According to recent data, a surprising number of households reduced their reliance on gas boilers for domestic heating last year.
To reach net-zero targets in the UK, it will be necessary to replace the gas boilers that currently heat most homes with lower carbon alternatives such as heat pumps. Yet for a surprising number of households last year, gas boilers were already falling out of use.
A government survey, the DZNEZ Public Attitudes TrackerOpens in a new tab, indicates that gas central heating declined as the main method for heating from 78% of households in winter 2021 to just 57% in winter 2022, whilst the primary role of portable heaters grew (from 3 to 11%) as did that of fixed, non-storage room heaters, such as stoves and gas heaters (from 2 to 11%). Some studies also show that domestic demand for gas fell by around 11%Opens in a new tab over last winter. These changes, of course, took place in the context of an acute and salient cost-of-energy crisis, and may (or may not) prove to be relatively short-lived. But they also point to wider implications for the decarbonisation of home heating, not only of the transition away from gas but also for how we think about central heating.
In a CREDS research project which investigated how householders in the UK kept warm in winter 2022/23 as compared to previous winters, results were consistent with a reduction in the use of gas central heating. A non-representative survey of 337 householders aged between 20 and 65 focused on what people did to keep warm during sedentary activities like working or watching TV. It showed that whilst the majority (63%) frequently used central (or storage) heating, a third (32%) could have but did so either only occasionally or not at all. Of this third, most (79%) reported making a reduction in central heating use that winter; this was markedly more than for those who frequently used central heating (37%). Since this focuses on working at home and other sedentary activities only, it is important to note that it is not a complete picture: central heating may be used more regularly outside of these times, for instance, in the morning.
Nevertheless, many (42%) of the group who did not frequently use central (or storage) heating whilst doing something sedentary at home said they felt uncomfortably cold at least sometimes and were not able to make appropriate adjustments. This was less likely amongst those who used central heating frequently (23%). Typical estimates of room temperature were lower for non-frequent users (14-16°C), with some reports of temperatures below 10°C, than for those who used central heating more frequently (17-18°C). Those who heated less were also more likely to report difficulty managing living costs (26%) than more frequent users of central heating (18%).
These findings indicate some of the impacts of last winter’s cost-of-living crisis. Research has long highlighted the health and wellbeing implications of living in fuel poverty, which over the last two years is thought to have affected almost 2 million additional households, rising to an estimated 6.3 million in October 2023 (NEAOpens in a new tab). The sharp fall in central heating use last winter is therefore a cause for concern.
The trend is also relevant to building a better understanding of patterns of heating demand and the challenges of decarbonising domestic heating. In particular, the survey’s findings illustrate how flexibility in demand for central heating can be achieved. Most of the survey respondents (89%) said they made some effort to reduce the energy associated with heating last winter, including most of those who frequently used central heating during sedentary activities. Popular reduction measures were running the heating for fewer hours of the day (70%), turning down thermostat settings (65%), delaying turning the heating on until later in the year (44%) and turning off radiators in rooms that weren’t used (44%).
But it wasn’t just heating use that changed. In fact, more widespread changes were seen for other methods of keeping warm but surprisingly, not for alternative, more local types of heaters. Overall use of portable heaters during sedentary activities was reported to have remained much the same (at 14% last winter) and use of alternative, fixed heaters, like stoves and open fires, (as frequently used by 8%) actually seemed to decline. In contrast, there was a marked growth in ‘personal warmth’ measures, with large numbers reporting greater use of warm clothes (57%), blankets (54%), hot food and drinks (40%) and moving about (40%) to stay warm compared to previous years. Indeed, several of these measures were in more widespread and frequent use during sedentary activities like working or watching TV than central heating (63%). For instance, 92% of respondents frequently wore warm clothing, 77% used hot drinks and food to warm up and 62% used blankets and throws. Moving about (48%), hot water bottles or equivalent (30%) and heated throws, pads and cushions (10%) were somewhat less popular than central heating but were nevertheless still used by many.
By retaining body heat, boosting metabolism or applying heat directly to the body, such personal warmth measures are more energy-efficient and less costly than using space heating alone to stay warm. Yet there is an enduring vision of clothes and blankets as poor alternatives to, or substitutes for, central heating. In the context of fuel poverty, their use is often understood as a ‘coping mechanism’, necessary to cope with the cold discomfort that results from living in an unheated home. When seen as alternatives to central heating, localised and personal warmth techniques might even be considered as somewhat dangerous, in so far as they ‘enable’ unhealthy, under-heated indoor environments in which mould grows or which otherwise damage health, even if the temperature itself feels tolerable for occupants.
Yet their widespread use, as apparent in the survey, calls for an additional understanding of personal warmth measures: that is, as a supplement to central heating and an integral component of ‘healthy’ thermal comfort. In the face of the cost-of-energy crisis, central heating was still frequently used by most respondents to the survey, albeit with lower thermostat settings and shorter heating hours, but in a way that was increasingly supplemented – rather than replaced – by more body-centric warmth techniques. In other words, for the majority, it seems there was a greater pluralism of warmth practices last year that allowed for the flexibility to make desired adjustments to reduce energy use and costs and to do so comfortably.
This recognition of both central heating and body-centric methods as part of a composite of keeping warm is hardly controversial or surprising. Yet within energy research, there has been very little interest in the latter. This may mean that opportunities are being missed to help improve the quality, performance and safety of ‘body-centred’ methods, like clothing and heated throws, both in their own right and as part of a composite mix with space heating. For example, moderate ambient levels of central heating might be effectively supplemented with localised ‘hot spots’ throughout the home and thermally well-designed clothing. In the short term, such prospects are relevant not only for making much needed reductions in carbon emissions, but also, potentially, for helping to keep energy costs affordable in more healthy ways.
In the medium term, the transition to heat pumps also calls for greater insight into how supplemental warmth measures interact with central space heating to enable greater flexibility of demand for the latter. This might, for instance, include more responsive provision of on-demand warmth when people get cold – perhaps through heated clothes or throws, since heat pumps are not as responsive as gas boiler systems. Supplemental warmth methods might also help to enable demand shifting at peak times, something which will become increasingly important as heating is electrified.
Banner photo credit: Kate Stone on Unsplash
