Reinventing the district heating network
- Passiv’s technology reduces heat network annual operating costs by up to 40%
- Over 80% of occupants appreciate improved control and comfort
While the use of district heat networks is well established in some countries, they currently supply just 2% of the UK’s total heat demand. Whilst this is a small contribution at present, an Energy Technologies Institute (ETI) forecast suggests that decentralised heat networks could cost-effectively supply over 40% of the UK’s peak space heat capacity needs by 2050. However, fulfilling this potential means addressing some of the fundamental issues that have troubled district heating schemes in the past.
Whilst it is difficult to gain a comprehensive view of how the UK’s networks operate, anecdotal evidence suggests that both legacy and new heat networks can sometimes suffer from excessive heat losses because they operate at high temperatures year round to ensure they can meet peak user demand. They are also prone to experience high return temperatures, which are wasteful and lead to generation inefficiencies. Legacy systems were often over-specified so that they were capable of meeting high peak demands, which result in higher initial costs and disproportionate standing charges for consumers.
From the customer perspective, high bills are one reason why consumers have a poor impression of communal heating schemes; some are also unhappy about the controllability of systems and general comfort levels.
In order to address these problems, Passiv worked with a team of expert district heating analysts and engineers from the Energy Solutions group at WSP Parsons Brinckerhoff to retrofit an existing heat network with Passiv’s measurement and control systems. The overall aim of the project was to assess and demonstrate the performance gains and benefits made possible by the application of innovative technology to an existing network.
“While district heating has been around for over 50 years, we’ve shown that Passiv’s use of pioneering technology, including Internet of Things and sophisticated software algorithms, can significantly enhance the performance of district heating networks,” said James Eland, an Associate with the Energy Solutions group, WSP Parsons Brinckerhoff. “Anyone familiar with district heating knows that some of the networks installed in the 1960s and 70s suffer from numerous problems. Typically, they are difficult to control, are inefficient, and suffer from heat leakage problems.”
Passiv updated the control and measurement systems on 28 homes in a comprehensive trial that took place in 2015 / 2016. One of the core objectives of the study was to evaluate the degree to which it would be possible to flatten demand across all the homes on the network without sacrificing the comfort of individual householders. In achieving this aim, Passiv was able to lower demand peaks, reduce return temperatures and reduce heat losses – significant benefits that contributed to a calculated 12% overall demand reduction, 73% less pump energy required and 36% increase in utilization of a main generation unit (a combined heat and power – CHP – plant).
“Advanced technology is now demonstrably helping heat networks to function more efficiently. The performance of a heat network depends on knowing what’s going on – having good data acquisition, analysis and control. Being able to manage data correctly and analyse it in sufficient detail is critical to system success,” stated James.
A network may have been well designed, but commissioning it properly is also vital. Having access to key information highlights where the commissioning process may have gone wrong.
“Passiv’s ability to provide detailed data insight is a huge advantage when it comes to troubleshooting the installation and optimising the performance of the system,” James confirmed. “Another advantage of Passiv’s technology is ease of use for residents. The end users we surveyed loved the remote web and mobile access through the PassivLiving HEAT smart controls; it’s was a very well-received part of the offering. Ultimately, the usability of an interface is one of the key factors in how end users form an impression of their network operator.”
There are several features that contribute to user satisfaction with Passiv’s controls. For example, when the programmer fires up in the morning, the householder is able to use their phone or other device to see the temperature their home is set to, and can easily adjust it without having to refer to complex instructions.
“Passiv’s technology combines multiple enhancements – from an increase in primary generation plant operation to enabling lower pumping requirements, which deliver significant improvements to the performance of the heat network”, commented James. “By reducing peak demand, return temperatures and end user heat demand, Passiv’s approach can positively impact the financial viability of district heating schemes.”
As a result of the project, the team identified automated meter reading (AMR) and prepayment control as key issues that were in need of a solution for existing heat networks. Passiv has subsequently deployed its heat metering technology, which incorporates Sigfox narrow-band radio technology, to remotely retrieve meter data from heat networks.
James concluded: “Apart from the technical successes of this project, Passiv are really easy to work with. It was an enjoyable project with a great team.”
About WSP Parsons Brinckerhoff
WSP Parsons Brinckerhoff is a global engineering consultancy firm employing over 35,000 people worldwide.