There is an old saying that there is nothing new under the sun and district heating certainly isn’t a new idea. The concept, also known as community heating, has been around for decades and has been implemented successfully throughout the world, particularly in urban environments and other areas of high building density.
District heating is a straightforward idea which can bring fantastic efficiencies and while its uptake in the UK has been relatively slow, the agenda to combat fuel poverty may mean this is about to change. Simply put, heat and hot water are supplied to a number of buildings from a central energy source via a network of insulated pipes. Heat exchangers in each of the buildings deliver the heat to them, removing the need for individual boilers or other heat source, with the network acting as a normal wet system.
The drivers for district heating in the UK are also well established. Regional and national targets for energy saving and carbon reductions are forcing councils to implement as many sustainable strategies as they can think of. You will not read a Core Strategy or Local Development Plan without coming across the phrases ‘sustainable communities’ or ‘district heating.’
Many UK local authorities are taking a keen interest in district heating following the success that has been seen in some nearby European cities. Copenhagen for one has had a network since the 1970s, and today this delivers 98% of the city’s heating needs. London and the rest of the UK have come a little late to the party however and will view this figure as an impossible goal. There are currently not enough heat networks so retrofitting to meet demand is a certain challenge on the infrastructure.
Local and Regional policies are however pushing for the need to future proof. The beauty of heat networks is that once an insulated network of pipes is laid, what is connected at the end to produce the heat can change and adapt as the environment around it changes or a technological development is achieved. This could involve replacing fossil fuel plant with renewables such as biomass or tapping into waste energy, such as the scheme currently being considered to utilise the 25°C air which is vented all year round from the London Underground.
If you are building a major development within the confinements of the London Plan (the GLA’s overall strategic plan) it is mandatory to consider decentralised generation of heat and power. The expectation is, where appropriate, that the developer’s proposals should seek the follow a hierarchy as follows: 1. connecting to an existing heating or cooling network, 2: implementing a site-wide CHP network, 3. installing a communal heating and cooling network. Any system should be future-proofed and designed to connect to a district network if one becomes available.
When designing the layout of the site, thought should be given to its density and optimising installation of a system. This will include understanding the energy demand of the site, identifying locations suitable for heating plant and associated hot water storage as well as internal layouts for the risers required to move the water around the building.
There are a number or online tools which can help developers maximise the potential savings available for implementing community and district heating. Arup for example has developed a Carbon Calculation Tool which allows developers to estimate CO2 savings for new and existing district heating schemes with different sources of heating. Another useful resource is the London Heat Map which has been developed as an interactive map which identifies where existing heat networks are located and areas outlined as having potential for decentralised energy.
Where a site has been identified as suitable for a community heating system, consideration must be given to the use of Combined Heat and Power. This is a well-known approach to simultaneously producing electricity and heat onsite increasing energy security. Further to simple environmental benefits, the introduction of CHP can bring both social and economic benefits in the form of low cost electricity and affordable warmth, lower life cycle costs and lower management/maintenance costs. The system must be sized adequately in order to ensure a constant operation which will maximize the potential savings.
With stricter regulations on installation, regulation, maintenance and control the installation of a district or community scheme enables the efficient transportation and use of heat for a wide variety of users. There are unrivalled opportunities to allow a broad range of energy generation technologies to work together to meet demand for heat enabling fuel flexibility. Although capital cost can be high, the whole life cost benefit from infrastructure which can be expected to last much longer provides a means of securing significant reduction in CO2 emissions through the optimisation of heat supply.
The opportunity for improved local fuel security via district heating must be seen as key to helping to provide a long term method of tackling fuel poverty.