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Energy efficiency
Part L2 uplift – what does it mean
From 2025, the Future Homes and Buildings Standard (FHBS) will deliver new non-domestic buildings that are zero-carbon ready and built to the highest possible fabric standards. Griff Thomas from GTEC explores the first step in achieving this goal, the interim uplift to Part L of the Building Regulations and explains what commercial building services engineers need to do to comply
T
he built environment accounts for around 40% of greenhouse gas emissions in the UK – something that needs to be urgently addressed to align with our Net Zero commitments. In the Clean Growth Strategy, the Government set out an intention to revise standards in non-domestic buildings to ensure they are zero carbon ready, including opportunities to promote low carbon and high energy efficiency heating, ventilation and air conditioning systems. The result is known as the Future Homes and Buildings Standard (FHBS), a document designed to complement uplifts to the Building Regulations to achieve a significant reduction in carbon emissions from 2025.
The first step to zero carbon
Uplifts to the Building Regulations came into force this year, acting as a first step towards the FHBS. The new regulations require non-domestic buildings to achieve a 27% reduction in CO2 compared to 2013 standards – the more ambitious of the two options that were consulted on. The changes are set out in ‘Approved Document L,
Conservation of fuel and power, Volume 2: Buildings other than dwellings’ (Part L2). The new Approved Document contains new minimum standards for both new buildings and existing buildings that are being modified or extended.
New performance metrics
Three performance metrics for non-domestic buildings were proposed in the government consultation, all of which have been adopted into the new Part L2: • primary energy • CO2 emission targets • minimum standards for fabric and fixed building services.
Primary energy is an energy efficiency measure that includes regulated energy, such as lighting, heating and hot water. The calculation considers factors such as the efficiency of the building’s heating system, power station efficiency for electricity and the energy used to produce fuel and deliver it to the building.
Around 80% of respondents, including a large
proportion of building designers and engineers, raised concerns about the use of primary energy as a performance metric. But despite this, it was adopted on the basis that it will improve our use of national energy resources and prioritise energy efficiency across all heat sources. The measure is due to be consulted on in 2023 before the FHBS is implemented in 2025.
Improved building standards
Part L2 covers a wide range of energy efficiency improvements. These include new minimum standards for: • Fabric elements – most types of new window, including roof and curtain walling, must achieve a U value of 1.6, compared to 2.2 under the 2013 regulations. Minimum U-value for new walls is 0.26W/m2 K, compared to 0.35W/m2 K previously. • Fixed building services – as in new domestic buildings, wet space heating systems in new commercial buildings must be designed to operate at a maximum flow temperature of 55°C. • Building automation – BACS is now mandated for buildings with HVAC systems over 180kw. • Airtightness - CIBSE’s TM23 is now the single approved methodology for testing the airtightness for non-domestic buildings. What new technologies will help to meet Part L2? Heat pumps, heat networks and solar PV will play an increasingly important role in achieving
increased efficiencies and reducing emissions from commercial building services. R&D and innovation in this area in recent years has led to the development of a wide range of ultra-high efficiency heat pumps designed for industrial and commercial applications or integration into heat networks. CIBSE has played a key role in influencing the
Government’s proposals; a partnership that has been largely supported across the industry. Technical guidance produced by CIBSE covering large heat pump installations in commercial settings will be available in 2023.
How can installers prepare?
These changes mark a momentous step forward for the energy efficiency in commercial and non- domestic buildings. System design is key, including heat loss
calculations, correct sizing of heat emitters, pumps and pipework. Building services engineers and designers should undertake relevant training to ensure they are up to date with the latest compliance metrics and design principles. Level 3 heat pump training is ideal for those taking
their first steps into heat pump installations, covering domestic and small commercial schemes. A good understanding of heat loss calculations is essential – correct sizing not only ensures compliance with the new Part L2 but also helps building operators to make savings today, while preparing their heating systems for future technologies.
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