Commercial and Residential Green Roofs – Life at the Top

The iconic skylines that we see every day, on our way to work, on mugs, memorabilia, pictures and the television, might be set to change over the coming years. The harsh lines and sharp edges of the vistas of New York, London, San Francisco, Paris and the rest, could well be softened by a wave of green technology ever growing in its popularity.

Increasingly, developers are opening their eyes to the need for energy efficiency, sustainability and environmental performance for their buildings and ‘Green Roof’ technology is rapidly becoming one of the foremost ways to achieve this. In some countries, this already translates into legislation. Germany, for example, is leading the way with a Green Roof industry growing at 10,000,000m² a year, fuelled by Government incentives reducing business rates for compliant developers. In this case, adopting green roof methods is seen as providing a service to the community. Similarly, in Switzerland green roofs are a legal requirement in many cantons.

The Technology

A ‘green roof’ is one that has been fully, or partially, vegetated. These can be broadly categorised into three systems.

–  Intensive (a full roof garden containing grass, perennials and even trees).

–  Extensive (lightweight, low-maintenance vegetation landscape not requiring irrigation and containing only grass, moss, herbs and sedum).

–  Semi-intensive (Biodiverse green roofs that mirror soil types and attract insect, bird and plant species natural to the surroundings in an attempt to exist harmoniously with the surrounding area and enhance its established characteristics).

Installation costs are seen by many to be initially too high. This can also be compounded by continued maintenance outlay, but proponents argue that increases of roof longevity (by up to an additional 25 years) and, in some cases, of real estate value, as well as heating efficiency and moisture reduction, mean the process is generally both cost effective and sustainable.

The UK

The UK, however, is lagging far behind its European counterparts. Less than one square kilometre of green coverage exists in Greater London, despite the Greater London Authority recently estimating that 32% of available roof space had the potential to be ‘greened’.

Things look set to change though. Benefits to flood prevention, noise reduction (reducing sound within a building by up to 8dB), energy conservation, roof longevity (protecting it from temperature extremes and shielding against high levels of UV exposure), air quality, the urban loss of green space and the urban heat island effect have convinced some developers to look again at Green technology. Already green roofs are popping up around the UK, the new Rolls-Royce Factory at Chichester, West Sussex, for instance, incorporates a vegetated roof area of 40,000m². Furthermore, the 1.5 acre Kensington Roof Gardens illustrate that a roof garden can become a valuable land mark feature.

The economy, particularly the construction sector, has shown itself to be both fragile and capricious, but it seems certain that if Green Roof Technology can continue to convince surveyors, architects and builders of its merits, then this is one area of construction that is set to keep on growing.

24th May 2011