Can household heating be more flex-friendly and keep occupants cosy?

30 May, 2022

Sarah Higginson

Kay Jenkinson

Peter Mallaburn

David Shipworth

Jacopo Torriti

Ben Anderson

Philipp Grunewald

Reading time: 7 minutes

In a recent workshop with BEIS, CREDS researchers explored how households flex their heating demand.

The British Energy Security Strategy (2022) has called for the creation of ‘hyper-flexibility’ in electricity networks within this decade to match supply and demand.

The IEA’s Net Zero 2050 (2021) report requires demand side flexibility to increase seven times globally by 2050 (page 177, Fig 4.18, pdfOpens in a new tab). As the National Grid ESO recently concluded, flexibility is critical in a decarbonised energy system to manage intermittent renewables and to minimise the investment needed in new energy infrastructure.

Matching available supply using flexibility requires shifts in the timing of the energy inputs required to meet people’s needs for comfort (heat/cool) and other energy services. With UK households projected to more than double their electricity use through uptake of electric vehicles (EVs) and heat-pumps, the UK Smart Systems and Flexibility PlanOpens in a new tab (2021) sees an opportunity to use both to offer substantial managed flexibility to the grid. For heat pumps this would be by managing the timing of heating, especially in energy efficient buildings.

Measuring how households flex their heating demand was the focus of a recent workshop held by BEIS and CREDS. Businesses are already able to participate in an energy flexibility market, and CREDS has been researching the opportunities for households to both actively flex their energy use and take part in services where the flex is automated. With flexible electricity tariffs, people are paid for shifting their energy use energy away from times of heaviest demand and/or get cheaper prices at periods of low demand. However, there is increasing evidence that many energy uses (practices), especially those done in the early mornings and evenings, are difficult to shift because they are part of the interlinked flow of everyday life. It is hoped there may be greater scope to shift some energy demand for heat.

Flexing heating means adjusting when energy for heat is used, sometimes by preheating ahead of a critical time of day – such as in anticipation of cold winter mornings/evenings – or by switching off for short periods when demand is greatest. The extent of this flexibility depends on a complex interaction of technologies, buildings and people.

When heating is suspended, the temperature in a building starts to drop. The better insulated and the more air-tight it is, the more slowly temperatures fall. Temperature, however, is only one element of comfort and it’s ultimately how occupants’ comfort changes that matters. For example, if someone is happy to put on a jumper the temperature can fall further before they feel uncomfortable. People experience the same temperature differently: old and young, males and females, the sick and the well, the active and the sedate can feel the same level of comfort at different temperatures. Similarly, preheating can cause discomfort (especially when occupants are sleeping), unwelcome noise and a sense of lost control.

This creates great variation in households’ capacity to flex their heating. How long the heating can remain switched off and, therefore, when the heat input can shift, depends both on the house and the household occupants.

Behaviour is also important

This workshop mainly considered the thermal properties of the house – but acknowledged that the behaviour of the household was also important to understand. Only when we understand that the ‘comfort system’ integrates both aspects can we really estimate which homes (or groups of homes) can offer flexibility services. Understanding how quickly buildings lose heat, and how we can measure that without large scale intrusive and expensive monitoring, was explored in detail in the workshop. If we can estimate this using smart meter or similar data, we could provide current and future households with a measure, or metric, of how rapidly the house loses heat. Such a measure could estimate domestic flexibility capacity in the energy system. This could drive policy and regulatory reform, and it could stimulate the development of new commercial flexibility services.

During the workshop, CREDS researchers discussed proposed “in-use metrics” derived from real time monitoring of energy use by smart meters to support this idea. A good starting point is to measure how quickly a house cools as heating is switched off under ‘standard’ conditions. Mapping house cooling rates under standard conditions could help to assess the suitability of properties for the installation of heat pumps, or to define the need for government support for installations in areas of fuel poverty.

However, householders aren’t the only ones who might benefit from the flexibility enabled by in-use metrics. Reducing the electricity used by heat pumps (and EVs) at certain times of day will help manage the strain on the electricity system and minimise the need for new grid investment. In this sense a zero-emissions energy system needs to ‘extract flexibility’ from its users whether there is a benefit to them or not.

This flexibility extraction also underpins new supply-side business models which are evolving to take advantage of household demand flexibility. Variable price tariffs are one example but others include more sophisticated approaches where businesses make a margin by ‘selling’ aggregated residential flexibility to the network operators. In this case the managed flexibility may be invisible to the householders and the business makes a margin in the middle. Other companies are developing “heating-as-a-service” offerings, based on an agreed level of thermal comfort rather than selling kWh.

What are the barriers?

The workshop also considered the significant barriers to the implementation of residential flexibility that remain, and how we might tackle some of them.

  • New technologies mean that people would have to become familiar with a suite of heating technologies and concepts that are unlike their old fossil-fuelled systems. This will require them to develop new ‘mental models’ of how to use them (efficiently).
  • Many, perhaps most, consumers are not engaged with their energy use and have no wish to be. Presuming that they will act as ‘rational consumers’ to follow cheaper prices may overestimate their capacity for flexibility. We need to explore ways to provide flexibility to the grid without necessarily requiring active consumer engagement – but ensuring that they are not simply exploited by corporate flexibility extractors!
  • Consumer protection rules around data, installation quality and allocation of risk in such a new system would need to be clear and transparent to ensure trust.
  • It is still largely unclear what the benefits for consumers would be, and how benefits might flow more widely across the economy
  • How could the most vulnerable consumers, who often find themselves excluded from the benefits of new technologies, be supported and protected to take advantage of these opportunities?

Decarbonising our homes is an enormous challenge. The current energy crisis highlights the sensitivity to heating costs of fuel poor households. Home heating solutions can contribute significantly to a net zero world and add to the required flexibility. Making sure they run efficiently and reducing the electricity they use is central to making them acceptable to the majority of householders and also of maximum value to a zero-emissions energy system. CREDS will continue to pioneer research in this area and work with BEIS in developing socio-technical solutions that recognise the need to ‘fit’ engineering solutions to householders’ perceptions, practices and ways of life.

Developing ‘in-use metrics’ to understand how quickly houses lose heat is just one example of how new data and socio-technical arrangements can help make flexible net zero homes a reality. To understand the full potential of ‘flexible heat’ we also need to consider the adaptive and context-specific thermal comfort of participants with diaries and surveys alongside smart meter data and other sensors. Only when we have ‘socialised’ these metrics to measure both the human and non-human dimensions of the comfort system will we really understand the scope for heating flexibility and who stands to benefit. Anything less and we will simply, yet again, be designing in the dark.

Banner photo credit: Alex Geerts on Unsplash