HEAT NETWORKS | QUEENS QUAY HEAT PUMP be a rarity, and in the warmer summer months when there is little heating demand it would be dropped as low as 60C. To deliver efficiency over these parameters, it was necessary to design a heat pump-ready HIU, with an intelligent core, that could monitor the changes in flow temperature and the domestic hot-water temperature, and compensate to ensure optimum performance. Vital Energi spent two years developing the new technology to meet these requirements. While it was designed with the next-generation district heating systems in mind, it can perform efficiently at higher temperatures. This, combined with its ability to react to temperature changes, means it will stay optimised as the flowrates change throughout the season, giving real-time optimisation to the project. Ian Spencer, associate design director, says: Reduced temperatures mean reduced losses and, while losses created by an individual HIU are comparatively small, when you multiply this by 1,200 and operate them over a 20-year period, it can deliver significant savings in operating costs and carbon. Retrofit and new-build performance A review of a buildings energy system is essential to understand the changes needed to make it compatible with a lower-temperature district energy system. This, combined with a survey of historical energy consumption, begins to paint a picture of what is necessary, but historical oversizing of heat emitters and antiquated controls systems can actually provide a benefit, as they reduce the need to change the secondary side heating system. Improved standards and advances in technology mean buildings The abstraction pumps drawing water from the river Clyde that are only years old can compare poorly in relation to current buildings. The Queens Quay development has buildings that are a few decades old, but because of their fabric construction and existing heating system design, we need to be able to deliver flow temperatures of 80C and return temperatures of 60C. On the new buildings, where we can have an input on design, we can deliver 70C flow and 45C, resulting in lower temperatures and a higher temperature differential. Retrofits require more consideration in the design process, but we believe Queens Quay demonstrates that heat pumps are viable for buildings of all ages. Lowering temperatures, while improving insulation, emitters and controls, can be an extremely efficient energy solution. CJ LEE MORAN is design director, operations North & Scotland at Vital Energi 40 August 2021 www.cibsejournal.com CIBSE Aug 21 pp38-40 Queen s Quay.indd 40 23/07/2021 14:42