Good morning, everyone. I've been invited here today to talk about a relatively new architectural feature that is gaining popularity in many cities around the world. Now, have any of you seen a roof covered with vegetation and asked yourself 'What's that?' What you saw is known as a Green or a Living Roof. Plants and small shrubs are grown in up to six inches of soil on a flat roof. You probably think it looks a lot more pleasing to the eye than the black or grey asphalt coverings we normally see, and you'd be right. But Green Roofs don't just look pretty; they have distinct environmental benefits too. Firstly, they absorb heat from the sun and so insulate the building. This means they reduce the energy needed to power air conditioning systems, by up to 75 per cent in some cases, and so cut down on toxic gas emissions. Another important benefit of Green Roofs is their ability to reduce water run-off. Because traditional roofs are impermeable, an area of a city produces four times as much run-off as that of a rural area of the same size, and this can lead to flooding. Green Roofs absorb up to 40 per cent of the precipitation in the rainiest months of the year. And there's more. Living Roofs remove impurities from the air, produce oxygen and provide shade and a living environment for wildlife.