The Peter McVerry Trust saw an 88% increase in the number of people in emergency accommodation last year.
The homelessness charity is releasing its annual report today and says 2015 was their busiest year on record.
The group is calling on Minister for Housing, Simon Coveney to take a proactive approach to the issue of vacant private housing in order to increase housing supply.
CEO of the Trust, Pat Doyle says the issue of rent continues to be a major problem: "The big issues that are facing us in 2016 and into 2017 will be rents.
"We are continuing to see not enough private rented accomodation, you hear now, all the students are now competing for rented accomodation.
"So the rents are not going down. They are not being maintained and people are losing their place in rented accomodation.
"We are also seeing a huge amount of kids coming out of care and there are not enough places for them."