The UK has no chance of meeting its 2050 target for CO2 emissions without a fundamental change to the way homes are heated.
Even with the most modern gas boilers and state-of-the art insulation, the nation cannot continue to heat so many homes by natural gas and still achieve an 80 per cent cut in emissions.
The Academy's report, ‘Heat: degrees of comfort’, looks at the challenges of matching demand for domestic heating with the legally binding requirement to reduce overall carbon emissions. The report looks at new technologies including heat pumps, considers options such as district heating and combined heat and power schemes and looks at incentives and drivers for the creation of new markets.
It also questions the assumption that space heating and provision of domestic hot water are interlinked, saying “a dispassionate analysis of the needs for DHW may show it is better provided by instant water heaters, possibly adjacent to the point of use, rather than as an adjunct to a central heating system.”
Many sources of renewable energy are, by their nature, difficult or impossible to schedule. They are available only when the wind blows or when the sun shines. To switch a large part of the domestic heating load to electric heating would greatly increase the demand on the grid and increase the challenge of meeting peaks in demand. To attempt to meet the whole of such a load by renewables based on wind, tides or sun would require a level of installed capacity that would be almost impossible to build and that would be standing idle for most of the summer months, thus making energy very expensive.
Storage, whether of natural gas, biomass, large scale thermal storage, or an intermediate vector such as hydrogen, electricity or heat, will be essential.
“Managing the UK's energy systems in a way that reduces CO2, avoids expensive imports, ensures energy security, does not exacerbate fuel poverty, supports job creation and works with, rather than against, the competitive market will be hugely difficult,” said Professor Roger Kemp FREng of Lancaster University, who chairs the Academy's Heat working group.
Most of the houses that will exist in 2050 have already been built. New houses should be built to the highest standard of energy efficiency but that, by itself, will not be enough. To meet the 2050 targets, says the report, major improvements will have to be made to the existing housing stock. This will be disruptive to householders and expensive. There are various options for funding this but it will undoubtedly add to householders' bills (only partially mitigated by lower energy costs).
The provision of heat cannot be analysed in isolation. Wider energy policy will determine the mix of electrical generation technology and this in turn will influence strategies for building insulation. Highly variable generators (such as wind) lead to large variability in prices that encourages heat storage; whereas highly dispatchable generators will lead to a strategy of heating on demand. These two strategies influence whether a house should be insulated on the outside to enhance its thermal mass or on the inside so it warms rapidly. These decisions can best be decided in the context of a national energy policy that provides a coherent framework for decision-making. At present, this framework does not exist, the report says.
In their conclusions, the authors point out that consideration of the heat supply and demand in the UK economy at a systems level brought in unavoidable interdependencies with other aspects of the energy market, consumer behaviour and national skills provision. “There is clearly no single solution for the provision of heat in the UK economy,” they say. “The choices of which technologies should be supported and which will ultimately be commercially successful in the market place will depend, largely, on how rigorously the 80 per cent emission reduction targets are pursued. Looking at the domestic heat sector alone, there could a case of ‘the best being the enemy of the good’.”
Read the Academy's report 'Heat: degrees of comfort'