The London-based firm, which took on Ken Yeang as a partner last year, is facing competition from two US firms, Morphosis and Kieran Timberlake, and Germany's Behnisch Architekten.
The two new buildings, the £55 million Campus Calgary Digital Library and the £73 million Institute for Sustainable Energy, Environment and Economy, will add space for an additional 7,000 students by 2010.
The university is planning a wider expansion programme worth £485 million - the largest such programme in its 40-year history.
'We are very excited to be shortlisted for these important projects, and we commend Mr Sinclair [dean of the faculty of environmental design] for his enlightened selection process and for choosing such a competitive group of architects,' said Yeang.
'We look forward to delivering an innovative signature green building that will inspire and delight the students, faculty and visitors of the University of Calgary,' he added.
Construction is believed to be scheduled to begin on both projects as soon as this autumn.