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Mixergy develops intelligent, cost-effective solutions for domestic water heating and are working towards a greener energy sector by modernising hot water.

The Challenge

Mixergy’s hot water tanks are the only smart hot water solution approved by National Grid. Unique in their ability to offer a Demand Side Response (DSR) service, the tank works by heating up when too much renewable energy is generated and electricity demand is low, to free up more space for renewable generation.

Domestic hot water uses 12% of the total energy consumed in the typical UK home. This means that conventional boiler tanks potentially store more hot water than required, causing wasted energy through heat loss from the tank. The Mixergy Tank monitors temperatures and only heats water that is needed, separating hot and cold water and making use of its internet connectively to take advantage of smart energy tariffs and DSR initiatives.

With their new smart hot water solution ready for market, Mixergy sought to gain consumer trust by getting the Mixergy Tank independently verified through Energy Saving Trust’s product certification service.

Taking Action

To verify the energy savings, Energy Saving Trust evaluated Mixergy’s comparative test against a market-leading equivalent boiler. The testing facilities were inspected prior to testing, to ensure they were compliant with the efficiency of domestic electrical storage heaters and testing methods.

The results revealed that the Mixergy Tank was more efficient than the market-leading tank over the course of a 24-hour draw cycle in all combinations of the tank / boiler loop temperatures. Energy Saving Trust analysed the results with Mixergy and found that savings of up to 21% were achievable where boiler short cycling occurs regularly, whereas a 12% improvement may be considered as more typical.

Energy Saving Trust verified Mixergy’s own research and specific energy saving claims with our independent and trusted analytics.


Mixergy’s hot water tank successfully met the standards and achieved Energy Saving Trust’s ‘Verified’ product certification – a brandmark trusted by consumers that provides independent assurance about the performance and claims associated with energy saving products.

“Working with Energy Saving Trust has been easy and plays a pivotal role in our marketing strategy as they have great brand equity in the sustainable energy space with their unbiased opinions and statistics.” David White, Business Development Manager

Mixergy offers customers a 25-year warranty against faulty materials or manufacture, subject to the customer registering and using the product within Mixergy’s operating standards.

Pete Armstrong, CEO of Mixergy said the technology could pave the way for new energy tariffs, which would “reduce energy consumption and carbon emissions by storing excess renewable energy on the grid. At the same time, we reduce bills for householders by only heating the amount of hot water they require.”

Download this case study.

Why work with Energy Saving Trust?

We offer a range of services relating to the evaluation and verification of energy efficient and renewable technologies. Energy Saving Trust’s product verification is a bespoke service, designed to assist businesses in communicating the energy and performance benefits of their products. The process involves the independent verification of a product’s performance characteristics followed by the development of factual and informative, consumer-facing claims for use in promotional marketing materials.

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