District heating is completely normal. Multiple residences or buildings without boilers of their own, connected to one central source of heat. In Denmark 64% of homes are heated in this way. But from where we're sat, you have to admit it sounds a little weird.

There are currently only 94 heat network schemes in Northern Ireland, only one of which supports an area that exceeds 100 homes, and most of which are communal heating serving a single building.

But why would you want district heating? Mainly because it's more efficient to operate, and therefore both greener and cheaper.

Take an example from Scotland. Aberdeen's combined heat and power network, which uses waste heat from electricity generation to warm 33 multi storey blocks, 2 sheltered housing blocks and 15 public buildings in the city. Buildings connected to the scheme have seen emissions reduced by 56% and residents' fuel bills by up to 50%.

Of course it's not easy or cheap to design and build heat networks from scratch, particularly when it comes to retrofitting existing homes. And there are always other options to carefully consider in the mission to make sure everyone benefits from a warm home and clean air: heat pumps and insulation being two of the most important.

But we have to make hard, expensive decisions about heating. That much is clear. And we can make them alone, or we can make them together.