Summary
Adveco considers the current recommendations and outlines efficient, lower-cost means of securing sustainable school hot water systems. This can include gas or electric, but to achieve both sustainability and lower costs requires a hybrid approach, such as the award-winning FUSION electric water heating system leveraging heat pump, electric boiler, cylinder and controls to cut energy demands and carbon emissions from schools.
Adveco considers the current recommendations and outlines efficient, lower-cost means of securing sustainable school hot water systems…
According to the National Audit Office (NAO), there are more than 32,000 schools and early learning centres throughout the UK. These sites represent a great variety of buildings in terms of age, size and design, each averaging approximately three buildings. This real estate, of close to 100,000 buildings, represents a considerable source of carbon emissions despite ongoing new build and modernisation programmes.
The requirements for hot water, from kitchen services to basins and showers, can equate to as much as 30% of daily energy demands, so more efficient, and crucially lower cost means of securing water heating services should be a paramount element of school planning before we even consider the advantages of improving sustainability.
The Department for Education (DfE) currently recommends a variety of approaches to school hot water generation, with centralised systems for catering functions which represent a large, single Point of Use (PoU) of hot water, while “design and installation shall prioritise the use of local non-storage (or low storage) ‘point of use’ electric hot water heaters. This is to reduce standing losses from centralised systems and to prevent pipework heat loss, increasing the risk of overheating.”
This approach is driving the specification of heat pumps to support the ‘centralised’ kitchen and then large numbers of POU electric water heaters. The problem is that specifications derived from this advice inherently lead to system oversizing, which equates to greater capital investment and operational costs. A real-world example recently presented to us required a system based around a pair of 50kW CO² heat pumps and a 1500L buffer to provide water for three sinks and three wash hand basins in a primary school kitchen. The 350 pupils would have hot water supplied in classrooms and toilets by PoU water heaters, essentially small boilers above each sink. The capital cost of this specification would be approximately £150,000. If it is assumed that funding allocated to each student is £8,000, this specification at £430 per student equates to a staggering 5% of annual funding. That is simply not good enough.
The drive to adopt this technology is being pushed by zero-carbon goals, but is this even the right approach for school hot water?
First and foremost, heat pumps are not a zero-carbon technology. They have an operational electrical demand, and nothing becomes carbon-free until the grid does. That also includes electric boilers. Better we refer to heat pumps as a low-carbon technology. If an electric system can be engineered to save a little less carbon for a lot less outlay, and it passes Part L of the building regulations, then it is a better design. For this reason, electric only is being stipulated in essentially all new school buildings. For the large proportion of schools operating existing buildings, the push is clearly to emulate this trend and transition to electric. Even and the macro government level, the UK is incapable of making the jump to net zero in a single bound, hence the imposition of carbon budgets to deliver a gradual step-by-step process.
The same must be the case for schools. Faced with budget constraints and ageing buildings, there is going to be resistance to change, especially when you start comparing the costs of electricity versus existing gas, with electricity varying from four to five times that of gas in recent years. That’s a big hit to ongoing budgets if not correctly factored in. This reticence to move off gas led the government earlier this year to relax the timeframe for phasing gas out, meaning new gas appliances can continue to be installed until 2035, although the expectation is that from next year, all new gas water heaters must be able to accept a blend of natural gas and hydrogen. Current generation units already offer this option without requiring hardware updates, so the industry is well provisioned to meet demands. With improved efficiency comes appliance longevity, meaning there will still be many operational gas boilers in 2050. That immediately greys the line for net zero in 2050, but the implication is that by the 2040’s hydrogen replacement will be advancing rapidly nationwide, and government schemes to switch over to hydrogen appliances will be in place.
Modernising gas water heating through retrofit shouldn’t be reviled in terms of sustainability but rather be seen as a necessary stepping stone to affordably transition the large proportion of school buildings towards true net zero by 2050. There is no reason for new buildings to change path. They should continue to be all-electric, but to make this viable, and also enable schools that choose to transition faster to electric, requires a move back to better engineering instead over choosing lower carbon regardless of cost strategies.
Equipment selection, whether electric or gas, should be made based on performance, safety, environment, but also critically on capital cost and ongoing running costs. Would you rather pay £150,000 for a CO² heat pump and PoU system, or gain a well-designed hybrid electric system that can do the same job and at just one tenth the cost? A system that could offset as much as 70% of the costly direct electric energy demands by using a heat pump more efficiently to supply pre-heat, rather than direct high-temperature heating. This is the thought process behind hybrid design, which takes the best of low-carbon technologies and combines them to gain greater effectiveness. Despite initially seeming a more complex approach, it allows for smaller, more compact appliances to be deployed in pre-sized arrangements, and this allows for a reduction in costs, simpler installation and better daily management from the necessary integrated controls. Adveco has been championing this approach for several years, beginning with bespoke iteration, which evolved into the multi-award-winning FUSION. By combining an electric boiler and storage cylinder, FUSION offers an indirect water heater configuration that, with balancing controls, can be integrated with a range of heat pumps to preheat water and offset much of the boiler energy demands, since it is required to simply top up heating and meet extra peak demands. An immersion can also be included to provide a backup heating option, ensuring there is no single point of failure where hot water services are deemed operationally critical.
FUSION has been conceived to support basin-led demands, whether in a new build property or one seeking to transition from gas to electricity. It is a centralised system, so would be located in the existing plant room or can be installed within a packaged plant room to take advantage of unused exterior space and free up more internal space, to extend a classroom, for example. This compact, preconfigured approach gives more options and, crucially, is how systems can be delivered at a much lower cost.
As with the more expensive systems, FUSION uses the same grid electricity source, so both options will ultimately become carbon neutral at the same time.
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