Over the last 14 years several biodiverse extensive green roofs have been in stalled in Basel in combination with Solar panels. This has included both Solar thermal and solar energy (PV). Part of the drive for this has been to improve biodiversity in the city through the need for ecological compensation on new developments. Something was taken and to be compensated for. This is different from ecological replacement or restoration.
Each roof needs to replicate the ecological characteristics to be considered as compensation. Taking the surroundings, the green roofs acts as stepping-stones for several species to migrate between habitats in the city.
The city of Basel wrote an inventory of the nature within the city. This is based on the national inventory – this lists species of national importance. based on the national one with it's existing objects of National importance. The Basel Inventory lists relevant red-listed species, protected species and characteristic species that have been mapped in the city. This inventory was finished in 2011. The list is regularly updated and is publicly accessible.
St. Johanns-Park: Dry meadows in a part of a public park in the centre of Basel City - nature conservation within the
city: a high plant diversity and animal diversity is to be found in this location (several red list species).
These inventories are important for Swiss cities, as they help the city make decisions regarding on how construction sites impact on habitats ( and species).
In intensively used areas both outside and within urban areas, the cantons (similar to counties) provide ecological compensation with measures like: hedges, copses, river embankments and other natural vegetation restorations. This is a National requirement since 1987 of the Article 18b of the Federal Act on the Protection of Nature and Cultural Heritage (NCHA) of 1 July 1966 (Status as of 12 October 2014).
• Such compensation also includes:
• Unsealing of asphalted surfaces,
• Site-specific and indigenous planting
• Creation of nesting opportunities
• These types of actions are not to be confused with replacement or restoration ecology.
Ecological replacement or ecological restoration
The ecological replacement or ecological restoration divers from compensation in that the habitat lost to development needs to mitigated for. This is means it needs to be replaced or restored if it is of national and cantonal importance. Construction companies must do this and it is legally stronger than ecological compensation but can make the process very difficult and complex. For example amphibians, which are highly protected nationally, a construction site will need to consider how amphibians can live side by side with human beings. The construction will have to fulfill all the needs of the amphibians in question if the construction is to go ahead.
As discussed biosolar roofs are covered by the ecological compensation requirements at national and cantonal level. Each roof needs to replicate the ecological characteristics to be considered as compensation. Taking the surroundings, the green roofs acts as stepping-stones for several species to migrate between habitats in the city. The roof design, even if it is to have solar panels installed, will have to consider what species in the nature inventory that could move. There are many examples of how this has been achieved in the City of Basel.
Stücki Shopping Centre - a building project with green roof and green facade which was about restoring and compensating ground surfaces where before thermophil species were found (red list species as well) in typical ruderal /rubble surfaces and along a railway line. Especially the blue-winged grasshopper, Oedipoda caerulescens, was found there and therefore this roof had to restore the conditions of habitats for this red-list grasshoppers (reproduction and forage).