In part one Adveco considered the challenge of adopting a net zero approach to UK care home operations. In this concluding part, we consider how combining new and existing technologies in a hybrid system could be the best current option for the care sector…
Part 2- Embrcing Hybrid Systems
For buildings 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 a better hot water design could help avoid. As a result, specifications are being revised back to gas when connections are available.
Reasons cited in the research for reverting to gas included it being much simpler, familiar, and cost-effective to replace and run. 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.
That said, heat pumps do have a valid role to play, but for water heating, they need to be used as part of a wider process to ensure cost-effective, efficient operation. Known as hybrid systems for water heating, the approach is particularly relevant to buildings in which there is already a gas connection. Hybrid systems will require two heat generators and two energy connections, one of which being an environmental heat source such as an ASHP for preheating cold water up to 55°C as it flows into the system. This is more than achievable for most heat pumps using current R-32 refrigerant. There are ASHP units capable of higher +70°C temperature outputs which use propane as a refrigerant. Whilst attractive on paper, the initial generation of products in this class are larger, heavier and more costly. In trials, efficacy at lower ambient temperatures drops steeply, meaning greater electrical input is required with once again operational cost implications. There have also been concerns cited by BESA relating to a lack of regulations relating to the transit and use of propane heat pumps given the flammability and volume of refrigerant housed inside the appliances. The smaller, compact, and lower-cost R32 ASHPs are currently the better option when it comes to maximising efficiency and reducing the energy required to run an ASHP unit.
This warmed water is then fed into a cylinder where a second heating source tops up the water temperature to a safe 65°C for use throughout the building. This top-up can come in the form of a gas water heater, gaining very low operational costs, but a less meaningful reduction in carbon emission, typically around 30%. To maximise emission reduction, the preferred option is to deploy an electric boiler for a truly carbon-neutral water heating application.
Electric boilers are a versatile option, compatible with existing systems and pipework, they offer a compact, easy-to-install and resilient alternative to gas. Like solar, electric boilers also operate silently, an important consideration for resident comfort. Although electric boilers will be subject to higher running costs than gas, the application of the technology in a hybrid system, plus smart controls for balancing a system will maximise efficiency and minimise energy demands. The balance of carbon reduction versus operational costs should be more than acceptable and capital investment can be relatively low, especially compared to the ASHP.
For care homes with heavy, daily demands for hot water, a more bespoke system is likely to be required, although the basic premise remains the same, using ASHP preheat and a secondary energy source, preferably electric. It may also be possible to integrate solar thermal technology as a mid-heat to further cut energy demands, offset operational costs and reduce emissions
Silently capturing solar energy as heat through collectors on rooftops and transferring it to a storage tank for heating water, solar thermal is a true renewable. Solar thermal systems are well-suited to residential care with high hot water demands and offer significant cost savings on hot water heating. Given the propensity for gas installations, the number of recent care home projects incorporating solar thermal installations has been surprisingly low (just 3%) given the proven nature of the technology.
Capable of offsetting at least 30% of daily gas demands for water heating for notable carbon emission reduction and operational cost savings, the expectation is for the adoption curve for solar thermal to increase. This should be 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 systems for care home water heating. The much-improved return on investment from solar thermal should also go a long way to offsetting concerns about the upfront costs, with systems paying for themselves in less than a decade. The gains are also immediate, so are helpful in terms of demonstrating actual investment in renewables.
With the growing awareness of environmental responsibility, care home owners/operators are at a crucial juncture in their approach to building and water heating as they are challenged to address the use of traditional gas boilers in favour of these ‘renewable’ alternatives. So how can care homes better embrace sustainability moving forward?
Each 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 care homes to net zero by 2050 and beyond.
Visit Adveco’s healthcare pages for more information on water heating technology for hybrid systems.
