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Welcome to heatflex

What is HeatFlex?

HeatFlex UK is a partnership between Nesta, Centre for Net Zero and Octopus Energy. This project explores how households can support a lower-carbon grid by shifting the energy demand of their heat pump away from peak times.

The research builds upon a small-scale pilot project that took place between March – April 2023. The full report for the pilot stage of the project can be found here

Why are we doing this research?

Peak times are when demand for electricity is very high, usually in the mornings and evenings. When electricity demand is high, it’s more likely that fossil fuel power stations need to be switched on to generate it. This increases the overall cost of electricity for consumers, in addition to releasing harmful CO2 emissions to the atmosphere. 

As more and more homes switch to electric heat pumps, this situation has the potential to get worse, as heat pumps will increase electricity demand. But, heat pumps could also be part of the solution if they can use energy more flexibly and reduce their demand at peak times. One way this could work is by “pre-heating” a home to a higher temperature before the peak period begins, meaning that they don’t need to use electricity during peak periods.

Higher levels of flexibility can be achieved if consumers are willing to automate their heating systems to modulate their consumption. One way to do this is by allowing a third party, for example, an energy supplier, to send signals to turn heat pumps off when demand is very high.

The technology to use heat pumps flexibly already exists. Nesta and CNZ want to better understand how this flexibility can be delivered in a way which works for household occupants, minimising the impact it has on how warm they feel.

What does taking part in the research involve?

HeatFlex aims to explore how to automate heat pump flexibility so household occupants don’t have to do it manually themselves. Taking part would involve being part of 2-3 events per week, during which we would remotely heat your home and then let your home cool. During events, we aim to minimise the amount of electricity your heat pump uses at specific periods in the day.

We recognise that everyone has different preferences for the temperature of their home, so we would ask you to provide us with a maximum and minimum comfortable temperature at the beginning of the trial. We will also give you opportunities to adjust these as time goes on.

Don’t worry – if you ever feel uncomfortably hot or cold, you can opt-out of the event by changing the temperature setting on your smart thermostat. 

We’ll send you a notification 24 hours in advance of each event so that you can opt-out if the event timing is inconvenient or if you are not going to be home. We’ll also send a reminder 1 hour before the event just in case you have forgotten or missed the previous notification. At the end of each event we would ask you to fill out a short survey so that you can tell us about your experience. 

How do I join?

We are interested in having a wide range of participants take part in the trial. To take part there are a few criteria that you need to meet:

  • You must use a heat pump to heat your home
  • Your home must be located in specific areas of the the UK 
  • You must be an Octopus Energy customer 
  • You must have a Tado smart thermostat, or be willing to have one installed (we will help arrange this for you)
  • You’re not on the Octopus Cosy or Agile Octopus tariff 
  • You’re not taking part in the EQUINOX trial for heat pumps

If you meet these criteria and are interested in taking part in the trial you can apply and receive more information by emailing We unfortunately can’t accept everyone who applies, as we need to make sure we’re selecting a range of homes and living arrangements.

What are the benefits for me of participating?

We’re very excited about this research, as it’s exploring how heat pumps can be used better for everyone in the future – and we hope that being part of the research will also be something that you’ll find exciting. You’ll be directly contributing to understanding about how we can decarbonise home heating, reducing carbon emissions and trying to reduce the impact of climate change.

Each household will receive a £100 gift voucher as a thank you for participation. Each household that is involved in the research will also receive an incentive for participating in the trial, specifically an OEM heat pump monitor. If your household does not currently own a Tado smart thermostat, we’ll install one for free, too. You can keep any devices we provide to you for the trial, so that you can continue to get the most out of your heat pump once the research has finished.

How long will I participate for?

We aim to run events during times of the year when your heat pump is heating your home. We are expecting to start running some events in December 2023, with the final events around March or April 2024 (depending on what the weather is like in these months). This means that we can find out how your heat pump works when it’s in the cold months of winter, as well as when the temperature starts to warm up.

Frequently asked questions

Getting started

Who is eligible to join HeatFlex?

Participation in HeatFlex is only eligible for Octopus Energy customers with heat pumps. Sadly those with Agile Octopus or Octopus Cosy tariffs will not be able to participate in the trial. We can not guarantee that all requests to join the trial will be successful as we have limited spaces and need to ensure a diverse sample of participants.

We also will exclude households with the based on the following criteria:

  • Participants themselves, or those who live with a household member, who has been advised by a medical professional that this health condition can be negatively affected by cold temperatures
  • Participants who don’t know whether they live with a household member that has been advised by a medical professional that this health condition can be negatively affected by cold temperatures

Is a smart thermostat required?

Yes. A smart thermostat will be required to allow us to remotely control your heat pump. We will provide a Tado smart thermostat free of charge and will arrange for one of our engineers to install it for you. If you already have non-Tado smart thermostat it will need to be replaced. 

Is a smart meter required?

Yes. All participants should have a smart meter installed in their property. We will not be installing a smart meter as part of this project, but you can directly contact Octopus to get one installed for free as part of the smart meter roll out.

How does the Octopus Energy R&D app integrate with Tado?

First you need to create an account for our R&D app. Then register your Tado as a device in the app. You should then receive a Tado pop-up, add your Tado credentials and click accept to allow Octopus to control your Tado. You can find step by step instructions for how to do this in your Welcome Pack (this will be provided to you by email).

How does the R&D app work?

The R&D app can be accessed directly via a browser or can be downloaded for free from The App Store/Google Play. Once you have created an account and logged into the R&D app we will be able to update your heating schedules during the HeatFlex events.

taking part 

How can I opt out of events?

There are a few ways to opt-out of events. We encourage you to opt-out of events if you are not at home or if you are feeling too hot or too cold. 

  • To opt-out in advance of an event you can simply click the opt-out out button on the reminder email we sent you. 
  • If you are feeling too hot or too cold you can directly change the temperature on the Tado smart thermostat. This will opt you out of the event. 

What needs to be installed in my house?

Octopus Energy Services will be installing a Tado smart thermostat. Additionally, an Open Energy Monitor will be provided for your house. The Tado allows us to control your heat pump and the Open Energy Monitor records your heat pump’s electrical consumption. This requires a power socket near to your heat pump consumer unit, so it may be that we are unable to install it into your home.

Will I get to choose when my Tado is installed?

The Tado will be sent to you by post, and a qualified Octopus engineer will be in contact to arrange an installation time that suits you.

Will I have the option to install other Tado products?

We will only be installing a Tado smart thermostat in the households of participants who do not have a Tado smart thermostat. We won’t be installing other products, but you are free to do so. There is a range of products and partners who work with Octopus that offer a seamless experience that might be of interest – please see here for more information.

What if I already have a different smart thermostat?

You will need a Tado smart thermostat to participate in this research, so we’ll need to replace your smart thermostat with a Tado. Note that we will not be able to replace your original smart thermostat at the end of the trial. If you would prefer not to replace your existing smart thermostat, you won’t be able to join the research. 

Do I need to let you know if there are changes to my household’s circumstances during the research?

If there are material changes to your household’s circumstances, such as changes in the number of people living in your household, please do let us know by contacting If there are changes in circumstances for a specific HeatFlex event, you can provide feedback in the surveys after each event. 

About HeatFlex events

How long will the research take?

We intend to start the research during the beginning of winter 2023 and continue through to the end of the winter (aiming to finish completely by April 2024). You may be invited to start participating a little later than this date.

How frequent will the HeatFlex events be?

We will aim for a maximum of one HeatFlex event per day, with an expectation that there will be 2 or 3 during a typical week. This number might vary and we will always notify you ahead of the events so you have the chance to opt-out if necessary.

At what time of day will the HeatFlex events occur?

The HeatFlex events will occur at times near to when there tends to be a peak in electricity consumption, i.e., in the morning and evening. As we are interested in exploring whether consumption can be moved away from peak consumption, to times close to this, this could end up happening before you wake up in the morning.

What if I’m too hot or too cold during a HeatFlex event?

One reason for this research is to understand whether the way we shift your heat pump’s electricity demand still gives you the comfortable temperature you want. We’ll ask you to tell us about this after each HeatFlex event. However, you can change the settings on your Tado smart thermostat if you are uncomfortable. So if you’re too hot or too cold, we don’t expect you to stay that way!

What do I do if I want to stop participating in the research?

Participants are free to leave the research at any point. We would also be grateful if you could notify us of your decision by emailing If you leave the study, you will not be involved in any further HeatFlex events. You will also not qualify for any additional incentive.

How do I provide feedback after the event?

We’ll ask for feedback via a survey sent by email. This will be a short survey that should take a few minutes each time.

Other questions

Do I get to keep the Tado smart thermostat if I leave the research study?

Yes. We will not be replacing original smart thermostats after the research study for participants, and you will not need to return the Tado smart thermostat provided as part of the research. 

Will you share the results of your research?

Yes. We will be publishing the results of our research publicly, All participants will be anonymised in the final report. 

What is Tado’s role in this research?

Tado is not an official project partner, however, they are aware of our research.

Will participating in the research increase my electricity bill? 

We can’t be certain about this, but would not expect your participation in this trial to have a significant effect on your bills. You will be using a little more energy at some times, and a little less at other times. If you have any concerns at all about affordability you may prefer not to participate.

Have you considered the research ethics of this study?

Yes, this research will be conducted in accordance with Nesta’s Research integrity policy and Centre for Net Zero’s Data Privacy and Ethics Statement.

Can I participate in other Octopus Energy promotions at the same time as this research?

Yes, participants are free to opt into other trials run by Octopus Energy, including Saving Sessions. Unfortunately, participants of the EQUINOX trial for heat pumps won’t be eligible to participate in the HeatFlex trial. 

Can I change my energy supplier during the research?

No, all participants are required to be customers of Octopus Energy for the duration of the research. If you wish to change to an alternative supplier, you will be unable to continue participating in the research.