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Hybrid heat is key to delivering domestic demand response from fuel flexibility, which offers uncompromised heat at lowest cost, lowest disruption and lowest carbon for customers and the energy system


  • £5.2m ‘Freedom’ hybrid heating innovation project demonstrates financial benefits for consumers both on and off the gas grid
  • Increased annual spend of £178m on the gas system will deliver savings of more than £1.3bn per year comparing to full electrification
  • Approach decarbonises the existing energy grid infrastructure without any increase in peak electricity load, avoiding DNO reinforcement and using the storage and flexibility of the gas grid.
  • Hybrids provide ideal technology to balance renewable gas and power potential to offer full domestic heat decarbonisation
  • Consumers protected from major in-home disruption from deep insulation retrofits and transfer over to low temperature heating systems.

Newbury, UK, 18 April 2018 – Interim results from the Freedom Project, a £5.2m innovation project designed to trial hybrid heating systems, has shown that smart switching between gas and electricity is key to delivering flexible demand response services (DSR) in a domestic setting.

During 2017, PassivSystems installed 75 hybrid heating systems in private and social housing properties in Bridgend, South Wales, to prove the economic benefits of providing a flexible choice between fuels for heating. The Freedom Project is funded through the Network Innovation Allowance by Western Power Distribution, the electricity distribution network operator and Wales & West Utilities, the gas distribution network operator.

Combining efficient gas boilers with air source heat pumps (ASHP), while employing smart switching between the gas and electric load, enables the choice of fuels to match consumer demand for heat.

This highly flexible approach has the potential to enable consumers to participate in DSR programmes. National Grid pays aggregators to reduce demand, which enables grid balancing without the need to generate more power to meet peak demands. In the past, participating in DSR programmes has been restricted to businesses or major energy users who can turn down or turn off equipment in response to a request from National Grid.

“Homes equipped with hybrid heating can play a major part in decarbonising heat while providing the flexibility we need to balance the electricity grid,” commented Colin Calder, Chief Executive, PassivSystems. “Alongside reform of the capacity market, enabling householders to participate in demand side response will open the door for consumers to benefit financially from delivering a more flexible energy market.”

Calder continued: “Hybrid heating systems can move as much demand to gas as they like – they have complete load flexibility. The Freedom Project has demonstrated our ability to deliver DSR without the usual constraints that businesses face. We can share heat load between gas and electricity without compromising consumer comfort.”

The results of the trial to date have proven that using connected, coordinated controls can execute smart switching to gas to avoid electricity capacity restrictions, or indeed use of marginal carbon intensive peaking power generation, while maintaining comfort for occupants. For example:

  • Overnight: the heat pump charges house using cheap electricity when intermittent renewable generation is available
  • Mid-afternoon: gas boiler used to quickly reheat house
  • Early evening: system flips to gas to avoid peak demand

Avoiding the use of electricity during times of peak demand will help reduce the need for further investment in generation capacity as well as paying consumers to help balance the power grid.

As well as helping to balance the grid, DSR in a domestic setting enables DNOs to better manage grid constraints and control their investment in network reinforcement as they seek to manage local grid capacity. The Freedom Project is utilising existing electricity network infrastructure capacity and demonstrating disruptive and costly wholesale DNO reinforcement can be avoided. A further benefit from hybridised domestic heating is that it does not require in-home disruption and modification to change over to low temperature heat delivery and deep insulation retrofits

PassivSystems is leading the day-to-day project management, development of control algorithms, designing the architecture of the smart switching system and has overseen the recruitment of homes and the procurement and installation of hybrid heating systems. The project’s principal funders are Western Power Distribution, the electricity distribution network operator and Wales & West Utilities, the gas distribution network operator.

The Freedom project’s hybrid heating system includes an external air source heat pump, a reliable, high-efficiency gas boiler inside the home and a hybrid control panel that enables switching between the two heat sources to automatically use the most cost-effective heating mode at any time of the day or night.

Modelling the 2030 energy system, Imperial College’s analysis shows that an increased annual spend of £178m on the gas system as a substitute to electricity in ASHP-only scenarios, the whole system is able to achieve gross savings in total cost of more than £1.3bn per year.

PassivSystems is continuing to demonstrate the advantages of advanced control through the remainder of the 2017-18 heating season. A full report will be released in the autumn detailing the consumer, network, carbon and energy system benefits of a large-scale deployment of hybrid heating systems with an aggregated demand response control system.

About Freedom

The Freedom Project is seeking to understand the potential role of multi-vector solutions in the decarbonisation of domestic heating. Based in Bridgend, South Wales, the project is investigating the consumer, network and energy system implications of hybrid heating system deployments, where domestic heating systems have the option of operating using a standard gas boiler, an air source heat pump (ASHP), or both.

The Freedom Project has completed 24 months of a 27-month project programme. The Project has installed 75 hybrid heating systems in a mix of private and social housing, with the focus now on the optimised controlling, monitoring and consumer feedback throughout the 2017-18 heating season.

The remainder of the project will now focus on the optimised controlling, monitoring and consumer feedback throughout the 2017-18 heating season. A full report will be released detailing the consumer, network, carbon and energy system benefits of a large-scale deployment of hybrid heating systems with an aggregated demand response control system.

About PassivSystems Ltd

PassivSystems has developed a secure, scalable cloud-based ‘PassivEnergy’ smart home energy management platform for collecting and optimising data collected from smart meters, solar PV systems, batteries and all types of residential heating systems, including district heating. Its smart heating service has been demonstrated to significantly reduce lifetime operating costs to UK households worth hundreds of pounds a year per household. PassivSystems is the leading provider of domestic solar PV asset management services and its technology has been selected by leading utilities to differentiate their supply services.

The intermittent nature of renewable sources like wind and solar is challenging grid operators to maintain stable electricity networks that can manage both highly variable sources of supply and demand. PassivSystems’ vision is that every household can benefit from cheaper, cleaner energy by playing their part in balancing the grid. By developing and operating smart data services that manage equipment in homes, PassivSystems’ mission is to create sustainable value from energy systems.

The company was founded in 2008. It employs 50 people and operates through its headquarters in Newbury. For more information, visit www.passivsystems.com