Stonecrop most common
Green roofs exist in several different varieties: everything from moss and stonecrop (sedum) purchased in rolls to proper gardens with bushes and trees. The most common is stonecrop, which only needs a little earth and hardly any maintenance.
“It’s sufficient if you water it in the event of a drought and fertilise it every other year,” says Åsa Eriksson from Ekologigruppen, who performs ecological analyses for Fabege. You immediately get a green space that has many advantages. These include absorbing water, purifying the air, reducing noise and making the underlying topsoil of the roof last longer.” Studies have shown that seeing a green roof rather than a regular roof improves people’s well-being.
“In Stockholm, buildings have traditionally been built at the same height, which means that few people can see the green roofs that actually exist,” says Johan. In Arenastaden, the differences in level between the buildings mean that many people can enjoy them.
Bringing nature into the capital
Constructing this kind of roof has become an accepted building method now that cities are becoming denser and green spaces are being built on. It is also a requirement for environmentally certifying properties to BREEAM, which Fabege works with.
“It’s incredibly important to try to recreate green spaces in various ways if you build new properties on them,” says Johan. “We’ve done this several times in Arenastaden, and there’s now more green space than before the district was built. Along with green roofs, we’ve created several pocket parks in the area.”
Another advantage of the roofs is that they contribute to biodiversity. They become a place where bees, bumble bees and butterflies like to settle, which in turn gives more diverse bird life.
“Stonecrop roofs bloom for about a month in early summer and are a source of food for bees and bumble bees during this period,” says Åsa. “Other types of green roof that have deeper plant beds, such as meadow roofs and rooftop gardens, provide greater scope for biodiversity, as they are able to house a greater number of plant species, meaning that they bloom for a longer period.”
Some green roofs in Arenastaden
- Evenemangsgatan 17 – stonecrop roof.
- Evenemangsgatan 31 – view of stonecrop roof from lightwell building.
- Stjärntorget 1 (above Mall of Scandinavia) – stonecrop roof.
- Stjärntorget 4 – SEB’s rooftop park with solar cells and flower beds, to be fully completed in 2018.