The “Heat Networks Code of Practice” for the UK, a guide produced by Chartered Institution of Building Services Engineers in association with the Association for Decentralised Energy, has been, since its publishing in June 2015, the go-to document for consultants when advising clients on all things District Heating.
The guide does a terrific job in raising issues and considerations that parties are sometimes blind to, either by lack of technical knowledge or unawareness of the most far-reaching implications of their decisions.
It is time to be a bit more ambitious in the scope of the Code. With a new revision expected, CIBSE are taking consultations from the industry on how to improve the Code.
We think the Steering Committee should consider the following for a more practical, useful and effective Code:
Heat Loads, Diversity & Benchmarks – To include guidance on peak & annual heat loads and offer benchmarks for different types of dwellings, commercial units, etc. This being the single most important factor in District Heating Network design, it should not be largely left to designer’s criteria. Although the argument can be made that “each case is a case”, the reality is that, particularly in London, large developments have shown that peak load conditions are a fraction of what was originally anticipated. Benchmarks, even if slightly conservative, should help put a cap on the oversizing that has historically taken place.
Design examples – To include example mechanical layouts for all circuits of the network. Inefficiencies in DHNs have, to a considerable extent, derived from poor design. Rectification is often extremely costly and requires downtime. The current Code includes some good examples of mechanical layouts for parts of the network. These should, in our view, be extended to the remaining portions, including risers & laterals and the DH Primary Network.
Off-site Connections – To offer guidance on off-site connection to both boroughs and developers. As the industry evolves, with regulation in sight and Boroughs becoming more aware of the benefits of connecting to Networks, it is important that technical, managerial and contractual guidance is given for both (developer & council) sides on how to get the best of these partnerships.
O&M guidance – To recommend the introduction of incentivised contracts. The performance of O&M providers (and of the DHN itself) is usually left largely unchecked. This is partly because Estate Managers tend to lack the technical knowledge to critique the data they are sent and the conflict of interest arising from the higher rates charged by O&M providers in reactive call-outs when compared to pre-planned maintenance works. Indexing charging rates to network performance is a potential way of benefiting both parties.
Real-life approach –Being such a complex system, effort should be made to focus guidance on the most practical and actionable aspects of DHN delivery, i.e., sharing the all-important “how-to”. Although customer education is important, relying on customers good habits is an inherently fragile strategy. One potential alternative to this could be to make data analysis a requirement to operators, whereby competent professionals monitor and react to data supplied via the network.