The proportion of landlords under 45 has decreased from 35% in 2017 to just over 24% in 2021, new CSO figures show.
Meanwhile, the most common heating efficiency BER rating for rental properties is C while an A rating is the least common, although the proportion of rental properties with an A rating is increasing, the figures also show.
C ratings account for approximately 40% of properties. The proportion with an A rating has been increasing every year from 1.1% in 2017 to 4.8% in 2021.
The proportion of properties with A or B BER ratings is lowest for those in receipt of Housing Assistance Payment (HAP) scheme or Rent Supplement.
And the median size of rental properties is smallest in Dublin city and largest in Roscommon.
The total floor area of rental properties is lowest in Dublin and particularly in its inner city.
More than half (50.5%) of landlords in 2019 had a rental income of less than €10,000 while the most common sector of employment for landlords is human health and social work, at just over 12%.
Almost a third (33.0%) of landlords with 20 or more tenancies work in the financial and real estate sector.
About three in ten more landlords receive between €10,000 and €20,000 in rental income. Just over 1% received more than €100,000 in rental income.
Rent as a proportion of total disposable income is highest for tenants living in and around Dublin with 36% of tenants living in Dublin city spending more than 35% of their disposable income on rent in 2019.
Employee income is the primary source of income for 71% of tenants.
The Rental Sector in Ireland 2021 report was developed in collaboration with the Residential Tenancies Board (RTB) and the Department of Housing, Local Government and Heritage (DHLGH).
Statistician Justin Anderson said: “The Rental Sector in Ireland 2021 provides analysis on the properties, landlords and tenants that make up the rental sector in Ireland.
“The publication examines, amongst other topics, age and income of landlords, rent burden of tenants and characteristics of rental properties across time and at different geographic breakdowns.”