The previous ordinance expires in mid-March. The new one will apply immediately afterwards for a further five years in the 81 so-called social conservation areas. According to the building authorities, around a third of Berlin's population lives in these neighbourhoods. The extension of the ordinance is intended to secure affordable housing and protect the population structure in the neighbourhoods, said Gaebler. The conversion of rental flats into owner-occupied flats is one of the main reasons for the loss of affordable rental flats and the displacement of the resident population in these areas.