Economists say the owners of vacant sites must be taxed "aggressively" to reduce housing costs.
Just 10 local councils are ready to charge the vacant sites levy of 3%.
The ESRI also said 2,000 fewer homes would be built, and the cost of sites is having an impact as well as Brexit.
It comes as the Residential Tenancies Board's latest index shows a 7% annual increase in national rents.
Professor Kieran McQuinn said more must be done to put vacant sites to work.
Prof. McQuinn said: "Because there's no cost to hoarding it, it means that speculative development, the speculative cost of land is very high in the Irish market.
"So I think a site tax properly implemented could target that and get at that issue and help to reduce the speculative component of the land price.
"Thereby reducing the land price, thereby reducing the cost of supplying the house and increasing the amount of supply at a given price."