From 2002-2004 he served as president of the Royal Society of Ulster Architects (RIBA Northern Ireland) and in 2005 he served as Ulster representative to the Royal Institute of the Architects of Ireland (RIAI).
In one column in 2006 he called on the Westminster government "to commission a design competition for the proposed centre for conflict transformation earmarked for the Long Kesh prison site."
In 2012 he was appointed as a member of the Maze/Long Kesh Development Corporation and re-appointed for a further term in 2017 [3] He contributed an essay to the Arts Council of Northern Ireland collection on arts and the Troubles, which focused mostly on Belfast "the largest urban area in Northern Ireland, as the principal ground of the conflict and as the historical arena for the expression of sectarian conflict even before partition of the island.
"[4] Mackel's works include the Bunscoil an tSleibhe Dhuibh and the Kinnaird Street office building, both in Belfast.
[citation needed] In 2012 a house extension, designed by Mackel, at Osborne Park, Belfast, won an RIBA Award.