Almost one in three houses in Greece were non-residential in 2011, a report by Hellenic Statistical Authority (ELSTAT) said on Tuesday. The statistics service, in the report, said that the number of houses in Greece totaled 6,384,353 in 2011, of which 6,371,901 were conventional houses (99.8 pct) and 12,452 were non-conventional houses (0.2 pct).