• Energy Research

Abstract Storing carbon in construction products and building components seems a particularly attractive strategy for compensating the initial greenhouse gas (GHG) emissions from production and construction. Typically, in LCA methods, when a sustainable forestry management is assumed, biogenic carbon is not included in the calculation since forest products are considered as carbon neutral due to the full regeneration of biomass in forest at the end of a rotation period. The purpose of this article is to investigate the effect of storing carbon in biogenic materials and lime-based products when they are used as construction materials and left long in a building. Five different alternative exterior walls with different construction technologies are compared. In the first two alternatives (STR and HEM), a significant amount of fast-growing biogenic material is used as thermal insulation, while the third (TIM) represents a typical timber frame structure with mineral insulation. The last two are traditional wall alternatives based on bricks (BRI) and cast concrete (CON) with an additional external thermal insulation composite system (ETICS) in EPS. A model based on a dynamic LCA is adopted to include timing in the calculation. The results, expressed in terms of radiative forcing in the atmosphere, show that storing carbon in fast-growing biogenic materials is much more efficient than in timber elements. The carbon stored in fast-growing biogenic materials is fully captured by crop regrowth only one year after construction, while a longer time is expected for forest products due to the long rotation period required for forest regrowth.

(PE)-UHPFRC, a novel strain hardening ultra high-performance fiber reinforced concrete (UHPFRC) with low clinker content, using Ultra-High Molecular Weight Polyethylene (UHMW-PE) fibers, was developed for structural applications of rehabilitation. A comprehensive life cycle assessment (LCA) was carried out to study the environmental impact of interventions on an existing bridge using PE-UHPFRC compared with conventional UHPFRC and post-tensioned reinforced concrete methods in three categories of global warming potential (GWP), cumulative energy demand (CED), and ecological scarcity (UBP). The results showed 55% and 29% decreases in the environmental impact of the PE-UHPFRC compared with reinforced concrete and conventional UHPFRC methods, respectively, which highlighted the effectiveness of this material for the rehabilitation/strengthening of structures from the viewpoint of environmental impact.

Abstract The transition to renewable energy sources is pivotal in addressing global climate change challenges, with rooftop solar photovoltaic (PV) systems playing a crucial role. For informed decision-making in energy policy, it is important to have a comprehensive understanding of both the economic and environmental performance of rooftop solar PV. This study provides a high-resolution analysis of existing rooftop solar PV systems in Switzerland by assessing the robustness of the potential estimation to properly derive the amount of electricity generated by individual systems, and subsequently quantify the levelized cost of electricity and life cycle greenhouse gas (GHG) emissions of electricity generation from PV and compare them with those of grid electricity supplies. Our results indicate substantial geographical variations between potential estimations and real-world installations, with notable underestimations of approximately 1.3 Gigawatt-peak, primarily for systems around 10 kWp in size, mainly due to the quality of input data and conservative estimation. The study finds that in many regions and for most of the installed capacity, electricity generated from rooftop PV systems is more economical than the grid electricity supply, mainly driven by factors including high electricity prices, larger installations and abundant solar irradiance. The GHG emissions assessment further emphasizes the importance of methodological choice, with stark contrasts between electricity certificate-based approaches and others that are based on the consumption mix. This study suggests the need for more accurate geographical potential estimations, enhanced support for small-scale rooftop PV systems, and more incentives to maximize the potential of their roof area for PV deployment. As Switzerland progresses towards its renewable energy goals, our research underscores the importance of informed policymaking based on a retrospective analysis of existing installations, essential for maximizing the potential and benefits of rooftop solar PV systems.

Challenging climate goals demand immediate greenhouse gas emissions reductions for long-term temperature stabilization. Given the nearly linear relationship between warming and cumulative net emissions, the carbon budget approach is a useful tool to quantify remaining carbon allowances for countries, sectors, and even buildings. The built environment plays a crucial role in today’s carbon emissions and future reduction potentials. Although much progress has been achieved towards energy efficient buildings, less attention has been given to the impact of materials put in place. Furthermore, the construction sector lacks of quantified reduction efforts and time horizon limits to clearly define a climate neutrality pathway. This article proposes a definition of yearly targets until 2050 for the operational and embodied carbon of buildings in line with a global 1.5 °C carbon budget and the Swiss climate strategy. The proposed targets are then compared with the impact of current practices and future technical developments. Gaps between targets and practices are quantified and discussed to better understand the upcoming challenges of the Swiss construction sector. Energy and Buildings, 278 ISSN:0378-7788 ISSN:1872-6178

Using bamboo-based construction materials has been identified as a potential way of reducing pressure on resources and on the environment. These materials have environmental and mechanical advantages over conventional construction materials. In the present research, the life cycle assessment of five bamboo-based construction materials was carried out: bamboo pole, flattened bamboo, woven bamboo mat, glue laminated bamboo and woven bamboo mat panels. The main objective of the present research is to develop a series of life cycle assessment data that can represent the diversity found in the global production of bamboo-based construction materials. This research also aims to present a simplified and cost effective approach to developing this kind of data while maintaining its quality. The results show that the environmental impacts of the studied materials grow with increased industrialization and that electricity mixture and heat energy sources contribute most to the variability of the results. It was found out that the species of bamboo and harvesting practices do not make a significant contribution to the overall environmental impact of bamboo-based construction materials. It was also found out that, in general, the processes contributing most to environmental impact are not always the most significant contributors to the variability of the result. It was possible to establish a relationship between the processes contributing to the variability of the results and the results' uncertainty. In this way, it was demonstrated that it is possible to identify the main processes contributing to the variability of the results and that by improving the quality of this data the overall uncertainty of the results can be reduced. Thus, the proposed approach can be successfully used to assess the environmental impact of non-conventional materials with a high degree of accuracy in a cost-effective way.

This research explores the carbon removal of a novel bio-insulation composite, here called MycoBamboo, based on the combination of bamboo particles and mycelium as binder. First, an attributional life cycle assessment (LCA) was performed to define the carbon footprint of a European bamboo plantation and a bio-insulation composite, as well as its ability to remove CO2 along its lifecycle at a laboratory scale. Secondly, the Global Worming Potential (GWP) was estimated through a dynamic LCA with selected end-of-life and technical replacement scenarios. Finally, a building wall application was analyzed to measure the carbon saving potential of the MycoBamboo when compared with alternative insulation materials applied as an exterior thermal insulation composite system. The results demonstrate that despite the negative GWP values of the biogenic CO2, the final Net-GWP was positive. The technical replacement scenarios had an influence on the final Net-GWP values, and a longer storage period is preferred to more frequent insulation substitution. The type of energy source and the deactivation phase play important roles in the mitigation of climate change. Therefore, to make the MycoBamboo competitive as an insulation system at the industrial scale, it is fundamental to identify alternative low-energy deactivation modes and shift all energy-intensity activities during the production phase to renewable energy.

Applied Energy, 258 ISSN:0306-2619 ISSN:1872-9118

Society’s increasing concern for sustainability aspects is inducing the emergence of digital technologies to overcome the inefficiency and reduce environmental impacts in product manufacturing. As the use of digital processes such as 3D printing grows, innovative applications into large scale processes are emerging. The combined methods of computational design and robotic fabrication are demonstrating a large potential to expand architectural design and transform conventional construction processes. But, the most impressive impact may be their contribution to the improvement of sustainability in construction. The challenge of digital fabrication at building scale is to achieve efficiency in parameters such as material use, energy demands, durability, GHG emissions and waste production over the entire life cycle of a building. The goal of this paper is to investigate the environmental implications and opportunities of digital fabrication in construction. The research focuses specifically on measuring the flow of materials, embodied energy and potential environmental impacts associated with digital fabrication processes. With this objective, the case study of a wooden roof digitally fabricated is presented. The project was assessed according to the Life Cycle Assessment (LCA) framework and compared with a conventional wooden roof with similar function and structural capacity. The analysis highlighted the importance of material-efficient design to achieve high environmental benefits in digitally fabricated architecture. This research is the initial step towards the establishment of a knowledge base and the elaboration of guidelines that help designers to make more sustainable choices in the implementation of digital fabrication in construction.