Smart technology and government support is raising the appeal of district heating for both entire communities and industrial areas, explains Jeremy Bowden.
9 January 2017 | Jeremy Bowden
The potential for collaborative energy generation in communal residences has never been greater in the UK than it is now.
New technologies have dramatically improved efficiency and control, while the choice of district heating provides facilities managers with a means to enhance sustainability, backed by strong government support.
Above all, district heating can cut bills and maintenance by avoiding the need for many individual boilers.
Community heating is central to both the UK and the EU's plans to slash greenhouse gas emissions from heating - an area that (with cooking) represents over a third of total UK emissions and in which there has been little progress towards mandatory emissions targets so far. With limited alternatives available to reduce such emissions, district heating is being heavily supported by the current UK government, despite cutbacks in other areas of low-carbon subsidy. It is hoped that such systems will reduce greenhouse gas emissions by improving efficiency, as well as by using waste heat and more renewable energy sources.
In late 2015 the then Department for Energy and Climate Change (DECC) announced a £300 million fund for developers throughout England and Wales to be spent on district heating projects. DECC also increased funding for the UK's Renewable Heat Incentive to £1.15 billion by 2020 to 2021 - the world's first long-term financial support programme for renewable heat. The UK government hopes the number of homes connected to heat networks will rise to eight million by 2030, from around 250,000 now, and by 2050 it estimates heat networks could provide 43 per cent of the UK's total heating needs.
Even without the support and greater efficiency, district heating provides several advantages to building developers and residents. Such schemes can mean lower fuel costs as the bigger the purchases, the more potential there is to take advantage of supply contracts that are cheaper than household energy tariffs. And, whereas district heating used to be associated with public housing, and tended to be charged at a flat rate with little control over temperatures, today's smart technology makes it flexible and easy to control.
The schemes are best suited to densely populated urban areas, and the bigger the shared energy system, the more widely fixed costs are shared - cutting the average cost per user. Often systems can be used by more than one building, with non-residential buildings, such as offices or schools, which tend to see demand peak during the day - complementing residential peak demand in the evening, which produces a more efficient system overall, cutting costs further.
Setting up schemes
There are several key issues that need to be addressed and practices that need to be followed when establishing a heat network. For guidance, facilities managers should consult the Heat Trust scheme which was launched in November 2015 primarily to safeguard the needs of heat customers. Although voluntary, the scheme is supported by government and consumer groups as an industry led, self-regulation initiative, designed to establish and encourage best practice.
In addition, FMs need to be aware of the CIBSE/ADE Code of Practice, launched in July 2015, which acts as a comprehensive guide and provides a set of minimum practice and best practice recommendations for installers to inform and influence the way a heating system is planned, implemented and maintained. CIBSE - the Chartered Institution of Building Services Engineers - is a professional association with close links to government.
According to Dr Tim Rotheray, director of the Association of Decentralised Energy (ADE): "The CIBSE/ADE code is a valuable framework for heat providers to use to make the best job of putting together an efficient and effective heat network. Decarbonisation, improved sustainability and enhanced customer service can only be consistently achieved if developers follow the [code]".
CIBSE's code applies across the whole life of a project, helping integrate the various parts of the supply chain under a common best practice standard. And, unlike the Heat Trust guidelines, it is not just voluntary guidance, but is compulsory for CIBSE members, representing an important step for an industry that is maturing and improving governance and standards.
The code's main goals include ensuring that you get the right-sized plant and network by accurately estimating the peak heat use and the total annual consumption of any proposed system. If the plant is too big, build costs will be more than necessary and it will operate below optimum efficiency. This will push up standing costs to customers. If it's too small there will be insufficient heat at peak times, and undue stress will be put on the system, increasing maintenance costs. Failure to accurately estimate demand also undermines operating and other cost forecasts.
The system needs to allow for variation in use, as well as ensuring low heat loss, flow rates and return temperatures to guarantee the efficient and flexible operation of the plant. Low heat loss and return temperatures means as much of the system's energy as possible is transferred to residents' accommodation. Low flow rates minimise the amount of water that needs to be heated, keeping fuel costs down.
The CIBSE code is also a good guide for a scheme's tendering and contracting process, as it includes clear and measurable minimum project specifications to which contractors must adhere, providing greater confidence for developers. In addition, contractors that are members of CIBSE have to meet certain competence standards aligned to those of the Engineering Council, which can help guarantee performance.
Once heat is supplied through a heat network, customers lose the ability to switch supplier, so customer relationships must be treated especially carefully. This has been made easier by the introduction of smart technology, which enables much improved control, flexibility, communication and visibility than earlier systems. Customer satisfaction is also the main purpose of the Heat Trust guidelines, which outline minimum guaranteed performance standards, customer service and protection levels.
The guidelines should address the problems of earlier district heating schemes, which failed to prioritise customer needs - the Which? report 'Turning up the Heat' in early 2015, looks at the different areas of consumer dissatisfaction in more detail. The Heat Trust also offers residents an independent process for settling disputes. If consumer dissatisfaction grows the guidelines may be replaced by mandatory regulation - like that provided by Ofgem for power and gas supply, which could be far tougher.
To ensure customer satisfaction the Heat Trust guidance makes a number of recommendations, including the need to be clear about exactly what residents are paying for, especially any fixed price element in the charge. The guidelines recommend that contracts take account of requirements or constraints the customer has informed the supplier of, and should also be clear about any obligations the customer may have - including the right of access for maintenance purposes.
There are also legal requirements. All billing arrangements need to conform to the EU Energy Efficiency Directive 2012, which set out requirements regarding metering and billing on all new and existing heating and cooling systems. These have been implemented in the UK through the Heat Network (Metering and Billing) Regulations 2014, which require operators to provide a minimum level of fair and transparent heat billing.
Heat Trust guidance also encourages planning for fuel price changes and debt risk. If pre-payment meters are not part of the design, there may be a risk of debt accumulation. It suggests fuel price fluctuations should be evened out if possible, and any variation in charge that is passed on to residents should be done so gradually. Using renewables helps to reduce exposure to volatile fossil fuel prices, creating more predictable energy cost for authorities and tenants as well as attracting public funds and cutting carbon emissions.
Heat networks should incur lower (and less intrusive) maintenance costs than the equivalent number of individual boilers. But they are high capital cost assets, requiring a long period to provide a good return on investment, and need to be designed with this in mind. The long life means maintenance needs should be carefully considered - build costs may need to be higher to ensure lower maintenance and operating costs, especially as reliability is essential for customer satisfaction.
The CIBSE code recommends a long-term repair and replacement strategy should be developed to ensure that the true long-term costs are fully considered. Once a scheme has been chosen more detailed contingency and maintenance plans need to be put together early on, setting out action to be taken regularly or in emergencies. Easy access to key parts of the system is an important factor in maintenance costs and must be considered at the design stage.
Plans should be put in place to enable the regular maintenance required for reliable heat production, control, transportation and metering - including appropriate monitoring and reporting of central plant and building connections - to pick up issues before they become problems.
The maintenance plan should, above all, minimise health and safety risks to staff, customers and the public. It is important to get this right as emergencies resulting from a flood, fire or electrical failure could involve injury or serious damage to property. Emergency calls need to be answered and dealt with quickly.
Achieving high-quality installation of heating unit and pipelines is also critical to keep maintenance costs down. The installer of the system may be willing to offer an extended warranty on the materials and possibly installation of the system for up to 20 years. This must be established early at the time of tender, including whether these are underwritten through an insurance scheme.
With the focus on sustainability, and backed by the latest technology and strong government support, there has never been a better time to introduce district heating into residential or commercial facilities in the UK. Above all, it should cut residents' heating bills, while at the same time enhancing green credentials by guaranteeing a more efficient and lower carbon heat supply.
Background to district heating
The roots of district heating can be found in the hot water-heated baths of the Roman Empire, with early systems often taking advantage of naturally occurring heat or hot water, such as those beneath Bath. One similar system in France has been in operation since the 14th century.
American hydraulic engineer Birdsill Holly is considered the founder of modern district heating, having introduced the first commercially successful district heating system in New York in 1877. The Holly Steam Combination Company built 50 coal and wood-fired systems across the US over the next five years. District heating has been most successful in Scandinavia and Eastern Europe, including Russia, where cold winter temperatures, strong central planning and large-scale public housing have encouraged its development.
In the UK, it was the London smogs of the 1950s that drove district heating development. Several projects were set up ahead of the Clean Air Act of 1956, to combat pollution by supplying heat to housing without the need for coal fires. These schemes included the Pimlico District Heating Undertaking (PDHU). It was set up following the Great Smog of 1952, which caused the death of an estimated 4,000 people. These early schemes were public works and simply channelled hot water to domestic and commercial properties, with little in the way of temperature control or flexibility. Since then, technology has improved, helping improve district or community heating's reputation, and making such systems an attractive addition to private housing and commercial sites.
Several UK cities now have central systems, including Southampton, which in the 1980s began using combined heat and power district heating, taking advantage of geothermal heat in the area, alongside a gas-fired combined heat and power (CHP) scheme. The power is used locally or sold to the grid, with waste heat from the process distributed through 11 km of heat networks.
District heating examples
A prominent example of district heating can be found at 1 Angel Square - the Co-op's head office and support centre in Manchester. Its source of heat and power is a CHP plant, from which surplus power is sold to the National Grid. Heat recovery from the IT systems also helps heat the building. Opened in November 2013, it scored the highest-ever Building Research Establishment Environmental Assessment Method (BREEAM) score of over 95 per cent, leading it to be acclaimed as the most environmentally friendly building in the world.
As well as systems serving just one building, there are many that serve large areas within cities, presenting an alternative option for FMs who may not wish to install a plant. These include examples such as the PDHU, which is owned by Westminster City Council and managed by CityWest Homes. Begun over 50 years ago to help combat London's air pollution, it initially used waste heat from Battersea Power Station to provide heating and hot water to one local housing estate. The system was later upgraded with CHP units, and now provides heat to 3,256 homes, 50 commercial premises and three schools in the area.
London's district heating customers include St George, which specialises in regeneration in London, combining new homes, apartments and penthouses with retail and leisure amenities for residents.