Green roofs

Solaranlage auf dem Gründach der ufaFabrik

The roofs of the ufaFabrik buildings were not insulated and covered with tar roofing felt. The roads and squares were mostly sealed with asphalt. During the summer, this caused both interior and exterior to heat up uncomfortably and large amounts of dust to whirl up. By now, 4000 square meters have been planted with greenery, such as native grasses, herbs and shrubs.

The green roofs improve the insulation of the buildings and absorb around 500 grams of dust from the air per square meter each year, which is about the content of a dust bag inside a vacuum cleaner. Collectively, the green roofs absorb around 2000 kilograms of dust per year. Approximately 1,5 square meters of planted greenery will produce enough oxygen to cover one person’s needs per…

The green roofs have two more positive effects:

Firstly, they filter rain and absorb polluting and harmful substances, thereby contributing significantly to keeping both groundwater and surface waters clean.

Furthermore, the green roofs provide a slower drainage of rainwater since the substrate can absorb large amounts of water. Per year, around 75% of the rain is evaporated back into the air by the plants. Hereby, in case of heavy rainfall, the chance of a flooding of dirty waste water from the sewerage into the surface waters is reduced. This effect could also be achieved by the construction of rainwater retention basins, but the construction of a rainwater retention basin with the storage volume of one cubic meter costs 2000€. For the same amount, 50 square meters of green roofs can be planted, with a 10 cm thick substrate. In the case of 30 mm of heavy rainfall, these will absorb 1,5 cubic meters of water. This means, that green roofs are more cost-efficient than rainwater retention basins, aside from the positive ecological and climatic effects.

In recent years, our green roofs have become the topic of research projects of the Technische Universität Berlin (physics, LINK) and the Fachhochschule Neubrandenburg (vegetation, LINK). Every year in May and June, the plant diversity is scientifically researched to determine the long term development of the growth and the durability of the roofs. A number of selected roofs is watered with collected rainwater. As a result, the vegetation on these roofs include robust plants like cheatgrass (Bromus tectorum), sheep fescue (Festuca ovina), canada bluegrass (Poa compressa) and various types of sedum, but also colorful plants of the faboideae-family, like alfalfa (Medicago sativa), hop clover (Medicago lupulina) and anthyllis. Overall, around one hundred different plant species can be found on the ufaFarbik’s green roofs, which is much more than on most city meadows. This diversity of species pleases both spectators, as well as the many insects and birds, for whom it provides an extensive “menu”.

To seal the green roofs, nontoxic foils made out of recyclable polyolefin were used. The substrate consists of soil, expanded clay and expanded shale, which is lighter than regular soil when containing water, but is able to contain more water at the same time. The substrate and vegetation also function to protect the sealed roofs against weathering, thereby increasing their durability.