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Ex-ante LCA is a novel approach that provides a way to assess the eventual environmental performance of technologies that are currently under development. Between now and the investigated time several changes may have occurred to the foreand background system, which may affect the results of the assessment. If this is the case, such changes should be integrated in to the life cycle inventory. The goal of this study was to determine how influential those changes are to the foreground system and if it is relevant to apply a cornerstone scenario approach when assessing potential changes. This is analysed using an emerging electro-mass separation technology as a case study. This technology can separate fly ashes based on their particle size. The main benefit of the technology lies in the ultra-fine fly ashes that are produced, which can be used to produce Ultra-High-Performance Concrete. Results showed a considerable difference between the reference and mitigation scenarios, and a smaller but still noticeable difference between the different mitigation pathways.

Nowadays a vast number of concrete structures are approaching the end of their expected service life. The need for sustainable rehabilitation (maintenance and repair) is urgent and due to the expected deterioration of buildings and civil structures, there will be a great need for preventive and/or curative interventions in the near future. More than 2/3 of the damage to reinforced concrete structures is linked to reinforcement corrosion, which can affect the durability of the structure and the residual load-bearing capacity. With the necessary transition towards a circular economy and the Sustainable Development Goals in mind, it is important to deviate from considering only the technical requirements and initial costs during the design of concrete structures. Hence, the environmental impact over the entire life cycle and the intended service life extension need to be considered as well. A typical residential building in a Belgian coastal environment with damaged reinforced concrete balconies is selected as case study to evaluate different frequently used repair techniques (i.e. patch repair, conventional repair, galvanic cathodic protection, impressed current cathodic protection and total replacement) by means of a life cycle assessment. Several sensitivities are mapped by analysing the influence of the intended service life extension, the volume and configuration of the construction, the repair mortar composition and the application of coating/waterproofing. It was stressed that these uncertainties could have a substantial effect on the environmental impact and highlight the domains where further research is needed (e.g. assumed life span and composition of repairs). Due to this manner, it is not possible to identify one environmental optimal repair method. However, for a short service life extension (e.g. 5y) small interventions like patch repair seem to be more sustainable while methods like cathodic protection and conventional repair are preferable for longer service life extensions (e.g. 40y).

Addressing urban air pollution is a pressing challenge, prompting the exploration of mitigation strategies such as urban greening. However, certain innovative greening approaches, while promising, may inadvertently incorporate unsustainable elements that undermine their eco-friendly philosophy. In this context, our research focuses on addressing the replacement of a petroleum-based filter substrate in an existing 'green' outdoor air purification system that utilizes 'moss filters', known as a 'moss wall'. This initiative is driven by concerns about microplastic leakage from the substrate and the need to optimize the moss wall system in terms of circularity. This preliminary study presents a crucial first step, aiming to assess the feasibility of developing a circular, bio-based plate as a replacement for the existing microfiber filter substrate. The focus is on the potential of this plate to recycle moss from the system itself as raw material, ensuring structural integrity and the ability to support its own weight. To achieve this goal, a series of controlled experiments were conducted in a laboratory setting using cellulose, corn starch, and metakaolin binders. Our findings indicated that cellulose was crucial for the structural integrity, starch significantly enhanced the sample strength, and metakaolin improved the water resistance. These insights culminated in the creation of a laboratory-scale moss-based composite prototype, with moss constituting more than half of the total mass. This prototype demonstrated promising results as a starting point for a more environmentally friendly and bio-based moss wall substrate. Subsequent research efforts will concentrate on optimizing the binder and fiber composition, evaluating and improving the bioreceptivity and filter properties, conducting outdoor testing, and scaling up the prototype for practical implementation. [ABSTRACT FROM AUTHOR]

Smart building technologies and building automation and control systems (BACS) can offer a range of additional benefits beyond energy savings, in particular by improving building responsiveness to user needs. Although in recent years these technologies have gained popularity as a means of reducing energy consumption and improving building performance, a clear picture of the role of BACS in providing a wider range of benefits is still missing. This review identifies and collects BACS impacts in office buildings with a special emphasis on improving indoor environmental quality by adapting building operation to changing conditions and guaranteeing feedback and real-time interaction with occupants. The resulting benefits, such as increased employee productivity, fewer occurrences of sick leave, and lower rates of absenteeism are highlighted. Offices represent an interesting field of application, as small improvements in the built environment can have a significant impact on labour costs which are the predominant share of the total operating costs. Furthermore, quantitative relationships between physical factors of the indoor environment and benefits have been displayed where available. This literature review aims at establishing an approach that comprehensively evaluates BACS across their entire spectrum, leading to the promotion of novel business cases. [ABSTRACT FROM AUTHOR]

Airtightness of the building envelope is an important parameter affecting the performance of (low energy) buildings. In case the airtightness is effectively measured, this is typically only done once as part of the commissioning of the construction work. Several factors could affect the evolution of the airtightness of the envelope after the building is constructed. In this work, follow-up airtightness tests have been carried out to investigate the evolution of the performance in the interval of 0.5 up to 12 years compared to the original pressurisation test. The results on 41 low-energy dwellings indicate that the airtightness is indeed not a fixed value over time. Of the 41 buildings, 29 display an increased air permeability resulting in an increase of up to 200% in relative terms or up to 1.36 ACH50 (air changes per hour at 50 Pa pressure difference [h-1]). Conversely, four of the buildings in the dataset show a significant improvement of the airtightness; resulting in a decrease of air leakage of up to -1.19 ACH50. Analysis of the data shows that on average the air permeability at 50 Pa pressure difference increased by 38%, but with great variation depending multiple factors such as initial airtightness value and construction type. This corresponds to an average increase of the specific air permeability of the building envelope of 0.15 m³/(h·m²). Most of the buildings under analysis are low energy buildings or passive houses which were very airtight at time of construction. Despite the observed evolution in air permeability, many buildings under investigation can still be considered sufficiently airtight a few years after initial construction.

Exposed heavyweight constructions with a high specific heat capacity can dampen and delay transient heat flows in buildings. This paper explores the dynamic effects of various construction assemblies and explores the effect of different temperature control strategies in relation to the thermal mass. The thermal inertia of a building not only affects the pace of heating up a thermal zone, but also the temperature set-back that can be attained with an intermittent heating regime, and thus the setpoints of control regimes. Based on a simulation study, it is demonstrated that the impact of the thermal mass on the heating demand of dwellings is rather limited in a temperate climate. Lightweight timber frame construction can display an annual heating energy demand of up to 6.6% higher compared to a heavy mass concrete and limestone construction in case of fixed thermostat setpoints. If a different control strategy with a highly intermittent thermostat schedule is implemented, the energy use of the lightweight construction can conversely have a lower heating energy expenditure, with a reduction of up to -4.5%. Modelling assumptions on the HVAC system capacity, the timing of the start-up moment of intermittent heating and the type of thermostat control – either based on air temperature or operative temperature – can have a significant influence on the simulation outcomes. Depending on the modelling assumptions and temperature control strategies implemented, the detailed dynamic simulations display that heavy mass buildings will not necessarily yield a lower heating demand as would be predicted by simplified monthly quasi-steady state calculations. In general, it is advocated that a better understanding of control strategies and resulting comfort sensations is required in building design and performance simulation.