Ernst graduated with a Bachelor of Architecture degree with honors from the School of Architecture at Andrews University, in 1987. After graduating he joined the management team of ASI Mission Church Builders, a volunteer organization building churches in the southwestern United States. In 1989 he joined Vigen Associates in Fresno where he designed commercial retail buildings and carried lead roles as computer systems manager and job captain. In 1992 he began working for Hanford Community Medical Center and until June of 1997, when he started Ernst Architects, worked with various Adventist Health hospitals maintaining and renovating hospital buildings.