Based on socio-economic assumptions, our Clockwork scenario sees over eight million new homes being built by 2050 to meet a total demand of 34 million. These homes are constructed to a good thermal standard, minimising additional space heat demand. In addition to this, another ten million existing homes undergo whole-house retrofits to improve thermal performance by 20-30%. With occupants expecting increasing levels of comfort in the home, indoor average temperatures continue to rise slowly through to 2050, as they have done historically. Despite the increase in numbers of homes and comfort levels, the higher efficiency of new builds, combined with retrofits means total space heat demand in 2050 is similar to today.
Clockwork also shows that adoption of electric heat pumps begins in the 2020s, although deployment at scale only begins in the 2030s as consumers begin to feel the effects of carbon prices on gas boiler operation. Here, electric heat pumps are typically deployed as part of hybrid solutions, supported by gas boilers playing a supplementary role. By 2050, the scenario shows that heat pumps account for 20% of all building heat capacity but over 50% of annual space heat production across the UK.
From 2030 onwards, the Clockwork scenario shows large district heat networks rolled-out. However, since high take up of rates are essential for the economic case of heat networks, local strategic planning is required to identify areas where heat networks offer customers the best, most cost-effective solution. In those areas where heat networks are not economic, there is a recognition that full electrification would place undue stress on electricity networks. For this reason, existing gas networks in these areas are maintained but energy throughput is much reduced, with gas boilers now playing a supplementary role in support of electric heat pumps, as part of a hybrid solution.
Looking at Patchwork, we see that a growing urban population leads to a significant shift in housing needs. By 2050 there are 34 million homes, predominantly apartments and terraced/semi-detached houses, and out of today’s existing 27 million homes, ten million undergo extensive retrofits. This combination of lower demand, retrofits and a focus on higher density new housing leads to a reduction in energy for space heat by 2050.
Again, electric heat pumps prove popular as consumers face increasing carbon prices and electric storage heaters provide a complementary boost, harnessing electricity when it is more plentiful and cheap, to be released during periods of peak demand. In Patchwork, as electric systems gain consumer trust they begin to grow to provide over 70% of space heat by 2050.
The Patchwork analysis shows that there is strong public engagement and support in urban areas for community-scale district heat networks. With this focus on district heat networks together with the electrification of cooking appliances means that gas networks in those areas are largely decommissioned. Over time, as these local schemes expand, they are gradually connected into larger networks to enhance their resilience against variations in supply and demand. In this scenario, hydrogen conversion fails to materialise without a national programme to drive investment in the necessary production, storage and transportation infrastructure, and natural gas boilers provide less than 50TWh in 2050.
Looking at the challenges for low carbon heat presented in both scenarios, we see Patchwork describe a more affluent society. Here, the assumed lower heat demand may result from poorer households being unable to afford the higher energy bills resulting from less strategic decision making. In Clockwork, utilisation of the gas grid has declined considerably by 2050 and if carbon emissions are to reduce further in line with net zero targets, there may be no room for natural gas distribution much beyond the climate deadline.
Across the whole energy system, both scenarios see a role for hydrogen as an important energy vector. The idea of using hydrogen for heat in buildings has gained traction in the last couple of years. We believe that for hydrogen to make a meaningful contribution to long-term emissions reduction, this would involve a complete transition from natural gas, as opposed to blending a small proportion of hydrogen within existing natural gas networks. This conversion would involve the construction of a new gas transmission network, the conversion of existing gas distribution networks to carry hydrogen and upgrading of household heating and cooking appliances.
The hydrogen required for this would need to be produced by low carbon means, and while the likely production and storage technologies to do this are largely understood, the extent of the requirement would present a hugely significant scaling challenge if this solution is to fulfil anything like the role played by natural gas today.
Our model has been modified to include hydrogen transmission, distribution and domestic end-use technologies and has been used to extensively study hydrogen for heat strategies. The Clockwork scenario has been informed by this work and might be viewed as being based on optimistic but plausible assumptions. However, the degree of coordination required to implement hydrogen for heating at scale by 2050 is inconsistent with a Patchwork scenario.