Life cycle assessment (LCA) is recognized as a trustworthy, scientific while understandable approach to address the environmental sustainability of human activities. It is applied for multiple uses in internal and external information supply and for decision support. However, LCA application in practice must fulfill three basic criteria: (1) It must be reliable in order to ensure the credibility of information and results generated, (2) it must fit into existing information routines and practices in business to ensure applicability, and (3) it must provide quantitative and relevant information to inform decision makers. Over the last two decades, LCA methodology and related data have become a suitable and professional tool to address and beneficially influence environmental aspects of sustainability of virtually all anthropogenic activities. LCA is a field of scientific research but is also a business of growing importance. Many users from the academia, industry, or consult

Assessing the economic and environmental life cycle impacts of long-lasting construction projects presents numerous methodological challenges. Three advances over established methods are presented for the life cycle evaluation of construction projects. First, future uncertainty during the project life or study period is explicitly accounted for. This involves moving from a deterministic approach requiring precise data to a probabilistic approach where uncertain variables are defined by ranges. The outcome of life cycle evaluation is then given by probability distributions, generated by Monte Carlo simulation. Second, flexible strategies are considered that allow for adaptation to changing conditions during the project life. Flexible strategies (also modelled by Monte Carlo simulation) incorporate specified ‘life cycle options’ which are exercised if it is advantageous to do so, otherwise they remain unexercised. Third, cost-based life cycle costing (LCC) and environmental life cycle assessment (LCA) are linked in a single LCC+A evaluation tool. There are still differences between cost and environmental evaluation, but the use of a shared framework enables the two aspects to be compared systematically. The two-dimensional ‘ecoportfolio’ diagram presents one way of analysing results. The innovations are demonstrated in a case study that assesses both economic and environmental impacts while accounting for future uncertainties. L’évaluation des incidences économiques et environnementaux du cycle de vie des projets de construction de longue durée présente de nombreux problèmes méthodologiques. Il est présenté trois avancées par rapport aux méthodes établies concernant l’évaluation du cycle de vie des projets de construction. En premier lieu, est explicitement prise en compte l'incertitude future pendant la durée de vie du projet ou la période d’étude. Ceci implique de passer d'une approche déterministe nécessitant des données précises à une approche probabiliste dans laquelle les variables incertaines sont définies par des plages. Le résultat de l’évaluation du cycle de vie est ensuite donné par des distributions de probabilités, générées par la méthode de simulation de Monte-Carlo. En second lieu, il est envisagé des stratégies flexibles qui permettent l'adaptation à des conditions changeantes pendant la durée de vie du projet. Ces stratégies flexibles (également modélisées par une simulation de Monte-Carlo) intègrent des « options de cycle de vie » spécifiées qui sont levées s'il est avantageux de le faire, et qui sinon demeurent non levées. En troisième lieu, l'estimation du coût du cycle de vie (LCC) basée sur les coûts et l’évaluation environnementale du cycle de vie (LCA) sont liées dans un outil unique d’évaluation LCC+A. Il existe encore des différences entre l'estimation du coût et l’évaluation environnementale, mais l'utilisation d'un cadre partagé permet de comparer systématiquement ces deux aspects. Le schéma bidimensionnel de « l’éco-portefeuille » présente une manière d'analyser les résultats. Les innovations sont montrées dans une étude de cas qui évalue les incidences à la fois économiques et environnementales tout en rendant compte des incertitudes futures. Mots clés: adaptation économie du bâtiment stratégies de conception flexibilité évaluation du cycle de vie coût du cycle de vie options réelles incertitude

Carbon fibers (CFs) are a crucial material for lightweight structures with advanced mechanical performance. However, there is still a paucity of detailed understanding regarding the environmental impacts of production. Previously, mostly singled-out scenarios for CF production have been assessed, often based on scarce transparent inventory data. To expand the current knowledge and create a robust database for future evaluation, a life cycle assessment (LCA) was carried out. To this end, a detailed industry-approved LCI is published, which also proved plausible against the literature. Subsequently, based on a global scenario representing the market averages for precursor and CF production, the most relevant contributors to climate change (EF3.1 climate change, total) and the depletion of fossil energy carriers (EF3.1 resource use, fossil) were identified. The energy consumption in CF manufacturing was found to be responsible for 59% of the climate change and 48% of the fossil resource use. To enable a differentiated discussion of manufacturing locations and process energy consumption, 24 distinct scenarios were assessed. The findings demonstrate the significant dependence of the results on the scenarios’ boundary conditions: climate change ranges from 13.0 to 34.1 kg CO₂ eq./kg CF and resource use from 262.3 to 497.9 MJ/kg CF. Through the investigated scenarios, the relevant reduction potentials were identified. The presented results help close an existing data gap for high-quality, regionalized, and technology-specific LCA results for the production of CF.