Adveco discusses the best options for water heating to enable more sustainable schools now and in the future…
With more than 32,000 schools in the UK and a business-critical need for heat and hot water, the education built estate has historically represented a significant source of carbon emissions. Unsurprisingly, government expectations have, and will increasingly place the onus on the education sector to lead change from fossil-fuel dependency through the adoption of sustainable building practices and renewable energy. Schools will then integrate sustainability and energy education into their curricula, fostering a culture of environmental responsibility among students. However, it is estimated that at least 70% of the existing education sector building stock will still be in use by 2050 creating a huge challenge in terms of refurbishing school buildings with energy-efficient technologies.
As a hot water specialist with a long history of working with schools, Adveco has considerable experience dealing with the numerous challenges they face securing resilient, guaranteed hot water at a realistic cost. Traditionally the energy source of choice has been gas, but over the past five years new and lower carbon options have given greater choice but also presented new challenges. Recently commissioned research on the adoption of technology shows that gas-fired water heating continues to dominate, accounting for 90% of new or refurbished school systems between 2019 and 2023.
Although all lower carbon technologies (electric water heating, heat pumps and solar thermal) are showing increasing specification, adoption rates have remained generally low, despite available funding for sustainability projects. Of these low-carbon technologies air source heat pumps have exhibited a more rapid uptake in recent years, but the number of sites deploying the technology remains lower than expected and were almost exclusively new build. When questioning consultants and contractors, heat pumps will always be specified for heating, but most are realising that heating and hot water in many cases are best left separate, which from a design perspective makes absolute sense.
Hybrid hot water systems are being specified for new build, but when dealing with retrofit the majority of those questioned confirmed that while initially leaning toward heat pumps, they were encountering problems with cost, infrastructure and design. The cost has been a particular hurdle for schools, not only in terms of capital investment but especially concerns over operational costs which climb when transitioning to electricity. At the time of writing, gas costs 5.48p per kWh (kilowatt hour), versus electricity, at 22.36p per kWh which can lead to substantial operating costs, especially in school buildings with high hot water demands. Of more concern is that electric water heating can place a significant additional load on a building’s electrical system.
In school settings with substantial electrical usage, adding high-demand electric water heaters and heat pumps can strain the system. From our experiences, we are already seeing projects adding extremely costly upgrades to electrical infrastructure as part of refit, something better hot water design could help avoid. As a result, specifications are being revised back to gas when connections are available. Reasons cited included it being much simpler, familiar, and cost-effective to replace and run, and new generation appliances were seen to be more efficient with lower carbon and NOx emissions. Most are also 20% hydrogen-blend ready out of the box so offer a future-proof option for the next 15 to 20 years.
Given the propensity for gas installations, the number of projects incorporating solar thermal installations was also surprisingly low given the proven nature of the technology and the opportunities it presents to offset at least 30% of daily gas demands for water heating for notable carbon emission reduction and operational cost savings. Tertiary education was far more open to the integration of solar thermal. With universities tasked with developing green campuses energy-efficient buildings, and renewable energy installations, the expectation is that by 2026 they should be providing sustainability models and strategies that will be filtered to schools and other education facilities. The expectation therefore is for the adoption curve for solar thermal to increase in line with that seen in heat pumps, as both offer sources of necessary pre-heat to meet the complex high-temperature needs of hybrid school water heating systems.
So how can schools better embrace sustainability moving forward? Each school building creates new challenges and opportunities for low-carbon water heating. Location, infrastructure, size and usage all inform hot water sizing, design and technology choice. To gain efficiencies that meet demand, whilst cutting emissions and costs requires a thorough understanding of the building and its use. To this end, Adveco advises metering water flow for accurate demand modelling. It’s a fast, non-invasive activity which is extremely low-cost, yet pays dividends in terms of reduced capital expenditure and accurate modelling of future operational costs. It allows for improved planning and better decision making whether opting to stay on lower-cost gas, adding solar thermal offsetting, or transitioning over to electric water heating with the options of heat pumps or solar to better manage energy consumption and increase carbon reduction. All are fair choices that currently offer a means to bridge to future technologies, such as green gas and new variants of high-efficiency, high-temperature heat pumps which will take schools to net zero by 2050 and beyond.
