For school boards, academy trusts, operators and estates teams, domestic hot water (DHW) is becoming a strategic estates issue. Much of the education estate was designed around relatively inexpensive gas and high-temperature boiler systems. Today, those assumptions are being challenged by decarbonisation, electrification, ageing infrastructure and constrained capital budgets.
The implication is clear. Schools should stop treating DHW replacement as an isolated plant-room decision and incorporate hot water into long-term estate planning.
Understand demand before choosing technology
The first priority should be evidence. Traditional systems are frequently sized using assumed occupancy and theoretical peak demand. Yet a primary school, boarding school, SEN facility, sports complex and university residence can have radically different DHW profiles. Even within a campus, demand can vary substantially between buildings.
Metering is therefore increasingly valuable. Adveco's Live Metering approach records actual hot water demand and temperatures, allowing consumption, energy use, carbon emissions and operating costs to be modelled. This supports accurate sizing rather than perpetuating potentially oversized legacy systems.
For multi-school trusts, establishing a DHW baseline across the portfolio provides an opportunity to rank sites by condition, energy intensity, carbon reduction potential and replacement urgency.
Decarbonisation cannot compromise water safety
Lower-carbon hot water introduces a fundamental technical challenge. Heat pumps are most efficient at lower temperatures, while commercial DHW requires careful temperature management for Legionella control.
Water safety must therefore be designed into electrification rather than addressed afterwards. Storage and distribution temperatures, secondary circulation, pasteurisation strategies, outlets and periods of low occupancy all require consideration. This is especially relevant to education because weekends and holidays can create extended periods of limited water movement.
Estates teams should consequently treat water-safety risk assessments and DHW energy strategies as interconnected.
Replacing a 100 kW gas appliance with 100 kW of electric or heat pump capacity is rarely the most intelligent strategy. Heat pumps, direct electric heating and solar thermal behave differently from high-output gas systems. In appropriate retrofit situations, hybrid architectures can combine technologies, enabling lower-carbon generation to address base or preheat loads while another source provides higher temperatures, peak capacity or resilience.
This places thermal storage at the heart of future school DHW design. Rather than generating all the energy exactly when pupils, kitchens or changing facilities require it, a correctly sized cylinder accumulates energy ahead of demand. This can reduce required heat-source capacity and help control electrical peak loads.
Electrical capacity also deserves board-level attention. Electrified DHW increasingly competes with space heating, catering, ICT and EV charging for available power. Existing school electrical connections may constrain all-electric strategies, while unnecessarily oversized systems can increase both capital and operating costs.
Treat gas as a managed transition, not the destination
Many existing schools will not be capable of immediate full electrification. Building condition, electrical capacity, available capital and programme constraints can make this impractical. For sites requiring urgent replacement, modern high-efficiency gas DHW may therefore retain an interim role, particularly where existing infrastructure enables rapid replacement with minimal operational disruption.
Boards should, however, distinguish between tactical replacement and strategic direction. Investment should not inadvertently lock an estate into another generation of fossil-fuel dependence. Designing cylinders, controls and distribution systems for future integration with air source heat pumps (ASHP), solar thermal or electric top-up can establish a practical migration pathway. Hybrid systems can similarly use renewable preheat to reduce gas consumption today while preparing for deeper electrification later.
Consider the whole-life estate and build a phased DHW roadmap
A successful strategy must balance carbon reduction against capital expenditure, operating cost, maintenance, resilience and building condition. Higher education estates face an additional challenge because campuses can combine teaching buildings, laboratories, catering, sports facilities and residential accommodation. Changing utilisation can also leave inherited systems poorly matched to present demand.
The same principle applies across schools and academy trusts. A theoretically efficient system that cannot satisfy peak demand, exceeds available electrical capacity, compromises water safety or creates unacceptable operating costs is not sustainable.
The strongest strategy is therefore to measure, rationalise, reduce and transition. Establish actual hot water demand; identify waste and unnecessary out-of-hours operation; review storage, circulation and controls; assess electrical capacity and water-safety requirements; then determine the most appropriate technology pathway for each building.
For some schools this will mean moving directly towards heat pumps and electric DHW. Others may benefit from solar thermal, hybrid systems or an interim high-efficiency gas replacement. Across a diverse education estate, selecting one technology for every building is less important than establishing a common strategy based on evidence, compliance, resilience and whole-life value.
Ultimately, the goal should not simply be to replace today's hot water plant. It should be to create resilient DHW infrastructure capable of evolving alongside buildings, electrical networks, energy costs and carbon objectives. This transforms hot water from an overlooked maintenance requirement into a manageable component of the education estate's long-term decarbonisation strategy.