Urban areas involve essential infrastructure for energy, transport, water, food, shelter, construction, public spaces, and waste management. Transforming cities to achieve net zero sustainability means rethinking both
supply-side issues (power supplies and transportation) and
demand-side issues (reducing use through better urban design and policy.)
Energy To become a zero-carbon city, renewable energy must supersede other
non-renewable energy sources and become the sole source of energy, so a zero-carbon city is a renewable-energy-economy city. Transitioning to a zero carbon city means examining the generation of power sources, such as
renewable electricity and decarbonising electricity production. The transition from fossil-fuel-based cars and trucks to
electric vehicles (EVs) is occurring globally. China has been a major center of technology growth for EVs. Vehicle-fuel technologies that can contribute to reductions in energy use include
hybrid electric,
plug-in electric,
natural gas, and
bioethanol-powered vehicles. The last diesel and gasoline cars are expected to be produced in the 2020s, with 25% or more of all vehicles worldwide being electric by 2040 as
fossil fuel prices rise. By gathering large diverse datasets and modelling the impact of possible interventions, planners hope to identify and target key aspects of energy use, air quality, and traffic for improvement. By incorporating smart measurement technology into buildings, lighting, appliances and transportation, systems can better adapt to changing conditions, reduce energy consumption, and improve city services. Consumers are also switching heating systems from coal,
fuel oil, or natural gas to electricity-driven steam or hot water; and to
air-source or
ground-source heat pumps for both heating and cooling. The movement of food from producers to consumers also tends to involve major fossil-fuel costs, since many crops are grown far from their potential market and have a short shelf life. Many countries depend on international markets to obtain critical food supplies. Food production and
supply chains are being increasingly destabilized by the
effects of climate change on agriculture, the
COVID-19 pandemic, and the
Russian invasion of Ukraine. In the United States, at the same time that millions of Americans experience
food insecurity, as much as 40 percent of
food is wasted. to separate waste streams, and to improve handling of food waste are all important. Farmers and farming communities need scientific, technical, and financial support to move to more climate-friendly farming practices and to support initiatives for
climate change adaptation,
regenerative agriculture and
biosequestration. Collaboration between stakeholders at all levels of the private, public and civil sectors is needed to improve food sector infrastructure.
Construction The
energy efficiency of buildings can be assessed and improved in multiple ways that help to reduce carbon emissions. Insulation and energy-efficient windows are commonly used in colder cities. Incorporation of features such as solar panels, green roofs and walls, and heat pumps into new or existing buildings can significantly reduce energy use. New types of materials such as
smart glass are being developed to improve the energy efficiency of buildings. Energy efficiency is not the only factor to consider. Types of materials used can vary widely in both their up-front and over-time carbon costs. It is important to carefully consider the up-front embodied emissions of existing materials. Researchers are also working to develop construction materials that do not release carbon during manufacturing or that can absorb and store more carbon.
Steel and
cement are heavily used in construction and are very energy intensive to make. Biomass-based materials such as wood and bamboo have lower energy-formation costs. Practices for recycling and reusing construction waste can also save on the amount of energy that has gone into producing and transporting materials. Mid-size multi-unit buildings can support economies of scale during building and are likely to be more economical in use than single-unit homes. High-rise buildings, particularly in hot climates, are more costly to cool and operate. When planning an area, a mix of mid- and high-rise buildings in a compact urban format is likely to be efficient. The inclusion of green space in urban areas can also help with wide variety of other issues, from
stormwater to mental health.
Waste and energy exchange Wastes can be managed through a variety of ways, including reuse, recycling, storage, treatment, energy recovery, and disposal. In some cases, a by-product of one set of processes can be used to advantage by someone else, sometimes referred to as urban industrial symbiosis. The city of
Charlotte, North Carolina has identified becoming a zero waste city as one of four key areas of performance for the goal of developing a
circular economy. Technologies for
carbon capture and storage are being developed to mitigate emissions from fossil fuel power plants and industrial sources. The collection and disposal of waste can potentially be used for the generation of electricity, steam, or heat, but systems to support this are not yet well developed. Reviews of attempts to attain zero-waste note that the term is used widely and not consistently. Many countries lack an overall zero waste strategy. == Measuring net zero ==