Climate change not only triggers drier land surfaces, a rise of sea level but also provides the atmosphere with an increasing moisture content. This, among other factors, has increased the intensity and frequency of major natural disasters. Low areas all over the world tend to suffer flooding above living memory; whereas dry areas – severe drought and fire.

A report from The International Federation of Red Cross and Red Crescent Societies [1] indicates that over the past six decades, on a global scale, the number of disastrous events triggered by weather or climate has increased substantially - more than 3 times for storm, above 3 times for drought, about 9 times for flood, and approximately 10 times for fire, extreme temperature, and landslide combined.

Not all weather or climate-related events leads to a deadly disaster. However, they all tend to directly impact, in their own ways, hundreds of million, if not billions of people around the world. The chart below gives a ballpark figure of how many of us are being affected over the past decades (data adopted from [1]). No place is completely immune, and without an appropriate strategy for climate resilience, no one seems to be safe when such a disaster hits.

Reference(s):

[1] A. Freebairn et al., World disasters report 2020 : come heat or high water, https://www.ifrc.org/ document/world-disasters-report-2020.

Not only human lives are at risk, but their accommodations also suffer unprecedented challenges.

• Load-bearing skeleton of houses and buildings carries increasing pressures from the increasing intensity of wind, storm tide, or flood. Once the pressures exceed the ultimate load-bearing capacity of the structures, local damages or an overall collapse are inevitable.
• Higher flood level increases the risk of houses being submerged and/or washed away. Equally, scour under footing systems and soil with higher water content weaken the foundation, leading to numerous potential damages such as sinking, tilting, cracking, or collapsing.
• Modern houses with redundant, unnecessarily open spaces reduce insulation efficiency. While summer tends to be hotter and winter being colder in different areas, either higher energy consumption for air conditioning is required or these houses may become uninhabitable. According to a study from Department of Industry, Science, Energy and Resources, Australia [2], carbon emission due to energy consumption related to a normal operation of Australian buildings (e.g., heating, cooling etc.) currently contributes up to 84% the whole-life carbon emission, while the embodied-carbon coming from construction only takes up to 16%. This evidences the critical role of effective insulation for future builds to achieve sustainability.
• Combustible, structurally unsound, moisture sensitive, heat sensitive or fast degradable materials are being used for certain parts of houses and buildings due to economic reasons. This further increases the structures' vulnerability under fire, storm, and flood.
• Building high with monotonic material choices and an over-dependency on modular technology limits the ability of structural optimization for good. The structures are less resilient when it comes to dynamic impacts such as earthquake, storm tide, or cyclone.

Reference(s):

[2] J. Vickers, J. Chapa, S. Warmerdam, S. Qian, S. Mitchell, and N. Sullivan, "Title: Embodied Carbon and Embodied Energy in Australia's Buildings", 2021.

With the rise of sea level, coastal, low areas or island countries are predicted to be fully or partly underwater in the upcoming decades [3]. This, alongside increasing weather or climate-related events, challenges our existing infrastructure at multiple fronts:

• Road networks, especially in urban areas, experience regular, prolonged flooding. Road pavements made of unbound, water sensitive materials become weaker and tend to be severely damaged, demanding a mass repair or replacement. Increasing water content also means weaker sub-grade and sub-base, leading to increasing risks of unstable ground with uneven, additional movement, landslide, erosion, etc. which in turn cause further damages to the existing road networks. Traffic disruption, as a result, becomes more frequent.
• Higher flood level increases the risk of bridges being submerged and/or washed away. Strong flow causes scour under piers and abutments. Higher water content in embankment materials weakens the bridge approaches. Landslides under the approaches, as a result, happen more often, threatening the overall stability and serviceability of the bridges.
• Underground or soil supporting structures such as tunnels, retaining walls or pipe systems carry additionally heavy weights caused by saturated soils. Performance of these structures, including footings and foundations, is undoubtedly affected.
• With the rise of sea level, saltwater intrusion will see infrastructure in coastal areas facing higher corrosion risks. Bridges and seawalls, to name a few, made of corrosion-sensitive materials will become increasingly vulnerable to chloride attacks, leading to higher corrosion rate and a fast-shortening service life.
• Rising sea level also means that water crossing structures such as bridges experience a narrowing vertical clearance for waterways. Disruption of water transportation below these bridges, therefore, becomes more frequent.

Reference(s):

[3] R. J. Nicholls et al., “Ranking of the World's Cities Most Exposed to Coastal Flooding Today and in the Future, Executive Summary,” 2007. [Online]. Available: www.oecd.org

Continuous population growth in urban areas exerts extra pressure on both housing and infrastructure.

• Modern residential houses have experienced a squeeze in size to ease the housing stress. An equivalent floor area is now designed to fit way more occupants and facilities than it was decades ago. Ensuring sufficient space division for a basic living convenience also means extra loads put on the structures of the house, limited layout alternatives, and challenging fresh air circulation. Physical and mental health issues arising from congested living have been reported over the past decades and tend to be getting worse. Equally importantly, emergency evacuations (e.g., due to fire, earthquake, etc.) become more difficult to safely execute.
• Infrastructure, especially transportation networks carry extra, congested traffic, which may exceed the design traffic sooner than expected (i.e., at the end of the road service life).
• With roads, this means an increasing risk of severe midlife damage to the top pavement and all sub-layers. Strength, durability, and fatigue resistance are all affected. Reinforcement, or maintenance may be required more frequently than standard schedule.
• Noise, and noise-related health issues: This is particularly the case for busy traffic on rigid elements (e.g., road and tunnel pavements, bridge desks, etc.).

Reference(s):

Urban population: Data adopted from The World Bank "Urban population (% of total population) - Australia", https://data.worldbank.org/ indicator/SP.URB.TOTL.IN.ZS?locations=AU.

Average site area of house approvals: Data adopted from Australian Bureau of Statistics "New houses being built on smaller blocks", https://www.abs.gov.au/ articles/new-houses-being-built-smaller-blocks.

Most construction materials require manufacturing, processing, or refining. Despite own sustainability benefits, environmental sacrifices coming from the production of these materials are inevitable. Further lowering these environmental impacts appears to be a challenge, considering potential losses on strength and durability, not to mention additional cost.

Construction materials have various life spans, within which they maintain strength and other critical properties to ensure a normal, safe service life. Certain construction materials can be recycled, which can help partly tackle waste and pollution. As an integrated part of a sustainable economy strategy, efforts have been made to push their recycling rate even higher. However, this step is only effective and meaningful if and when it will not impact strength and durability. The future structure using recycled ingredients has to endure and survive a full service life with limited repair or replacement. This implies the equally critical role of material advancement and optimization to help enhance durability, improve material efficiency, thereby potentially extending the service life and reducing cost.

Beside strength and durability, D.Invent's future residential or infrastructure introduces climate adaptation to its core design concept. Climate adaptation may mean differently in different situations and may contains multiple intertwined or overlapped aspects. In the most general sense, it reflects the following capacities:

• Transformability: A flexibility to transform or re-align certain components and facilities of, for example a house, when necessary, to better adapt to fast-changing weather conditions and ensure its habitability. Heat insulation, air ventilation, power inputs for air conditioning etc. are all optimized and may be adjusted seasonally. For infrastructure, for example a stretch of a road, this reflects an improved setup to maintain extensive dry, flat, and strong surface conditions with minimized local defect or deterioration to support convenient traffic.
• Versatility: Ability to endure and survive extreme conditions including a large spectrum of disasters, from potential bushfire to flooding. The main load-bearing skeleton will be particularly protected so that it remains safe with sound serviceability.
• Resilience: Fast recovery or repair after a disaster with minimum demolishing or replacement.

At D.Invent, an alternative approach is being applied to provide satisfactory strength, durability, and climate resilience, while ensuring a reduced embodied carbon in the final builds. Instead of prioritizing any single one of them, various key construction materials are strategically combined at an optimum proportion or distribution, from which their structural benefits are fully utilized, and their disadvantages can be compensated.

The approach provides designers with the flexibility needed for creativity and effective structural optimization. It also helps harmonize key challenges the construction material industry is facing, a few of which are listed below:

• There are inevitably environmental sacrifices coming from the production of most construction materials, even though one may have less than the others.
• Some low-carbon materials may be restrained by a complicated, costly manufacturing process.
• In some cases, certain low-carbon materials appear to have less consistent or lower structural performance.

A sustainable future is unlikely to become a reality without a well-informed community, as they are in most cases the ultimate decision makers. D.Invent helps inform the community through its free knowledge base provided in two major forms:

• D.Build's technical resources: D.Build provides general technical information to address common issues in civil design and construction. It helps readers from a non-technical background understand the Could's, Should's, or Should Have's, before seeking professional services.
• D.Consult's questions and answers: D.Consult receives questions and provides answers, as a general reference point, for a topic of concern. This helps the community clarify the What's, Why's and potentially How's, before seeking professional services.