A huge set of proposals about heat networks was recently put out for consultation. Heat regulation and the implementation of minimum standards for heat networks are welcome. The Heat Networks Technical Assurance Scheme (HNTAS) and Technical Standard 1 (TS1) should provide a robust, outcomes focused framework that improves performance, protects consumers and supports long-term decarbonisation while remaining proportionate and practical. The proposals represent significant advancement, but there are important concerns.
First, HNTAS considers the performance of the network by elements, rather than as a whole. This is understandable to allow different parties to discharge legal obligations, but it should be possible to incorporate whole-network requirements. For example, assessing the energy centre and distribution network independently while also requiring that, all together, they deliver a carbon content of heat within limits.
Furthermore, the proposals place greater emphasis on process compliance than network outcomes, without guaranteeing the delivery of lower carbon emissions and operating costs, or improved system efficiency.
Related to this is a concern about the lack of energy and carbon performance metrics within HNTAS key performance indicators (KPIs), despite heat decarbonisation being a core policy objective. Carbon content of heat limits may be introduced as part of heat zones, but these zones may not cover all networks, especially existing ones, which will usually perform worse.
In addition, heat-zoning proposals state that ‘failure to comply with emission limits could see the removal of zone developers’ rights to further development in the heat network zone’. This is very ambiguous, as it is not definite and could imply that the penalty is to prevent expansion, rather than requiring rectification to continue operating. This must be addressed, and HNTAS is the most straightforward way: carbon performance requirements should be part of HNTAS KPIs.
TS1 does not currently cover ambient loop and fifth-generation networks. This significant gap is acknowledged, but there is no timeline to address it. These systems are expected to play an important role in energy efficiency and decarbonisation, and this gap could create uncertainty and, potentially, discourage investment.
While recognising the need to avoid excessive burdens on smaller operators, CIBSE does not support exempting small networks. Consumers connected to these networks require the same protections as those on larger networks. Instead, requirements could be phased or tailored according to operator capability and network complexity.
Finally, CIBSE supports the establishment of a code manager and technical committees, but it is unclear what provisions will be made to ensure the manager’s independence, accountability and regulatory oversight, particularly by Ofgem. Additional powers, complaints procedures and enforcement mechanisms – including financial penalties alongside certificate withdrawal – are recommended.
The public register should be part of this governance, with comprehensive and accessible information on performance, to allow scrutiny and increase accountability.
UK NZCBS requirements
Buildings connected to a heat network can meet the UK Net Zero Carbon Buildings Standard (NZCBS) if the network meets performance outcomes (below). This ensures a fair comparison with buildings with onsite plant, the heat for which must be low carbon.
- When calculating the building’s energy use against the standard’s limit, the energy used by the heat network (for example, generation, distribution) should be accounted for, apportioned to the heat the building received from the network.
- New networks should have a carbon content of heat no higher than that of heat supplied by an onsite ASHP with a seasonal coefficient of performance (SCOP) of 2.8. This is not very ambitious, so new networks can achieve the limit with heat pumps of higher SCOPs (for example, using waste heat), compensating for unavoidable network losses. As the electricity Grid decarbonises, networks will be expected to deliver lower-carbon heat.
- Existing networks are allowed a higher carbon content of heat, equivalent to that of a network
with a heat pump with a SCOP of 2.8, distribution losses of 20% and parasitic losses of 2%. - Existing networks are allowed to operate on fossil fuels if they meet the carbon content of heat limit and have a committed plan to transition from fossil fuels by 2040. There are already networks in the UK with similar or more ambitious timelines – for example, in Bristol, Vattenfall has committed to install only low carbon new plant and to phase out existing gas-fired assets by 2030.
- Julie Godefroy is head of net zero at CIBSE