District Heating - Delivering Low-Carbon Energy

Mark Whettall, managing director, CPV Ltd

Although it’s been around for many decades in the UK, if you were to ask the average person in the street what district heating is, the likelihood is that they won’t have a clue. This will hopefully change in the coming years as the technology looks set to play an ever-increasing role in helping decarbonise our nation’s heating and hot water supplies.

It’s a simple concept. Use a pair of highly-efficient, buried pre-insulated pipes to deliver hot water from a centralised energy source to multiple consumers. The exact definition of what constitutes a district heating system is still up for debate – but if there’s more than one consumer sharing the same heat source, then it’s district heating.

As local authorities rushed to demolish swathes of back-to-back terrace housing during the late 1960s and 70s, a large number of the new housing estates that were built, utilised this wonderful technology called district heating. Some systems flourished, whilst others were beset with problems that ranged from leaking underground pipe networks, through to unreliable control systems and non-existent or inaccurate heat metering. Inevitably, this led to the technology’s reputation being seriously damaged and many systems were eventually abandoned in favour of individual gas-fired boilers or even electric storage heating.

With a widely-held perception of being unreliable, coupled with the fact that the cost of installing pre-insulated pipe networks was capital intensive – unfairly judged against gas and electric networks that had been installed by the then publicly-owned utilities - growth in new district heating schemes slowed down – with the market penetration, when compared to traditional heating systems - reached less than two percent of homes in the UK.

With such a small share of the UK’s heating market, it was hardly surprising that the technology remained largely unknown. It has since been thought that the progression of the technology was also hampered in the UK due to its origins in the old-style social housing estates run by local authorities. With the onset of Right to Buy and an increase in home ownership – people wanted to own their own home and have their own gas-fired heating system – and to many, at the time, communal systems were stigmatised as ‘council heating’.

During the late 1980s as energy prices continued to rise and the issue of greenhouse gas emissions started to make their presence felt, some more visionary local authorities recognised that although the technology had presented problems, the sheer fact that the concept was such a success in Scandinavian countries – Denmark being a prime example, with more than half its homes heated this way – there really must be something in this idea.

One such authority, Sheffield City Council, boldly pushed on with developing a large, city-wide network that would capitalise on waste heat produced by its refuse incinerator and deliver hot water to homes, public and commercial buildings throughout the city. Recognising and correcting what had caused the technology to falter previously, their new approach was to act as a catalyst and paved the way forward for a whole new generation of systems that have been constructed since.

Step forward the best part of twenty-five years and the growth in the new generation of district heating networks has continued to gather apace – as have allied technologies such as combined heat and power and biomass boilers. With more than two decades of reliable operation, the reputational issues have been addressed. Confidence is at an all-time high and this position has been cemented by DECC publishing its long-awaited Heat Strategy document earlier this year, in which district heating is billed as one of the leading ways in which the sizeable carbon emissions from heating can be tackled – regardless of whether it’s a domestic, commercial or industrial consumer.

With the UK Government having signed-up to legally-binding targets to lower emissions and increase the proportion of renewable energy generation, district heating’s appeal is growing. Developers wishing to meet the ever-more stringent carbon targets for the built environment – particularly as they move towards zero emissions - are looking to renewable-fuelled district heating systems. With financial stimuli such as the Renewable Heat Incentive and Renewables Obligation both supporting the construction of new energy generation – district heating looks set to be playing a key role in delivering sustainable energy for some time to come.

Whilst the market conditions are more favourable than in previous decades, the government could do more to stimulate the uptake of district heating by ramping-up planning policy and building regulations to encourage developers towards the technology. Furthermore, government should also introduce legislation that prevents power companies from wasting heat during the electrical generation process – effectively forcing them to seek district heating consumers for the energy that would have otherwise been wasted.