Opinion: Energy efficiency key to unlocking huge emissions reductions in cities

Seattle. Photo credit: C40 Cities.

By Frances Downy

The C40 Cities Climate Leadership Group, now in its 10th year, connects more than 80 of the world’s greatest cities, representing more than 600 million people and one-quarter of the global economy.

Created and led by cities, C40 is focused on tackling climate change and driving urban action that reduces greenhouse gas (GHG) emissions and climate risks, while increasing the health, wellbeing and economic opportunities of urban citizens.

Building energy consumption is a major source of GHG emissions, constituting nearly 50% of emissions in C40 cities on average, and rising to over 75% in cities such as New York and London.

This is why half of C40’s member cities have identified energy efficiency in existing buildings as one of their top priorities and are working through the two building focused networks to tackle the problem.

Since the global COP15 climate talks, C40 cities have taken 10,000 actions to mitigate and adapt to the effects of climate change – and over 20% of these specifically addressed energy consumption and emissions reduction in the building sector, with energy efficiency and retrofit actions the most common.

The number of building performance rating and reporting related actions has also seen a dramatic increase, with the number of C40 cities introducing commercial building benchmarking rising to 30 in 2015, compared to just 12 in 2011.

However, tackling residential properties, which account for 20-25% of global GHG emissions, remains a challenge for cities who tend to have fewer powers over the private residential sector and assets, compared to the level of control they have over municipal buildings which they own or manage. Further challenges can arise through a lack of or limited performance data to inform strategies.

Untapped opportunity

There are less awareness and technical expertise of residential building owners – meaning opportunities for improvements can be missed. Echoing the problems faced in the commercial building sector, the split incentive between owners and tenants in the rental market means landlords are less willing to invest in improvements they don’t benefit from and tenants don’t want to invest in a place they don’t own.

Multifamily buildings, also known as condominiums or apartment blocks can have several different models of ownership, governance and administration structures, making agreements to improve the building difficult. Together these factors mean that many of the opportunities present in the residential sector remain untapped.

Nevertheless, C40 cities are increasingly turning their attention to this sector in a number of ways.

While most cities have minimum energy performance standards in place for new residential developments and renovations that are set at the national or regional level, some cities are choosing to go beyond this. For example, the city of Houston has implemented a Residential Energy Conservation Code that is 15% above what is mandated by state law.

To raise awareness, some cities are carrying out home energy assessments or audits; Seattle’s City Light and Community Power Works, a comprehensive energy upgrade program provides subsidised home energy audits resulting in an Energy Performance Score to enable owners to understand how their home performs relative to a benchmark.

Many cities such as Melbourne, Seattle and London provide free or subsidised energy efficiency advice and technical assistance to homeowners on how to improve their homes. And Chicago piloted an innovative approach to demand management with real-time electricity pricing to encourage consumers to save energy and money, which has now successfully expanded to customers in Illinois.


Cities are also exploring how to finance improvements and since 2013, 33 cities have established revolving funds for low carbon, energy efficiency or green projects. Funds such as the ones in Toronto, Melbourne and Amsterdam provide low-interest loans to homeowners for building energy upgrades.

Cities commonly need to act in partnership with other actors such as the private sector and other cities, state or national actors to leverage their respective powers, and those that do are the ones that deliver the most action.

For example, the city of Sydney was able to provide 30 apartment building owners with free energy audits up to AU$10,000 each, made possible through joint financing with the New South Wales office of Environment and Heritage. And when expanding Retrofit Accelerator, which provides technical assistance for energy and water efficiency upgrades, Sydney worked closely with the Housing Preservation and Development department and Housing Development Corporation to support affordable multifamily buildings.

Collaborative action is required at all levels if we are to limit global temperature rise to well below 2 degrees, as agreed in Paris at COP21.

The role of cities is critical as global urban policy decisions made in the next five years could determine up to a third of the remaining global carbon budget that is not already “locked-in” by past decisions. C40 cities are already taking action and over 30 cities have pledged to exceed the ambition set by the universal climate agreement made at COP21.

These case studies show what can be done at the city level to save energy and help reduce global emissions.

New York City

Building energy use accounts for nearly three-quarters of New York City’s GHG emissions – and residential buildings represent one-third of this value.

Mayor de Blasio committed New York City to achieving citywide GHG emissions reductions of 80% from 2005 levels by 2050, starting with One City: Built to Last – an ambitious plan to retrofit the city’s public and private buildings. Part of One City, the NYC Retrofit Accelerator provides free retrofitting technical assistance and advice to all private building owners.

The program builds on the datasets gathered through the city’s Local Law 84 and 87 (benchmarking, audit and retro-commissioning requirements for all buildings over 50,000 square feet) to identify and prioritise the highest improvement opportunities.

Working with the New York City Department of Housing Preservation and Development (HPD) and the New York City Housing Development Corporation (HDC), the city has extended the Accelerator to all of the affordable multifamily buildings in their portfolios, including smaller buildings.

The city also recently launched a major expansion of the NYC Carbon Challenge to include over 700 multifamily residential buildings that committed to a 30% reduction in building emissions by 2025. The city’s One City: Built to Last received the C40 Cities Building Energy Efficiency Award in Paris at COP21.


Improving the energy efficiency of buildings is a high priority for the City of Seoul as this sector accounts for 56% of the city’s total energy consumption. The Building Retrofit Project was launched in 2008 to deliver significant improvements in the city’s building stock by providing ultra-low interest loans and promoting Energy Service Company projects to enable building owners to benefit from energy improvements at no up-front costs.

By 2014, 72,000 buildings had been retrofitted, with almost 70,000 of these in the residential sector. The city is aiming to retrofit 90,000 buildings by 2018 while also targeting public engagement and participation from its 10 million citizens in energy saving and generation, as expressed in its Seoul Sustainable Energy Action Plan (2014).

These efforts are part of the city’s commitment to reduce its CO2 emissions by 25% by 2020 and by 40% by 2030 from 2005 levels.


More than 73% of Sydney’s residents live in apartments, with these residential buildings accounting for 10% of the city’s GHG emissions, 38% of its water use and 14% of its waste output.

The city launched the Smart Green Apartments Programme in 2011 to help apartment owners and managers reduce their environmental impact (energy, water and waste) and utility costs. Through this program 30, apartment buildings benefited from subsidised water, energy and waste assessments from professional auditors, including advice on potential improvements.

On average, energy savings of up to 30% were identified across participating buildings. This program has also enabled the city to establish a database of energy consumption data, improvement opportunities and progress made in the 30 apartment buildings, generating important lessons that are currently being shared through a network of over 100 apartment buildings, using targeted communications and workshops.

Knowledge outcomes from the program were also used to shape the Residential Apartments Sustainability Plan. If fully implemented, the actions outlined within this draft plan will reduce GHG emissions in new and existing apartment buildings by 40% by 2021.

In parallel to the Smart Green Apartments program, the city has also contributed to the creation of Smart Blocks, a national program providing guidelines on how to navigate energy efficiency upgrades of common areas in apartment buildings.

Frances Downy is Network Manager at Private Building Efficiency, C40 Cities Climate Leadership Group.

First Published by The Climate Group.


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