The building sector accounts for approx. 40% of total energy consumption and approx. 36% of all greenhouse gas emissions in Europe. As the EU climate targets for 2030 call for a reduction of greenhouse gas emissions by more than half compared to the emissions of 1990 and also aim for climate neutrality by 2050, there is an urgent need to achieve a significant decrease in the energy use in buildings towards Nearly Zero-Energy Buildings (nZEBs). As the energy footprint of buildings includes the energy and greenhouse gas consumption both in the construction phase and during service life, nZEB solutions have to provide energy-efficient and less carbon-intensive building materials, specific thermal insulation solutions, and a corresponding design of the nZEB. Carbon reinforced concrete (CRC) materials have proven to be excellent candidate materials for concrete-based nZEBs since they are characterized by a significantly lower CO₂ consumption during component production and much a longer lifecycle. The corresponding CRC technology has been successively implemented in the last two decades and first pure CRC-based buildings are currently being built. This article presents a novel material system that combines CRC technology and suitable multifunctional insulation materials as a sandwich system in order to meet future nZEB requirements. Because of its importance for the life cycle stage of production, cost-efficient carbon fibers (CF) from renewable resources like lignin are used as reinforcing material, and reinforcement systems based on such CF are developed. Cutting edge approaches to produce ultra-thin lightweight CF reinforced concrete panels are discussed with regard to their nZEB relevance. For the life cycle stage of the utilization phase, the thermal insulation properties of core materials are optimized. In this context, novel sandwich composites with thin CRC layers and a cellular lightweight concrete core are proposed as a promising solution for façade elements as the sandwich core can additionally be combined with an aerogel-based insulation. The concepts to realize such sandwich façade elements will be described here along with a fully automated manufacturing process to produce such structures. The findings of this study provide clear evidence on the promising capabilities of the CRC technology for nZEBs on the one hand and on the necessity for further research on optimizing the energy footprint of CRC-based structural elements on the other hand.

Authenticity is considered a central feature in the context of teaching and learning mathematical modelling and is often demanded for both learning tasks and test items. Although large-scale studies hark back to this construct for years, it is largely unclear how a theoretical and empirically robust model for the description and practical operationalization of authenticity in modelling test items might look like. The article addresses this research desideratum and aims at deriving such a model based on existing theoretical concepts in mathematics education. The article provides a broad theoretical overview of the status quo of the construct and presents the “Model for Authenticity in Modelling Test Items” (MAMTI) as a result of those theoretical considerations. The model is based on the ideas of constructivist object authenticity and comprises a total of 8 aspects: real-world context, events, objects, question/assignment, data, figures, use of mathematics and purpose. The model enables further empirical studies to analyze and classify modelling test items or to vary them in terms of authenticity expression.

Higher education institutions (HEIs) compete for the best students, making it important to understand the factors that shape students’ HEI choice. In this context, HEI-led selection days may represent an additional influence factor. Building on Chapman's model of factors influencing students’ HEI choice, the present study pursues three research goals: (a) investigating the relative importance of choice factors, (b) identifying latent student profiles based on these factors, and (c) examining profile differences in the relevance of university-led selection days in students’ decision-making. Data were collected from 546 first-semester students at a German university, and latent profile analysis was used to identify student profiles. Across all students, HEI characteristics were rated as the most important factor, followed by efforts to communicate with students, selection days, and significant persons. Latent profile analysis revealed five distinct student profiles, each with a different pattern of HEI choice factors: Location-independent Candidates, Location-bound Candidates with Information-distant Orientation, HEI Characteristic-oriented Candidates with Information-led Orientation, Peer-led Candidates, and Candidates with Unknown Factors. Analyses of the relevance of university-led selection days indicate that they can be a substantial factor in students’ decision-making. However, this applies only to certain profiles rather than representing a universal pull factor. This study contributes to a deeper understanding of HEI choice by applying a person-centered approach and identifying distinct student profiles. In doing so, it provides a conceptual basis for HEIs to engage prospective students more effectively and to design recruitment and selection activities more strategically.

1. A central goal of mathematics education is to enable students to use mathematics in a variety of real-world contexts (Niss & Blum, 2020; OECD, 2023). Niss and Blum (2020, p. 2) emphasise that it...