From 1910 to 1914, Orpen was in an architectural partnership with Page Dickinson, with the two collaborating on plans for the new Dublin municipal gallery and conversion of the Turkish Baths, Lincoln Place. Lane rejected Orpen and Dickinson's gallery plans, leading to Orpen refusing to work with Lane's choice of architect, Sir Edwin Lutyens. In 1914, Orpen was appointed a guardian of the National Gallery of Ireland, and lectured at the Dublin Metropolitan School of Art on architectural history in 1914 and 1915. He was involved in the design of a number of memorials including the setting for a bronze relief by Beatrice Campbell for the members of the Royal Irish Regiment killed in the South African war and the war memorial at the Rathgar methodist church. He served as president of the arts and crafts section of the Royal Dublin Society. He was also a governor of the Royal National Hospital for Consumption for Ireland in Newcastle, County Wicklow.