Green Roof Innovation
Mineral Wool on Green Roofs – Chance or Challenge?
Green Roof Technology Reveals Latest Study about Mineral Wool on Living Roofs
Since their first commercial production in 1871 (Georgmarienhütte, Germany), mineral wool found its way in many applications like thermal insulation andsoundproofing. Mineral wool, mineral fibers are typically referred to synthetic materials like fiber glass, ceramic fibers and stone or rock wool.
Two main types of mineral wools are on the market – water repellent (Hydrophobic) and water adsorbent (Hydrophilic). For horticultural purposes, only the hydrophilic type is useful. Many patents were granted for simple Hydroponic systems or the germination of seeds with mineral wool in the early 80’s.
In modern green roof technology the first green roof systems came on the market around 1985 in Germany at a time as the German green roof industry gained tremendous momentum. As a lightweight solution with high water retention, mineral wool seemed an ideal material. The higher costs and the higher carbon footprint - comparing to lightweight aggregates – were argued with easier installation and higher water retention.
Extensive research over more than 5 years at the University of Geisenheim and on numerous buildings confirmed the high water retention properties. However, in the mid-run these tests also revealed that the performance and the health of the vegetation were far below conventional green roof systems with standardize green roof components. Mineral wool manufacturers and green roof system suppliers stepped away from the idea of using mineral wool as a growing component for green roofs.
“Today we can see a revival of mineral wools in the green roof industry,” says Jorg Breuning, CEO, Green Roof Service LLC,” in countries with hardly any green roof experience, mineral wool is getting rather popular with potentially fatal results in the mid and long-run.”
Especially in the United States, the market is growing rapidly for mineral wools on green roofs, disregarding existing studies and without extensive long-term tests. It isn’t even proven whether certain fibers can cause health problems, leach out chemicals or whether these components can be recycled when the green roof doesn’t perform anymore.
In 2012, the lack of performance of mineral wool as a vegetation carrier resulted in a major green roof restoration at Amsterdam International Airport. 90,000 square foot of green roof – built with mineral wool - had been taken off and replaced by a standardized green roof system. At this point, this was the largest green roof restoration in the history of mineral wool on green roofs. Costs that could have been avoided.
Doing it right in the first place.