CP1 (2015) represented a major step forward for the industry. It brought everything together in one place and introduced the concept of “minimum standards”. It has also made it quite clear that detailed design was only one part of the story and set out distinctly the different stages in development.
For FairHeat, as a company focused exclusively on Quality Assurance, CP1 has been an invaluable tool. Having Minimum Standards enables an assessment as to whether these have been met and puts in place an imperative for change where they have not.


In addition, setting out clear requirements at each stage has highlighted that Quality Assurance has to start much earlier in the project lifecycle. This has helped enormously with ensuring that poor decisions are not baked in at the outset (e.g., ensuring that an assessment of pipe routing within buildings is carried out before the architectural design for the building is locked down).


In many ways CP1 (2015) has enabled FairHeat to exist, as it tacitly created the requirement for an entity to ensure compliance with minimum requirements.


CP1 (2015) proved to be a catalyst for major change in the industry and it is doubtful that we would have been able to drive the sort of successes we have had without them. Today, we have a large number of high-performance schemes, such as the one below, that are largely a product of the CP1 (2015) initiative.

CP1 (2020)
Energy centre heat meter data showing 60C stable flow temperature and low return temperature

If there were criticisms of CP1 (2015), then they were primarily that:

  1. Lack of quantitative measures against minimum requirements and, associated with this, lack of performance metrics
  2. A focus on district heating scale as opposed to building level performance
  3. Heavy bias toward CHP systems
  4. An absence of any integral mechanisms for assessing compliance

CP1 (2020) represents a major step forward with respect to addressing these issues. It also represents an important triumph for the industry in regard to defining itself as an industry. Around 51 experts were able to come together and agree over 540 Minimum Requirements and 110 Best Practices. This indicates that the heat network market is maturing.


The team at FairHeat have participated in the CP1 steering committee, playing an important role in the changes you see today. In particular, the business has pioneered a number of the processes and techniques that have now become minimum requirements within CP1.

Gareth Jones, Managing Director at FairHeat, and Mike Ridge, Principal Engineer at FairHeat, are steering committee members.

What are the key changes CP1 (2020) will bring?

  • It’s much bigger! – 240 pages compared to the original 92 which goes to show that this more than an update.
  • A new 7th goal in addition to the original 6 – Additional focus of providing customers with affordable heat and a reliable service
  • Compliance, compliance, compliance! – With the statement of applicability and the new checklists, the new version seeks to fill the biggest gap from the original document – what is a CP1 compliant heat network? In conjunction with performance metrics, this makes the document much stronger as it can be used to hold designers, installers, commissioners, and operators to account. FairHeat drove the development of many of the performance metrics that are now within CP1 and, in particular, championed a transition from a percentage-based metric to absolute kWh/dwelling / kWh/kWp. This is important as the metric is not impacted by consumption and allows assessment at the point of handover. The minimum requirement is now 876 kWh/dwelling per year and a best practice target has been set of about 550 kWh/dwelling per year.
  • The transition to low carbon technologies – 13 mentions of heat pump in the 2015 document, there are now 68! But the change relates not only the heat generating technologies but also the infrastructure to enable them, with a greater focus on lower operating temperatures through better design and operation.
  • Domestic Hot Water – Over the last few years FairHeat has championed a reduction in domestic hot water temperature to 50°C for systems with instantaneous DHW HIUs. Furthermore, FairHeat has been instrumental in introducing minimum requirements with regards to hot water delivery times for resident comfort, a requirement that DHW should be delivered to the tap at 45°C within 45 seconds a standard element within FairHeat’s design supplement since 2016. It is gratifying to see that both of these requirements are now minimum requirements in CP1 (2020), as it is fundamental to enabling lowering operating temperatures (and improved heat pump performance as a consequence) and improving customer outcomes.
  • Pipe Sizing – There has been a fundamental change in approach to diversity and pipe sizing methodology in CP1 (2020):
    • Rather than having a range of diversity curves to choose from, there is now a single approach, based on a correct utilisation of DS 439 (with a fully worked example in Annex D)
    • There is a generic shift toward using velocity limits, rather than pressure constraints, for sizing pipework in risers, laterals and terminal runs. This provides a better whole life-cycle approach to energy use.
  • BESA HIU Standard – Best practice states that where indirect HIUs are specified, the BESA HIU VWART results should be used. There is also reference to using BESA data for demonstrating low standby losses. We are delighted that this has made it into CP1 (2020), as this is an excellent example of a consumer led test standard, governed by a Steering Group of industry stakeholders. We are also proud of our role in this, as the original test standard was developed by FairHeat (specifically by Gareth Jones, Managing Director of FairHeat, Tom Naughton, Associate at FairHeat, and Martin Crane, Managing Director of Carbon Alternatives, who worked with FairHeat on this).
  • Oversized systems – Based on the work of Huw Blackwell, Principle Associate at Anthesis, we welcome that the guide now states that for typical dwellings (e.g. 3 bed/2 bathrooms) there should be no need to provide more than 35 kW of instantaneous domestic hot water. The ability to apply both space heating and greater domestic hot water diversity will result in a reduction in oversized systems. Through the analysis of extensive dwelling-level heat meter data we have recommended a similar approach to sizing.
  • Some big changes in minimum requirements – For example, insulation thicknesses are much greater and water quality is much tighter than in 2015.

Acceptance Testing is significant to CP1 (2020)

Acceptance Testing is one of the outlined major changes in CP1 (2020) and it represents a significant change in the approach from CP1 (2015).

FairHeat have been developing Acceptance Testing as a methodology over the past five years, since we first trialled it as part of a BEIS funded SBRI project in 2015. What we found then, and have continued to find since, is that validation of performance is critical to ensuring that heat networks perform well in practice.

CP1 (2020)
Low flow return temperature was achieved due to 100% Acceptance Testing

CP1 (2020) has taken FairHeat’s learning and built it into the regulation as an integral mechanism. It has also made two other key changes which facilitate this approach:

  1. The concept of a Statement of Applicability, with clear performance requirements specified from the outset
  2. Added quantified metrics with minimum requirements

Taken together, this all provides a platform for assessing whether or not CP1 (2020) requirements have been met – in an outcome-based way. Critically, a number of these metrics are focused on customer outcomes (e.g., Domestic hot water delivery times and maximum heat network losses). As such, this provides a platform for not only assessing whether the network performs well from an efficiency perspective, which is critical from a cost and carbon perspective, but it also provides a basis for ensuring good outcomes for end users – comfortable residents – which is fundamental. It might seem subtle, but the switch to an outcome based, verification approach is a fundamental change. It is also timely, as it allows for Quality Assurance, which is fundamental as we move toward regulation of the industry.