Explore the vast range of titles available.

PurposeEN 15804 and EN 15978 are the established standards to calculate the environmental impact of building products and buildings. Despite the importance of circular building, many life cycle assessment (LCA) studies based on EN 15804/15978 are not set up to evaluate circularity. This paper aims to research how an LCA study should be developed that can determine the environmental impact of a circular versus a linear building element within the methodological framework of EN 15804/15978.MethodsFirst, it is clarified how the methodological framework of EN 15804/15978 considers different circular principles. There is a particular focus on the concept of multi-cycling and module D. Second, and as the main objective of this paper, it is analyzed which scenarios throughout the lifespan of a building element should be modeled. The focus lies on combining characteristic transformation and end-of-life scenarios into characteristic life cycle scenarios and examining if this provides sufficient insight into the possible environmental impact. This is illustrated by an LCA study of a linear and circular facade system. When representing the results of the LCA study, it is analyzed how the inclusion of module D changes the results.Results and discussionTo account for the concept of ‘multi-cycling,’ the authors propose to consider multiple use cycles (i.e., transformations) within one life cycle instead of considering several life cycles. This is done through module B5 Refurbishments. Module D is important to stimulate recycling and reuse at the end of life. However, the concept of module D must be handled with the necessary care to provide correct information. Characteristic life cycle scenarios are determined for a more robust understanding of the possible environmental impact of a building element by modeling only a limited amount of scenarios. For the facade systems, the considered transformation scenarios are more determining for their environmental impact than the choice of end-of-life scenario, especially when module D is not considered.ConclusionsBy setting up an LCA study that can evaluate the important circular principles and consider characteristic life cycle scenarios, detailed insight into the environmental impact of circular versus linear building elements can be obtained. The proposed approach leads to more robust LCA studies of circular versus linear building elements.

PurposeHow to build in more environmentally sustainable manner? This issue is increasingly coming to the fore in construction sector, which is responsible for a relevant share of resource depletion, solid waste, and greenhouse gas (GHG) emissions. Carbon-reinforced concrete (CRC), as a disruptive innovation of composite building material, requires less resources and enables new forms — but does it make CRC more environmentally sustainable than steel-reinforced concrete (SRC)? This article aims to assess and compare the environmental impact of 45 material and production scenarios of a CRC with a SRC double wall.MethodsThe life cycle assessment method (LCA) is used to assess environmental impacts. The functional unit is a double wall and the reference flows are 1 m3 for concrete and 1 kg for fiber. CML methodology is used for life cycle impact assessment (LCIA) in the software GaBi© ts 10.0. A sensitivity analysis focuses on electricity grid mixes, concrete mixes, and steel production scenarios.ResultsThe midpoint indicator climate change respective global warming potential (in kg CO2e) ranges between 453 kg CO2e and 754 kg CO2e per CRC double wall. A comparable SRC double wall results in emissions of 611–1239 kg CO2e. Even though less raw material is needed for CRC, it does not represent a clear advantage over SRC in terms of climate change. In a comparison, the production of steel (blast furnace vs. electric arc furnace vs. recycled steel) and the choice of cement type are of decisive relevance. For concrete mixes, a mixture of Portland cement and blast furnace slag (CEM III) is beneficial to pure Portland cement (CEM) I. For fiber production, styrene-butadiene rubber (SBR) has an advantage over epoxy resin (EP) impregnation and the use of renewable energy could reduce emissions of fiber production up to 60%.ConclusionCRC requires less material (concrete cover) than SRC, however, exhibits comparable CO2e to SRC — depending on the production process of steel. In the future, fiber production and impregnation should be studied in detail. Since in terms of climate change neither wall (CRC vs. SRC) clearly performs better, the two other pillars of sustainability (economic and social, resulting in LCSA) and innovative building components must be focused on.

PurposeDecarbonizing cities is one of today’s biggest challenges. In this regard, particular attention has been paid on improving the environmental performance of buildings. In this framework, this work consists in assessing the environmental impact of an innovative building envelope component derived from urban agriculture (UA) wastes. In fact, rooftop UA seems to be a possible solution to the rising food demand due to increasing urban demographic growth. Consequently, rooftop UA wastes need to be treated in sustainable ways.MethodsThis study aims to determine the carbon footprint and embodied energy of a new infill wall material, derived from UA wastes produced by a building rooftop greenhouse tomato crop, and evaluate the potential biogenic carbon that such by-product could fix temporally until its end of life. After an initial description of the manufacturing process of the new material, its carbon footprint and embodied energy have been calculated by means of the life cycle assessment (LCA) methodology according to the ISO 14044 and the ISO 14067 guidelines adapted to the analyzed context. In particular, the inventory analysis is based on data collected from the production of samples of the new material at the laboratory scale.Results and discussionThe results of the LCA indicate that, when the biogenic carbon fixed in the UA wastes is considered, a negative carbon footprint of − 0.2 kg CO2 eq. per kg of material can be obtained. Hence, it can be assumed that from a life cycle perspective the material is able to fix carbon emissions instead of emitting them. Specifically, for the considered scenario, approximately 0.42 kg CO2 eq./m2 per year could be sequestered. However, the crop area required to produce enough waste to manufacture a unit of material is quite high. Therefore, future studies should focus on individuate solutions to reduce the density of the new component, and also different urban crops with higher waste production rates.ConclusionsThe outcomes of the study put in evidence the potential of the new proposed infill wall component in fixing carbon emissions from UA, allowing to also compensate those relating to the production and transportation stages of the component life cycle. Moreover, producing by-products with UA wastes, hence temporally storing the carbon fixed by crops, may contribute to reduce the carbon cycles speed conversely to traditional waste management solutions, other than lower new raw materials depletion.

PurposeEnergy consumption of buildings is one of the major drivers of environmental impacts. Life cycle assessment (LCA) may support the assessment of burdens and benefits associated to eco-innovations aiming at reducing these environmental impacts. Energy efficiency policies however typically focus on the meso- or macro-scale, while interventions are typically taken at the micro-scale. This paper presents an approach that bridges this gap by using the results of energy simulations and LCA studies at the building level to estimate the effect of micro-scale eco-innovations on the macro-scale, i.e. the housing stock in Europe.MethodsLCA and dynamic energy simulations are integrated to accurately assess the life cycle environmental burdens and benefits of eco-innovation measures at the building level. This allows quantitatively assessing the effectiveness of these measures to lower the energy use and environmental impact of buildings. The analysis at this micro-scale focuses on 24 representative residential buildings within the EU. For the upscaling to the EU housing stock, a hybrid approach is used. The results of the micro-scale analysis are upscaled to the EU housing stock scale by adopting the eco-innovation measures to (part of) the EU building stock (bottom–up approach) and extrapolating the relative impact reduction obtained for the reference buildings to the baseline stock model. The reference buildings in the baseline stock model have been developed by European Commission-Joint Research Centre based on a statistical analysis (top–down approach) of the European housing stock. The method is used to evaluate five scenarios covering various aspects: building components (building envelope insulation), technical installations (renewable energy), user behaviour (night setback of the setpoint temperature), and a combined scenario.Results and discussionResults show that the proposed combination of bottom–up and top–down approaches allow accurately assessing the impact of eco-innovation measures at the macro-scale. The results indicate that a combination of policy measures is necessary to lower the environmental impacts of the building stock to a significative extent.ConclusionsInterventions addressing energy efficiency at building level may lead to the need of a trade-off between resource efficiency and environmental impacts. LCA integrated with dynamic energy simulation may help unveiling the potential improvements and burdens associated to eco-innovations.

Purpose3D printing has been put forward for its supposed environmental benefit, yet to be confirmed. This article describes an environmental assessment of a 3D printing process that represents one of the most commonly used technologies in the field. It then suggests a generic framework to evaluate the environmental impact of 3D concrete printing through a parametric model.Material and methodsThe studied system is a 3D printing cell based on a 6-axis robotic arm assessed through a cradle-to-cradle life cycle assessment. It provides data details for subparts of the 3D printing process allowing other researchers to compose and recombine those subparts to represent other 3D concrete printing processes and faster the inventory and eco-design process of such technologies. As the concrete sector usually focuses on its global warming contribution, an analysis of relative importance of environmental categories was performed using both normalization/weighting and an endpoint evaluation. An uncertainty assessment based on the pedigree matrix allows to evaluate result confidence.Results and discussionThe results show that the main contributors to the 3D printed building element are first the high requirement concrete and second the robotic system, mainly the electronic parts. A detailed uncertainty study has been conducted to evaluate error margins. The sensitivity study on the electricity mix also shows the relative low importance of the technology localization to assess its environmental balance.ConclusionsA first sketch of a generic framework to assess extrusion-based 3D printing in the construction sector is proposed. A detailed LCA is performed and highlights ways of improvement of the technology. Further research on similar technology and scale-up scenario is needed to consolidate the framework and is seen as main research perspectives of this work.

PurposeAn estimation of the environmental impact of buildings by means of a life cycle assessment (LCA) raises uncertainty related to the parameters that are subject to major changes over longer time spans. The main aim of the present study is to evaluate the influence of modifications in the electricity mix and the production efficiency in the chosen reference year on the embodied impacts (i.e., greenhouse gas (GHG) emissions) of building materials and components and the possible impact of this on future refurbishment measures.MethodsA new LCA methodological approach was developed and implemented that can have a significant impact on the way in which existing buildings are assessed at the end of their service lives. The electricity mixes of different reference years were collected and assessed, and the main datasets and sub-datasets were modified according to the predefined substitution criteria. The influence of the electricity-mix modification and production efficiency were illustrated on a selected existing reference building, built in 1970. The relative contribution of the electricity mix to the embodied impact of the production phase was calculated for four different electricity mixes, with this comprising the electricity mix from 1970, the current electricity mix and two possible future electricity-mix scenarios for 2050. The residual value of the building was also estimated.Results and discussionIn the case presented, the relative share of the electricity mix GHG emission towards the total value was as high as 20% for separate building components. If this electricity mix is replaced with an electricity mix having greater environmental emissions, the relative contribution of the electricity mix to the total emissions can be even higher. When, by contrast, the modified electricity mix is almost decarbonized, the relative contribution to the total emissions may well be reduced to a point where it becomes negligible. The modification of the electricity mix can also influence the residual value of a building. In the observed case, the differences due to different electricity mixes were in the range of 10%.ConclusionsIt was found that those parameters that are subject to a major change during the reference service period of the building should be treated dynamically in order to obtain reliable results. Future research is foreseen to provide additional knowledge concerning the influence of dynamic parameters on both the use phase and the end-of-life phase of buildings, and these findings will also be important when planning future refurbishment measures.

PurposePrevious life cycle assessments (LCAs) of buildings and building components show a broad range of values for the impact of maintenance and replacement, some highlighting these operations as major hotspots while others consider them insignificant. This article highlights methodological aspects explaining this discrepancy. The influence of three aspects is investigated further in a case study of façade materials: the reference study period (RSP), service life data, and the use of a round-up number of operations or annualized impacts.MethodsA comparative LCA of seven façade alternatives is carried out as an illustrative case study. For each alternative, global warming potential (GWP) is calculated using three possible RSPs, four possible material service lives (one from industry practitioners and low, standard and high values from a generic database), and two possible calculation methods (round-up or annualized impacts).Results and discussionWhile the same façade alternative had the lowest GWP in all cases, different methodological choices significantly affected the GWP and respective ranking of other alternatives. Some alternatives showed a significant increase in GWP over longer RSPs, while others were still dominated by the impact of initial production after 200 years. In nearly all cases, generic service life data lead to a higher GWP than data from industry practitioners. Major discrepancies were found between generic and practitioner data in some cases, e.g., for the brick façade. In most cases, annualized impacts led to a slightly lower (or equal) GWP than using a round-up number of operations. However, when a major operation happens shortly before the end of the RSP, the annualized method leads to considerably lower GWP.ConclusionsMaintenance and replacement are rarely significant over a 50-year RSP but sometimes become hotspots over longer RSPs. Using round-up operations or annualized impacts does not make much difference in average, but leads to significantly different results in specific cases. As building LCA enters certification and regulation, there is a need to harmonize such methodological choices, as they affect LCA results, hotspot identification, and recommendations. Discrepancies in service life data also call for the gathering of reliable data.

Flood damage repairs to the built environment generate substantial greenhouse gas (GHG) emissions, yet these indirect climate impacts are rarely integrated into flood consequence assessments. In this study, we present a fragility-based modeling framework to estimate material replacement needs for building components damaged at specific flood depths. We develop fragility curves for each building component using a triangular cumulative distribution derived from expert judgment due to the lack of empirical data on flood losses, especially at the component level. By combining these estimates with life cycle GHG emissions for each component in a Monte Carlo simulation, we derive probabilistic, emissions-based damage curves for single-family residential structures which comprehensively account for uncertainty in the estimates. We then applied these damage curves to estimate the GHG emissions caused by a 100-year flood in two testbed regions in the Mississippi River Valley. Our results show that including the social costs of GHG emissions can increase the valuation of total flood damages by over 6%. Our results also show that flood impact estimates are highly uncertain our model can be used by planners in cost-benefit analyses of flood risk management projects to show that such projects are more economically efficient than current methods would report.

PurposeThis paper reviews the state-of-the art research in life cycle assessment (LCA) applied to buildings. It focuses on current research trends, and elaborates on gaps and directions for future research.MethodsA systematic literature review was conducted to identify current research and applications of LCA in buildings. The proposed review methodology includes (i) identifying recent authoritative research publications using established search engines, (ii) screening and retaining relevant publications, and (iii) extracting relevant LCA applications for buildings and analyzing their underpinning research. Subsequently, several research gaps and limitations were identified, which have informed our proposed future research directions.Results and discussionsThis paper argues that humans can attenuate and positively control the impact of their buildings on the environment, and as such mitigate the effects of climate change. This can be achieved by a new generation of LCA methods and tools that are model based and continuously learn from real-time data, while informing effective operation and management strategies of buildings and districts. Therefore, the consideration of the time dimension in product system modeling is becoming essential to understand the resulting pollutant emissions and resource consumption. This time dimension is currently missing in life cycle inventory databases. A further combination of life cycle impact assessment (LCIA) models using time-dependent characterization factors can lead to more comprehensive and reliable LCA results.Conclusions and recommendationsThis paper promotes the concept of semantic-based dynamic (real-time) LCA, which addresses temporal and spatial variations in the local built and environmental ecosystem, and thus more effectively promotes a “cradle-to-grave-to-reincarnation” environmental sustainability capability. Furthermore, it is critical to leverage digital building resources (e.g., connected objects, semantic models, and artificial intelligence) to deliver accurate and reliable environmental assessments.

PurposeThe purpose of this research is to estimate the renovation potential of a city’s building stock and evaluate the environmental impact reduction and greenhouse gas emission reduction realized by clustered renovation. These reductions are compared to the climate goals for 2050 by the city of Leuven, i.e., 81% reduction in CO2-eq. compared to 2011 to support the development of an optimal renovation strategy for the city.MethodsThe building stock of Leuven is analyzed and subdivided into various clusters of buildings with a similar renovation potential. This paper presents the existing status of one cluster consisting of terraced buildings built between 1946 and 1970 and assesses its required renovation measures using a life cycle approach by applying the Belgian LCA method for buildings. The environmental impact of this cluster and the potential reductions obtained by the renovation are upscaled and compared to the city climate goals. Based on these results, the total impact of this cluster on the greenhouse gas emissions of Leuven is calculated and the most impactful renovation measures identified.Results and discussionThe results reveal that renovating the walls, floors, and roofs of the houses in this cluster in Leuven (representing ca. 5% of the stock) can lead to a reduction in CO2-eq. emissions of 0.9 to 1.9% compared to the emissions by Leuven households in 2011. This estimate ignores the improvement of the airtightness and the renewal of heating systems. So, higher reductions may be possible. The renovation impact of each of the building elements is evaluated separately, indicating that the highest improvements can be obtained by improving the insulation level of the walls. A sensitivity on the original state of the building has been performed by assuming the absence of (a small) insulation layer in the original roof state. This reveals a significant higher CO2-eq. reduction potential due to renovation.ConclusionsThe results demonstrate the appropriateness of the clustering approach in estimating the greenhouse gas emissions of a certain housing type and the potential contribution of renovating these to reduce the city greenhouse gas emissions. By extending this analysis to all identified clusters, the full potential of renovating the housing stock in Leuven can be estimated and can help in setting priorities in the overall goal to reduce greenhouse gas emissions.