Mixergy, which makes smart hot water cylinders, has closed a £12 million funding round led by Barclays Climate Ventures, the company announced on 4 March 20251. The round drew continued backing from existing shareholders Oxford Sciences Enterprises, Kiko Ventures (IP Group), Nesta and EDP Ventures2. The Chartered Institute of Plumbing and Heating Engineering, of which Mixergy is an Industrial Associate, reported the funding on 5 March 20252.
The money is to support a shift in how the company sells its technology. According to both announcements, the funding "will drive Mixergy's transition towards a technology licensing and strategic partnership model, focusing on new builds, social housing retrofits, and commercial properties"2. Mixergy said it will expand research and development to improve hardware and software for social housing providers, property developers, energy utilities and HVAC OEMs2. The company also announced the appointment of David Tuohy as Executive Chair2.
Mixergy states that its technology is "helping homes today save up to 60% on their hot water bills"2. Both announcements attach the same qualification: the figure was calculated on real-world Mixergy customers using machine learning paired with the Octopus Agile smart tariff in 20242. The company describes its cylinders as smart energy storage devices that store cheap energy and use it when needed, "like a huge distributed battery for the nation"2. It says its integrated hot water heat pump and its smart hot water cylinder work with any heat source, and that its innovations have been embedded in the UK government's new Home Energy Model2.
Named collaborations include Daikin, Birmingham City Council and British Gas, which offers homeowners a rebate for using a Mixergy cylinder through what the company calls its Mixergy Extra bolt-on energy offer2. James Ferrier, Director at Barclays Climate Ventures, said the company was addressing grid capacity and building energy efficiency at the same time2.
"This investment accelerates our ability to develop scalable solutions for our technology partners, helping them navigate the changing global energy landscape. With Barclays' support, we can bring our technology into more homes and buildings in the UK through a broader range of channels, while improving the grid capacity to integrate renewable energy. Why pay windfarms to shut down when we can pay households to switch on?"
Why it matters for households
Hot water is one of the larger and steadier draws on a home's energy use, and it is the part of household demand most often left out of the conversation about electrification. A cylinder that heats water when electricity is cheap, and stores it until it is needed, changes when a household buys its energy rather than only how much it buys. That is the mechanism behind the 60% saving figure, and it depends on a smart tariff: the same cylinder on a flat tariff would not deliver the same result2.
The funding points to where the technology is expected to go next. The stated focus on new builds, social housing retrofits and commercial properties means the near-term growth is aimed at installations arranged by developers, councils and landlords rather than at individual households buying a cylinder directly2. The licensing model suggests the company expects its controls and software to appear inside other manufacturers' products, rather than only under its own brand2. For a household, that could mean the option arrives through a heating installer, a housing provider or a heat pump package rather than as a standalone purchase. Details of how licensing would work for existing owners have not been reported.
What happens next
No timetable has been given for the licensing transition, the research and development expansion, or the effect of the new Executive Chair appointment2.
Sources2 cited
- Mixergy Secures £12 Million in Funding Led by Barclays - Mixergy, mixergy.co.uk
- Mixergy Secures £12 Million in Funding, ciphe.org.uk