A heat network – also called district heating – is a distribution system of insulated pipes that takes heat from a central source and delivers it to a number of domestic or non-domestic buildings. The government has stated that heat networks form an important part of its plan to reduce carbon and cut heating bills for customers, as “they are one of the most cost-effective ways of reducing carbon emissions from heating, and the efficiency and carbon-saving potential increases as they grow and connect to each other.”
Of course, heat networks are not a new approach, especially in delivering heating and hot water to multi-dwelling buildings, such as apartment blocks. In fact, they have been used for two decades or more, but the key difference in recent years has been the opportunity to exploit/incorporate renewable heat sources such as heat pumps.
To support this strategy, CIBSE’s CP1 2020 Heat Networks Code of Practice puts even more emphasis on achieving low return water temperatures. A system designed with this approach will have reduced peak-volume flow rates, requiring smaller pipework which will lead to lower heat losses and reduced pumping energy.
Although heat networks are generally technology neutral, low return temperatures have an impact on the transition to low carbon technologies. This has meant that manufacturers, specifiers and heating engineers are now embracing the renewable technology of heat pumps on the primary circuit – commonly referred to as a fourth generation heat networks.