Clifford Chance (CC) has halved its carbon footprint during the past three years, on the back of a rethink of its real estate requirements.

The Legal Sustainability Alliance (LSA), which has been tracking law firm carbon emissions since 2007, earlier this year published its 11th annual report. The report shows that CC emitted 9,953 tonnes of CO2 in 2017, down 49% from 19,429 in 2015, the sharpest fall among its immediate peers.

The firm has made a number of significant changes to its London real estate in recent years, including subletting 400,000 sq ft of office space at its Canary Wharf headquarters to Deutsche Bank in 2015, while the same year the firm also moved 400 back-office staff from the Canary Wharf base to alternative offices nearby.

CC facilities and business resilience manager Sam Clark says: "Our key tactic has been managing our estates really well, because we used to have more buildings and space than we actually needed. By reducing this, we emit less CO2 and less waste, enabling us to work in a more modern and agile way."

Other moves the firm has taken to reduce CO2 emissions have included refitting its office floors with LED lighting, putting in energy-efficient air conditioning and purchasing green-tariff electricity.

Clark says: "The value we associate with it is through our clients – our clients want us to be responsible in the way we treat the environment; they want to be associated with a business that's conscientious of the environment and [its] carbon footprint. In the past, we've just done the easy thing of switching off lights, but now we need to think about changing people's behaviours."

The LSA was founded in 2007 with a founding group of 18 UK firms, which chose to publicly reveal their environmental impact and commit to reducing their carbon footprint. It has since grown to include almost 300 law firms.

While CC signed up to the LSA initiative in 2013, the rest of the magic circle firms have been involved in the movement since day one.

The organisation's first report in 2007 revealed that Allen & Overy (A&O) had the largest carbon footprint of the magic circle, emitting 27,269 tonnes of CO2 – 8.52 tonnes per employee. Linklaters came in second with 20,848 tonnes, and Freshfields Bruckhaus Deringer third with 16,270 tonnes. Slaughter and May emitted 9,211 tonnes of CO2.

Since then, the LSA's 2018 report shows that A&O has reduced its footprint by 40% to 16,411 tonnes of CO2, with Linklaters down 39% to 12,692, and Slaughter and May down 34% to 6,078.

Freshfields did not submit data for the LSA's most recent report, but continues to work with the organisation. In recent years, the firm has looked to use more renewable energy in London and Germany, while it has also overhauled its travel policy in an effort to minimise CO2 emissions.

Linklaters, meanwhile, has adopted the ISO 14001 standard, which specifies requirements for an effective environmental management system in all of its offices. This has included installing automated lighting and heating, switching from LED to T5 lights and installing an onsite electric car charging point.

The firm's head of corporate responsibility Matt Sparkes says: "We continue to focus on the aspects we have control over: that being our building premises and business travel. We also have a carbon offset programme, where we contribute to the improvement of the environment in projects outside of our offices. We are currently investing in a rainforest project in Sierra Leone to protect the region from deforestation.

Other examples of law firms to have significantly reduced their carbon footprint in recent years include Addleshaw Goddard, which has cut its emissions by 40% from 4,344 tonnes in 2015 to 2,619 in 2017, and Kennedys, which has reduced its footprint by 72%, from 5,415 tonnes in 2015 to 1,515 last year.

When moving offices in Leeds and Manchester in 2016 and 2017, Addleshaws prioritised choosing premises that had good EPC ratings. The firm has also reviewed its central power plant, making sure gas and electricity was controlled centrally and only used when needed.

Addleshaw head of premises, client and office services Caroline Cleverly says: "Traditionally at law firms we don't think we are heavy users of gas and electricity, but we all need to do our bit. It's about being socially aware and responsible, thinking about our impact on the environment, and talking about what we can do to reduce that."