Getting smart with system design
The UK’s notoriously inefficient building stock is low hanging fruit for dramatic carbon savings. But today’s multiple equipment plant room requires smart system design if it is to achieve the anticipated savings. Remeha’s National Sales Manager James Porter discusses.
Climate change is arguably the greatest challenge of our times. If we are to prevent further environmental disaster, we must change the way we generate energy and reduce the harmful carbon emissions we emit. Buildings are large users of energy with commercial buildings alone responsible for around 18 per cent of the UK’s total carbon emissions. Heating and hot water generation is one of the greatest single users of energy, accounting for around half a building’s total energy consumption and carbon emissions. So it follows that improving the thermal efficiency of our buildings will help us to combat climate change.
Tighter regulations are in place to ensure that new buildings are designed to use as little energy as possible for heating. When it comes to our existing buildings, some 60 per cent will still be with us in 2050, according to the Carbon Trust. Given that the UK has the most inefficient building stock in Europe, it is hugely important that we refurbish these buildings if we are to achieve our carbon reduction target of 80 per cent by 2050. Legislation like the Energy-related Products Directive and ESOS, which will be introduced later this year, underline the considerable potential for carbon and energy savings from buildings.
A significant proportion of the heating in UK commercial buildings is provided by commercial boiler plant. As heating manufacturers, our challenge is to engineer for the highest possible efficiencies for each application. So, while upgrading any inefficient boilers to flexible, fully modulating, high efficiency condensing boilers is the first step towards a reduced carbon footprint, the recommendation today is to include within the plant renewal budget an additional allocation for control upgrades and the addition of ‘bolt-on’ passive energy saving technologies such as flue gas heat recovery or complementary LZCTs to maximise carbon savings. Consequently, the heating system of the modern plant room resembles a series of complementary building blocks with the condensing boiler at its heart. And while the headline efficiencies of each individual product may be high, without smart system design, there is the risk of an energy performance gap.
So what constitutes a smart heating system design? First on the list are controls. Advanced controls have two functions, optimising the performance of individual components and ensuring good integration for improved overall performance. A smart control such as the iSense, for example, will help a boiler deliver more usable energy to reduce the energy used by a system and its associated carbon emissions. The minimum control strategy should encompass valved zone control, thermostats and timers. Further improvements can be achieved by two-zoned temperature and time control, weather compensation, and sequential control of boilers. Sophisticated building management control systems unite the equipment, maximising overall efficiencies. BMS controls are particularly important on hybrid systems using ‘bolt on’ renewable technology, as by integrating the two technologies they avoid any potential underperformance of the renewable equipment.
In response to the increased specification of hybrid systems to reduce a building’s carbon footprint, manufacturers now offer bespoke hybrid systems that are tailored to provide more accurate matching of an individual building’s heat demand. The control is central to optimal operation; in Remeha’s Fusion Hybrid, for example, a specially-configured, scalable building management control system serves to integrate condensing boilers with gas absorption heat pumps and, on old systems, will integrate this new equipment into the existing system. The control is central to the hybrid system achieving its optimal efficiencies (around 140%) and delivering more usable energy for heating.
Passive flue gas heat recovery technology is another technology that is gaining popularity on commercial refurbishment projects. It works by recovering the maximum useable waste heat from a condensing boiler which it passes back into the system for the benefit of cold water preheat, underfloor heating or space heating. The condensing boiler effectively becomes ‘super condensing’, offering full time maximum combustion efficiencies even on systems designed to run at high flow and return (82/71⁰C for example). For easy installation, integration and commissioning, look for manufacturers who offer prefabricated and preconfigured full time condensing boilers.
Further support for the move towards smarter system design comes in the form of Building Image Modelling (BIM). Many manufacturers now offer 3D BIM files on their products. The 3D format is more easily visualised, helping the project team work more efficiently for good integration at the design phase. The digital information contained in the file also facilitates greater accuracy and savings not only in the design process but throughout the life cycle of the product or system.
The final essential stage in smart system design is commissioning. Hydraulic, combustion and controls commissioning is crucial to ensure high performance, reliability and efficiency of the heating system. Good commissioning will fine-tune the system to ensure best performance and avoid any performance gap between thermal modelling and actual energy consumption.
The UK’s notoriously inefficient building stock is low hanging fruit for dramatic carbon savings. Research by the Carbon Trust estimates that our existing commercial buildings are capable of delivering a 35 per cent reduction in carbon emissions by 2020 with a net benefit to the UK of at least £4bn. Heating manufacturers have risen to the challenge with BIM-supported products that offer not only high efficiencies but increased flexibility of design, with ongoing research and development paving the way for revolutionary solutions to both energy-efficient heating and high hot water demand. With today’s smarter knowledge combined with smarter products for smarter design, we can raise the efficiency of our existing buildings and edge closer to achieving our steep environmental targets.
This article originally appeared in HVR Magazine
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