Major cities across Europe have favoured the use of district heat networks for many years, as a way of increasing energy efficiency, reducing the amount of fossil fuels used and consequently, reducing associated carbon emissions.
In the UK, the Government believes that there is ‘technical potential for district heat networks to meet up to 20 per cent of heat demand by 2030’. In addition to the current £320 million investment over the next five years, a further £2 billion could be invested to achieve the 2030 target. One that London will meet its' carbon reduction targets, for example, is for 25 per cent of heat energy to be from local sources by 2025.
However, any investment decisions need to be wisely made, especially if the historical unreliability and inefficiencies of older heat networks is not to be repeated.
With this in mind, it is essential that the performance of heat networks is optimised, not only to reduce the risks associated with high capital costs of investment, but also to reduce whole life operation costs by ensuring better system designs and maintenance regimes are both possible and implemented.
It’s all in the proving
Even with a well-designed network, it is essential that the system and its subsystems are thoroughly and successfully commissioned. Otherwise, a network could operate for years at a lower than expected level of system efficiency – with a resulting increase in energy costs and carbon emissions.
Good commissioning needs to fully prove a network’s operation and ensure that the network is achieving the required level of performance and efficiency. And if commissioning leads to any deviations from the proposed design outputs, then it at least allows further remedial and improvement work to be carried out immediately. This ensures the cost of remedial work is borne by the contractors and not the residents.
CP1 – best practice commissioning
In addition to best practice for design and construction, CIBSE/ADE Heat Networks: Code of Practice for the UK (CP1) also includes important guidance on commissioning activities. This includes inspection and testing to check that:
- Low return temperatures are consistently being achieved.
- The system and its heat interface units have been balanced to meet demands.
- Heat metering and meter reading systems are accurately reading system parameters.
- The centralised energy generating equipment is operating efficiently and reliably.
These checks will ensure a smooth handover to the system operator, with improved customer confidence that the system is going to be reliable.
The Heating and Hotwater Industry Council have also produced a ‘Benchmark for consumers’, which includes the Benchmark Commissioning Checklist and/or Service Record.
Don’t forget seasonal commissioning
Initial commissioning is essential. But regular commissioning is also critical if network efficiencies are to be maintained, carbon emission reduction targets achieved and costly maintenance breakdowns avoided.
Regular commissioning as the seasons change may highlight the need for further fine-tuning activities, which can then become indoctrinated into the annual maintenance plan.
This is where the investment in heat metering and automated meter reading (AMR) systems pays for itself. That’s because the metering will provide invaluable operating feedback data which can be used to check network operating performance levels are being maintained and also predict potential maintenance issues.
For this reason, metering needs to be installed to provide critical data at the customer interface, at building level and also around the network distribution system and within its plant rooms.
- Initially, commissioning proves the system is operating at the required performance output levels.
- Commission needs to be carried out over a period of time. As seasonal and full load scenarios should be tested.
- Metering information is essential to this important commissioning regime which should be part of the network’s overall maintenance programme