The growing aviation industry is one of the worst offenders when it comes to CO2 emissions, although there's - relatively speaking - not much of it. It's the altitude which makes it more harmful. But everyone is increasingly environmentally conscuious these days - and one prominent leader in this field is the German construction industry. From June this year, German buildings can gain a standard certificate - the - 'Green Seal'-' for environmentally friendly construction. Good for the environment - and good for property values too!