It’s not surprising that designers are starting to embrace the concept of green, or living, roofs as the industry moves to meet the increased demand for environmentally conscious buildings. In addition to the obvious benefits of providing a habitat for many small animals and insects, they also work effectively as giant air filters, removing pollutants and putting oxygen back into the atmosphere.
They can also make a significant contribution to reducing the flood risk to built-up areas as they retain a huge amount of rainfall. A well designed green roof will retain around 90% of the rain that falls onto it, stopping the roof from discharging water straight into the drainage systems and contributing to flooding.
The challenge for designers and engineers is that the potential weight of all of this earth and water means that the roof structure has to be bolstered to cope with the increased stresses. Bringing daylight through such structures presents a new list of problems through these deep roofs.
A traditional skylight delivers an amount of light which corresponds directly with the size of its aperture – the bigger the aperture, the more light there will be. But bigger apertures also weaken the roof structure. The trick is to get maximum light through small apertures, and this is where tubular daylighting devices can really be used to great effect.
For example, a 530mm diameter Solatube Daylighting System will light an area of up to 32m2, with an aperture that can be easily accommodated without affecting the structural integrity of the roof. And because the Solatube Daylighting System uses reflective tubing to bring the daylight into the building, it can be positioned above the roof level allowing for the green medium to grow without blocking out the light entering the tube. The light can then be piped deep into the heart of the building, greatly reducing the reliance on electric lighting and boosting the building’s environmental credentials.