Before studying abroad, Greenwell had been articled to the firm of Kent & Budden, and in 1912 he joined them in partnership as Kent Budden & Greenwell. During this time, Greenwell designed a number of now heritage-listed houses for family and friends in Strathfield, New South Wales and Killara, New South Wales. His design for a substantial domestic dwelling in Woodside Avenue, Strathfield, is characteristic of his houses of this period. Another notable design showing his distinctive rough-cast stucco columns is 'Terhyn Worthle' which was featured in "Domestic architecture in Australia" edited by William Hardy Wilson (Sydney : Angus and Robertson, 1919). These homes had elements of the Federation Arts and Crafts and Federation Bungalow styles.