Bett er living through chemistry

Derbigum Olivine membranes have a naturally occurring mineral upper layer that neutralises CO2 via an irreversible chemical reaction when it comes into contact with rainfall

Ben Green, Divisional Marketing Manager for Alumasc, discusses the installation of its carbon dioxide-neutralising roofi ng at Nott ingham Trent University D evelopments that design with environmental concerns in mind are becoming the norm. As well as teaching the eff ects of positive actions towards the environment, Nott ingham Trent University (NTU) considers that the best way to press home the ecological and sustainability agenda to its students is through demonstration. To this eff ect, it has installed a new CO2 -neutralising roofi ng system.

Alumasc Derbigum Olivine roofi ng contains a top layer of Olivine, an iron-magnesium silicate that is a common, naturally occurring mineral. When CO2 in the atmosphere comes into contact with the roof as rainwater, it is absorbed and neutralised in a chemical reaction, the residue of which is water, silicon dioxide (sand) and magnesium carbonate. All these are harmless to the natural environment, so when the rainwater rolls off the roof and reaches the drains, it’s carbon-free.

In addition, the roofi ng has a bituminous felt membrane system, 40% of which is recycled. Belgium company, Derbigum, recycles 4,000 tonnes of bitumen a year, and notes that the material suff ers no loss in quality from the process (like gold, which can be melted and recast). The membrane is 7.27m long, 1.1m wide and 4mm thick. It can be applied as a single or two-layer system, and cold-bonded or welded to cover the necessary area. Once the roofi ng system has reached the end of its lifespan, it can all be recycled and reused.

The Olivine grains themselves decrease in size with each reaction. However they are large enough to last more than 30 years before having completely reacted. Adding a second layer of Olivine grains increases the lifespan to more than 60 years. One kilogram of Olivine granulates has the capacity to neutralise 1.25kg of CO2 over 30 years.

Nott ingham Trent University

This ground-breaking technology has been used in the recent redesign and refurbishment of NTU’s Clift on Campus Library, which now features more than 1,000m 2 of Olivine, providing a waterproof, BBA-approved, ecological roofi ng solution.

Durability and sustainability are also in evidence in other aspects of the design and specifi cation. This included Alumasc Roofl ights with kerb design to prevent water penetration and domed glazing moulded from Marlon FSX polycarbonate, which has an impact resistance up to 200 times that of glass. The Harmer AV roof outlets and GX pressed aluminium gutt ers used in the project have the ability to drain up to 40% more roof area than conventional drains – a signifi cant consideration bearing in mind the large surface area of roof and higher predicted peak rainfall arising from climate change. The membrane is guaranteed for 40 years, carrying the longest British Board of Agrément (BBA) certifi cate in the UK, and its high melting point ensures membrane stability in the hott est weather while the polyester/glass fi bre reinforcement provides high tensile strength. The entire roofi ng system, including the gutt ers and drains, is 100% recyclable. Moreover, the Olivine granules have a green hue that makes this the next generation green roof in every respect.