It is clearly seen that the lower frame height decreases the impact factors and that the final design for both steel and wood even is performing better than the lowest roof height of 4 meters, requiring less roofing material than the final frame design with a height of 6.5 meters.
5.4 Conclusion 74
the materials that are lost during the demolition and recycling process, also will have CO2 effects over time.
Some of the difficulties with conducting an LCA is the large amount of data required and the lack of availability. Finding intumescent paint used for fire protecting steel beams was impossible and the solution was to figure out the substances and then try to incoporate a corresponding chemical. Furhter inves-tigation and cooporation with a company would have been needed to figure out the exact combination of chemicals in such a paint, but for this project a rough estimate was assumed sufficient.
Without a broader knowledge of life cycle assessments it was possible to gain insight to the program and create useful results. Further understanding of the program will be needed in order to conduct more detailed LCA’s. The five impact categories of the program set by default, are suffcient for initial estimates of the LCA although for a more comprehensive understanding of the environmental impact of the structure, the different impacts included in the categories could be beneficial to understand and depict. The inddor exposure to chemicals could be of consideration to this project due to its job at facilitating art possibly sensitive to some chemicals. Furthermore could use of land be a concern due to extensive harvest of forestry influences several other impact catetegories as ecosystem quality and eutorfication.
Lastly the end-of-life stage is complex due to its high uncertainties including the processes of the futures [Silvestre et al., 2014]. Waste incineration might not be an option in 100 years, if energy is produced solely by renewable power sources. Thus different recycling methods for especially wood will be needed as the energy from using it as a biofuel not will be represented in the life cycle assessment. This could lead to a better design for dismantling and buildings designed to adapt to new tenants.
The time dependent uncertainty is thus of concern in general when conducting an LCA, as the end of life cannot be predicted and might change over time com-pared to the initial end-of-life scenario. A risk analysis and reliability analysis would thus be of interest in order to gain a broader perspective of both life time expectancies and the end-of-life phase.
Discussion
The work conducted throughout this report, its theory, structural analysis and Life Cycle Assessments will be discussed. Possibilities and weaknesses will be discussed on the basis of the theoretical background. The relevance of the results and how they can be of use to the industry will be discussed towards the end of the chapter.
6.1 Possibilities and limitations of the developed program 76
6.1 Possibilities and limitations of the developed program
The developed program in Grasshopper and Karamba have proved sufficient for the initial optimisation task. The complexity of the structural calculations sets limitations for the program. If quick results are desired for the initial design stage, the results will also not be as accurate. This is both due to the time limit and the uncertainties of the structure in the early design phase. At the later design phase it is possible to conduct a more accurate analysis as more details are known. In the initial design stage it is assumed that the results of an optimisation like the one conducted throughout this study, giving rough estimates of the optimisation possibilities, are allowing the architects to further develope their design in a material efficient way.
Further investigations and optimisations are allowed through the developed pro-gram as the design process progresses. For a design methodology including cooporation between architects and engineers this program could show benefi-cial. The program provide the engineer with real-time optimisation possibilites and could thus be used during a meeting when discussing different possibilities.
Simple results giving an idication of the material efficiency would be provided in an instant and could be used to change the design in a sustainable direction.
In order to use the program a knowledge of structural design is needed. Knowl-edge of the modelling tool Grasshopper is important but can easily be learned through the tutorials and discussion forums provided by the supplier. Further-more is the used software programs either free or inexpensive, and are thus generally easily available.
The tool has proven able to decrease the global warming potential through optimisation of the structural design. It could thus be used to provide architects in the industry with environmental friendly choices during a design process.
The developed design method, using the visual output of Rhino, the parametric modeling tool of Grashopper and the FEM-tool Karamba allowed for an anal-ysis of the structural performance material-wise. The method of reducing the material consumption of a structural system based on environmental and life cycle thinking is thus in compliance with the STED programme (section 3.1).
6.1.1 The use of on-the-fly Life Cycle Assessment
The Quantis Suite software revealed able to provide quick life cycle assessments of the different solutions investigated. The tool cannot be used through the modelling program Grasshopper and must thus be conducted on-the-fly as the optimisation progressed. The tool was easy to navigate and could quickly pro-vide the needed results.
A real-time LCA tool made in Grasshopper by A. Otovic[Otovic, 2015] was investigated with the intention of linking it to the structural model conducted in this study. The tool was based on the surfaces of a building, thus providing energy consumption from the volume. The two programs were not linkable due to the two different approaches, the structural program developed in this study did not include the surfaces and was mainly conducted in 2D in order to gain the sufficient results. Furthermore was a lack of understanding of the structure of the real-time LCA tool an issue in order to make use of it.
A further issue with the real-time LCA tool by A. Otovic was the lack of impact categories, the Quantis Suite program could provide fast and detailed life cycle assessments whereas the LCA tool in Grasshopper only conducted the GWP impact, based on the material used and the energy consumption. The different stages and material options were limited especially the end-of-life stage had very limited options. By conducting an LCA through Quantis Suite the different life cycle steps were taken into consideration and a large database was available.
The simple LCA tool was considered unnecessary as the developed structural program, could optimise the material efficiency of the structure and thus de-crease the GWP. The further investigation was then conducted through the use of LCA’s in Quantis Suite for a more detailed perspective on the structure. In subsection 2.1.1 it was confirmed that by simply optimising with the intent of decreasing the material consumption it was possible to decrease the GWP for the structure. Thus is it sufficient to optimise for mateiral efficiency and later on conduct more detailed Life Cycle Assessments.
The results in chapter 5 proved that the structure alone is only a smaller part of the entire environmental impact from the building, although large savings were made during the optimisation. The need for improved life time of the building parts at minimal costs are relevant as well as the demountability allowing the building parts to be reused and recycled. Enhancing the overall resource utiliza-tion must be a goal not only in the structural design but for the entire building and its secondary structural parts as well as interior and cladding.