Water heating will account for a significant portion of a building’s energy consumption, ranging from 15-40% depending on its use. This makes hot water both familiar and often business critical, so reducing hot water demand and implementing efficient heating methods translates to substantial energy savings and emission reductions that have recognisable advantages to its users across the education estate.
The most consistent issue we see in school hot water systems is oversizing, whether through a lack of understanding of application design or concerns over providing suitable backup to ensure system continuity. The result of oversizing is however always the same, unnecessary capital costs for system supply, installation and ongoing excess operational costs associated with higher energy demands and therefore greater carbon emissions.
As schools plan to adopt greener building operations, replacing old gas-fired systems with like-for-like electric is another guaranteed way to gain an oversized system, but it can also lead to under-sizing if storage is not large enough to account for low, slow heating associated with heat pump based electric systems.
Getting that balance right is critical as the per kW price of electricity remains much higher than that of gas. Plus, if not optimised, the system will generate excess capital costs in terms of size and number of water heating appliances and complexity of installation. That in turn can also become more time-consuming and disruptive, a cause for concern if refurbishment work is scheduled into the narrow window afforded by the school holidays. More importantly, if the new electric system is oversized the required amperage could exceed a building’s available electrical supply. Bringing new supply in means excavating, possibly as far as the substation, which will see costs soar, or even stall the project.
This can best be avoided by collecting live onsite data. A valuable, non-invasive, and low-cost exercise, hot water metering for schools should be undertaken to assess actual usage, including time and duration of peak demands which is critical for correct sizing. When assessing a school’s domestic hot water (DHW) usage, it is important to also establish basic information on energy sources, be they gas or electric, planned use of renewables such as heat pumps or solar thermal and the level of system redundancy and backup. This helps steer the design of the replacement system.
Adveco provides a comprehensive metering service that for very low investment creates an accurate, cost-effective system design that can deliver carbon reductions and meet all your building’s hot water demands. This provides the data you need to evaluate any upgrade and a benchmark against which to explore various alternatives such as high-efficiency gas or electric boilers, heat pumps, and solar thermal systems, which can be deployed in isolation or as hybrid systems. It also enables consideration of other factors like budget, space constraints, and fuel availability, which all factor into launching a sustainable strategy for a building.
Doing this as a first step not only gives you access to expert guidance from qualified professionals, it can also help secure the necessary support from within the organisation to push for government grants. This is key because a well-designed low-carbon electric system still has several cost implications. Correct sizing with metered data can reduce the costs of purchasing and installing new hardware, potentially saving tens of thousands of pounds depending on the scale and complexity of the DHW application. Recognising a need for lower-cost electric systems, Adveco has developed the award-winning FUSION range, combining an electric boiler, a specially designed cylinder and pipework that is fast to install and resilient to operate. Iterations with a monobloc air source heat pump deliver a reduction of up to 71% in carbon emissions over equivalent gas-fired systems. These smaller systems help avoid the need for increased electrical supply and excavation works that can run into hundreds of thousands of pounds! Despite this, operational costs do climb and will continue to do so while grid electric prices remain much higher than those of gas grid supplies
The application of renewables can go a long way towards solving this, despite extra system complexity and upfront capital investment. A balanced use of renewables, whether heat pump, solar thermal or a combination of the two can offset much of the grid energy demand needed to safely operate high-temperature water systems demanded by school buildings. Adding solar thermal to a system is a proven method for offsetting as much as 30% of the annual energy needed for heating or cooling water in building systems, thereby actively cutting operational costs. It also readily lends itself to school buildings which have large, often underused roof spaces that could easily accommodate the technology.
The advantages of hot water metering for schools are clearly defined in the reduction of carbon emissions, and, as work continues to decarbonise the electricity grid, the emission reduction figures supplied by the new hybrid system design should improve considerably, adding further environmental value to the system throughout its operational lifespan.
