On 
On the day I visit Octopus Energy’s heat pump factory in Craigavon, Northern Ireland, temperatures in London reached 29C.
Some of the staff meeting me, who are usually based in the south of England, are beaming. It’s wonderful to escape the heat, they say.
And who can blame them. Climate change is making the UK hotter. In order to do something about that, decarbonising our energy systems – including domestic heating – is becoming more and more urgent.