Modern Building Services

FEATURE COMMISSIONING 18 MODERN BUILDING SERVICES JUNE 2022 U pdates to the Approved Document L of the Building Regulations, which sets the standards for the energy performance and carbon emissions of new and existing buildings, were published in December. The revisions include a formalisation of existing commissioning practices with the requirement to provide building owners with information on the energy performance of installed building services. Approved Document L introduces a new metric, a primary energy rating target that sits alongside the existing emission rating target. This takes into account both the amount of energy required to produce the fuel in the first place as well as the energy used within the building to generate a more precise figure for total energy use. The target value for both metrics will be set according to the national building specification. As collating information and carrying out commissioning are already requirements of Building Regulations, the assumption is that this should not require additional work. Why, then, the need to tighten the process? It’s all part of the government’s roadmap to help move the UK towards its 2050 net-zero target by significantly improving the energy performance of existing buildings. Energy-efficient and low-carbon heating and hot water technologies have a part to play inmeeting the challenge, which is why direct-fired water heaters are also included in the latest updates to Part L. From 15 June, all direct-firedwater heaters must achieve aminimumheat generator seasonal efficiency of 91% (GCV) for natural gas and 92% (GCV) for liquefied petroleumgas (LPG). In practice, this will effectively begin the phase-out of non-condensing direct-firedwater heaters in favour of more efficient condensingmodels. Condensing water heaters like the Andrews Water Heaters MAXXflo EVO, ECOflo or SUPAflo EVO are all easily capable of achieving the tighter efficiency standards. But like all heating and hot water technologies, they will only perform as intended if they are installed and maintained correctly both to the manufacturer’s recommendations and to the specification. And it’s the commissioning process that ensures that all installations – from direct-fired water heaters to condensing boilers to air source heat pumps – are set up correctly from the outset and continue to perform well throughout their operating life. What’s more, as the heating system design evolves and becomes more complex, integrating traditional and renewable heating equipment, the more important commissioning – and a good control strategy – becomes to ensure that the technologies operate optimally and in harmony. So what does the process involve? A thorough commissioning process consists of a sequence of installation, safety, operation, performance and failure checks that are carried out by certified professionals – typically the manufacturer’s specialist engineers. A robust commissioning procedure will identify any potential issues or snags at the outset and enable them to be caught and fixed prior to handover. Take boilers. Firstly, a series of detailed installation checks are completed to ensure that the equipment is installed according to the design specification and manufacturer guidelines. Comprehensive operational testing then confirms that the equipment and system respond correctly in all conditions. Full performance testing then ensures that the boiler performs as intended. A robust commissioning process will identify any potential issues or mistakes at the outset and enable them to be caught and fixed prior to handover. Equally importantly, commissioning provides certainty that the product and system will operate safely. The comprehensive checks that form part of boiler commissioning will ensure both the predicted high performance from the equipment and its safe operation. These safety tests confirm that it responds in a safe and controlled manner during failures or shutdowns. For specifiers and building services engineers, commissioning provides assurance that the specified output, efficiency and emission levels will be achieved. Andy Green, Baxi’s Technical Director, discusses the vital role of commissioning in driving down emissions and mitigating soaring energy costs. Boosting building energy performance