Impact targets as guidelines towards low carbon buildings: Preliminary concept

Developing building projects with low environmental impacts is a real challenge, yet a problem faced every day by designers. To that end, in the design process, iteration between propositions and objectives have been used that are complex and time consumption. The impact targets leading to low-carbon buildings have the potential to simplify this complexity and saving time in the building design process. This study introduces a methodology for the definition of impact targets for components and systems of buildings. The definition of impact targets has been envisaged as a two-step process combining top-down and bottom-up approaches. The desired impact target of building is defined by a top-down approach and the targets for components and systems by a bottom-up approach. Impact targets for the Swiss context are defined applying the methodology to the smart living building that aim at reaching the 2050 goals of the 2000-watt society vision. Through this approach, we were able to set up impact targets on the components and systems level for global warming potential indicator. Impact targets can be used as guidelines in the design process for developing component or system one by one without analysing the whole building, which is guided toward low carbon objectives.

Component reuse in structural design: emerging practices and tools for the circular economy

Jan Friedrich Georg Brütting, Corentin Jean Dominique Fivet, Jonas Warmuth

Structural engineers play an increasing role in ensuring the transition towards a more sustainable construction sector: a) they are responsible for the design of the most resource- and energy-intensive part of buildings and infrastructure, and b) they regularly interact with architects, contractors, and clients, and hence are full stakeholders in the overall decision process. Traditionally, structural engineers follow two paths to reduce structure environmental impacts: 1) minimizing the volume of material, and 2) adopting low impact (e.g. low carbon) materials. A third strategy that has recently re-emerged in practice and research is the reuse of structural components over multiple service cycles, which allows drastically reducing raw material use, reprocessing energy, and waste. Therefore, employing reuse strategies in structural design has considerable potential to reduce structure environmental impacts further. Although reuse is not new, systematic adoption in practice implies an important paradigm shift: rather than manufacturing components after the structural system has been designed, the system must be synthesized from a stock of available components. The first part of our contribution provides an overview of historic and contemporary structures that efficiently reuse structural components. It also highlights the influence of component reuse on the structural design process. The second part presents a new computational tool for the conceptual design of structures from a stock of reclaimed elements. The tool combines Combinatorial Equilibrium Modelling, graphic statics, efficient Best-Fit heuristics, and Life Cycle Assessment to explore different design options in a user-interactive way and with almost real-time feedback. The method applicability is demonstrated through a realistic case study for the design of a complex 3D spatial structure made of reclaimed structural elements originating from deconstructed buildings in Switzerland. Results show that structures made of reused elements have a significantly lower environmental impact than solutions made of new material only. Link to the video: https://youtu.be/VCyD1yqXH8w

fib2021

Introduction of a dynamic interpretation of building LCA results: the case of the smart living (lab) building in Fribourg, Switzerland

Marilyne Andersen, Endrit Hoxha, Thomas Bernard Paul Jusselme

Although a building lifetime is not predictable, it is an essential data in the yearly impact calculation. Yet, in the assessment of the environmental impacts of building the lifetime is considered as a fixed value. The purpose of this study is to introduce a new dynamic interpretation of LCA results, which aims at improving the reliability of assessment of buildings’ environmental impacts. To that end, are compared: - the environmental impacts assessed for 50, 70 and then 100 years of the building’s lifetime; - and environmental impacts assessed for anytime during the first 100 years of building’s lifetime. Since the impacts depend on the type of the building’s components and their quantity, in this study two scenarios have been applied: one compares two building projects that differ from each other on the shape and functionality; the other compares two projects that differ only on components and systems employed in the building. Possible projects of the smart living building have been selected as case studies. This building aims at reaching the goals of the 2000-watt society vision and will be built by 2020 in Fribourg, Switzerland. The dynamic interpretation of building’s impacts shows that the LCA results could vary up to 20%, according to the assumed building’s lifetime and thus, completely change the conclusion in the comparison of the impacts of different building projects when the projects differ from the components and systems. The dynamic interpretation assessed more reliable LCA-results, that are useful for strengthen comparisons in the decision making process.

2016

Influence of energy-use scenarios in Life-Cycle Analysis of renovation projects with Building-Integrated Photovoltaics – Investigation through two case studies in Neuchâtel (Switzerland)

Sergi Aguacil Moreno, Sophie Lufkin

Since tomorrow’s cities are already largely built, and as many of their buildings – with a low level of energy performance – will still be standing in 2050, urban renewal processes play an essential role towards the sustainable development of European cities. In this context, Building-Integrated Photovoltaic (BIPV) systems can potentially provide a crucial response for achieving long-term carbon targets. Functioning both as envelope material and on-site electricity generator, they can simultaneously reduce the use of fossil fuels and greenhouse gas emissions. Focusing on the architectural design, this paper presents the results of a multi-criteria evaluation in terms of Life-Cycle Assessment (LCA) and Cost (LCC) of different renovation and energy-use scenarios. The goal is to identify which strategies can allow to achieve the ambitious targets for the 2050 horizon by integrating into the design process: 1) Passive strategies, to improve the envelope through low-embodied energy materials and construction systems; 2) BIPV strategies, using innovative photovoltaic products as a new material for façades and roofs; and 3) Active strategies, adapting HVAC systems to improve the efficiency of the BIPV installation and reducing the dependence on the feed-in-tariffs to ensure the profitability of investments. An emphasis is placed on testing the impact of a proposed selection process of BIPV surfaces in order to maximise self-consumption and self-sufficiency, evaluating the effect of electricity storage systems with and without the possibility of injecting the overproduction into the grid. Our methodology and results are presented through the comparison of two real case studies in Neuchâtel (Switzerland). Proposing a new approach to address renovation projects of existing buildings in the urban context towards Low Carbon Buildings, the outcomes provide architects and engineers with advanced BIPV renovation strategies depending on the building typology, the architectural design goals and the level of intervention.