St Pauls Cathedral seen from a green roof in the city of London.

A map has been compiled of all the known green roofs in central London, but the researchers are convinced that they have missed some and are asking for people to tell them about any not shown on the map.

The research, conducted by the Greater London Authority and the Green Roof Consultancy, is based on studies of aerial images of London taken in 2013 by the Geoinformation Group. They counted 678 green roofs but are convinced there must be more.

It is an astonishing number; the greatest concentration appears to be in central east London, around the City, and north Southwark, but there are plenty all over the district.

It's estimated that the total area covered by the green roofs is 175,000 m², equivalent to around 25 football pitches.

On the map, clicking on a green dot brings forth information about the particular green roof, its area, perimeter and location. You can also search the map by postcode.

Many of the green roofs also visible via Google satellite imagery.

The Greater London Authority has a target of increasing green cover in central London by 5% by 2030.

Green roofs have a number of benefits:

• Increasing biodiversity;
• Creating space for recreation and urban food growing;
• Contributing a slight increase in insulation;
• Counteracting the 'heat island effect' of cities;
• Helping with drainage during periods of excess rainfall by delaying some run-off;
• They are visually pleasing.

The Authority has produced its own guidance on installing green roofs and living walls, and Transport for London have installed green roofs on St James's tube station and West Ham bus garage as well as a green wall at Edgware Road tube station.

The City of London, the capital's financial heartland, is also doing its bit and has produced a booklet of its own case studies.

This green roof DIY Guide will help you create your own green roof. And here's one for making green walls.

If you would like to add a green roof to the map, or are able to provide more details about a green roof already on the map, contact [email protected].