To meet the net zero challenge, growing industry expertise needs to be translated into tangible steps to support a wider understanding around prioritising investment to decarbonise existing and new stock. Jordan Marshall explores ways real estate owners can pick up the pace

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“According to estimates, it will take Europe 400 years to decarbonise all its existing building stock,” explains Helena Rivers, dnet zero lead for Buildings + Places Europe at Aecom.

That startling statistic is mirrored in the UK. The UK Green Building Council estimates that the country’s 29 million homes must be retrofitted at a rate of 1.8 every minute to achieve net zero by 2050.

“We need to meet this challenge by picking up pace,” says Rivers. “Initiatives such as the Public Sector Decarbonisation Scheme are leading by example, accelerating improvements in building fabric and moving away from gas to electric heat sources – but that is just a tiny element of our building portfolio.”

“As for new-build, the healthcare sector is an exemplar of best practice,” says Dave Cheshire, a director in Aecom’s sustainability team and specialist in new buildings and major refurbishments.


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The UK capital has adopted whole lifecycle carbon assessments in its latest London Plan

He adds: “We are also seeing policy shifting in the right direction, which should accelerate the rate of change,” referring to the London Plan’s whole lifecycle carbon assessments for referrable projects, and the proposed stringent LETI and RIBA targets.

Considering these examples, how can experts support other private and public building owners to decarbonise existing and new stock at the pace required?

“The language around net zero can be jargon-heavy and we know that those responsible for buildings can feel that the whole topic of sustainability is impenetrable, so they find it hard to know where to start,” says Cheshire. “The statistics show that there are a lot of people in this situation – and that’s understandable, as there are no straightforward answers to the net zero challenge.”

Rivers agrees, saying: “As net zero specialists in the built environment, it’s our job to translate our expertise into tangible steps to support our clients through the journey so that they understand where best to prioritise investment to decarbonise existing and new stock at the pace required.” 

Take a portfolio approach

“Generally speaking, the organisations who are making the most progress with decarbonising their existing building stock are those that take a portfolio-wide approach,” says Rivers, citing the positive impacts of initiatives such as the  Net-Zero Asset Owner Alliance, which requires members to reduce the overall emissions of their portfolios across all asset classes, from listed equities to real estate.

As asset owners recognise the benefits of adopting a more structured approach to estate decarbonisation, methodologies that provide strategic energy portfolio planning, design and delivery are in greater demand. Rivers shares two relevant examples from Aecom’s suite of decarbonisation tools.

For campus-level strategies, Aecom’s interactive Rosetta methodology is used to create dynamic decarbonisation roadmaps where constraints can be changed and analysed to realise the impact on operational and capital expenditure, phasing, resilience and operational carbon. For estates that are geographically distributed, Aecom’s OCEAN tool provides internal and external benchmarking and also integrates with Carbon Risk Real Estate Monitor (CRREM) in a secure environment.

“Both are being used by our clients to achieve their carbon and energy goals while maintaining building operations and staying in control of costs,” she says.

Three steps for buildings owners to accelerate the journey to net zero
1 / Set operational and embodied carbon targets in the brief no matter what the project, whether it is new-build, refurbishment, retrofit, or replacement of kit
2 / Proactively invest in your building management to ensure efficient operation from soft landings to long-term energy management. This should include strategies for lifecycle projects to shift to lower carbon solutions rather than like-for-like replacement
3 / Seek collaboration on whole building carbon performance between landlord and tenant; embrace green leases and sharing of energy data. Collaboration is a critical element in achieving net zero

Think beyond completion into operation

Cheshire and Rivers agree that developers, operators and occupiers need to think holistically about how commercial buildings are designed and operated.

“Think about how you’re going to use your building against how that building was originally designed,” advises Cheshire. “If you are in a large building but only have four employees who need to use it 24/7, then update the control strategy accordingly so that you are not heating, ventilating or cooling the entire building unnecessarily.”

He adds: “The famous landlord/tenant divide is interesting from a carbon perspective as the landlord loses control over the energy demands of the building once the tenants move in.”

Some farsighted developers are crossing that divide and taking a new approach, particularly at the end of a lease when landlords take responsibility for the equipment in the tenant’s demise and work closely with the tenant’s fit‑out team to ensure that the design fits with existing net zero targets,” he says.


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Real estate owners need to start carbon budgeting right away or risk incurring greater capital outlay later

Don’t delay carbon budgeting

Another tangible step is carbon budgeting. To meet the Paris Agreement target of limiting global temperature increase to 1.5ºC, every building in the world must operate at net zero carbon by 2050. Real estate owners need to start carbon budgeting right away, says Rivers.

“These decarbonisation commitments are really challenging, so carbon budgeting is not something that can be put off,” she says. “Organisations that start to carbon budget now will give themselves a clear pathway to achieving their net zero commitments.”

There are financial implications of delayed action too. “If organisations delay spending money on decarbonising their existing real estate until closer to their target dates, they risk a higher one-time capital spend later down the line,” Rivers continues. There’s also the carbon cost to consider too as inaction will result in unnecessary emissions in the interim.

“To pick up the pace of change, our emphasis must be on action and implementation,” she says.

Dave Cheshire

Dave Cheshire

Dave Cheshire is a director in the sustainability team at Aecom and provides advice on sustainable, circular and net zero buildings. He is the author of Building Revolutions and The Handbook to Building a Circular Economy, RIBA books that explain how to apply the circular economy to the built environment.

Helena Profile 2022

Source: Paul Grace

Helena Rivers

Helena Rivers is net zero lead for Buildings + Places Europe at Aecom, supporting both public and private sector clients on their journey to net zero, focused on their existing real estate assets. She is also vice president of the Institution of Mechanical of Engineers. In 2019 Helena was named as one of the most influential women in engineering by the Financial Times and in 2022 won the WICE award for digital innovation.