The Clean Growth Fund has made its first investment in low carbon heating, leading a £2.5m investment round in tepeo to support commercialisation of its ‘zero emission boiler’ for the domestic heating market
The boiler, from Tepeo, is a drop-in replacement for a gas or oil boiler that similarly heats water to any set temperature between 35-80°C and use existing radiators, pipework and insulation. It has a ceramic core which acts as a heat battery, with smart tech that controls when it is charged up using highly efficient electric resistive heating elements. The heat can then be released, as needed, in a controlled manner, so the boiler can decouple electricity demand from heating demand and take advantage of green or variable electricity tariffs. The charge cycle of the ZEB is automatically optimised to minimise cost and carbon.
Tepeo also plans to aggregate the boilers at a scale that can provide grid flexibility services.
Johan du Plessis, founder and chief executive of Tepeo and inventor of the ZEB, said: “We have carried out successful trials of the ZEB in a range of house types, and with the welcome investment from the Clean Growth Fund, we are in a strong position to launch our commercial ZEB in the autumn and extend our product range. We are initially targeting all types of dwellings of up to three bedrooms, but we intend to market future models to larger homes too.”
“Importantly, the ZEB will cost roughly half the price of a heat pump and we are confident that as we scale-up our manufacturing, the cost of the ZEB will drop and be competitive with the lifecycle cost of a typical gas boiler, so making the consumer’s decision to replace their gas boiler that much easier.”
The boiler that will be launched later this year is a replacement for a regular or system boiler which works for homes with a separate hot water tank. Tepeo intends to develop a ‘combi’ version that does not require a separate water tank and a larger capacity ZEB suitable for larger homes.
UPDATE Tepeo has closed its £3 million investment round with additional investment from Bonheur ASA, a Norwegian-listed investment company, which has significant interests in the renewable energy and maritime sectors. Bonheur is said to have an interest in the domestic heating sector.
Johan du Plessis said, “Whilst it might not be immediately obvious, there are synergies between tepeo and Bonheur as they are a major investor in UK and European onshore and offshore wind. The National Grid paid over £282 million in 2020 to curtail the wider wind industry’s renewable energy generation – i.e. to stop wind turbines from generating. The more storage and flexibility we can embed in the electricity system, the more we can avoid renewable energy generation going to waste. Thermal storage technologies like the ZEB support renewable generation, driving down the cost for everyone and speeding up the decarbonisation of our planet. They will be an essential enabler for the UK to achieve a 100% low carbon grid over the next 10-15 years.”
Lloyd Butterworth, Investment Manager at Fred Olsen & Co, the company being in charge of the day-to-day operations of Bonheur, said: “tepeo’s ZEB technology is impressive, its market proposition is strong and with the Clean Growth Fund alongside as a co-investor, we are excited about tepeo’s future growth potential. Johan and his team seem well positioned to establish a sizeable share of the UK and international heating markets. We have been particularly impressed with the ZEB’s ability to effectively load shift, moving household electricity demand away from its most expensive and constrained hours of supply. The ZEB is software-enabled hardware, designed with the end user in mind. tepeo’s offering appears particularly compelling because it requires minimal end user interaction, with the ZEB programmed to charge and discharge in optimal fashion, both for cost and carbon-saving.”
Tepeo said the ZEB currently costs roughly half the price of a heat pump and, as its manufacture is scaled-up, the cost will be competitive with the lifecycle cost of a typical gas boiler.

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