How do heat pumps work and unlocking their efficiency with Sunamp Thermino for low-carbon retrofit in social housing

As the world continues to grapple with climate change challenges, the need for energy-efficient heating solutions has never been more urgent. 

A recent UK survey has revealed that the majority of homeowners are satisfied after making the switch to heat pumps, an encouraging shift highlighting the increasing popularity and effectiveness of renewable heating technologies. 

A key feature of the HM Government – Heat and Buildings Strategy has been to create a new market for low carbon heat, according to a Climate Change Committee (CCC) report. The government has set ambitious targets. By aiming to install 600,000 heat pumps annually by 2028 and implementing a ban on natural gas boilers by 2033, it is clear that heat pumps are considered the key technology for replacing traditional boilers. Furthermore, both the CCC and Government pathways are aligned in their vision to phase out gas boilers in new buildings by 2025.

These strategic measures demonstrate a determined effort to revolutionise the way we heat our homes and buildings and highlight the vital role that social landlords will play in achieving a sustainable future. Despite this momentum, however, barriers to widespread heat pump adoption among social housing landlords still loom large, among them reluctance to be early adopters of new technology, concerns about noise pollution, space constraints and anxieties about tenant satisfaction.

Let’s address the most important question first.

How do heat pumps work?


Heat pumps use electrical energy to extract heat from low-temperature reservoirs, such as the outdoor environment, and then deliver that heat at a higher temperature where it is needed most. There are various types, including air source heat pumps, ground source heat pumps, and water source heat pumps.

Heat pumps possess a remarkable versatility that sets them apart. In certain scenarios, the direction of a heat pump can be reversed, enabling it to provide cooling as well. When heat pumps are used for cooling purposes, they consume less electrical energy than when used for heating. This is because they work in sync with the natural flow of heat, channelling warmth from a higher temperature indoor environment to a lower temperature outdoor environment.

The interaction between electrical energy and heat manipulation is what makes heat pumps a game-changer in the quest for energy efficiency. By tapping into the natural laws of thermodynamics, they maximise the potential of available heat sources and minimise waste, making them an ideal choice for sustainable heating and cooling solutions.
So, in short, heat pumps extract heat from the environment, amplify it and use it for heating and hot water providing a low-carbon, more efficient system for social housing residents. They can extract heat efficiently from temperatures as low as -15C.

However, unlike a combi boiler, domestic heat pumps are not designed to supply hot water quickly enough to meet the social housing residents’ demands of baths, taps, and showers, and cannot provide hot water ‘on demand’. This makes thermal storage a critical part of the system.

Hot water options for heat pump systems

What do people want from their hot water system (a heat pump water heater)?
Ideally, comfort and convenience with fast flowing hot water on tap that doesn’t cost the earth. Social landlords also demand reliability. If heating fails it is possible to supply temporary heaters for tenants while a fix is found, but they can’t be expected to live in a home without hot water for long, and alternative accommodation must be provided which doesn’t come cheap.

One thermal storage solution is to store hot water in a traditional hot water cylinder until it is needed. However, storing water between 20°C and 45°C increases the risk of legionella bacteria growth, especially if the water remains stagnant for extended periods. An electric immersion heater fitted into the top of the hot water cylinder can be used to heat the water for periods of time to the temperature required to kill the bacteria. For maximum efficiency, a cylinder with a larger coil capacity than a conventional model is needed to compensate for the heat pump’s lower water delivery temperature compared to a traditional boiler.

When there’s no space for hot water cylinder

When considering the transition from gas boilers to heat pumps in social housing, limited space can often pose a challenge for landlords. If space constraints make a hot water cylinder impractical, alternative options are available, including:

A hybrid system combines a heat pump for space heating and a separate boiler (such as a gas or oil boiler) for hot water. This setup is also suitable for homes with high heat demands but doesn’t rid homes of fossil fuels.

Instantaneous water heaters, such as electric showers, produce hot water on-demand using electricity. They can be installed to supply a single tap and are cost-effective since hot water is generated only as needed. However, they may not be ideal for providing hot water to a bath due to the required volume and flow speed.

A heat battery stores excess heat or electricity in a phase change material, releasing heat when hot water is needed. Bulky hot-water systems and extensive pipework may not be feasible, especially given how space is a particularly valuable in social housing residences. An integrated heat pump system with a Sunamp heat battery sits neatly in a cupboard, taking up minimal space and maximising energy efficiency.

Sunamp’s heat pump-compatible heat batteries

Sunamp’s Thermino heat batteries, using Plentigrade phase change materials, are highly effective at storing store thermal energy. These PCMs operate at temperatures that closely match the desired water temperature, harnessing the latent heat of melting and crystallising processes. An integrated heat pump system with a Sunamp heat battery sits neatly in a cupboard, taking up minimal space and maximising energy efficiency. This approach allows for a remarkable energy density and efficient storage of thermal energy and offer landlords a highly reliable hot water solutions for their residents. The ability to store and distribute hot water so efficiently makes Thermino an ideal choice for meeting the hot water needs of social housing communities reliably and sustainably.

For every social landlord facing mounting pressures and regulatory constraints set by HM Government, compact and energy-dense Thermino heat batteries lead the road to net zero by redefining efficiency and revolutionising hot water systems.

Sunamp heat batteries seamlessly integrate with heat pump systems to store excess heat generated during off-peak hours. The heat batteries are highly energy dense and protected by high-performance vacuum insulation, retaining over 95% of the energy collected, i.e., only half a KWh is lost in a day a consistent supply of on-demand hot water even during peak demand periods. This creates a more reliable and sustainable heating solution particularly in social housing where efficiency is key.

Separately, heat pumps are renowned for their exceptional efficiency compared to direct resistance heating methods. However, they typically have limitations when it comes to reaching high temperatures beyond 80ºC. This is where the Thermino makes a difference, as it operates at lower temperatures that align with the heat pump’s capabilities. By leveraging this compatibility, Thermino seamlessly integrates with heat pumps, unlocking the full potential of both technologies.
It doesn’t just end here. The merits of the Sunamp heat battery go beyond, such as

Overcoming grid constraints

The impact of Thermino heat batteries extends beyond enhancing heat pump efficiency. As heat pump adoption increases, concerns about the strain on the electricity grid have emerged. By storing excess heat, the heat batteries help shift the demand for electricity to off-peak hours. This balancing effect reduces the grid load, mitigates the risk of power shortages and ensures a smooth transition to renewable heating. With Thermino heat batteries installed, housing associations can then reap the decarbonisation benefits of heat pumps without compromising the stability of the grid, particularly critical for achieving the net zero targets and EPC ratings.

Making retrofitting easy

A recent Ridge and Partners’ research pointed to the retrofitting crisis in the UK currently. Despite several ambitious net zero plans, few organisations actually included the energy performance of their own stock. Given that housing associations provide around 5 million houses, retrofitting has a critical role to play in the decarbonisation plan. Government’s funding for retrofit initiatives, such as £500mn sustainable warmth competition, green homes grant scheme or £800mn Social housing decarbonisation fund wave 2.1 present housing associations with an opportunity to enhance the energy efficiency of their housing inventory, enabling tenant comfort and lowering fuel bills while paving the way for the energy transition.

However, retrofitting needs to account for certain practicalities. Many of these properties have been lived in for several decades and accumulated numerous belongings, which make clunky installation of traditional hot water system extremely hassling. A National Housing Federation report showed 14% of the obstacles to retrofitting included resident resistance. Additionally, a staggering 47% of housing associations expressed concerns about ‘unproven technology’.

Because Sunamp heat batteries are compact, easy to install, and fit with the existing infrastructure, large-scale heat pump adoption becomes a possibility without disrupting residents. Sunamp’s award-winning heat batteries are thoroughly tested and proven successful in housing associations across geographies–around 25,000 heat batteries have already been installed by residential customers and social landlords in the UK and in commercial buildings in New York State in the US, and elsewhere around the world.

Gentoo Group’s ‘Core 364’ gas replacement programme in Sunderland combined ground loop array heat pump with the Thermino heat batteries and replaced gas in seven tower blocks reliably providing low-carbon hot water without decanting them.

Enabling scalability

Easy installation and large-scale retrofitting allows social housing landlords, who often manage large housing portfolios, to implement heat battery integration across multiple properties, enabling the efficient management and optimisation of heating systems at a broader scale, with no disruption. This scalability makes Thermino an ideal choice for social housing providers looking to achieve energy efficiency and sustainability targets across their housing stock.

Get in touch with us to learn how you can improve the energy efficiency of your stock and embark on your net zero journey.

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