties associated with different aspects of EE in the building sector. Different parameters that affect EE have been identified. Then the relation between the EE and other life cycle stages has been investigated. An inventory data of 20 Norwegian case study buildings with around 2000 inputs have been classified into 14 main material categories. The categorization has been tested by the K-mean clustering method for two attributions of emission intensity and material quantity.
According to the characterization of the material categories, Probability Distribution Functions have been fitted to each category as the model inputs. Then, based on the Monte Carlo random sampling method, the distributions of EEs for each case building have been analysed. By assessing the uncertainty analysis of the model inputs, it has been found that the embodied emission (median value) can vary from 250 kgCO2eq/m2 to around 1400 kgCO2eq/m2 if the source of variation is set to the emission intensities. Meanwhile, if the quantity of the materials would be considered as the source of uncertainty, the results can be up to 4 times larger variation (per floor area) in extreme cases and can be reduced to half for the rest of the case studies.
Lastly, a couple of Global Sensitivity Analysis methods has been used to evaluate the contribution of different material categories in the uncertainty of the embodied emissions. In the scenario of only changing the emission intensities, Plaster, Technical Installation, and Aluminum have the highest elementary effects on the results. On the other hand, the Façade, ceiling and membranes are the most critical material when the quantities change. Other material categories such as Insulation materials and Flooring materials are come afterward for being the most important contributors to the sensitivity of EE. Doors and windows had been the least important material category. The results can be used for the Benchmarking of EE in the Norwegian ZEB context. | |