Demand for electricity peaked for 2007 across Ireland yesterday evening, Energy Minister Eamon Ryan told the Dáil today.
The 5,077 MW level was lower than the 5,250 MW estimate by Eirgrid, which the Green Party TD attributed to greater energy efficiency.
He added that yesterday's peak electricity level was a 1% increase on 2006 which was below the annual average.
He said: "That, to my mind, is encouraging because it shows the benefits of energy efficiency - that is getting the same services but using less electricity.
"This is the first time I've seen where the winter peak was significantly below what was being forecasted. That is very encouraging."
Mr Ryan said the holiday season generally prompts a natural reduction in demand for electricity due to offices and business closing.
Last year, electricity peaked at 5,035 MW on December 19.