Talk about heat maps, and most people will assume you're referring to a map with colours used to represent intensity of something like poverty or crime. This new map - published his morning by the Department for Energy and Climate Change - is much more literal than that. It really is a heat map.

Created by the Centre for Sustainable Energy, it mashes together several very detailed datasets to show heat use at building level. It has a pretty specific purpose - local authorities have been mapping heat use to work out which areas would be suitable for local heat networks.

Individual heat generation, through boilers, is responsible for the bulk of residential carbon emissions, so know where the densest areas are is useful. But mapping it can be expensive - not all councils have created these so far and those that have spent between £5,000 and £60,000 on them. By creating a national map, that process has been circumvented.

DECC heat map zoomed in

But it has a wider interest too - by merging the locations of every publicly-owned building, and heat use at a really local level, the maps give us a view of the whole country never seen before. It shows kilowatt hours per square metre and covers all 388 local authorities. The disaggregated datasets are not available - but you can download csvs of your query.

It has some useful features too - users can zoom into several different views at one go - and integrates Google street view, and can then generate a discrete url for that query, so you can find it again.

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