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The most important consideration when developing a district heating network is the heat demand density, i.e. areas which have buildings with high heat demand that are in close proximity to each other - this demand can be either from existing or planned buildings or a mixture of both. Areas with a heat demand density of greater than 150 TJ/km2 are considered to be feasible for developing a DH network. The second consideration is the heat supply. Utilising an existing heat source such as an industrial waste heat source may further increase the feasibility of a project, however, developing a new heat source such as gas CHP may also be feasible. The final area to consider is any physical constraints, e.g. river or rail crossings, which can impact the cost of the network and reduce its financial viability.

District heating schemes operate all across Europe. The European Heat Index shows that the majority of Europe is within +/- 20% of the average European heat demand, and there are hundreds of district heating schemes operating effectively within this area. District heating also provides hot water for showers and etc. which is not dependent on external temperatures. This explains the use of district heating networks in areas where annual space heating requirements are low, such as southern Spain and Portugal.

No, district heating is not only for large cities. The heat demand density, which is one of the main indicators for feasible district heating networks, can be achieved not only in cities, but also in small towns and villages.

The following steps are suggested:

1. Undertake heat mapping of demand and heat sources
2. Identify and rank opportunity areas where new district heating networks would be best developed
3. Include sections in planning policy to support district heating and the utilisation of local waste heat sources
4. Carry out a feasibility study for one of the high-ranking opportunity areas to determine its suitability for district heating
5. Develop policy to prioritise locating new high-density developments within or adjacent to the opportunity areas identified and future-proof these by adopting centralised hydronic heating systems with provision for future connection to a district heating network

Yes, home heating systems will operate in the same way as traditional hydronic heating systems where each heat emitter (radiator, under floor heating loop, etc.) will have temperature controls to allow room temperatures to be adjusted as required.

It is not difficult to connect existing buildings to a district heating network. In cases where the building has an existing boiler, this would be replaced by a heat exchanger, which would typically take 1-2 days’ work to complete. Heat exchangers are less expensive than boilers and require less maintenance, as they have no moving parts.    In cases where a dwelling is directly heated with electricity (e.g. through storage heaters), replacement of the electric heaters with a wet system is estimated to take 3 days.  Furthermore, in Ireland, district heating can comply with Part L (Conservation of Fuel and Energy – Dwellings) of the country’s Building Regulations more cost-effectively than other common heating technologies such as building-level heat pumps, with a capital cost saving of 50 - 60% for a typical apartment.