Call for Industry-Wide District Heating Quality Standards

Mark Whettall, managing director of CPV Ltd - one of the UK’s oldest manufacturers of district heating pipe systems, highlights the bright future for district heating as a technology that will help decarbonise the UK’s space heating and hot water supplies, but tempers this with a warning that the industry must not repeat the same mistakes made during the last boom of the 1970s.

The simple concept of district heating, district energy or even community heating – call it what you will - is going through a renaissance in the UK. With the ability to deliver efficient and affordable heating and hot water to homes and businesses from a variety of sources – including those from low-carbon, renewable generation technologies, it will not only help our country reach its legally-binding targets to reduce greenhouse gas emissions, but will also go a long way towards alleviating fuel poverty for the most vulnerable members of society.

The Department of Energy and Climate Change (DECC)’s report published in the spring of 2012: The future of heating: A strategic framework for low carbon heat, highlighted the key role that district heating will play in lowering carbon emissions and it is clear that the technology’s market share is set to increase in the coming years – particularly as it is estimated that around 50 percent of carbon emissions come from our increasing need for space heating.

It’s hardly a new solution and there are systems in this country that have been around for many decades; indeed the Pimlico District Heating Undertaking in Westminster was created shortly after the Second World War and fed new-build homes with waste heat from the now world-famous Battersea Power Station.

Often inspired by the Scandinavian countries that had seriously embraced the technology during the oil crisis, there was a surge of interest in 1970s and 80s when social housing providers bulldozed back-to-back terraced homes to make way for modern, progressive housing, often fed by oil and coal-fired, centralised boilers.

Hundreds of kilometres of underground district heating pipes were installed, but there was little or no serious consideration given to the design or quality of the installation. Standards and specifications from other sectors of the heating industry were wrongly applied and although there were some successes, there were many more failures and they have been well documented over the ensuing years.

At the time, pre-insulated steel pipe systems comprising of a steel carrier pipe encased in an HDPE plastic outer casing and a bonded polyurethane foam insulation were the only real option available. These systems were vulnerable to failure if ground water was able to penetrate the often poorly-fitted casing joints.

The saturated insulation lost its thermal properties and quickened the corrosion of the carrier pipe, leading to leaks and inevitably, the reputation of the technology was very badly damaged as consumers were often left without heating and hot water – typically on some of the coldest days of the year.

In the decades that followed, many local authorities abandoned their district heating systems in favour of decentralised gas heating systems, but some, undaunted, recognised the true potential of the technology and they persisted.

These schemes, in cities such as Sheffield, Nottingham and the City of London, paved the way for today’s new generation of district heating networks and clearly demonstrated how successful the technology could be when introduced properly. The reason was largely due to developers recognising the importance of good design, implementing relevant quality standards and establishing a programme of planned preventative maintenance for the lifetime of the network (in excess of 30 years for a pre-insulated steel system).

Subsequent innovations by pipe manufacturers have led to the introduction of pre-insulated plastic pipe systems that can be used in district heating distribution networks and these are proving to be a popular choice with today’s developer. Often using carrier pipes such as cross-linked Polyethylene (PEX), the risks of corrosion are effectively removed and with a range of diameters available delivered in rolls, the number of on-site joints is much reduced and installations can proceed more quickly.

This said, pre-insulated steel pipes still have a very important role to play in the future of district heating as they are often the best choice for the arterial systems on larger schemes - a recent example of this being the new city-wide district heating system being constructed in the city of Leicester.

With the Government hailing district heating as a technology that will play a significant role in decarbonising this country’s space heating and hot water supplies, the industry has started to scale-up production and more organisations are being attracted to business opportunities for the design and construction of the networks.

Whilst there are many, good-quality suppliers in the sector, the increase of new projects will undoubtedly lead to an influx of designers and installers with little or no experience of district heating network infrastructure entering the market. It is of the utmost importance that all stakeholders concerned with the planning, design, installation, operation and maintenance of the next generation of district heating networks take every possible care to ensure that the costly mistakes of the 1970s and 80s are not repeated.

From correctly sizing a network to ensure it can accommodate additional heat loads as new consumers connect in the future, through to advanced stress analysis modelling to accurately profile how the system will respond during the day-to-day operation throughout its life are just two examples of areas that have previously been overlooked.

Already mooted by the UK industry, standardisation of the design criteria, operating temperatures and pressures will also ensure that smaller networks can easily be joined to larger arterial infrastructure – creating city-wide district heating systems that will deliver much larger economies of scale in terms of opportunities for both cost benefits and carbon reductions.

It has been said that the three most important parts of a pre-insulated pipe system are the joints, the joints and the joints. This really does emphasise just how critical the training and supervision of on-site installers is. It is critical that our industry steps up collectively and establishes a system of quality standards to cover all aspects of district heating networks.

Collectively, we need to ensure that system owners and developers insist that their supply chain all use the new quality standards and all manufacturers work together to provide accredited training for the designers, installers and supervisors.

I am more than optimistic for the future of the technology - otherwise I wouldn’t have committed more than £1million of my company’s money into expanding production, warehousing, design and training facilities for this upturn in demand for district pipe systems; but without these checks and balances being put into place and enforced by scheme owners and developers, the reputation of the technology at such a critical stage in its development will be put at risk and moreover, threaten the UK’s ability to tackle a sizeable proportion of the UK’s carbon emissions.