‘London’s Burning (Fossil Fuels)’ — can heat pumps come to the rescue?

Centre for Net Zero
Jun 30 · 6 min read

We’re not talking enough about heating and its impact on the environment. In a survey commissioned by National Grid last year, just 5% of respondents thought that heating their homes was a major contributor to climate change. That’s in sharp contrast to the 89% of those surveyed who cited transport as a key area of environmental concern.

It’s insights like these that encouraged us to host our first webinar yesterday in partnership with Advanced Infrastructure as part of London Climate Action Week. ‘London’s Burning (Fossil Fuels)’ took a data-driven look at how the capital can wean itself off fossil fuels through an increased adoption of heat pumps.


Alex Howard, our Director of Research, kicked things off by explaining that we’re only at the starting gates: London currently has the lowest take up of heat pumps, with less than 500 installations across the capital. Clearly, changing the way we heat nearly four million households is not a small undertaking and the scale of the challenge shouldn’t be underestimated. Yet we have to act now if we’re to hit net zero by 2050. Rather than gazing into the distant future, we wanted to explore the opportunities — and potential challenges — that low carbon technologies offer in the next 10 years.

Our research team decided to investigate four areas: how London heats its homes today, how the need for heating varies across London, the difference that heat pumps could make and what needs to happen to accommodate that change.


At the heart of our approach to research at Centre for Net Zero is a belief in the importance of bringing real-world data to bear in energy modelling. We took anonymised gas smart meter data from across London and looked at how readings varied as a result of home type (e.g. houses and flats) and EPC ratings. We scaled up our analysis from those 1,200 households according to the housing stock in each MSOA (Middle Level Super Output Area, a subdivision of local authorities), arriving at a gas demand for the 3.8 million homes in London. We then considered what might happen in the future and inferred a heat pump profile for a chilly week in February 2021. Those were drawn from a few hundred Octopus Agile users: customers on a dynamic time-of-use tariff. We excluded households with EV chargers.

We then assumed that heat pump adoption will increase in London over the next decade in accordance with the most bullish National Grid and UKPN estimates, taking installations from 500 today to 500,000 in 2031. We also included projected household growth and looked at the level of growth in peak electrical demand.

We focused our analysis on the coldest day of the year so far: 13th February 2021. On this one day of gas consumption, Londoners generated more than 74,000 tonnes of CO2. To put that into perspective, that’s equivalent to two million diesel cars driving the whole way round the M25.

To showcase how gas consumption varies across the city, we showed our audience household consumption by borough on that day — but not before getting them to hazard a guess in our poll as to which borough came out lowest. Whilst Westminster was the most popular answer, it was in fact Tower Hamlets that indexed lowest, with residents consuming 60% less gas than those at the highest end of the spectrum in Bexley. Why might this be? Alex explained that the EPC ratings and housing type in these boroughs vary significantly, with differences in energy efficiency and home insulation driving this divergence.

The results

Christopher Jackson, co-founder of Advanced Infrastructure, took us through the results of this research with some fantastic, eye-catching visualisations of London energy usage. He showed us a video (Figure 1) that depicted the coldest day in 2021 in terms of gas demand and then contrasted this with a video (Figure 2) showing what electricity demand would look like in the same conditions in 2031 (assuming heat pump adoption meets predicted rates).

Figure 1
Figure 2

We witnessed a clear surge in electricity demand, with particular spikes in parts of London where heat pump uptake is likely to be high. These areas, highlighted in red in Figure 3, are expected to contain lots of new build properties installed with heat pumps. Using a crude rule of thumb, if peak electricity demand exceeds 20% of 2021 levels in these areas, we will need to find ways to manage that increase — by reducing it, being smarter about when we use energy or reinforcing the network.

Figure 3

What tools do we have to accommodate this predicted growth in electricity demand? As Alex pointed out, we can manage these challenges if we focus our efforts on improving energy efficiency, smartness, flexibility and infrastructure. But there’s an onus on all actors in this space, including government, network companies, researchers and the general public, to work together and make the right calls for each local area and move us towards a greener future for heating.

A diversity of perspectives

We then brought in our expert panellists, Madeleine Greenhalgh, Policy Lead at Regen, and Alastair Buckley, Academic Director at Sheffield Solar, to answer some pressing follow-up questions from both our team and the audience. We know we need to look at the solutions Alex highlighted, from improvements in energy efficiency to the adoption of smart technologies, but how can we avoid taking a siloed approach? Madeleine stressed the importance of joined-up thinking and called for a team or organisation to look at the challenge in its totality, from a systems architect to an ‘Office for Net Zero’ to bring different government actors together.

We then went to Alastair to find out more about the importance of data accuracy when modelling future energy scenarios. His message was clear: access to real data from people’s homes is key to being able to accurately measure what’s happening today and to use that to project the future. In this case, using recent data from homes that already have heat pumps in place is a significant step forward, as typical profiles get out of date quickly and fail to reflect variation from home to home.

Inertia to change was a concern that our audience voiced: how do we catalyse progress and stop the damage that installing gas boilers today is doing to our net zero goal? As Christopher pointed out, the average lifespan of a gas boiler is between 10 and 25 years. We need to confront today’s legacy behaviours. Alex highlighted the importance of intervention at the right time, from home renovations to gas boiler breakdowns. Can we find ways to install heat pumps at times that are convenient for people?

Our final question from the audience pointed to the real paucity of data on granular heat demand and the need to get beyond averages. What were the panellists doing to feed these insights into BEIS as they prepare the hotly anticipated ‘Heat and Buildings strategy’ — and what are they hoping to see in the plan?

Madeleine wants to see coherence around the funding model for the decarbonisation of homes. How do we make the transition financially viable for those who don’t have the necessary capital? Those on low incomes will hopefully be supported by grants and social housing schemes, but what about the middle-bracket who can’t justify the necessary financial outlay? Alastair supported Madeleine’s earlier calls for an end to siloed thinking and highlighted the overlap between our electricity and buildings strategies. More joined-up thinking is required as we consider the impact of one on the other. Alex closed the discussion by sharing his desire for the publishing of the strategy to prompt a wider public discourse around the decarbonisation of heating. We cannot drag the general public through this without building understanding of and support for the requisite changes.

We believe there is significant opportunity for London to showcase leadership in this area and drive the adoption of heat pumps forward, providing important lessons and insights that can be adopted and adapted by other cities around the world as we all drive towards the decarbonisation of heating.

Want to watch the discussion in full? We’ll be sharing links to the recorded webinar on our social media channels soon — so watch this space.

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Centre for Net Zero

An open research lab that uses data-driven modelling and simulation to provide the critical insights that policy makers need to take bold climate action.