🏢 Bio-based construction materials

Almost 60% of the built environment required to accommodate the earth’s urban population by 2050 remains to be built. Materials going into the built environment are currently dominated by non-renewable carbon-intensive minerals, such as concrete, asphalt, bricks, sand and gravel. As urbanisation increases, demand for these materials increases and related negative environmental impact follows. Substituting conventional materials with renewable bio-based materials can successfully cut demand for virgin materials—thereby decreasing the overall environmental impact of the built environment. Bio-based materials have far lower embodied carbon and can even act as carbon sinks, sequestering emissions from the atmosphere. They can replace hazardous materials like asbestos and improve the health and well-being of communities. Examples of these materials include: wood, bamboo, hemp, crop residues, as well as more sustainable forms of concrete (seaweed-crete, timber-crete, etc.). Local governments can promote the adoption of bio-based construction materials, for instance, by drawing up new tender criteria where bio-based products are part of new development projects, or by funding research and then regulating new cutting-edge materials that can substitute conventional construction materials.

👕📱 Packaging and goods made from bio-based materials

As a result of its cheapness, durability, and range of uses, plastics have become ubiquitous with contemporary life. However, these same characteristics are contributing to a global challenge of plastic pollution, in large part driven by an influx of single-use plastic products, most notably used for packaging and bags. Much of this plastic packaging and bags, which can take hundreds of years to decompose, are not disposed of correctly and pollute and degrade ecosystems. Where packaging is absolutely necessary, alternatives can be made from bio-based materials that are sourced from renewable sources that can readily decompose. There are a range of types of biobased materials, from mycelium, starch, and even discarded fruit, which can be used as alternatives to conventional fossil-fuel derived plastics. Local governments can support use of such packaging and goods made from alternative bio-based materials by banning or creating a bio-based plastic content mandate on single-use plastic packaging. Governments can simultaneously support the uptake of alternatives through incentive schemes such as subsidising their production as well as encouraging further research, innovation and development through incubator schemes or eco-design competitions. A good first step in creating the demand for such products is by integrating such criteria within the local public procurement strategy to supply, for example, municipal canteens. It is important to note that, if local governments plan to support the uptake of this packaging type, they must also educate residents about the correct way to dispose of biobased plastics based on their waste management plan. Bioplastics often cannot be disposed of with normal plastics as they would contaminate their recycling. Moreover, if they plan to incentivise this type of packaging they should adapt the waste management practices accordingly (such as having an aerobic digester where compostable plastics can be disposed of with organic waste).

⚡ Harnessing renewable energy from natural processes

Cities consume about 75% of global energy and emit between 50% and 60% of global greenhouse gases (<a href="https://unhabitat.org/topic/energy">UN-Habitat). To reduce the negative impact of their energy consumption, cities need to shift away from fossil fuels and move towards renewable energy sources. Such a shift will help cities work towards their climate change mitigation and adaptation action plans. Renewable energy technologies such as wind, water, solar, and geothermal can also help improve access to energy in vulnerable and marginalised neighbourhoods through, for example, decentralised, off-grid solutions. Renewable energy technologies can harvest the energy in nature’s processes, such as wind, and solar radiation and geothermal heat, that can be replenished within a human lifespan. In contrast, fossil fuels are materials that are not replenished within a human lifespan and are combusted for energy, losing the fuel material and resulting in emissions. Local governments can develop sustainable energy plans, considering different energy resources and requirements, to develop a robust strategy for the development of renewable energy technologies and infrastructure throughout the city. They can also institute specific legislation and tax systems to regulate energy production and consumption, incentivise research and development of cleaner, more efficient technologies. Via Power Purchase Agreements cities can buy renewable energy from green energy providers and fix the price in order to provide security to financial institutions to finance renewable energy infrastructure. Furthermore, increasing awareness and facilitating capacity-building on planning urban sustainable energy projects can help the uptake of clean energy across the city by different stakeholders—from citizens to businesses and institutions. Facilitating collaboration, then, will be crucial, since private companies operate most of the world’s energy systems.

🚌 Low-carbon energy input for mobility

The mobility system is a major consumer of fossil fuels. All modes of transportation that consume fossil fuels contribute to global greenhouse gas emissions, as well as air and water pollution. Despite growing recognition of electric mobility, global oil demand for transportation (personal and freight vehicles, aircraft, rail and also marine) over the next two decades are expected to exceed demand for the previous two, largely because of projected transportation sector growth in the global south (<a href="https://www.aps.org/policy/reports/popa-reports/energy/transportation.cfm">APS). A shift towards sustainable energy sources for transportation is needed to counteract the escalating climate crisis and its threat to our planet's ecosystem and society. Increased electrification and use of low-carbon fuels must be a priority over the next decade to decrease the negative impact of the mobility system. Electrification must be coupled with a decarbonisation electricity system, moving away from power generation from fossil fuels, in order to gain the potential carbon emission reduction benefits. Low-carbon fuels (LCF) such as biodiesel, bioethanol, green hydrogen and renewable compressed natural gas (R-CNG), for instance, can also help to lower carbon emissions from transportation. Local governments can stimulate the use of low-carbon energy throughout the urban mobility system by improving the availability of electric charging infrastructure to help ensure that it can be financially attractive compared to that of fossil fuels. Additionally, cities can transition their own mobility fleet towards electric vehicles or to be powered with low-carbon fuels. The production of such low-carbon fuels can be produced by residual materials that are collected and managed by the municipality (such as developed biofuel from food loss and waste, which can power buses or waste collection vehicles).

💧 Rainwater harvesting

Harvesting and utilising the rainwater harvesting that falls across a city can reduce the pressure on water local reserves and catchments, while at the same time enabling stormwater runoff and providing water for human use. This practice is not new, it has long been used in many parts of the world. Cities can introduce various water saving infrastructure solutions that harvest rainwater, from roofs, paved and unpaved areas, parks, and other buildings—either to use it or to replenish local aquifers. Reworking city-wide master plans that promote policy alignment is vital, as well as the involvement and cooperation of the communities vital for implementation. Cities can also incentivise their citizens to capture and reuse rainwater through subsidy schemes. This in turn can reduce costs for the city in maintaining the local water system.