Many life cycle assessments (LCA) studies on wooden buildings show potential to decarbonise the building industry, though often neglecting to consider the systemic changes of such a shift at the building stock scale. This study applies a consequential LCA to evaluate the transition from conventional construction to increased wood-based construction in Denmark from 2022 to 2050. The assessment models a material flow analysis of the two construction scenarios, incorporating an area forecast and case buildings. By that, we assessed suppliers' capacity to likely meet the demand for wood, steel, and concrete, employed an input-output model to enhance completeness and country representativeness for other materials' markets, and considered the competition for land by indirect land use change. We implemented a dynamic IPCC-based assessment of GHG-emissions concurrently with a carbon forest model to anticipate the relationship between the delayed carbon storage resulting from using wood in buildings and forest regrowth management. The findings indicate wood construction is the most climate-friendly option for multifamily houses. In contrast, single-family houses (SFH) and office buildings (OB) exhibit the lowest climate impacts in the conventional scenario. The SFH result could be credible due to the sizable GWP impact gap between construction scenarios despite uncertainties related to the weight proportion of sedum roofs. The less conclusive OB findings relate to the substantial steel quantities in the wood case buildings, requiring further investigation. Generally, metals, cement-based- and biobased materials demonstrate the largest climate impact among the material categories. Across all three building typologies, the change to timber construction increased the impact on nature occupation (biodiversity). In conclusion, this study emphasises the need for further research on forest management model inputs, land use change approaches, potential steel suppliers' impact, and a broader array of case studies. It is because these are influential factors in facilitating informed decision-making of the increased implementation of wood in buildings. As the first study to integrate these modelling characteristics, it contributes to the research gap concerning geographical circumstances, forestry, and markets relevant to decision support for increased wood utilisation in Europe's building industry.
This initial study of environmental impacts by continuing current conventional building practices and by changing to increased use of wood is in Danish but has a 5 page illustrated summary in English.
What are the options for Nordic Ecolabelling to support the reduction of global warming from buildings by adding more requirements for specific building materials or building parts, e.g. by requiring calculations of the global warming impact for either a part for the entire life cycle of the buildings? We investigate this question by reviewing the current landscape of life-cycle based standards, methods and tools available for designers and producers of buildings and building materials. We identify a number of ambiguities in the standards that cause inconsistencies in their interpretation and practical implementation, resulting in a limited comparability of results from different databases and tools.
We conclude that the current consistency and comparability of life-cycle based calculations for construction products are insufficient to be the basis for the Nordic Ecolabelling programme to require such calculations as part of their criteria. In spite of this, we identify three areas where ecolabelling criteria would currently be verifiable:
• Requirements on specific construction products with identical functionality, where greenhouse gas emission reductions are clearly verifiable, e.g. when obtained through light-weighting.
• Requirements aiming at increasing recycling, such as design for disassembly and minimum recycling targets specified by material type.
• Requirements to reduce overall material demand over the forecasted service life of the building under well-specified, realistic use scenarios.
It is obviously not the role of the ecolabelling programmes to rectify the current consistency and comparability problems of life-cycle based calculations or the ambiguities in the standards. Nevertheless, to incentivise radical building design changes, it is imperative to seek cooperation with other stakeholders that have similar interests in obtaining consistent and comparable results from life-cycle based calculations, an issue that is not limited to building materials. We recommend a cooperation of stakeholders with the aim of establishing a common open database that:
• Has globally complete system boundaries,
• Links unit processes according to verifiable cause-effect relationships,
• Enforces a strict completeness requirement on the included unit processes, using mass and monetary balancing,
• Includes future scenarios based on realistic and transparent procedures,
• Requires activities, and thus flows, to be clearly specified in time, and
• Requires all flows to be provided with uncertainty.
All of these aims can be seen as supported by the current standards. Once a database with the above specifications has been established, we recommend that Nordic Ecolabelling requires LCA calculations to be performed with data from this database, unless the user can provide improved data.
We recommend that such calculations be required at the whole building level, in a phased approach comparable to that currently applied in the Norwegian FutureBuilt programme. Here, a total of four calculations are required:
• A baseline calculation, following detailed, unambiguous rules,
• The targeted building, where a reduction criterion relative to the baseline building must be met,
• For the completed building, as built, for the building after 2 years of operation, with data for realised consumption and transport patterns of users.
An additional calculation is also recommended for the choice of demolition of any pre-existing building and building new versus renovation of the pre-existing building.
Concrete hybrid manufacturing is an emerging technology for the construction industry sector. Herein, an innovative construction machine based on a cable robot, which is able to carry additive and material removal modules is presented and the challenges for its assembly are given. The robots’ motion along with the finished part quality are discussed. The information management system including BIM, path planning and control is explored and presented. In addition, material challenges and corresponding approaches are given. Finally, building parts are illustrated and the overall performance in terms of parts quality and machine lifecycle is discussed.
A life cycle assessment (LCA) was conducted on an innovative concrete 3D printing system, offering the following main advantages: (1) additive and subtractive capabilities, allowing for the automated post-processing of printed parts, including operations such as surface polishing, grooving and drilling and (2) the use of a cable robot, which is less expensive, lighter, more transportable, more energy-efficient and more easily reconfigurable than alternatives such as gantry-type systems. The production of a 4-m height structural pillar was assessed, comparing it to production with traditional methods, namely, using a mould. The study included the entire supply chain of the 3D printing equipment, operation and end-of-life, based on real data from the design and operation of a demonstration plant installed in Spain. Data for traditional construction was based on literature and expert judgement. The 3D production process included printing the pillar perimeter in four pieces with 3D printing concrete, transporting to the construction site and reinforcing and casting with conventional concrete. Traditional production involved reinforcing and casting with the mould on-site. The results show that when only one pillar needs to be produced, 3D printing has a lower environmental impact in all the environmental indicators assessed when compared to using a mould that is discarded after a single use. As an example, GHG emissions are lower by 38%. It was also found that the contribution of 3D printing to the environmental impact of producing a pillar is almost negligible, representing less than 1% of the pillar’s total GHG emissions. However, when the same pillar needs to be produced in higher numbers, the results show that 3D printing and conventional production have a similar environmental impact, given that the mould used in conventional production can be reused, becoming a comparatively efficient option.
ShareIt link: https://rdcu.be/cdbFy
Pre-print for download: Preprint_HINDCON (pdf-file)
This project for Nordic Ecolabelling reviewed the current landscape of life-cycle based standards, methods and tools available for designers and producers of buildings and building materials. The primary objective was to assess the feasibility of adding additional ecolabel criteria for specific building materials or parts requiring calculations of the global warming impact for either a part or the entire life cycle of the buildings. The project resulted in a publicly available report where we identify a number of ambiguities in the standards that cause inconsistencies in their interpretation and practical implementation, resulting in a limited comparability of results from different databases and tools. We conclude that the current consistency and comparability of life-cycle based calculations for construction products are insufficient to be the basis for the Nordic Ecolabelling programme to require such calculations as part of their criteria. The report includes a number of additional recommendations to Nordic Ecolabelling.
The project covered:
In collaboration with DAMVAD Analytics and Goritas.
The final report (in Danish) can be read here.
Rapporten er blevet til på baggrund af et opdrag fra Center for Byggeri (tidligere under Energistyrelsen, nu under Trafik- og Byggestyrelsen).
Opgaven er løst i samarbejde mellem DAMVAD Analytics, Goritas, Bygge- og Miljøteknik og 2.-0 LCA Consultants.
Selve opgaven har været at afdække potentialer og barrierer ved anvendelsen af træ i dansk byggeri, herunder:
Life cycle assessment (LCA) is broadly applied to assess the environmental impact of products through their life cycle. LCA of bio-based products is particularly challenging due to the uncertainties in modeling the natural biomass production process. While uncertainties related to inventory data are often addressed in LCA by performing sensitivity analyses, the sensitivity of results to LCA methodologies chosen is seldom addressed. This work investigates the influence of common methodological choices on LCA climate impact results of forestry products.
Performing a consequential LCA, the study compares results obtained through different choices concerning four methodological aspects: the modeling of land use change effects, the choice of climate metric for impact assessment, the choice of time horizon applied, and the completeness of the forest carbon stock modeled. Eight scenarios were tested, applied to the same case study to ensure the full comparability of the results. A dynamic life cycle inventory of annual forest biomass production and degradation was obtained through a methodology accounting dynamically for the annual carbon fluxes in a forest plot.
The results obtained for the eight scenarios showed a great variability of the estimated climate effect, ranging from a net carbon sequestration of 24 kg CO2 equivalents to a net carbon emission of 3220 kg CO2 equivalents, though seven out of eight scenarios resulted in a net carbon emission. The results are particularly sensitive to the choice of time horizon, especially when combined with the choice of static or dynamic climate indicator and different climate metrics as GWP and GTP. The case study showed a lower variability of results to the choice of forest carbon stock compared to the effect of the other tested assumptions.
LCA results of forestry products were highly sensitive to the tested methodological choices. A description and motivation of these choices is required for a clear and critical interpretation of the results. The choice of climate indicator and TH applied depends on the goal and scope of the study and strongly affects the contribution to climate impact results of all LCA processes. Those choices need to be carefully discussed and should be in accordance with the goal of the study, since different climate metric and TH have distinct interpretations. The interpretation of different climate indicators and their time horizons should be linked with the considered endpoints of climate change.
Advanced Manufacturing has been highlighted by the EU as one of the key enablers to support and promotion of business research and innovation in key enabling technologies. Therefore, a number of objectives, aligned with pursuing the large scale targets, have been set for advanced manufacturing through four pillars: technology, economic, social and environment.
Thus, HINDCON aims to adapt manufacturing technologies to the construction sector, advancing towards industrialisation and overcoming the limitations of actual approach for introducing Additive and Subtractive Manufacturing in construction activities. The project has a duration of 36 months.
The main aim of HINDCON is to develop and demonstrate a hybrid machine regarding 3D printing technologies with concrete materials focused on the industrialization of the Construction Industry, delivering to this sector an innovative technology that reduces environmental impact at the same time it reduces dramatically economic costs. The collaborative structure of the project will help to:
1) Integrate different technologies that converge in a hybrid solution. The HINDCON "all-in-one" machine will integrate Additive Manufacturing concrete extruder and Subtractive Manufacturing tool kit with the use of cementitious materials including mass materials with alternatives in concrete and additives, and reinforced with composites.
2) Cover the different aspects concerned (technology, economic, social and environment) and demonstrate the hybrid machine from different perspectives. On the one hand, it includes testing basic capabilities of the integrated prototype in laboratory. On the other hand, it involves the demonstration of the manufacturing system in a relevant environment.
The video below introduced the overall project:
LCA result presented in a short video below - and has resulted in these articles Life cycle assessment of integrated additive–subtractive concrete 3D printing and Concrete hybrid manufacturing: A machine architecture
