Retrofitting heat networks to maximise performance and enable low carbon technologies

Retrofitting heat networks will play a major role in improving building performance and facilitating a net zero environment by 2050. A 94-dwelling social housing development based in the UK, was operating a heat network and experiencing significant issues with overheating, resident discomfort, and poor network efficiency. An Automatic Meter Reading (AMR) system was installed to baseline network performance and identify improvement opportunities. The data revealed the network was operating with a 74/66 °C temperature profile, and that the total network losses exceeded 1000 W/dwelling. This paper sets out the detailed methodology and considerations in retrofitting the heat network to enable future connections to low carbon heat sources such as heat pumps or low temperature district heating. Quality assurance was undertaken during the design, install and commissioning stages to facilitate the project’s success and hit key milestones. At present, the operating temperatures have been reduced to a 55/37 °C flow and return temperature, enabling a gas consumption reduction of 38% and network heat loss reduction of over 90%, with heat losses currently at 56 W/dwelling. This data driven approach to retrofitting has simultaneously improved resident comfort, reduced heat costs and enabled a straightforward connection to low carbon heat sources when available. Practical Application: This paper outlines the interdependencies of typical issues on existing heat networks and the effect of these issues on operational performance, cost, carbon emissions and resident satisfaction. A methodology is given which outlines the importance of maximising heat network performance prior to moving to low carbon heat sources. The results of carrying out this methodology on an existing heat network act as an example to the industry showing that the 100 W/dwelling heat loss target in CIBSE CP1: heat networks code of practice can not only be achieved, but significantly improved upon in existing buildings.