Clare homes are among the least energy efficient in the county.
New figures from the CSO show the average amount of energy used by a home here is the highest in Munster.
CSO figures published today show that more than half of the 14,000-plus homes in the county have a Building Energy Rating of D1 or worse, meaning it costs more to heat them and that they are less friendly for the environment.
On the other end of the scale, less than one per cent of homes here are in the A or B1 categories.
Heating oil is the main heating fuel used in 63% of Clare homes, compared with the overall figure for Ireland of just 41%.
Older homes are typically less energy-efficient, but at 30 years, the average age of a house in County Clare is line with the national average.
