Kildare has the highest number of homes with the best energy rating.
It's followed by county Dublin and Meath, according to the CSO.
20 % of homes in Kildare which have been tested for a BER rating were given an A standard, while Meath and county Dublin have 19% and for Wicklow it's 15%.
The Building Energy Rating calculates a house's efficiency.
Roscommon and Leitrim have the highest proportion of G ratings - which is the worst awarded.
Both counties have 12% G rated - followed by Tipperary on 11, and Mayo and Westmeath with 10%.
Longford and Leitrim have the fewest BER ratings, while Dublin's postal districts have the most with 229,000.
C2 and C3 are the most common ratings nationally at 12%.
In total over 1 million BER ratings have been given out since 2009.
No Changes To Starting Team As Wicklow Football Yearns For Historic Croker Triumph
Wicklow Braced Once More As Coillte Signal Orange Fire Warning
Wicklow Boss Targets Tailteann Cup Glory As Down Challenge Looms At Croke Park
Wicklow TD Calls For Straw Incorporation Funding For Struggling Tillage farmers
New Operator at Wicklow Gaol Brings A Reopening Date Closer