Swiss Review 5/2018

Swiss Review / September 2018 / No.5 8 Focus Concrete and people per square metre: density calculations Density measures may vary by canton, for exam- ple, including or excluding parts of the basement in the reference areas, says Nicolas Bassand. Several indices are used by architects, including the land use index (IUS), which calculates the gross living area with regard to the plot. The den- sity (IUS) of a skyscraper may be 15, providing 30,000 square metres of living area on a 2,000 m² plot. If the IUS of a small house is 0.3, the 1,000 square metres of land will generate 300 square metres of living area. Other indices of density are those linked to human presence per hectare or square kilometre. The City of Geneva is the densest municipality in Switzerland (with 12,800 inhabitants per square kilometre, against 4,500 in Zurich). “Density is an accounting notion,” comments Jérôme Chenal, who advocates a scientific ap- proach to this question, capable of indicating whether or not densification represents the best solution for a given space. For example, he says, “closely packed tall buildings are not optimal for capturing solar energy”. The director of CEAT From the 2017 “Bevölkerungsdichte” (Population Density) atlas from the Federal Statistical Office. ©BFS Districts of detached houses like these are no longer compatible with today’s demands for urban con- centration. Photo: Keystone also points to a certain lack of preparation in Switzerland in the face of the densification of cities, notably in conjunction with the capacity of built land to absorb heavy rains. On this point, he cites the serious flooding which occurred in Lausanne in June. Another point for attention is pollution, “since if we invite people to live in the centre, we increase the time that they spend in a polluted atmosphere. This is one of the factors which we should take into account when we approach the question of density,” the town planner concludes. Inhabitants per km 2 total area ≥ – – 500.0 2000.0 1000.0 4999.9 1999.9 5000.0 – 999.9 300.0 – 499.9 200.0 – 299.9 150.0 – 199.9 100.0 – 149.9 50.0 – 99.9 < 50.0 Switzerland: 210.5