Net zero.
It’s a phrase many of us hear time and time again.
Whether it’s in government reports, corporate sustainability commitments, and all-over mainstream media… there seems to be a “net zero” waiting at every turn.
It’s fascinating how this concept, since emerging in the late 2000s, has become so embued with emotion, politicised and even weaponised, with sceptics refuting ‘proven’ science.
But how often do we stop to reflect on what “net zero” (“Net Zero”?) actually is?
In this article, I’ll dive into where it comes from, how it’s interpreted and why it matters.
So, what does net zero mean? And according to whom?
Importantly net zero is not a defined plan, but an ambition to reach
Amy McEwen Policy and Public Affairs Graduate for Mitsubishi Electric
According to a physicist…
Back in the 2000s, Myles Allen, dubbed ‘the physicist behind net zero’ by the BBC, published several papers quantifying the extent to which human activity was responsible for climate change.
Allen suggested that we shouldn’t be measuring global warming by looking at the composition of greenhouse gases in the atmosphere, but rather the tonnes of carbon dioxide we’re pumping into it.
He rejected the focus on the individual to reduce their ‘carbon footprint’ (a narrative pushed by BP in their marketing campaign in the mid-2000s) and instead, turned to industries to help solve the issue by reducing carbon emissions to net zero.
Allen poses that, in theory, ‘Britain could stop using CO2 entirely’ and instead rely on renewable resources to reach net zero.
However, this would mean taking action like stopping flying and international shipping – huge asks for the UK as a developed country, and unimaginable ones for developing countries.
A less extreme route to net zero, he suggests, would involve carbon capture and storage (removing CO2 from exhaust gases and storing it safely underground). Allen is such an advocate of this concept that this has become his definition for net zero: “100% carbon capture and storage by 2050” (the mid-century referring to UK government’s legally-binding target).
According to the IPCC…
In Myles Allen’s definition of net zero, he specifically refers to carbon emissions.
However, the Intergovernmental Panel on Climate Change (IPCC), the UN’s body for assessing climate change science – which Allen made some significant contributions to – makes a distinction between ‘Net zero CO2 emissions’ and ‘Net zero emissions’, although the principle is the same:
Net zero CO2 emissions – Net zero carbon dioxide (CO2) emissions are achieved when anthropogenic CO2 emissions are balanced globally by anthropogenic CO2 removals over a specified period.
Net zero emissions – Net zero emissions are achieved when anthropogenic emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals over a specified period.
The IPCC’s focus on ‘anthropogenic emissions’ (meaning emissions caused by human activity) has been crucial to the world of climate science, forming the basis for its Assessment Reports (ARs) on climate change.
These reports highlight the damage of human-caused emissions on the planet, the risks of continuing to produce them and the need to phase out fossil fuels to achieve net zero emissions.
According to the UK government…
The latter of the IPCC’s definitions aligns with that of the UK Government, which under Theresa May’s Conservative government in 2019 set a target requiring the UK to bring 100% of greenhouse gas emissions to net zero by 2050, compared with 1990 levels.
This of course, like all government decisions, has not escaped criticism. Anti-net-zero rhetoric in the UK has only grown since this target was set, and saw particularly aggressive reproval in 2025 with the Conservative party and Reform UK both pledging to scrap the target (the latter’s leader Nigel Farage famously describing net zero as ‘net stupid’).
This sentiment comes from what Allen sees as an unhelpful conflation of the state of the economy and a piece of science – some even refute clear scientific evidence to push their own agenda; many of our energy and production systems are set up to run on cheap fossil fuels, leading to the belief that aiming for net zero will involve more expensive, renewable systems.
One of the latest reports to argue this is ‘The Cost of Net Zero’ published by the Institute of Economic Affiars (IEA), which criticises the Climate Change Committee (CCC) for relying on ‘some heroic estimates of the cost of renewables and other low-carbon technologies’, yet fails to acknowledge the costs of continuing reliance on fossil fuels (not to mention their global volatility, as we saw with the energy price crisis of 2022).
According to Mitsubishi Electric…
At Mitsubishi Electric, we understand that ‘net zero’ can be easily swept up in a sea of sustainability jargon (you can even find it in our A-Z Sustainability Jargon Buster!).
Advocating for the target, though, should be seen as just one piece of a much broader picture on sustainability, giving a long term ‘line in the sand’ that companies, countries and communities can work to achieve.
Our Guide to the Sustainable Buildings Landscape illustrates how government policy and legislation is driving the UK’s built environment towards net zero.
It lays out four paths the built environment must go down to reduce emissions: improving energy efficiency, decarbonising heating, mitigating climate change and reducing carbon in order to create ‘net zero buildings’.
While net zero gives us a clear, legislative ambition to drive towards, these pathways promote sustainability in the here and now – we must focus on ways for our buildings to achieve increased efficiency and reduced emissions, from design to operation.
That’s why we were quick to embrace the UK Net Zero Carbon Buildings Standard (UKNZCBS) a major, cross-industry initiative, supported by bodies such as CIBSE, RICS, LETI, RIBA amongst others. The Standard aims to provide the first unified politically neutral, technical framework for defining and achieving Net Zero Carbon Aligned buildings. While the concept of ‘net zero’ does not innately provide us with solutions, The Standard is an excellent example of a structured initiative we can use to work towards the 2050 ambition.
That, importantly, is what net zero is: not a defined plan, but an ambition to reach. This article is first of a two-part dive that I plan to take into net zero, and I’ll explore this idea more in the next article.
Amy McEwen is a Policy and Public Affairs Graduate for Mitsubishi Electric
