How to save money on domestic hot water costs in 2024?

The impact of domestic hot water consumption on the environment

Here are a few alarming facts concerning water usage in the UK:

On average, every household in the UK uses around 345 litres of water each day – that’s 145 litres per head, every day.

And 12% of a typical gas-heated household’s energy costs is from water heating for showers, baths, and hot water from taps.
Water heating contributes to around 5% of UK’s total CO2 emissions

Energy Saving Trust


Saving water saves energy. Energy is required to filter, heat, treat and pump water to our homes. Domestic water consumption leaves a significant carbon footprint.

Source: The hidden impact of your daily water use, BBC

Conserving domestic water directly helps protect our nation’s water supplies.

Water companies use an enormous amount of energy. Scottish Water is the highest consumer of electricity in Scotland. Conserving domestic water directly helps protect our nation’s water supplies. Given that across Britain, residents use about 350 litres of water daily and 840 billion litres annually on average, cultivating some good habits with water consumption can go a long way. Here are a few water saving tips that can have a direct impact on lowering household energy demand and reducing water costs, and here’s a handy guide to calculate your water saving calculations.

So while using less water goes some distance in saving energy costs, according to Energy Saving Trust, more than 16% of the UK’s average annual combined energy bill comes from heat generated by showers, baths and hot water from taps, which amounts to £228 every year for households on average.



The impact of water heating on energy costs

In a typical UK household, heating water accounts for about 17% of your energy bill, or about 25% of the fuel your boiler consumes. It may not seem significant, but it is important to know that hot water is needed all year round, while space heating is typically required only for a few months.

It is then worth looking at how you heat your water.

Typically, households heat water using their central heating, for instance a system boiler, while storing and heating a specific amount of water in a hot water tank or cylinder. Another option is immersion heaters, which are essentially electric water heaters immersed in an insulated hot water cylinder. And about 78% of UK households use gas boilers for heating water (80% of which are combi) as these are thought to be convenient for instant hot water delivery.
However, the need to make your home central heating futureproof, upgrading your heating system and replacing gas boilers with a sustainable energy alternative, is imminent. Even with the extended deadline, the UK government aims to phase out gas boilers in a decade to meet the legally binding emission targets. Gas boiler emissions in the UK homes emit twice as much CO2 and eight times NO2 as all of UK’s gas-fired power stations combined, and more CO2 emissions in a year than a person taking seven transatlantic flights .

Heat pumps are seen to be the most effective option to replace boilers and cut emissions from home & water heating. And while they are proven to be highly efficient for space heating, they too need additional thermal storage, such as a hot water cylinder or a heat battery.


Support available:

If you’re looking to transition from your gas central heating to renewable alternative, you can cut costs by taking advantage of heat pump adoption schemes available in the form of loans and grants – both for private residences and social housing residences. We have covered these in detail here.
Thanks to these state grants (particularly the increased Boiler upgrade scheme subsidy or Home Energy Scotland grants), the number of registered heat pump installations grew to a record 36,799 in 2023 across the UK.

When switching to a heat pump central heating system (or adding solar PV), you need thermal storage for hot water. Given that water heating for daily household needs takes up 12% of its total energy, it is critical that the thermal storage used is highly energy efficient. This is where a Thermino heat battery can help with household savings. And depending on the thermal store (a hot water cylinder or a heat battery), these could be both monetary and non-monetary savings.
Let’s make a quick comparison between a vented copper cylinder & a direct unvented cylinder vs Sunamp’s thermal store, Thermino heat battery:

On average, the cost per sq. ft. of space in England is £366.
Thanks to the highly energy dense phase change material used in a Thermino heat battery, it is about four times smaller than an equivalent hot water tank.
So, if you were to replace or retrofit an existing hot water cylinder in a cupboard with a Thermino battery, you’d save about 2 sq. ft, of space, whereas if you’re installing the Thermino battery in a new build or retrofitting it in a way that allows you to position it under the stairs or in a crawl space, effectively eliminating the need for a cylinder cupboard, you would save around 6 sq. ft. of space. Space is precious in the UK.
Using a heat battery helps overcome the key barrier in installing heat pumps in smaller homes, particularly in social housing which may not have space for a bulky hot water cylinder. Take a look at how our heat batteries were retrofitted in space-constrained council flats in Sunderland and Thurrock and enabled renewables.

Maintenance & cleaning:
According to Health and safety executive (HSG 274 Part 2), annual water tank inspections are a legal requirement, and tank cleaning needs to be carried out every 3 years – costing you anywhere between £200-£500 for 110-500L tanks. Thermino heat batteries, on the other hand, require no mandatory maintenance.

Daily standing heat loss:
You could lose between 1.4 kWh and 3.34 kWh in daily standing heat losses with a hot water cylinder (whether vented copper or direct unvented); the energy costs from these losses add up at an annual basis, and can be significant – whether the heat source is gas or electric. In comparison, the heat losses with a Thermino battery are about 0.67-0.87 kWh/24h, almost 25% lower.

Carbon savings: Regardless of the heating and hot water system you’re starting with, the compact Thermino battery can cut your carbon emissions significantly.
For instance, Thermino helps with pre-heating hot water in a combi. Preheating (where the boiler fires up every 30-90 mins) is necessary for instant hot water, but an untimed preheat takes up 500-750 kWh annually.
With a system boiler, the heat battery helps cut the amount of gas consumed significantly.
If you add solar PV, Thermino heat batteries will maximise the use of freePV-generated electricity to provide instant hot water, and when paired with off-peak electricity, the energy bills are lowered further.
And should you choose to go gas-free and switch to a heat pump, Thermino xPlus will work seamlessly with it and bring down the onsite carbon emissions to zero, completing your transition to net zero.

Find a Sunamp-certified installer or stockist near you if you’d like to install our ePlus or xPlus range of Thermino heat batteries: Find stockist and installer – Sunamp UK