Optimising Gas Water Heating in Schools
By Greg Brushett, sales director, Adveco
H
ot water in a school isn’t a comfort amenity. It’s a hygiene requirement, a safeguarding concern, and a public health obligation. Today there is an obvious push toward heat pumps in the education sector, driven largely by the Public Sector Decarbonisation Scheme (PSDS funding). But that doesn’t mean gas water heating has become irrelevant overnight, far from it. The reality on the ground is more complicated than the policy direction suggests.
Many schools are not eligible for (PSDS) funding, cannot afford the capital outlay for a full heat pump conversion, or have buildings that are not suitable for the technology. System-built schools from the 1960s and 70s with limited external space, poor insulation, and ageing infrastructure often need the existing gas system replaced or upgraded before any longer-term decarbonisation work can happen. You cannot install a heat pump system in a building that needs a new roof first!
Schools do, however, burn through enormous amounts of gas. This is a stark operational reality. On average, heating and hot water account for 40% of a school’s overall gas consumption, with water heating alone consuming up to 30% of a building’s total energy demands.
But modern condensing gas water heaters can offer a practical middle ground. They meet Part L minimum efficiency requirements, deliver reliable hot water at Legionella- safe temperatures without supplementary equipment, and have lower capital costs than heat pump alternatives. For a school that needs its hot water system replaced this year rather than in three years when funding might become available, a condensing gas unit is a sensible, compliant, cost-effective choice in the short to mid-term.
The financial implications of ignoring these ageing systems make for uncomfortable reading. According to UK Parliament data, average annual energy costs have climbed sharply by £5,100 annually in primary schools and £21,560 in secondary schools. When 40%
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of a gas bill is dedicated to heating and hot water, even modest efficiency improvements translate into significant savings, capital that could be redirected toward teaching, staffing, or learning facilities instead of feeding an inefficient boiler. The Non-Domestic National Energy Efficiency Data-Framework (ND-NEED) and widespread Department for Education (DfE) energy surveys, paint a clear picture of consumption patterns across the estate. Schools that take action see rapid results.
During the 2023/24 academic year, schools participating in the Energy Sparks programme achieved an average energy reduction of 10% compared to the previous year, effectively offsetting annual price rises but hardly moving the needle from where they had been a year before. One case study school, however, reported a 48% reduction in out-of-hours gas use. An unmanaged system burning gas for up to 16 hours overnight in an empty school is simply wasting money.
While the ultimate trajectory for the public sector is absolute decarbonisation, school business managers cannot focus solely on carbon reduction. They hold a strict legal obligation to manage Legionella risk.
The Health and Safety Executive (HSE) specifies that hot water must be stored at a minimum of 60°C and distributed so it reaches 50°C within one minute at the outlets. Legionella bacteria multiply rapidly between 20°C and 45°C, but they cannot survive above 60°C. This temperature requirement is where gas water heating maintains a significant practical advantage over low-carbon alternatives. While heat pump-based systems often require complex, energy-intensive electric booster heaters to periodically pasteurise stored water at 70°C, modern condensing gas water heaters handle these high temperatures naturally as a standard operating parameter. There is no need for supplementary pasteurisation or complex control cycles to manage bacterial risks; the system inherently ensures safety compliance.
Modern condensing gas water heaters therefore continue to represent a pragmatic,
Autumn 2026 issue 4185
compliant, and cost-effective response. They meet Building Regulations Part L minimum efficiency standards and cost a fraction of a full low-carbon retrofit.
Furthermore, a hybrid approach is increasingly favoured, utilising heat pumps to handle low- temperature space heating, and pre-heat for domestic hot water (DHW) to offset energy demands and reduce carbon emissions, while still relying on condensing gas water heaters to manage high-temperature DHW loops, peak and unplanned demands.
For school business managers and local authorities, addressing water heating inefficiency requires a systematic approach. Begin by collating baseline data to identify out-of-hours waste, review overnight and weekend gas usage to identify unnecessary cycling and critically track actual daily hot water consumption. The latter is crucial for accurate sizing and can deliver considerable upfront and operational savings.
With data in hand, utilise funding like Salix’s Low Carbon Skills Fund to map the estate’s energy profile and ensure funding readiness. A formal plan positions the school to move instantly when funding rounds open.
Where the building allows (i.e., it has an existing gas connection), specify condensing gas water heaters, such as Adveco’s Astute range for immediate 20% efficiency gains. Verify full HSE Legionella compliance, and plan for proper condensate drainage and flue upgrades. If you are unsure, talk to your contractor or specialist provider such as Adveco, which can help with metering, system assessment, design and appliance supply for water heating.
Ultimately, doing nothing is the most expensive option. Whether transitioning toward hybrid heat pump systems or upgrading to high-efficiency condensing gas, addressing water heating infrastructure immediately cuts operating costs, secures compliance, and protects tightly squeezed education budgets.
adveco.co
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