Biogenic Carbon Storage Research Articles

Life cycle assessment (LCA) of the industrial production of structural glued laminated bamboo

Bamboo is a promising bio-based construction material for achieving China’s carbon neutrality goal. This study developed methodological approaches for life cycle assessment (cradle to gate) of structural glued laminated bamboo (SGLB) produced from moso bamboo (Phyllostachys edulis), including measuring and calculating biogenic carbon storage and emissions during the manufacturing process. Primary data was collected through experiments and field investigation resulting in development of world’s first life cycle inventory (LCI) of SGLB; background data from Ecoinvent 3.10 was used, and the analysis was performed using OpenLCA 2.1: IPCC 2021 method AR6. Uncertainty analysis was conducted using Monte Carlo Simulation. The results illustrate that SGLB can store 1140 kgCO2e/m3, which is more than twice biogenic CO2 emitted (467 ± 9.1 kgCO2e/m3) during its production. Electricity, adhesive, and transportation are the top three emission sources, among which electricity contributed to 71% of the final emission and was mainly consumed at the fine-planed bamboo strip processing factories. The production process generates around 60% of bamboo co-products, which can be effectively used for heat and power co-generation that can drastically reduce the carbon emissions to 156 kgCO2e/m3. In addition, maximal use of sea transportation between factory gate and consumer can further mitigate carbon emission. Further research on the end-of-life scenarios of SGLB in structures, and research on SGLB produced from other bamboo species in Africa, Latin America, and Southeastern Asia need to be undertaken.

Demand-driven wood/bamboo doors: Carbon storage potential and greenhouse gas footprint

Due to large number of doors used housing and construction products, the greenhouse gas (GHG) footprint related to door manufacturing is an interesting topic. Timber and bamboo products can reduce GHG emission due to their biogenic carbon storage via photosynthesis. The scientific evidence on the climate impact using wood-based door (WBD) and bamboo-based door (BBD) to replace steel-based door (SBD) is limited. In this study, life cycle assessments for WBD, BBD, SBD were conducted to evaluate the carbon impacts of raw materials, production, transport, and end-of-life stages. The GHG footprint of WBD, BBD, and SBD ranged from 270.42 to 363.24, 285.31–398.31, and 983.8–986.76 kg CO2 e/m3, respectively, indicating that the bio-based doors exhibited lower energy consumption and GHG emissions. The raw material stage (484.78–569.34 kg CO2 e/m3) was identified as a major source of GHG emissions throughout the product life cycle, while hot-pressing and coating processes were identified as emission hotspots in the production stage. Regarding biogenic carbon storage, the use of bio-based materials instead of steel-based materials for fire door manufacturing significantly reduced emissions. Considering disposal methods, recycling and incineration should be prioritized over landfills. Future research should focus on field survey in raw material stage, along with conducting a technical and economic analysis. The results provide valuable guidance for selecting doors in China in term of biogenic carbon storage and resource protection.

Holistic regenerative design: the Common House by Common Practice

In the August 2023 issue of The Structural Engineer, Oliver Broadbent and James Norman presented the principles of regenerative design, and Will Arnold and Phil Isaac discussed how structural engineers can achieve this in buildings through designing for place, circularity and reuse, material choices and knowledge transfer. However, while the article gave example projects for each of these aspects of regenerative design, it noted that case studies that can be considered exemplars in all four areas at once were lacking. The Common House is a community gathering space and the heart of the Hazelmead co-housing development in Bridport, Dorset, UK. Featuring a locally sourced timber frame, straw-bale wall panels, and concrete-free foundations, its construction was also a catalyst for long-term social engagement and ecological conservation. The authors believe that the Common House project design process has roots in the four areas outlined above. With a quietly revolutionary vision for its surrounding land and communities, the Common House is a rare case study representing a holistic approach to regenerative design. Through conversation with designers Common Practice, this article examines the transformative potential of developing construction projects as strategies to empower local communities, support continuous-cover forestry, protect endangered crafts, minimise fossil carbon emissions and promote biogenic carbon storage, and make construction sites spaces of care and support.

Prolonged Carbon Storage and CO2 Reduction by Circular Design with Wood

The benefits of circularity and biogenic carbon storage are often overseen. This study links the circular design of buildings with prolonged biogenic carbon storage. Circularity in architectural design can involve extending the service life of a building frame, whilst forests grow back and store more carbon. Following this approach, Stora Enso has developed a mixed-use building concept with flexible and adaptable structures. Static and dynamic life cycle assessment (LCA) has been carried out to assess different scenarios, modelling and quantifying its potential benefits regarding whole life carbon. While whole life carbon is lower in all timber scenarios compared to conventional concrete buildings, dynamic LCA makes clear the benefits of carbon storage and carbon sequestration. Total emissions, considering a reference service life of 50 years, are 2,84 kg CO2-eq./m² floor area/year, considering biogenic carbon storage and carbon sequestration in regrowing forests. An increase of the building lifetime to 80 years aligns with a longer rotation time of forest trees, resulting in whole life carbon of -0,09 kg CO2-eq./m² floor area/year. This demonstrates that the effective implementation of built-in flexibility and adaptability can extend the service life of a building, unlocking environmental benefits of biogenic carbon storage of wood products in buildings.

Evaluating cotton apparel with dynamic life cycle assessment: The climate benefits of temporary biogenic carbon storage

Static life cycle assessment (LCA) methodologies fail to consider the temporal profiles of system inputs and outputs (including emission timing), such that they underestimate the benefits of temporarily stored biogenic carbon in bioproducts, such as cotton. This research focuses on greenhouse gas emission timing and applies dynamic emission accounting to the life cycle of cotton woven pants. The significance of temporary biogenic carbon storage and emission timing is illustrated by converting the 2017 Cotton Incorporated static LCA to a dynamic model using the Dynamic Carbon Footprinter (baseline scenario). A reduction in cumulative radiative forcing for dynamic relative to static modeling of 22%, 5%, and 2% are observed at 10-years, 30-years, and 100-years, respectively. Alternative scenarios analyzed include converting cotton woven pants at end of life to bioenergy, to compost, or to building insulation, an alternative cotton production scenario using regenerative agricultural practices, and two pants extended lifetime scenarios. The regenerative agricultural practice scenario provides reductions in cumulative impacts compared to the baseline scenario of 96%, 69%, and 105% after 10, 30, and 100-years, respectively. A 3x extension in the lifetime of pants provides a benefit in reduced cumulative impacts of 31%, 40%, and 41%, after 10, 30, and 100-years, respectively. This case study with cotton demonstrates that dynamic LCA is a useful tool for assessing the benefits of biobased products, and it allows for more nuanced analysis of reductions in climate impacts in both the short- and long-term time horizons.

The potential use of mass timber in mid-to high-rise construction and the associated carbon benefits in the United States.

Nonresidential and mid- to high-rise multifamily residential structures in the United States currently use little wood per unit floor area installed, because earlier building codes lacked provisions for structural wood use in those types of buildings. However, revisions to the International Building Code allow for increased wood use in the form of mass timber, as structural and fire safety concerns have been addressed through new science-based design standards and through newly specified construction materials and measures. This study used multiple models to describe alternative futures for new construction, mass timber adoption rates, and the associated carbon benefits in higher than three-story buildings in the United States. The use of mass timber, in place of traditional constructions (i.e., structures dominated by concrete and steel), in projected new higher than three-story buildings was shown to provide combined carbon benefits (i.e., global warming mitigation benefits), including avoided embodied carbon emissions due to the substitution of non-wood alternatives and additional biogenic carbon storage in mass timber materials, of between 9.9 and 16.5 million t CO2e/yr spanning 50 years, 2020 to 2070. These carbon benefits equate to 12% to 20% of the total U.S. harvested wood products carbon storage for 2020. Future research is needed to understand how greater mass timber adoption leads to changes in forest product markets, land use, and total forest sector carbon.

Future buildings as carbon sinks: Comparative analysis of timber-based building typologies regarding their carbon emissions and storage

The building and construction sector is responsible for a large share of carbon emissions resulting in the need to reduce them to mitigate climate change. Timber construction methods promise to lower emissions combined with biogenic carbon storage in the built environment. While there are several studies comparing the emissions of mineral-based and timber-based buildings, a consistent comparison of different timber-based building assemblies is still missing. This study compares carbon emissions from material production and carbon storage capabilities of four timber-based and two brick and reinforced concrete building assemblies. These assemblies were designed for a residential multi-storey building in Berlin, Germany. To compare and rank the carbon impacts of these assemblies we introduce a carbon storage-to-emission ratio. The calculations were performed using a Carbon Cycle Assessment Model implementation in Python. The results indicate an average reduction in carbon emissions of timber-based building assemblies by 32.6% to “Brick” and 40.4% to “Reinforced Concrete”, respectively. Across the timber-based building assemblies, the carbon emissions range between 85 t and 115 t, leading to an average of 105 t per building. Pronounced differences were observed in carbon storage, with the “Dowel Laminated Timber” building assembly storing more than three times the amount of carbon compared to “Light Weight Timber” assembly. To further reduce emissions from buildings and the construction sector and potentially enhance urban carbon storage, “Glue Laminated Timber” and “Dowel Laminated Timber” building assemblies were identified as the most promising.

Integrating LCA, BIM, and Surrounding Trees for Carbon Neutrality in Steel and Concrete Frame Public Structures: A Case Study in Hangzhou

The construction industry is actively working to improve its operations’ sustainability and reduce buildings’ ecological impact on climate change. One approach involves integrating Building Information Modeling (BIM) with Life Cycle Assessment (LCA) to streamline data input, calculate environmental impacts, and optimize output data. This case study focuses on using the One-Click LCA plugin to explore LCA-BIM integration for sustainable construction.The study examines the carbon emissions of steel and concrete frame public structures and assesses the role of surrounding trees in achieving carbon neutrality. Two innovative public buildings in China’s Zhejiang province serve as the case study’s subject. The One-Click LCA plugin in Revit is a quick and user-friendly tool, providing concrete and steel structure results and generating informative graphs for easy comparison.The findings reveal that the A1-A3 material stage during the design phase contributes the most to emissions and biogenic carbon storage. By demonstrating the practical implementation of LCA-BIM integration using the One-Click LCA plugin, this case study contributes to the knowledge base on sustainable construction practices. The results can guide decision-making for architects, engineers, and construction professionals, empowering them to make informed choices that minimize carbon emissions and promote environmentally-friendly design strategies.

Comparative carbon footprint estimation of three types of wooden door: A case study from China

As one of the most vital wood-based products, the carbon footprint of wooden doors has received increasing attention in recent years. The studies on the carbon footprints of different types of wooden doors are few. In this study, the cradle-to-grave carbon footprints of three types of wooden doors produced in China were comparatively analyzed. Models used for calculating the total life-cycle carbon footprint of a wood-based composite door, a solid wood composite door, and a solid wood door were developed. Considering the biogenic carbon storage and its delayed emissions, the wood-based composite door, solid wood composite door, and solid wood door featured carbon footprints of 0.379, 0.257, and −0.277 kg CO2 e per kg product, respectively. The solid wood door exhibited a negative carbon footprint, indicating that its carbon storage was higher than the carbon emission during the life cycle stage. The raw material acquisition (38%–66%) and the transportation stages (23%–38%) of the three types of wooden doors were the main contributors to the total carbon footprints (excluding the biogenic carbon). The product manufacturing stage released relatively small emissions (11%–24%). The waste disposal treatment at the end-of-life phase, the degradation of wood materials in landfills, and their service life displayed significant impacts on the carbon footprints of the three types of wooden doors. Fiberboard, laminated veneer lumber, sawn lumber, finger-jointed lumber, and electricity were identified as the main emission hotspots. This study provides guidelines for low-carbon development in the wooden door industry.

Unpacking bio-based alternatives to ethylene production in Brazil, Europe, and the United States: A comparative life cycle assessment

Plastics account for 4.5% of global greenhouse gas (GHG) emissions, which are hard-to-abate due to the use of fossil fuels as feedstock. Our study develops a cradle-to-gate life cycle assessment of bioethylene production, exploring 33 pathways across Brazil, the EU, and the US. It aims to understand whether substituting fossil-based ethylene with bioethylene contributes to lowering carbon emissions, and in which of the relevant bioenergy-producing regions/countries the valorisation of biofuels as feedstocks would provide a less carbon-intensive bioethylene production. Results indicate that bioethylene production through catalytic dehydration of sugarcane bioethanol in Brazil presents lowest GHG emission. This pathway could deliver up to −2.1 kg CO2e/kg ethylene when accounting for biogenic carbon storage in long-lived applications such as infrastructure. In contrast, beef tallow performs the poorest as a raw material, regardless of whether land-use change (LUC) emissions are considered. When biogenic carbon storage is factored out, none of the pathways outperforms conventional fossil-based steam cracking; however, some are within the fossil-based range indicating potential indirect benefits through reduced refinery utilisation. Our study underscores that biomaterials production as a climate mitigation strategy must be on par with circular economy measures and the conservation of native forestry ecosystems. These results are particularly relevant to policymakers and industries seeking to align polymer manufacturing with sustainability objectives.

Greenhouse gas footprint assessment of wood-based panel production in China

China is one of the largest manufacturers, consumers, and traders of wood-based panels (WBPs) globally. The Chinese manufacturing process for WBPs is significantly different from that used in other countries and the greenhouse gas (GHG) footprint assessment of this process has not yet received attention. And a comprehensive evaluation of the effect of different approaches to estimate the delayed emission of biogenic carbon on the GHG footprints of different WBP types is still missing. This study aims to quantify: i) the GHG footprint of WBPs produced in China, and ii) the influence of different methods to assess the delayed emission of biogenic carbon. Cradle-to-gate life cycle models are developed for plywood (PLY), fiberboard (FB), particleboard (PB) and oriented strand boards (OSB). Based on two common end-of-life (EoL) destinations (i.e., incineration and landfill), three approaches to the estimation of the delayed emissions of biogenic carbon in cradle-to-grave assessments are compared. The cradle-to-gate results show that the GHG footprints of PLY, FB, PB and OSB without considering biogenic carbon storage are 538 kg CO2 e/m³, 406 kg CO2 e/m³, 348 kg CO2 e/m³ and 552 kg CO2 e/m³, respectively. For the four types of WBPs, resources extraction stage provides the largest contribution to the GHG footprints (55%–81%), followed by the production process (18%–31%) and raw material transportation (1%–18%). The methodologies used to assess delayed emissions in cradle-to-grave WBP GHG footprint assessments play an important role, especially for incineration scenarios. Finally, emission reduction measures are proposed based on reducing the consumption of adhesives and of energy use in the production process.

Metrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt

Achieving a circular economy (CE) is seen by society and policymakers as crucial to achieving a sustainable, resource-efficient, renewable and competitive economy. Given the current threat of climate change, we must develop new products that not only maximise the circularity of resources but also minimise climate change impacts. While these two goals are usually aligned, trade-offs exist. For instance, recycling biobased asphalt is a better end-of-life option than landfilling from a resource efficiency perspective. However, landfilling of biogenic non-biodegradable material leads to permanent carbon storage and, therefore, climate benefits. To fully understand the potential benefits and impacts of biobased circular innovations, we need metrics to capture their complexity from both a circular and climate point of view. This study explores the use of different circularity and sustainability metrics to understand the impacts and trade-offs of lignin-based versus bitumen-based asphalts. The analysis is done by calculating the Material Circularity Index (MCI) and two newly developed indicators quantifying the biogenic carbon storage (BCS) of products (BCS100 and c-BCS) while following the CE principles. In addition, the impacts regarding climate change, life cycle costs and ECI (environmental costs indicator) are also provided. Based on the MCI, it can be concluded that lignin-based asphalt roads have slightly higher material circularity than their bitumen-based counterparts. The BCS analysis indicated that the least circular lignin-based alternative sequesters the highest amount of carbon in the long term due to permanent storage in foundations. Despite these trade-offs, the results from the newly developed BCS indicators allowed to align both climate and circularity goals, guiding policymakers and industry actors to implement circular biobased strategies where the value of biobased materials is optimised. Finally, this article discusses the use of different circularity and environmental metrics for decision making in the context of a circular biobased economy.

A Highly Sustainable Timber-Cork Modular System for Lightweight Temporary Housing

In recent years, global society has been subjected to great change due to unpredictable events such as pandemics, migrant flow, urban homeless, wars, and natural disasters. There has been an increased demand for fast and easily constructed buildings characterized by limited space and used for a limited time, modular and flexible self-assembly homes that are reusable without compromising comfort and environmental sustainability. A highly sustainable timber-cork modular system for lightweight temporary housing (LTH) is proposed in this paper. The structure of the proposed LTH was designed as a succession of modular timber portal frames composed of spruce boards hinged together. The concept of the prototype was a full modular shelter. It was possible to interchange every piece of the building, the structural elements, and the walls with each other. Due to the modularity of the elements of which the shelter was composed, this system could offer different solutions to the events above. The proposed LTH was analyzed in terms of its structural, thermal, and environmental performance. The structural system is very reminiscent of the platform frame, characterized by a light load-bearing frame consisting of solid timber uprights and crosspieces connected to the internal frame by means of a mechanical connection. The structural FEM analysis highlighted the structure’s capacity to withstand wind with a velocity of 72 m·s-1, corresponding to the F3 of the enhanced Fujita Scale (EF Scale) of tornado damage intensity. The thermal analysis highlighted a yearly energy use of 430.49 kWh to maintain a set-point temperature indoors of 20-26°C compared with a yearly energy use of 625.93 kWh for a common container house (CH) with the same dimensions under the same environmental conditions. Finally, a Life Cycle Analysis comparison between the proposed LTH and the CH was carried out by means of the One Click LCA software. Two different scenarios of service life were considered: one of 10 years and the other of 5 years. The results highlighted the higher sustainability of the proposed LTH than that of the CH for the required service life (Req SL) period. In particular, the calculated greenhouse gas emissions of the LTH (3.52ž103 kgCO2 eq) were less than 1/2 of the gas emissions of the CH (8.53ž103) for a Req SL of 10 years and about 1/3 for a Req SL of 5 years. Furthermore, the LTH showed a value of biogenic carbon storage (7.76E2 kgCO2) about 6 times bigger than the temporary house container (1.31E2 kgCO2). Doi: 10.28991/CEJ-2022-08-10-020 Full Text: PDF

Analysis of building materials used for the construction of family houses in the boundaries from Cradle to Gate with Options

The purpose of the research work is to analyse environmental impacts of building materials applied to the construction of family houses in the boundaries Cradle to Gate with Options. Within Life cycle analysis (LCA), environmental impacts such as global warming potential (GWP), ozone depletion (OP), acidification potential (AP), eutrophication potential (EP), photochemical ozone creation potential (POCP), non-hazardous waste disposal (NHWD) and biogenic carbon storage (BGS) are determined by using One Click LCA tool. This approach is selected to bring information about current state of construction trend used in Slovakia, to set a starting point for further critical reviews of different strategies as well as to inform about the impact significance of current selection of building materials. Results show that the biggest contribution to GWP are triple glazed exterior wooden doors and windows with aluminium elements, thermal insulation and reinforced concrete.

A Lifecycle Assessment of a Low-Energy Mass-Timber Building and Mainstream Concrete Alternative in Central Chile

While high-rise mass-timber construction is booming worldwide as a more sustainable alternative to mainstream cement and steel, in South America, there are still many gaps to overcome regarding sourcing, design, and environmental performance. The aim of this study was to assess the carbon emission footprint of using mass-timber products to build a mid-rise low-energy residential building in central Chile (CCL). The design presented at a solar decathlon contest in Santiago was assessed through lifecycle analysis (LCA) and compared to an equivalent mainstream concrete building. Greenhouse gas emissions, expressed as global warming potential (GWP), from cradle-to-usage over a 50-year life span, were lower for the timber design, with 131 kg CO2 eq/m2 of floor area (compared to 353 kg CO2 eq/m2) and a biogenic carbon storage of 447 tons of CO2 eq/m2 based on sustainable forestry practices. From cradle-to-construction, the embodied emissions of the mass-timber building were 42% lower (101 kg CO2 eq/m2) than those of the equivalent concrete building (167 kg CO2 eq/m2). The embodied energy of the mass-timber building was 37% higher than that of its equivalent concrete building and its envelope design helped reduce space-conditioning emissions by as much as 83%, from 187 kg CO2 eq/m2 as estimated for the equivalent concrete building to 31 kg CO2 eq/m2 50-yr. Overall, provided that further efforts are made to address residual energy end-uses and end-of-life waste management options, the use of mass-timber products offers a promising potential in CCL for delivering zero carbon residential multistory buildings.

The importance of biogenic carbon storage in the greenhouse gas footprint of medium density fiberboard from poplar wood and bagasse

Carbon storage in long-lived bio-based products is typically ignored or accounted for in a simplistic way in greenhouse gas (GHG) footprint calculations. We quantified the GHG footprint of medium density fiberboard (MDF) in Iran from poplar wood and bagasse, a by-product from sugarcane production. Inventory data was collected from sugarcane and poplar wood plantations and MDF factories in Iran during 2017–2019 to calculate cradle-to-grave footprints for 1 ​m3 of MDF. We quantify the effect of carbon storage, which depends on the crop rotation time and the economic lifetime of the product, with shorter rotation times and longer storage periods leading to lower footprints.

Paludiculture as paludifuture on Dutch peatlands: An environmental and economic analysis of Typha cultivation and insulation production

Paludiculture, the cultivation of crops on rewetted peatlands, is often proposed as a viable climate change mitigation option that reduces greenhouse gas emissions (GHGe), while simultaneously providing novel agricultural business options. In West Europe, experiments are ongoing in using the paludicrop cattail (Typha spp.) as feedstock for insulation panel material. Here, we use a Dutch case study to investigate the environmental potential and economic viability of shifting the use of peat soils from grassland (for dairy production) to Typha paludiculture (for cultivation and insulation panel production). Using a life cycle assessment and cost-benefit analysis, we compared the global warming potential (GWP), yearly revenues and calculated Net Present Value (NPV) of 1 ha Dutch peat soil used either for dairy production or for Typha paludiculture. We estimated that changing to Typha paludiculture leads to a GWP reduction of ~32% (16.4 t CO2-eq ha−1), mainly because of lower emissions from peat decomposition as a result of land-use management (−21.6 t CO2-eq ha−1). If biogenic carbon storage is excluded, the avoided impact of conventional insulation material is insufficient to compensate the impact of cultivating and processing Typha (9.7 t CO2-eq ha−1); however, this changes if biogenic carbon storage is included (following PAS2050 guidelines). Typha paludiculture is currently not competitive with dairy production, mainly due to high cultivation costs and low revenues, which are both uncertain, and will likely improve as the system develops. Its NPV is negative, mainly due to high investment costs. This can be improved by introducing carbon credits, with carbon prices for Typha paludiculture (30 years) comparable to EU-ETS prices.In conclusion, Dutch Typha paludiculture has a significant climate change mitigation potential by reducing emissions from deep drained peatlands. Nevertheless, attention is needed to increase its economic viability as this is a key aspect of the system change.

On the theoretical carbon storage and carbon sequestration potential of hempcrete

Hempcrete is a natural insulation material that is well known for exhibiting favorable thermal properties and low manufacturing emissions. Hempcrete is a biocomposite, consisting of hemp shiv and a lime-based binder composed of hydrated lime and either a hydraulic (e.g., natural hydraulic lime and ordinary portland cement) or pozzolanic binder (e.g., metakaolin). While long-term biogenic carbon storage can be achieved via utilization of hemp shiv in hempcrete, additional carbon storage can be achieved via carbonation of the binder. This study advances previous carbonation modeling approaches by deriving a theoretical model based on the fundamentals of cement hydration and carbonation chemistry to quantify the total theoretical in situ CO2e sequestration potential of hempcrete binders. To estimate the percentage of manufacturing CO2e emissions that can be recovered through in situ binder carbonation, the model is implemented in life cycle assessments of 36 hempcrete formulations of various binder contents and densities using an equivalent functional unit (FU) of a 1 m2 wall assembly with a U-value of 0.27 W/(m2K). Our model estimates between 18.5% and 38.4% of initial carbon emissions associated with binder production can be sequestered through in situ carbonation. Considering biogenic carbon storage, we predict that the total life cycle CO2e emissions of hempcrete can be negative, with a minimum of −16.0 kg CO2e/FU for the hempcrete mixture formulations considered herein. However, we estimate that some hempcrete formulations can exhibit net-positive emissions, especially high-density mixes (>300 kg/m3) containing portland cement, thereby illustrating the importance of materials selection and proportioning in designing carbon-storing hempcrete.

METHOD FOR ASSESSING THE NATIONAL IMPLICATIONS OF ENVIRONMENTAL IMPACTS FROM TIMBER BUILDINGS—AN EXEMPLARY STUDY FOR RESIDENTIAL BUILDINGS IN GERMANY

Since 2012, a set of new standards describing, among other aspects, the use of life cycle assessment (LCA) in the construction sector is available in Europe and provides a framework for consistently assessing the environmental performance of buildings. This article gives an overview of the actual state of art for evaluating the environmental properties of timber buildings in Europe and shows how these methods could be used as a basis for estimating the influence of a possible shift from conventional buildings to timber buildings on the national “Greenhouse Gas (GHG) budget,” whereby Germany serves as an example. Results from up-to-date LCA calculations of residential buildings for Germany are shown on a building level. Then a scaling from the building level to a national level is presented. On the national scale, the potential GHG impact of wood consumption in the building sector is modeled based on an insinuated future increase of the market share of timber buildings. The deviation of future emissions and removals due to the biogenic carbon storage effects for changing scenarios is presented. The approach shows how increasing timber construction (mass timber and timber frame) can contribute to achieving climate protection targets.

Climate impacts from road bridges: effects of introducing concrete carbonation and biogenic carbon storage in wood

The construction sector faces the challenge of mitigating climate change with urgency. Life cycle assessment (LCA), a widely used tool to assess the climate impacts of buildings, is seldom used for bridges. Material-specific phenomena such as concrete carbonation and biogenic carbon storage are usually unaccounted for when assessing the climate impacts from infrastructure. The purpose of this article is to explore the effects these phenomena could have on climate impact assessment of road bridges and comparisons between bridge designs. For this, a case study is used of two functionally equivalent design alternatives for a small road bridge in Sweden. Dynamic LCA is used to calculate the effects of biogenic carbon storage, while the Lagerblad method and literature values are used to estimate concrete carbonation. The results show that the climate impact of the bridge is influenced by both phenomena, and that the gap between the impacts from both designs increases if the phenomena are accounted for. The outcome is influenced by the time occurrence assumed for the forest carbon uptake and the end-of-life scenario for the concrete. An equilibrium or 50/50 approach for accounting for the forest carbon uptake is proposed as a middle value compromise to handle this issue.