There are almost 200,000 vacant homes across the country according to the new census figures.
The homeless charity Simon has described the figures as "scandalous".
The census figures shows Ireland's population has risen to 4.76 million - a 3.7% jump on figures from 2011.
The census figures come ahead of the publication of the Action Plan for Housing next week.
Housing expert Dr Lorcan Sirr of DIT says there are two ways to tackle the housing crisis: “One is increasing supply, but the other side of that coin is managing the stock that we have and a lot of the management revolves around things of for example the taxation of property, who encourage people who have properties lying about and there are a lot of them that they are not using, or they can’t use to put them back on the market.”