Mark Whettall, managing director of pre-insulated pipe system manufacturer CPV, draws attention to the issue of heat loss in pre-insulated district heating networks
In a quest 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.
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.
To illustrate this point, imagine an example scenario in which a 5,000-metre 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 £3.65million'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.
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.
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 - network owners and developers really need to get behind this initiative.
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.
A working group must be established to progress this which will need to include not only DECC and its new Heat Networks Delivery Unit (HNDU), but other bodies such as CIBSE, the Combined Heat and Power Association and the Energy and Utilities Alliance to name a few. Commercial interests must not be allowed to water down best practice at such an important time in the development of strategy for rolling out heat networks.
Whatever is created, it must be sensible and of course workable, but it's critical that this is done and done relatively quickly. With Stephen Brooks having recently been appointed to the helm of the new Heat Networks Delivery Unit, at least we have someone with a lot or relevant experience that should be able to make things happen.