Revolutionary approach to gas removal in high-rise homes is catching on fast with social landlords

By Mark Smith, Chief Revenue Officer, Sunamp | June 2022


For those of us who work in an industry committed to lowering carbon emissions by removing gas as an energy source in buildings, the need to develop and deliver creative, innovative solutions that not only decarbonise but, as an added benefit, also de-risk the potential spread of fire or explosion in high rise and multiple occupancy buildings such as tower blocks and mid-rise apartments, has to be recognised and prioritised.

Fortunately, there have been encouraging signs that this is starting to happen and, over the past couple of years, more and more housing associations and local councils in the UK have sought to do exactly that.

One of them is the northern England housing association Gentoo Group, who had a requirement to replace 364 gas combi boilers from apartments in seven tower blocks right in the heart of Sunderland.

Looking for a solution, they approached energy services provider Engie, where I was working at the time as Head of Energy and Innovation.

What to do for hot water when gas boilers are removed

As the existing gas combi boilers were coming to the end of their lives, Gentoo seized the opportunity to be creative and look for a solution that would also address a raft of headaches faced, almost universally, by social landlords and, at the same time, enable them to completely remove the entire gas supplies from each high-rise building.

The combi boilers had to come out – that was a given. It was then a question of their options for heating and hot water.

Gentoo decided on ground source heat pumps but the hot water side of it was more problematic. The apartments did not have the space for traditional hot water cylinders nor the structural capacity for the discharge pipework requirements of unvented cylinders.

What followed was my fortuitous meeting with Andrew Bissell, CEO of Sunamp, and an introduction to Sunamp heat batteries.

The Sunamp thermal batteries fitted neatly in the space where the combi boilers had been and, in doing so, also solved a whole series of additional problems.

Gentoo Group’s ‘Core 364’ project, as it came to be known, married Kensa heat pumps with Sunamp heat batteries, and ushered in a new order, not just in the UK but globally, where multiple occupancy buildings could now swap gas for renewable, low-carbon heat and hot water systems, with very little hassle.

There are seven very significant additional benefits for landlords:

1. Reducing risk

First and foremost, social landlords have the security of knowing that in installing ultra-efficient, low carbon heating and Sunamp thermal storage systems, they are not only cutting carbon emissions and guaranteeing comfort while lowering energy use for their tenants, but also removing risk from their properties associated with carbon monoxide poisoning or the potential for a gas explosion, improving safety.

2. No need for residents to move out during installation

Moving people out of their homes for overnight stays during installation is logistically complex and expensive. It can be particularly concerning when they are older or have mobility and other challenges.

The technology and process used in Core 364 allowed the primary system and pipework to be installed without any intrusion into individual residences. This was then followed by the complete removal and replacement of the old system in a single day meaning residents only had to vacate their homes between 9am and 5pm.

3. No need to find alternative accommodation for residents during power failures

As social landlords will know only too well, the rules around tenant safety and wellbeing don’t just apply during installation programs.

If the heating fails, space heaters can be provided temporarily but if there’s no hot water, residents must be moved and the situation can get messy with disruption, claims for compensation, and general bad feeling. In the event of a combi boiler failing, the tenant loses both heat and hot water and, as a result, the landlord has a difficult situation on their hands.

However, with a Sunamp heat battery, if the primary heat source goes down, there’s typically enough thermal energy stored in the battery to provide hot water for 24-48 hours, allowing time for the repair of the primary system and, as a result, there’s no need to find temporary accommodation for residents.

4. No annual servicing or Legionella checks

Sunamp heat batteries don’t need annual servicing as they have no moving parts and, as they are not storing water, they also don’t need any Legionella checks.

For social landlords, this means there is no need to employ staff to book in the services and checks, and to liaise with the tenants or engineers to carry out the work.

And as social landlords are legally obliged to make three attempts to organise a maintenance visit with a tenant before they have a right to enter, this saves substantial administration costs and wasted visits.

5. Reducing fuel poverty

With a highly energy-efficient combination of ground source heat pumps and thermal batteries, residents can benefit from energy savings of up to £300 per year.

6. Reducing carbon footprint

Heat batteries are up to four times more energy efficient than hot water cylinders, so every apartment is playing an important role in reducing the carbon footprint of the overall development. Core 364 is estimated to have a carbon saving of -70%, approximately 420 tonnes per year.

7. A cost-effective solution

Sunamp heat batteries come with a 10-year warranty. Our own testing has confirmed that, unlike electric storage batteries such as some of the lithium-based ones used for solar PV that can suffer serious efficiency losses in a relatively short periods of time, we provide a failsafe performance to over 40,000 cycles of charging and discharging. That’s equivalent to over 50 years of continuous use.

Furthermore, combi boilers have a typical life expectancy of around 10 years so, when taking into account the entire project costs, including the actual installation, comparative lifetime replacement, service and repair, Legionella testing and the associated admin requirements along with the running costs, the system provides an extremely cost-effective solution for the landlord and tenant alike.

There’s more information about the Core 364 project in this Sunamp case study.

Mark Smith, Chief Revenue Officer, Sunamp

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