Pipes & valves

Pipe insulation for heat networks

Kingspan Insulation urges installers looking to implement heat networks to consult CIBSE’s revised code of practice document in order to achieve energy efficiency and carbon savings


he move towards a net zero carbon-built environment is significantly changing how we heat our buildings, requiring the industry to adapt to new approaches and technologies. Heat networks are at the forefront of this change, and to support specifiers, engineers and installers looking to implement these schemes, CIBSE has now published a revised version of CP1 Heat networks: Code of Practice for the UK (2020).

The updated document includes a greater focus on how to insulate system pipework within buildings (secondary pipework), both to limit energy usage and to guard against overheating. This includes new minimum insulation thicknesses and guidance on how to ensure insulation continuity across the full system. It is important that project teams familiarise themselves with these requirements, and the benefits of installing more thermally efficient pipework insulation, to get the best results when designing these systems.

What’s new in CP1 (2020)?

At over twice the length of the 2015 version, CP1 (2020) provides much more detailed guidance on how to deliver heat networks. The document includes a total of 540 minimum requirements for different aspects of the system and looks to address oversizing issues by defining the expected energy demand per dwelling. In addition to these changes, there is also a more rigorous process for documenting and benchmarking system design, installation, commissioning and performance. This includes checklists which must be completed by all parties and are fed into evidence packs, providing a clear audit trail which supports long-term operation and maintenance.

Whilst CP1 (2020) is a voluntary document, the Department for Business, Energy and Industrial Strategy (BEIS) has indicated an intention to legislate around it in the current parliament and local planning codes may also require an assessment when developing a network.

Pipe insulation requirements

Objective 3.9 of CP1 (2020) specifically addresses secondary pipework, setting out a number of key criteria, including minimum pipework insulation requirements. Unlike other pipework insulation specifications, such as BS 5422:2009 and the Energy Technology List (ETL), which specify maximum permissible heat losses per pipe size, CP1 (2020) instead provides a table of minimum insulation thicknesses for phenolic and mineral fibre pipe insulation at different pipe diameters. In most cases, these are set at 50 mm.

Keep in mind that these thicknesses should not be treated as a recommended specification. CP1 states that a well-designed heat network servicing a multi- resident building should be able to achieve a heat loss of less than 50 W/dwelling. In practice, this is only likely to be achievable using enhanced pipe insulation

specifications. This is why many ESCo’s (energy services companies) heat network schemes already require thicknesses greater than those within the revised CP1. It should also be noted that phenolic insulation has a lower thermal conductivity than mineral fibre and this can also have a notable impact on system performance. For example, modelling on 60°C pipework has shown that heat losses increase by between 30% and 39% when the CP1 (2020) minimum mineral fibre specification is used in place of its minimum phenolic specification. To address these complexities, CP1 (2020) therefore requires calculations for heat losses from pipework to be carried out at the feasibility stage (Stage 2) and a detailed insulation specification at the design stage (Stage 3). This approach should allow the pipework insulation specification to be carefully tailored to the performance targets for the overall network.

CP1 (2020) also highlights the importance of maintaining continuous insulation and vapour barriers across all system components including valves, flanges and fittings and recommends the use of “rigid low-conductivity inserts” for pipe supports. Poor detailing in these areas can significantly undermine overall performance. For example, calculations show that a single 4” valve could allow 2240kWh of additional heat loss per year on a system operating at 75°C for 8,760 hours. By comparison, the same valve insulated to an ETL specification allows just 153kWh heat loss.

Effective networking

Heat networks are set to grow significantly in the coming years, both in terms of the overall number of schemes, and their size and complexity. CIBSE CP1 (2020) provides a useful framework for project teams, and by engaging with its recommendations and going beyond the minimum requirements, it should be possible to deliver schemes which provide lasting energy and carbon savings.

Available for both standard and non-standard pipe diameters, Kooltherm insulation provides an energy-saving and thermally efficient solution for secondary pipework

20 August 2021


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