Designers claim that plants not only provide a beautiful alternative to other materials used in construction, they also offer additional benefits, including noise reduction, natural cooling, air conditioning and a psychological boost to those who use the buildings.

Depending on the type of planting used, and where the wall is sited, there are habitat benefits to be had for the local wildlife. Some designs purposely incorporate bee boxes and nesting sites for birds.

Compared with other approaches to greening the urban environment: green roofs, parks and planting trees, vertical gardening is admittedly very high maintenance, with water and light being the main issues.

Some of these walls are actually sited indoors, or in internally facing courtyards, with poor quality light. The usual methods of keeping plants alive in these situations are plant selection, or artificial lighting: a poor environmental choice.

The watering problem is not an insurmountable one. Designs use drought tolerant planting at the top of the wall, with those preferring a wetter environment further down, an efficient watering system and water storage; rain water and even air conditioning condensate are used to reduce water costs.

Don’t forget water.

Water treatment is an energy intensive activity, and as such is an important contributor to our output of carbon dioxide. Unfortunately, data on the carbon balance of the water industry is harder to find than that for the power generators, so it is often conveniently ignored.

By soaking up rain water and releasing it back into the air as the plants transpire, green roofs reduce the amount of water flowing into our treatment plants. Their capacity to soak up water helps reducing the surge of water in storm sewers as a result of heavy rain. This is a great flood prevention measure, also reducing the incidence of emergency waste water release into the environment.

Controlling the temperature.

The transpiration process requires heat to produce water vapour, this cools the entire roof. A green roof comprises a number of layers and presents significant thermal mass, and as a result it helps to keep buildings cool in the summer. Both effects reduces the need for cooling in our buildings and saving energy.

It’s true that the UK climate is a little wet during the cold winter months for green roofs provide any insulation. However, the growing number of data centres that support our communications and Internet infrastructure generate large amounts of waste heat. It’s here that the cooling effects of the green roof may be most beneficial throughout the year.

The importance of green spaces.

Green roofs could provide important benefits for biodiversity of our urban areas, by providing green spaces where most people live people, and more varied habitat for embattled wildlife.

Aside from making our built environment a better place, many species will need to move in order find a suitable habitat, thus adapting to climate change. Green corridors are an important part of this mobility within urban environments, and by created them on our roof tops we are helping species find a viable niche in a changing world.

One of my next jobs is painting the woodwork, and that means oil based paints; I’ve tried the water based alternative, and both finish and durability were very poor.

These brushes need solvents to clean them, and the resulting waste is very hard to dispose of properly. It should never go down the drain, so I tried contacting the Council, and after some discussion, I now bottle the liquid waste up, label it, and leave it near the oil recycling tank at the local recycle centre. After that…

I started wondering whether it would cause less impact to buy new brushes each time, but they’d still need manufacturing, transport, and disposal: the waste would still be there.

I wonder if I can convince Clare that we should stop decorating on environmental grounds? Probably not, so may be I should start to look for alternatives.