Ermenc was born October 21, 1887, in Ljubno, Slovenia in the Austro-Hungarian Empire. He came to the United States in 1901, and finished his education at night school at the Milwaukee Technical School. Ermenc went into the real estate and insurance business, and organized the J. P. Z. Sloga fraternal society. He had held no previous public office prior to his election.
He ran for re-election in 1932, but was unseated by former Democratic State Representative Mary O. Kryszak in a redistricted Fifth district (now the 5th and 8th wards), with 7313 votes for Kryszak, 4020 for Ermenc, 2761 for Republican Harold C. Schultz, and 126 for Independent Joseph Plecha.[4]