HEAT NETWORKS | INTEGRATING HEAT PUMPS Over the past 18 months, heat pumps have replaced CHPs on heat networks, according to FairHeats Michael Ridge. The challenge now, he says, is to integrate the technology successfully, while still providing reliable and affordable heat for customers and residents Designing for large-scale heat pumps W orking in the construction sector as a heatnetworks specialist, I have seen my fair share of policy changes and new technology trends. of heat networks for low temperature design and operation. This is to combat the excessive heat losses and overheating risks that have plagued the industry from transition we are currently navigating: the heat pump has arrived, and it is here to stay. Heat-pump technology is our best bet to aggressively decarbonise the UKs heat sector, as we move from fossil fuel-based systems and take advantage of the falling carbon intensity of the Grid. Only 18 months ago, the projects I was supporting were gasbased combined heat and power (CHP), but this era feels well and truly behind us now. The new challenge is to integrate heat-pump technology into heating systems effectively, while still providing the resident with an affordable and reliable service. It is now common for a development to supply both residential and commercial spaces with heating and hot water, and a communal system is often the most cost-effective way to achieve this, rather than commercial units having to install standalone systems. This article is focused on optimising the design of low temperature can supply heating and hot water to meet the demands requires joined-up thinking between the dwelling and heat-network design. With the introduction of heat pumps, it is doubly important for the operating temperatures to be as low output temperatures. Perhaps even more challenging, most models on the market have not been optimised for operating in heating mode, but are really chillers operated in reverse. For the few high temperature (COP) generally starts to be compromised at output the operating temperature of heat networks. Effect of lower operating temperature on radiator size heat-pump technology. The LTHN system in question can be considered to comprise of: A site-wide heat network that supplies heating and hot water to end users through heat interface units (HIUs) that separate the network from the residents dwelling-level heating and instantaneous hot-water systems A centralised energy centre containing the generation and distribution plant that serves the site-wide heat network 200% 180% 160% 140% 120% 35 Its all about the temperature Even in CHP-led systems, FairHeat has been preparing developers 30 25 20 Increase in radiator size 220% 100% Difference between average radiator temperature and room temperature (20C), oC Figure 1: Impact of radiator operating temperatures on unit size 36 May 2021 www.cibsejournal.com CIBSE May 21 pp36-38 CHP to Heat Pumps.indd 36 23/04/2021 18:09