As they look for the lowest possible construction costs, developers and operators of district heating networks are missing out on significant levels of operational savings, both monetary and carbon-related, according to Mark Whettall, managing director of CPV, one of the UK's longest-established manufacturers of pre-insulated pipe systems.
Following the launch by DECC of its new Heat Network Delivery Unit (HNDU) and a £6m grant funding programme to help local authorities in England and Wales develop district heating networks, the number of schemes in development looks likely to increase. With this expansion in mind, Mr Whettall has drawn attention to the issue of heat loss in pre-insulated district heating networks. 'It's all about the opportunity for system developers to minimise the heat lost through the pipe system's insulation.'

'The EN 253 standards for bonded pre-insulated pipe systems actually includes three, different thicknesses of polyurethane foam insulation that are commonly available, but the vast majority of designers opt for the standard level - ignoring the better-performing Series Two and Series Three with their increased levels of insulation. With most developers focused on keeping the capital costs as low as possible - particularly when there's a competitive tendering situation - many are ignoring the opportunity to reduce heat losses and thereby missing out on significant financial and environmental benefits throughout a system's operational life,' he explained.

To illustrate this point, the company has presented an example scenario in which a 5,000m long network (flow and return) consisting of DN150mm steel pre-insulated pipes circulating hot water at a flow temperature of 100°C. If fuelled by a natural-gas-fired boiler, constantly operating all-year-round, the system with standard insulation - over its nominal 30-year life - will lose heat to the equivalent of around £3.65 million's-worth of gas. By spending around £40,000 extra at the time of installation in order to upgrade the pipe system's insulation thickness to Series Two, the cost of the heat lost would be reduced by some £1.2million - also saving 5,091 tonnes of CO2 from being emitted.

Mr Whettall continued: 'It's also worth noting that the operators of the systems are not losing just the cost of the fuel - but the cost of the heat sale if it's a commercially-based utility - so the savings figure of £1.2million will rise significantly - I'd expect this to at least be doubled to around £2.4million.'

'I realise that the cost of installation will increase marginally - largely due to the need to excavate a slightly larger trench to fit the increased insulation - but the step-up from Series 1 DN150mm steel only adds 65mm to the overall diameter - so it's negligible,' he added.

He continued to add that the whole issue of least-cost tendering is not just limited to the topic of heat loss - its effects are far reaching and is already compromising the long-term reliability of district heating networks. Having previously voiced concerns at the urgent need for the UK's district heating sector to put in place a cohesive set of quality standards that covers all aspects of a network's design, construction, operation and maintenance - Whettall believes that network owners and developers really need to get behind this initiative.

He continued: 'There will be resistance by some organisations, but until we pull together collectively and agree a framework on which best practice can be defined and therefore applied, we'll be risking the future growth of the sector and damage the potential for helping solving the challenges presented for the decarbonisation of heat in the UK.'