There are three hives on the roof at Evershed's . The great thing about Evershed's is the roofs also a 'field' of flowers. The resident honey bees have already nectar and pollen source right on their doorstep.

Bee HIves on a green roof in the Shadow of St. Paul's, London from dustygedge on Vimeo.

Although much of the interest in bees has naturally highlighted the honey bee issue, it is the other bees that are also being lost across the UK. The green roof at Evershed's is also home to visiting bumblebees, solitary bees and mining bees, who can also join in the harvest. There is a great deal of research in the UK on green roofs and bees, supported by similar research in Switzerland .

I am particularly interested in these 'other' bees. Whilst humans can tend to see nature in terms of it's immediate usefulness - bees = honey, we are often slow to recognise that nature in itself benefits humans.  One of the reasons the Honey bee issue is so prevalent is because we have decimated our other bee populations through intensive agriculture and changes to land use. In general these are often better pollinators of crops than the honey bee. So whilst a hive is good for honey and for honey bees, a green roof is good for all bees. When I sat on the London Food Board (LFB) a few years ago, there was a lot of interest in how London could encourage more hives on roofs. There are a lot of beehives now being put on roofs. A hive on a big flat grey roof is not half as interesting as a hive on a big flat green roof!

At the time I ask various parties involved in the LFB about how much honey per hectare was produced in London. This drew a silence. Everyone seemed to know it was a lot and was better than in rural areas but to what extend seemed to be a 'mystery' that would take a lot fo funding and research!!! One afternoon sitting with Justin Bere at The Muse in Islington . He had recently installed a hive on his green roofs and was in touch with a few beekeepers. So we rang one in Sussex. She gave us some figures - the amount of honey produced in the countryside compared to the amount in London. So armed with this I sat in the pub that evening and did some 'back on the envelope calculations (beware - maths was never my strong point!). When I wrote the London Living roofs and walls technical report, I had calculated that approximately 32% of central London's land area consisted of roofs that could be greened 'tomorrow'. So with a little simple arithmetic I can up with the following:

6km diameter centred on Traflagar Square = area of 30002 x π/10,000 = 290 Hectares x 32% = n 92.5 Ha of potential green roofs

1 acre rural can produce 30 – 50lbs of honey

.40Ha can produce 30 - 50lbs of honey

1 acre of urban can produce 100lbs of honey

.40 Ha urban can produce 100lbs

4000m2 can produce 100lbs

2000m2 = 50lbs

1000m2 = 25

500m2 = 12.5lbs

250 = 6.25lbs

125 = 3.125lbs

(As I understand it from beekeepers flower rich meadows are the best vegetation for production of honey – which fits with flower rich extensive green roofs)

Therefore 92.5 / .40 x 100 = 23,125lbs (10,500kg) of honey could be produced if all the roofs that could be greened in Central London were.

As I understand it this would amount would be much more in reality as we would have increased the greenspace by 32% so therefore it could be 32% more Honey i.e. 30,000lbs of honey.

I have no idea of what this would mean in terms of the amount of Honey used in London but I think you get the point.

Hives on green roofs = more Honey = more habitat for otehr bees/biodiversity

A no-brainer if ever there was one.

The first hives I know to have gone up on a green roof were in Hackney. A man had got in touch with Livingroofs. He was a beekeeper and wanted to convert his conventional flat roof to not only house his bees but he also wanted a green roof so they could forage close to home.. That was back in 2006 and hopefully the beekeeper, the bees and the green roof are all well and successful. Whether we come to green roofs from a climate change or architectural perspective, or a nature conservation or gardening one, green roofs that are designed with biodiversity in mind can we help honey bees, native bees and ensure the green roof work as best as they can for the headline climate change issues (excessive Urban Heat Island and reduction in flash floods). 

And a business such as Eversheds Ltd is definitely setting the a benchmark for others to follow.