Under-occupation of housing increases with age

Unlike overcrowding, assessing under-occupation is not mainly related to difficulties associated with housing conditions. Instead, it enables a reservoir of potential accommodation to be identified in order to ensure existing housing stock is better occupied.

A definition adopted by the European Union involves the relationship between the number of rooms and the number of people in the household using the following criteria:

• one room for the household ;
• one room per couple in the household ;
• one room for each single person aged 18 or more ;
• one room per pair of single people of the same gender between 12-17 years of age ;
• one room for each single person between 12-17, not included in the previous category ;
• one room per pair of children under 12 years of age.

Under-occupation of housing prevalent among over 65s

Under-occupation is particularly prevalent among people aged 65 and over with 76.9% of households under-occupied (moderately or severely) in 2016, in comparison with 49.9% among people younger than 65 years of age. This evolution is mostly explained by the departure of children from the parental home.

Unlike overcrowding, assessing under-occupation is not mainly related to difficulties associated with housing conditions. Instead, it enables a reservoir of potential accommodation to be identified in order to ensure existing housing stock is better occupied. Several recent initiatives have aimed to free up this under-occupied housing, by advocating residential mobility, involving households (particularly elderly people) downsizing to housing better suited to their needs, by encouraging alteration of housing or by developing intergenerational cohabitation.

This objective assessment of sufficient space is based on a definition adopted by the European Union in 2009. It involves the relationship between the number of rooms and the number of people in the household, applying the following criteria:

• one room for the household;
• one room per couple in the household;
• one room for each single person aged 18 or more;
• one room per pair of single people of the same gender between 12 and 17 years of age;
• one room for each single person between 12 and 17 years of age and not included in the previous category;
• one room per pair of children under 12 years of age.

Assessing under-occupation involves comparing the actual occupancy with the above requirements. A dwelling is considered under-occupied if the household has at least two habitable rooms more than it requires. Under-occupation is considered "moderate" if the number of rooms in excess of standard requirements is two or three. Under-occupation is considered "severe" if the number of rooms in excess of standard requirements is greater than or equal to four. Some housing which is not under-occupied may be overcrowded (see Overcrowding according to tenure status (2004 and 2016)).

Under-occupation is particularly prevalent among people aged 65 or over: in this age category, 43.2% of households occupy a moderately under-occupied dwelling and 33.7% occupy a severely under-occupied dwelling in 2016. The majority of these households has lived in the same accommodation for a long period and their children have generally left the parental home, thus causing an under-occupied dwelling.

The number of severely under-occupied households has increased quite considerably over the last decade: in 2016, 21.0% of households were severely under-occupied (compared with 15.2% in 2004), and 35.4% of households were moderately under-occupied (compared with 34.2% in 2004). This rise in the proportion of under-occupied housing is particularly marked among people aged 65 or over.