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How cities are decarbonising

A mobile garden in Chicago, USA.
A mobile garden in Chicago, USA. Photo: Art on Track

EUROPE: Cities around the world are taking action, even in the US where 30 cities now have stringent energy measures in their building codes. Now we know that an investment of $1.83 trillion a year in 16 low-carbon measures in cities – about 2 per cent of global GDP –  could reduce global urban emissions by 90 per cent by 2050.


The figures come from a report by the Coalition for Urban Transitions entitled Climate Emergency, Urban Opportunity: How national governments can secure economic prosperity and avert climate catastrophe by transforming cities which was released ahead of the Climate Action Summit in New York.

“In absolute terms, these savings are greater than the combined 2014 energy-related emissions of the two largest emitters, China and the US,” it says, and it presents a clear six-part action plan for national governments around the world.

Zero carbon cities offer a powerful lever to secure economic prosperity and boost living standards across a country. Such cities can both drive economic prosperity and effectively play their part in addressing the global climate emergency.

The 16 measures lie in the building, transport, materials, and waste sectors, with transport being the easiest and most cost-effective to decarbonise. Here we look at four of them available to city authorities.

1. Decarbonise transport

Decarbonising transport involves providing more opportunities for walking and cycling plus converting existing or making new transport use hydrogen and electricity.

It also involves joining up transport modes to make it cheaper and easier to use and planning cities around zero carbon transport.

Benefits that deliver savings include improved health, air quality and productivity as time lost in traffic jams is reduced.

This is much the same conclusion as was found by a different American survey on energy efficiency measures in the transportation, building and industrial sectors.

It finds that energy efficiency alone can reduce greenhouse gas emissions in the United States by 50 per cent. The report Energy Efficiency Can Slash Emissions and Get US Halfway to Climate Goals from the American Council for an Energy-Efficient Economy (ACEEE) says the changes are “ambitious,” but can be done, and highlights electrifying the transportation sector as the most cost-effective way of doing so.

This would deliver 46 per cent of the emissions reductions outlined and result in 32 per cent of the planned energy savings.

The building sector would also deliver 33 per cent of the emission cuts.

2. Improve the building codes

Building code changes are key to the transition to low and zero carbon cities, as they set benchmarks for performance as a condition of obtaining planning permission for a building design.

Stricter building energy codes are already being adopted, for example by American cities, to tackle climate change.

In the last year 30 US cities have taken further steps to reduce wasted energy in buildings by improving their codes, according to the 2019 City Clean Energy Scorecard.

The cities of Boston and Worcester now have the most stringent residential building energy codes in the US, because they adopted the Massachusetts Stretch Energy Code.

This code puts the emphasis on energy performance, as opposed to design targets.

It results in more cost-effective energy efficient construction than buildings built to the “base” energy code.

In Europe, a coalition of eight cities – including Madrid, Wroclaw, and Leeds – have pledged to completely decarbonise their existing building stocks by 2050. But they too recognise that they need national building regulations to support them.

Their routemap involves implementing a renovation and retrofitting framework for the built environment that will improve residents’ wellbeing and the local economies as well as dramatically reduce carbon emissions.

These cities will be required to lobby for national policymakers to set equally ambitious net-zero legislation for buildings as a precondition to success, and they will use local-level data to make their case.

In the UK, the government has just started a consultation on changes to building regulations using a Future Homes Standard that will require new build homes to be future-proofed with low carbon heating and high levels of energy efficiency.

Recognising that there is an issue with performance no matter what the regulations call for, it will aim to improve compliance in order to improve as-built performance. However, it won’t will be introduced until 2025.

The UK government is also planning to consult on uplifting standards for the refurbishment of existing dwellings, “where there are cost-effective, safe and practical opportunities to do so”.

One of the areas it says it will look that is airtightness, with new guidance on ventilation, that is often a problem in the design of highly energy efficient homes.

3. Provide 100 per cent renewable energy

Many cities around the world have adopted or are adopting targets to provide all electricity – and sometimes even all energy – completely from renewable sources.

London for example is forging ahead independently of the national UK government by establishing a new green energy provider for the capital, which will draw on electricity generated from 100 per cent renewable sources.

Called London Power and operated by Octopus Energy, it will launch in December, and any profits made will be reinvested into community projects to help tackle fuel poverty and make London a zero-carbon city.

4. Implement district heating systems

Heating is much harder to decarbonise than electricity. This is where district heating systems represent a possibility for urban areas keen to introduce efficiencies and renewable energy.

District heating systems involve networks of underground pipes that distribute hot or cold water to multiple buildings in a district, neighbourhood or city.

Their great advantage is that they can use any locally available energy source, including renewable and low-carbon energy sources that are not available on the building level, such as waste heat from industry and commercial buildings.

The District Energy in Cities Initiative, supported by UN Environment, has conducted many pilot studies and is supporting cities to implement new schemes and upgrade existing ones.

Every city will have its own barriers to implementing such systems, but they often begin with a lack of awareness about benefits and savings – something this initiative is addressing.

Other obstacles include high upfront costs and the scalability of projects due to a lack of integrated infrastructure and land-use planning.

Chile provides an excellent example of success. In 2019, the Chilean District Energy Municipality Network was launched to coordinate the actions of 13 cities, that are receiving technical support for pilot projects.

Potential for district heating in seven cities and for district cooling in three of these cities has been identified and city-wide district energy master plans are being drawn up for three of them.

The Chilean Ministry of Energy has also set up a national district energy delivery unit to support cities.

District heating systems were often set up in cities belonging to the former Soviet bloc because city master planning was ubiquitous.

Many of these are now being upgraded to make them more efficient and use renewable energy. One, in Belgrade, Serbia, has one of the largest district heating systems in Europe, supplying heat to about half the city’s population.

It is now switching heat sources from imported gas to renewables and waste heat.

David Thorpe is the author of the books The One Planet Life and the new One Planet Cities.

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