Domestic hot water production using a heat pump – Refurbishment

The building

Fargate House is a residential complex in the centre of Sheffield (UK) comprising 41 flats. As this is an urban area not connected to the gas mains, the property is designed as an all-electric building.

The challenge

Originally, domestic hot water (DHW) was provided by four direct-heating electric boilers, each with a capacity of 600 litres. This resistance-heating system generated unsustainable energy costs, amounting to approximately £14,000 per month for hot water requirements alone. The aim was to eliminate waste whilst ensuring complete continuity of service during the works: the replacement of the water heaters had to take place whilst the building was fully occupied, without any interruptions to the hot water supply or inconvenience to residents.

The solution

A cascade system comprising four Clivet EDGE EVO air-to-water heat pumps was installed on the roof of the residential complex. Thanks to advanced control logic, the units operate in parallel at different temperatures, modulating their output according to the actual simultaneous demand of the 41 flats. This allows the heat pumps to work in synergy during the day to meet peak demand, whilst at night the system automatically activates a single Clivet unit for maintenance heating only, eliminating any unnecessary energy consumption.

The results

The integration of Clivet EDGE EVO heat pumps has stabilised the building’s energy consumption, ensuring uninterrupted operation:

  • Monthly costs almost halved: Energy costs for hot water have fallen from £14,000 to around £7,500 per month.
  • Consolidated annual savings: The efficiency improvements ensure structural savings of over £78,000 per year.
  • System redundancy: The cascade configuration eliminates the risk of service disruptions; should maintenance be required on one unit, the remaining heat pumps cover the required heating load.

The Fargate House project was a finalist in the prestigious National ACR & Heat Pump Awards in the Sustainability Project of the Year category.

Fargate House UK Fargate House UK