Get in control
We have the technology to raise thermal efficiencies – the challenge now is to deliver the energy savings. James Porter, National Sales Manager at Remeha Commercial, looks at the role of intelligent controls in achieving high performance heating
Running a profitable business is never easy, but even though environmental legislation might add to the challenge, we have a duty to protect our planet through manufacturing best practice. In the heating sector, manufacturers have produced a wide range of high-efficiency, low-carbon technologies capable of significantly reducing the energy consumption of heating in buildings and its associated emissions. Unfortunately, the headline efficiency figures quoted by manufacturers are not always achieved in real life scenarios. So our focus now must be to engineer to achieve the highest energy standards at all times and under all conditions. And one of the most successful means of achieving best performance from heating, from individual high efficiency boilers to more complex low-carbon hybrid systems, is to include intelligent controls.
In the UK, commercial boiler plant provides the heating for a high proportion of our non-domestic buildings. Replacing inefficient boilers with high efficiency models can quite literally transform the performance of a building. Condensing technology is particularly efficient, with manufacturers quoting figures of up to 98% on their fully-modulating condensing boilers. But how often do condensing boilers actually achieve these potential efficiencies in real life scenarios? Not often enough. This is because many of our existing buildings, which offer huge scope for improved efficiency, typically have in place an LTHW system sized on high flow and return temperatures (generally 82/71°C flow and return), which prevents the boiler from fully condensing and achieving the greater savings.
Adding controls will enable boilers to operate at lower temperatures and at part load, maximising condensing and helping the equipment work more efficiently and for longer. The minimum control strategy should encompass valved zone control, thermostats and timers. According to the Carbon Trust, even lowering set points by just one degree could bring a reduction in an annual heating bill of up to eight per cent. We estimate that controls can lift efficiencies by between 10 and 12%.
Controls can also help boilers adapt to a number of variants which would otherwise affect performance, including the weather and occupancy. Weather compensation controls help the heating system adjust to the rise and fall of external temperatures and match more accurately the heat demand of the building. This reduces energy use and creates a more comfortable internal environment that in turn encourages greater productivity for financial profitability. Weather compensation is especially effective at improving efficiency on boilers operating under part load conditions, making it particularly relevant to the UK’s mild climate, where boilers operate at part load for around two thirds of the year.
Good design and smart controls can overcome the second factor influencing boiler system efficiency: occupancy. Installing boilers in cascade operation and using a sequential control is an effective means of improving the modulation of the boilers and helping avoid energy waste.
Achieving a relatively steady temperature is always a priority in buildings, but controls are key where maintaining a precise, consistent temperature is a critical requirement. A case in point is Aspire Charity which provides support to 40,000 people with spinal injuries. The water in the pool at its Middlesex-based Leisure Centre must be kept at a constant 31°C at all times for the safety and benefit of its users. Installing six Quinta Pro condensing boilers in cascade with upgraded controls has proved the perfect solution to maintaining the correct temperature in the pool. What’s more, the high performance of the system has helped the Charity save £7,000 in energy bills in just six months.
At the National Library of Wales in Aberystwyth, a similar requirement for reliable, closely-controlled, constant temperature was again helped by the strategic control of high efficiency condensing boilers. The Library’s main concern was for greater resilience and reliability of the heating plant in order to protect and conserve its priceless artefacts and collections. The installation of three Gas 310 Eco Pro boilers in the main boiler room and three Gas 610 Eco Pro boilers in the book stack boiler room has successfully achieved the all-important, closely-controlled temperatures whilst delivering a step change to the environmental performance of the Library.
For hybrid systems combining renewable equipment with condensing technology, good control is again fundamental to achieve the highest potential efficiencies. Controls help the various components to integrate well, avoiding the possibility of any underperformance from the renewable technology. At Lake House Care Home in Oxfordshire, the bespoke hybrid system designed to meet its high demand for heating and hot water consists of three Fusion gas absorption heat pumps supported by two condensing Quinta Pro boilers in cascade and a 1,000 litre twin coil buffer, all fully-integrated and controlled by a specially-configured Building Management System. The BMS is central to the outstanding performance of the hybrid system which is achieving efficiencies of 140% and gas savings in the region of 30%.
If we are to meet our legally binding target of an 80% reduction in carbon emissions by 2050, it is important not only that manufacturers and specifiers collaborate to ensure that the most appropriate products are used in a particular project within the budget framework, but that these products are operated in such a way that they achieve their full savings potential. As well as good design, installation, control and commissioning, we should add good training as educating building operators on how the system operates can help maintain accurate control settings. Using controls with a common platform and protocol also makes operation simpler and any snags easier to detect. At the end of the day, whether it’s a 30kW wall hung boiler, a multiple-boiler system or a 2MW CHP supported by large condensing boilers, the philosophy should be one and the same: control, control, control.
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