SIA Standard 180, Thermal insulation and moisture protection of buildings (2014) aims to ensure climatic well-being within buildings and to prevent damage to buildings. It describes concepts and requirements with which these objectives can be achieved in the case of usual use and maintenance. Compared to the 1999 edition, special attention is given to air quality.

In particular, it is mentioned that ‘for radon concentrations in rooms, the limit values of the Radiation Protection Ordinance apply. Due to the new standards of the World Health Organisation (WHO) and the International Commission on Radiological Protection (lCRP), the FOPH recommends that the value of 300 Bq/m3 should not be exceeded in living and residential areas and, in the case of renovations, conversions or for new buildings, to aim for a possibly lower level’.

Furthermore, ‘the construction parts of the building envelope of rooms that provide occupancy and are in contact with the ground must be sufficiently impermeable to prevent water, water vapour and radon from entering’.

Finally, ‘in new buildings with living spaces in contact with the ground or natural cellars, preventive construction measures must be in place to reduce radon concentrations thereafter if necessary’.