Smarter hot water, lower tenant bills: what our Barcud project means for Welsh social housing
Social landlords across Wales are working against three pressures at once: improving the condition of their homes, cutting carbon across the stock, and keeping running costs manageable for tenants who can least afford a surprise on their energy bill. Retrofit planning usually starts with the insulation, ventilation, heating systems, windows and solar PV. Hot water tends to come later in that list, yet it runs every single day in every home a landlord manages.
We think it deserves a place earlier in the conversation. Tenants don’t judge a retrofit by the measures on a spreadsheet. They judge it by whether the home is warm, whether the controls make sense, and whether the bill at the end of the month is lower than it was. Hot water sits close to all three, and our work with Barcud housing association in Mid-Wales shows what that can mean in practice.
Why hot water belongs in the retrofit plan
Hot water is a daily load, covering showers, baths and the kitchen, and in an electrically heated home it can be one of the larger draws on the meter. A conventional cylinder makes that worse by heating a full tank whether or not the household needs it, so energy goes in, sits there and cools down again, and much of it is paid for but never used.
As homes move away from gas and lean more on electricity and on-site generation, the way a property stores and times its hot water matters more, not less. Our cylinders heat only what a household needs and can draw on solar when it’s available, which turns a routine cost into something a landlord and a tenant can actually manage.
Meeting fuel poverty and decarbonisation together
Welsh social housing sits at the centre of a large retrofit challenge. In April 2022, the Welsh Government estimated that up to 45% of Welsh households could fall into fuel poverty as energy prices rose, and Wales has committed to net zero carbon by 2050. Landlords are being asked to improve the energy performance of their stock while protecting tenants from rising costs, and those two aims have to be met together rather than traded off against each other.
A home can look better on paper and still leave a resident struggling with bills they can’t predict or control. That is why hot water earns attention. It’s one of the areas where better control and smarter use of energy show up directly in what a tenant pays.
Inside the Barcud project at William Angie Court
Barcud set out to tackle fuel poverty and decarbonisation together at William Angie Court in Welshpool, a mixed development of 15 new-build flats and 23 existing homes. We installed our smart hot water cylinders across the site, both in the new builds and as replacements for the old, inefficient tanks in the existing flats. Solar PV went on across the development as a cost-effective way to cut CO2 and bring tenants’ bills down, and the priority was making the most of the electricity those panels generated.
The principal contractor, Mid-Wales Property, recommended our tanks for both the new and existing homes. As their project manager Harry Bowen described it:
The appeal was a year-round result: even without solar, the machine learning means a household heats only what it needs, and with PV topping the tank up, hot water costs very little when the sun is shining.
Harry Bowen, Project Manager at Barcud
What residents are seeing
The results that matter most are the ones residents can feel. At William Angie Court, we’ve seen savings of more than 30% on water heating bills, with tenants getting far more control through the Mixergy app and a simple gauge fitted to the tank. For many, it’s the first time they’ve been able to see and manage their hot water directly.
One resident, Mike, told us the app was easy to use and was saving him around £19 a week, taking his electricity bill down by about two-thirds. Mike’s saving is one household’s experience. Because our cylinders measure the energy used for hot water in real time, we can show the saving on the water heating bill itself, while Mike reported how far his overall electricity bill came down. Those water heating savings were measured against the energy price cap in place at the time.
Why the savings happen
Three things explain most of it.
The first is heating only what’s needed. Our tanks use thermal stratification, heating water from the top down, which roughly halves heat losses and reaches a useful temperature up to ten times faster than a conventional tank. A household that wants enough for a couple of showers doesn’t pay to keep a full cylinder hot all day.
The second is smarter scheduling. The app learns a household’s usage pattern and adapts the heating schedule, reducing the average daily energy used for water heating by 25 to 40%, so the system works around how a home actually lives rather than the other way round.
The third is making better use of solar. Because the tank only heats what’s needed, more of its capacity stays free to store solar energy, and the PV diverter can use even short bursts of generation to heat water for nothing. Where panels are installed, that turns electricity a home might otherwise export for very little into hot water the household actually uses.
Supporting energy performance under WHQS 2023
The Welsh Housing Quality Standard 2023 raised the bar considerably, and every social landlord in Wales is legally obliged to meet it. Its affordable warmth requirements set a long-term target of SAP 92, equivalent to EPC A, alongside a matching carbon score (an Environmental Impact Rating of 92) across a landlord’s whole stock. Getting there runs through a Whole Stock Assessment and a Target Energy Pathway for each home, with interim milestones and full compliance due by 2034. The standard deliberately ties decarbonisation to affordability, so the shift to low-carbon heat is meant to happen while keeping homes affordable for the people living in them.
Hot water sits on both sides of that. Because our tanks are listed in the SAP Appendix Q product database, Barcud can calculate and report the effect of the cylinder and its integrated solar PV diverter on each property’s energy efficiency, and capture it in the dwelling’s EPC rating. Smart hot water isn’t a standalone route to SAP 92, and fabric improvements come first. Modelled accurately as one measure within a Target Energy Pathway, though, it contributes to the rating and to the running cost a tenant actually faces.
What this means for landlords across Wales
What worked at William Angie Court can guide decisions elsewhere. For the right homes it cuts wasted energy and gives tenants more control over running costs, which also supports a landlord’s wider decarbonisation plans.
The strongest early candidates tend to share a few traits: homes with solar PV already installed or planned, electrically heated homes carrying high running costs, and flats or sheltered schemes where hot water is a large share of daily demand. We’d also point to properties lined up for a full heating-system change later, where a smart cylinder can bridge the gap, and homes where keeping disruption low matters or where a landlord wants clearer visibility of how hot water is performing across the stock.
Retrofit success is measured in homes, not ratings
Landlords across Wales are planning serious improvement across their stock, and energy ratings, carbon and reporting all have to be met. The resident outcome is what the work is for. William Angie Court shows that hot water can do more than sit quietly in the plant cupboard, and when it’s planned properly and paired with solar PV, it gives a tenant something they notice on the bill and feel in the home.
Planning retrofit works across your Welsh stock? Talk to Mixergy about where smart hot water storage could support tenant bill reduction, solar PV performance and your future low-carbon heat planning.
