Smart energy: Flexible energy and low carbon technology adoption

 Summary

• For the last three years, Which? has been tracking consumer attitudes towards sustainability, behaviours and barriers to change through an annual tracker survey. This article takes a deeper look at consumer adoption of low carbon technology and flexible energy tariffs in June last year.
• Nearly one in five households (19%) told us that they own at least one of the low carbon technologies that we asked about - an electric vehicle, heat pump, solar panels or energy batteries - with a higher proportion (27%) of higher income households owning one compared to lower income households (15%). 
• Those who have already adopted one type of low carbon technology are much more open to adopting others in the future; for example homeowners with an EV were twice as likely to say they know what heat pumps are and would or might consider installing one in the future than those who don’t have an EV.
• 17% of households surveyed told us that they were engaging with modern forms of consumer-led energy flexibility. 
• We find that the key driver of engagement with modern smart tariffs is whether the household has low carbon technology. Households with at least one type of low carbon technology are five times more likely to be on a modern smart tariff than those who do not. 
• However, a majority of households with low carbon technology remain on standard tariffs (56%), potentially missing out on hundreds of pounds of savings.
• Seven percent of households told us they aren’t on a modern smart tariff but have engaged with a smart offer from their energy company. Engagement with smart offers was similar regardless of the demographics of the household or which low carbon technology households they have. This indicates that a wide range of household types are engaging with flexible energy offers.

Note for readers: The data discussed here was collected before the conflict in the Middle East, so does not relate to the most recent volatility in the retail energy market, including the current reduction in the number of available smart tariffs

Introduction

The Government’s recently published Warm Homes Plan aims to dramatically increase the uptake of low carbon technology in homes across the country, including solar panels, batteries and heat pumps. Solar panels and batteries in particular have the potential to cut energy bills substantially (and reduce households exposure to energy price fluctuations), which in turn can support households shifting to modern electric heating sources that cut their environmental impact. At the same time, electric car sales continue to grow strongly supported by Government policies such as the Zero Emission Vehicle mandate and the electric car grant, with a 24% increase in 2025 sales compared to the previous year.

In parallel the Government is also seeking to create the conditions for many more households to benefit from innovations such as smart tariffs, where consumers can save money through shifting the times they use energy from the grid.

In this context, it is important to understand consumer trends and perspectives on low carbon technology and energy flexibility. This article provides insight from our Sustainability Tracker on the current landscape including:

• How many households are currently taking up what combinations of low carbon technology?
• What type of households are taking up low carbon technology?
• What type of households are engaging with smart tariffs and other forms of flexible energy use?

Take-up of low carbon technology is low but rising rapidly

While ownership of low carbon technologies is still relatively low, it is increasing. Our Sustainability Tracker survey from June 2025 found that nearly one in five households (19%) tell us that they own at least one of the low carbon technologies (LCTs) that we asked about - an electric vehicle, heat pump, solar panels or energy batteries. Solar panels remain the most common (11%), while electric vehicle (BEV or PHEV) [1] ownership amongst drivers we surveyed has grown from 4% in 2023 to 7% in June last year. Heat pump ownership sits at around 3% of all UK households. 

Figure 1: Low carbon technology ownership

Higher income households are more likely to have adopted low carbon technologies. One in four households surveyed with high income reported having an electric vehicle, heat pump, solar panels or energy batteries (27%), compared to 18% of households with a middle income and 15% of households with a low income. [2] Our data suggests that income is a key determining factor in uptake of low carbon technology, as we find that households with an income above £48,000 are 1.6 times more likely to adopt than those in lower income brackets, even when we control for a range of other variables including housing type, tenure, geographic location, social grade, and climate concern. [3]

Adopting one type of low carbon technology can be a route into more

Although take-up of multiple low carbon technologies is currently low (67% of LCT households surveyed only have one, 24% have two, 8% have three and less than 1% reported having all four), those with at least one are much more likely to have other low carbon technologies compared to other households. For example, four in 10 of those with an electric vehicle reported also having a heat pump, solar panels or energy batteries (40%), while only 16% of those without an electric vehicle have a heat pump, solar panels or energy batteries. This pattern also existed when looking at the other low carbon technologies in isolation. Whilst we weren’t able to explore which technologies households installed first (which may indicate adoption of one is driving another), this data indicates that adoption of different LCTs can be a driver to other types. 

Further evidence of this is that those who have already adopted one type of LCT are also much more open to adopting others in the future. As shown in Figure 2 below, homeowners with an EV were twice as likely to have said they know what heat pumps are and would or might consider installing in the future (68%) than those who don’t have an EV (31%). Similarly those with solar panels (61%) or energy batteries (52%) are much more likely to say they would be open to installing a heat pump in the future than those without (30% and 31% respectively). We see this pattern consistently across attitudes towards electric vehicles, solar panels and energy batteries. 

Figure 2: Homeowners without a heat pump who said they know what they are and would or might consider installing in the future by ownership of other LCT

Many households are engaging with forms of energy flexibility

These low carbon technologies provide the most benefit when combined with energy-flexibility; tariffs that charge different rates depending on when energy is used, and in particular lower rates for using energy away from peak times. To inform energy policy, it is crucial to increase understanding of how many households are engaging in different types of energy flexibility and what type of households are engaging. 

Therefore, in our survey we asked respondents if they are on an electricity tariff or receive discount offers from their electricity provider which encourage them to use more or less electricity depending on the time of day. For those who said they were, we asked about the type of tariff or offer they were on, carefully distinguishing between standard energy tariffs, older forms of time-of-use tariffs (Economy 7 / 10) and various forms of modern energy flexibility.

We found that 17% of households surveyed were engaging with modern forms of consumer-led energy flexibility in June 2025 (Figure 3). This is made up of:

• 10% of households surveyed telling us they are on a modern smart tariff - this includes modern static time-of-use tariffs (eg Octopus Go, E.ON Next Smart Saver, EDF GO Electric) and dynamic time-of-use tariffs (eg Octopus Agile).
• A further 7% telling us they aren’t on a modern smart tariff but have said they receive  smart offer discounts from their energy company. These include British Gas PeakSave Sundays or Green Flex, Octopus Fan Club, OVO Power Move and others.

Figure 3: Type of electricity tariff UK households have

Clarity and commonality is needed in smart tariff figures

Ofgem’s published data, collected from suppliers, found that in July 2025 “the market penetration of smart ToU [time-of-use] tariffs in the domestic retail market is currently at 2.8%”. This is collected directly from suppliers every quarter and reported in their State of the Market report 2026. Our figure for smart tariff adoption at 10% is higher than Ofgem’s figures. However, Ofgem have recently told us that they have changed their approach to data collection in this area from October 2025 and the new methodology is likely to show a higher market penetration. 

It is possible that our survey results may show a higher proportion of time-of-use tariffs due to respondents thinking they are on smart tariffs when they are not or mis-understanding what smart tariffs are. However, we attempted to mitigate this through our questionnaire design and will carry out further testing and refinement in the future to explore and reduce this discrepancy informed by discussions with Ofgem on their new methodology and what their updated figures show. 

This shows the importance of clear definitions and the transparency of data collection in this fast evolving market. In any case there are two issues with the current reporting of time-of-use tariffs, which we believe will still apply with the new methodology:

• Ofgem’s tariff data does not allow analysis of which type of households are taking up smart tariffs, such as demographic characteristics and income level. Our survey data allows some indication of this, which we explore below.
• Ofgem’s tariff data does not include data on households engaging in flexibility through offers. We found that, beyond those on modern smart tariffs, 7% of households are engaging with smart offers from their energy company. This equates to an estimated 2 million households. This illustrates the substantial appetite that consumers have for saving money through changing the way they use their energy - a similar point has been made through the recent Beyond Tariffs report by LCP Delta with E.ON Next, EDF, Octopus Energy, Ovo and So energy.

Additionally, adoption and awareness of smart tariffs is growing rapidly, demonstrating the need to more holistically understand the market. Ofgem also found that take-up continues to increase rapidly, at almost 70% per year, and the Department for Energy Security and Net Zero found that 90% of people have at least heard of time-of-use tariffs (although the survey does not distinguish between legacy tariffs such as Economy 7 / 10 and modern smart tariffs).

LCT ownership is the primary driver of smart tariff adoption

Despite the potential over-reporting of those on modern smart tariffs, our survey data remains a valuable tool for understanding who is engaging with both energy flexibility. 

Those who have low carbon technologies are much more likely to be engaging with smart tariffs. One in four households surveyed with at least one LCT said they were on a modern smart tariff (25%), compared to just 6% of those without any. Modern smart tariffs are most widely taken up by households surveyed with an electric vehicle, with 42% being on one (Figure 4).

Completing regression analysis on our results, we find that households with at least one type of low carbon technology are five times more likely to be on a modern smart tariff than those without. We find that LCT ownership is the key driver of smart tariff take up, even when controlling for housing type, geographic location, social grade, and climate concern. [4] This finding is also true, even when we control for income. Although takeup is higher amongst higher income households, we find that it is not a significant direct driver of smart tariff take-up in its own right. Instead, it appears to be due to higher income households being more likely to own an electric vehicle, heat pump, solar panels and/or energy batteries - and hence in turn more likely to take up modern smart tariffs.

Figure 4: Modern smart tariff engagement by LCT technology

Many households are missing out on possible savings

Whilst engagement with modern smart tariffs is much more common amongst LCT owners, a majority of these households are on standard tariffs (56%), [5] thus missing out on potential hundreds of pounds of savings. [6] 

Some of these households won’t be able to benefit, either fully or at all, from smart tariffs as they may not have a working smart meter or they are an EV owner but don’t have a charge point attached to their home. Even when we look at the most "ready" households though - households with an electric vehicle, working smart meter and EV charger attached to their home - a third (33%) of those surveyed are still on a standard tariff. This indicates there is a sizable number of EV owners missing out on possible savings from smart tariffs. Research we conducted in 2024 found that this is likely down to a general lack of awareness of smart tariffs and an inability to use comparison sites to aid in the switching process for smart tariffs. 

All types of households are on flexible energy offer discounts

As outlined earlier, seven percent of households told us they aren’t on a modern smart tariff but receive smart offer discounts from their energy company. We define smart offers as rewards or incentives households receive for using electricity at particular times of day that households sign up to and that operate separately to their tariff.  These include British Gas PeakSave Sundays or Green Flex, Octopus Fan Club, OVO Power Move and others. 

Engagement with smart offers was similar regardless of what low carbon technology households had - 7% of households without any LCT and 6% of households with at least one LCT reported receiving smart offer discounts. Additionally, looking at the demographics of these households, we find a more even cross-section of society is engaging with these types of offers than with smart tariffs. For example:

• 7% of low income households report being on an offer, 6% of middle income households and 7% of high income households.
• 8% of households that own their house outright are signed up to an offer, compared to 7% of mortgage holders and 5% of renters. 

None of these small differences are statistically significant. This data shows that, unlike smart tariffs, a wider market of households are engaging with energy flexibility through smart offer discounts from their energy supplier.

Conclusion

The results of our survey illustrate the growing importance of low carbon technology and energy flexibility for households as the country rapidly moves beyond nascent market developments to mature offerings. Our survey illustrates the importance of the government:

• delivering on their commitments in the Warm Homes Plan to widen access to solar, batteries and heat pumps to ensure that all sections of society can benefit.
• widening access to affordable EV charging through tackling barriers to on-street charging and working to improve the affordability and day-to-day experience of using the public charging network.
• ensuring that their approach to policy and regulation consistently recognises that engagement with energy flexibility is about more than tariffs themselves, and is already involving millions of households every day.

In this context it is crucial that the government builds its capability to understand:

• what type of households are engaging with LCTs and energy flexibility,
• how experiences differ amongst different types of households,
• the key barriers to greater engagement with energy flexibility, both by households with low carbon technology and without. 

In particular, official data on smart tariffs is limited. The current approach to data collection means that official sources do not report on those engaging with “add-on” offers, and also cannot provide evidence on the demographics of households who are engaging. The Department for Energy Security and Net Zero collects some data through the Public Attitudes Tracker, but this does not distinguish between legacy tariffs (such as Economy 7 and Economy 10) and modern smart tariffs. Ofgem’s forthcoming Flexibility and Net Zero survey will add to knowledge in this space, but it is also important that Ofgem fully refresh its approach to data collection from suppliers on smart tariffs (collected through Ofgem’s Tariff Request For Information) to reflect the importance of this fast growing area.

 Footnotes

[1] Battery Electric Vehicle (BEV) or Plug-in Hybrid Electric Vehicle (PHEV) ↑.

[2] Income bands are defined based on annual household income. The low income band includes those earning up to £28,000, the middle income band ranges from £28,001 to £48,000, and the high income band includes those earning over £48,000 ↑.

[3] We ran a multiple logit regression to analyse which factors were significant in explaining LCT uptake ↑.

[4] We performed a multivariable logit regression, with modern smart tariff take up as the dependent variable and a range of explanatory variables from our dataset ↑.

[5] 10% reported being on an Economy 7 or 10 tariff, 6% on a non-smart tariff but receive offers for changing energy use and 3% said they don't know ↑.

[6] Heat pump calculator: How much would a heat pump cut your energy bill? - Which? and Switching to an EV could save drivers up to £800 a year in refuelling costs ↑.