Barriers and opportunities of fast-growing biobased material use in buildings

Limiting global warming to 1.5°C requires immediate and drastic reductions in greenhouse gas (GHG) emissions. A significant contributor to anthropogenic global GHG emissions is the production of building materials. Biobased materials offer the potential to reduce such emissions and could be deployed in the short term. Timber construction has received the main attention from policy and industry. However, the implementation of timber construction at the global scale is constrained by the availability of sustainably managed forest supplies. A viable alternative is fast-growing plants and the use of agricultural waste products. These can be deployed faster and are better aligned to local supplies of biomass and demands from the building sector. Fast-growing materials are generally able to achieve net-cooling impacts much faster due to their short rotation periods. The GHG emissions due to the production of biogenic building material can be compensated by regrowth of the new (replacement) plant and, overall, this will absorb CO2 from the atmosphere. A range of biogenic materials can be promoted and used as insulation materials and structural materials. Policy relevance Materials play an important part of the transition to a low carbon society, especially as many existing construction materials have large amounts of ‘embodied carbon’ in their manufacture. Given the need to rapidly reduce GHG emissions, public policies can promote a rapid transition to low carbon biogenic materials. The use of fast-growing biogenic materials for use in construction products can create carbon-neutral or even carbon-negative products. The use of biogenic materials in construction materials delivers larger GHG savings than their use in other sectors (e.g. biofuels). The use of these materials can be scaled up quickly due to their short rotation period. An integrated policy approach is needed that provides synergy between the energy, industry, housing and agriculture sectors to encourage the use of biobased materials.ISSN:2632-665

Barriers and opportunities of fast-growing biobased material use in buildings

Limiting global warming to 1.5°C requires immediate and drastic reductions in greenhouse gas (GHG) emissions. A significant contributor to anthropogenic global GHG emissions is the production of building materials. Biobased materials offer the potential to reduce such emissions and could be deployed in the short term. Timber construction has received the main attention from policy and industry. However, the implementation of timber construction at the global scale is constrained by the availability of sustainably managed forest supplies. A viable alternative is fast-growing plants and the use of agricultural waste products. These can be deployed faster and are better aligned to local supplies of biomass and demands from the building sector. Fast-growing materials are generally able to achieve net-cooling impacts much faster due to their short rotation periods. The GHG emissions due to the production of biogenic building material can be compensated by regrowth of the new (replacement) plant and, overall, this will absorb CO2 from the atmosphere. A range of biogenic materials can be promoted and used as insulation materials and structural materials

Wood in buildings: the right answer to the wrong question

Reducing the embodied emissions of materials for new construction and renovation of buildings is a key challenge for climate change mitigation around the world. However, as simply reducing emissions is not sufficient to meet the climate targets, using bio-based materials seems the only feasible choice as it permits carbon storage in buildings. Various studies have shown that bio-based materials allow turning overall life cycle impacts negative, therefore, having a cooling effect on the climate. In recent years, scholars and policy makers have focused almost exclusively on the advancement of wooden buildings. Timber structures stand out as they can be prefabricated and used for high-rise buildings. Yet, one important aspect seems to be overlooked: the consideration of supply and demand. Large forest areas that allow sustainable sourcing of woody biomass only exist in the Northern hemisphere, notably in North America and Europe. In these regions, though, urbanization rates are mostly stagnating, meaning new construction rates are low. The largest amount of material requirements in these regions are derived from the refurbishment of the existing stock. Moreover, in areas where structural material is needed for new construction, in Asia, Africa and South America, rain forests need to be protected. Therefore, we need to rethink the desire to find one solution and carelessly implement it everywhere. Instead, we need to consider locally available material and know-how for grounded material choices. This paper explores the supply of a range of bio-based materials and matches it against the material demand of global building stocks. It is based on various previous studies by the authors, of South Africa, China, Portugal, and more. The analysis divides between structural materials for new construction, such as wood and bamboo, and thermal insulation materials for the refurbishment of existing buildings, such as straw and hemp. The results emphasize the need for diversifying bio-based material solutions

Dynamic life cycle assessment of straw-based renovation: A case study from a Portuguese neighbourhood

Action is needed to mitigate climate change. As the building sector is one of the main contributors to energy consumption, renovation of existing buildings is a key strategy. However, for a drastic greenhouse gas emissions (GHG) reduction, sensible material solutions are required. Bio-based products seem to be a promising alternative thanks to carbon sequestration in the new biomass, which needs to be regrown for substitution. The conventional life cycle assessment (LCA) framework seems unsuited to model temporal emissions and carbon uptake of such solutions. Dynamic LCA (DLCA), which models temporal aspects, is more appropriate to evaluate the environmental performance of bio-based products. Moreover, the different dynamic drivers of urban building stocks should be included to allow for informed material choices. A new methodology is proposed, integrating DLCA with material flow analysis (MFA) considering a dynamic renovation rate. The global warming potential over time of the thermal retrofit of a Lisbon neighbourhood with a straw-based technology is assessed. The results highlight the importance of the end of life scenario, greatly influencing the results in the mid- to long term. Increased renovation rates can yield higher carbon storage benefits. However, if accompanied by technological solutions that rely on carbon intensive materials, e.g. finishing, this can lead to increased embodied carbon emissions in the transition period

Fleet-based LCA applied to the building sector - Environmental and economic analysis of retrofit strategies

CO2 emissions need to be reduced by 40% in 2030 in Portugal as an intermediate target of the Paris Agreement. This challenging goal is expected to be achieved through incentive-based regulations and voluntary actions. This study improves the understanding of renovation strategies to reduce emissions caused by the built environment. A fleet-based Life Cycle Assessment (fb-LCA) is adapted and applied to the building sector. Fb-LCA integrates LCA and a fleet model to describe stocks and flows associated with a class of products over time. The method is tested for a neighbourhood in Lisbon, Portugal. The analysis compares 3 scenarios of dynamic renovation rates for the next 30 years: business as usual, a public economic incentive to renovate, and mandatory renovation. Different technology scenarios including bio-based ones, are compared. Among the latter, alternative material solutions, e.g. insulation cork boards, are emerging, providing carbon sequestration. Results highlight the environmental benefits of bio-based materials considering the temporal profile of renovation activity. Furthermore, the cost and sensitivity analysis help stakeholders to justify retrofit actions from an environmental and economic point of view. The adaptation of a fb-LCA approach proves to be an easy-to-use method to assess technology options and policy scenarios at a neighbourhood scale.ISSN:1755131

A matter of speed: The impact of material choice in post-disaster reconstruction

The effects of urbanization and climate change are dangerously converging. The most affected populations are the urban poor, settled in informal settlements vulnerable to increasingly frequent disasters. This severely contributes to the existing housing gap of these regions, already struggling with housing demand. The speed of shelter delivery becomes key for an efficient response in order to prevent spontaneous informal resettlements on unsafe lands. The present study aims to understand the impact of material choice on post-disaster shelters delivery through a multiscale analysis of construction speed. The scales considered are: Constructive technology, Shelter Unit and Post-disaster settlement. At the the Constructive technology scale, nine different reconstruction solutions for the Nepal earthquake are compared, covering a range from local to industrialized. Successively, twelve shelter designs by the International Federation of the Red Cross have been studied under the same lens at the Shelter unit scale and for Post-disaster settlements. The study identifies a clear correlation between material procurement and speed at the constructive technology scale. At the shelter scale, this correlation becomes secondary and construction time is seriously impacted by the complexity of roof design. Moving to the settlement scale, the choice of local over industrialized materials seems to drive the speed again. The study indicates how a multiscale approach is necessary to analyze the impacts of material selection, providing efficient guidelines for post-disaster reconstruction. Beyond that, it highlights that effective reconstruction can be developed with diverse materials, but its emergency responsiveness can seriously be compromised by a non-appropriate design

Land availability in Europe for a radical shift toward bio-based construction

The renovation and construction of buildings presents an opportunity for climate change mitigation in urban environments. Bio-based construction is particularly promising since the plant's sequestered carbon offsets the building's carbon emissions. However, the required land to cultivate suitable biomass and the feasibility of environmentally sustainable materials for resilient cities should be understood. This study analyzes timber, straw, hemp and cork construction and renovation in Europe. A prediction-based model, tuned-up on four systems (built environment, natural environment, carbon balance, industrial processing), converts construction activities until 2050 into required material, embodied land and carbon storage. A novel material-land nexus concept analyzes the required land for bio-based construction. Land transformation is not analyzed. The aim is to evaluate the biomass supply considering the current cross-sectoral use of land in Europe. The results indicate that current forests and wheat plantations are more than sufficient for supplying construction materials. Straw seems better than timber, in terms of resource availability and carbon storage potential. Cork is only favorable locally in southern dry countries. The current legal limitations hinder hemp's potential at a large scale. A wider application of bio-based materials remains unrealistic until an appropriate legal framework is provided

Dynamic life cycle assessment of straw-based renovation: A case study from a Portuguese neighbourhood

ISSN:1755-1315ISSN:1755-130