If there’s been a dominant storyline in the world of architecture practice this year, surely it’s been the rising level of mergers and acquisitions. Marking another chapter in the story, Atlanta-based Perkins + Will announced this week that it acquired the New York City firm Guenther 5 Architects. Terms of the deal were not disclosed.

Robin Guenther, FAIA, founded the firm that eventually became Guenther 5 in 1991. Over the years it has grown into an 18-person office practice specializing in health care and sustainability. Clients include Beth Israel Medical Center, New York Presbyterian Hospital, Maimonides Medical Center, and the Mt. Sinai Medical Center. In addition to Guenther, its other principals are Jason Harper, AIA, and Peter Syrett, AIA.

Perkins + Will ranks as No. 5 on Engineering News-Record’s annual list of the Top 150 Architecture Firms with $268.3 million in 2006 revenue. The firm maintains offices worldwide and, as part of a growth initiative, has acquired firms during 12 of the last 16 years. Most recently, in July, it purchased the Minnesota-based education and civic building specialist Rozeboom Miller.

Offering praise for Guenther 5, Perkins + Will health care principal Chris Bormann said the small firm “enjoys a very positive, unusually high national profile.” He added, “Guenther’s reputation for both design and green architecture dovetails with our goals on a corporate and local level, as well as with our healthcare sector practice.”

Robin Guenther serves on the boards of the Center for Health Design, the AIA Guidelines for Construction of Hospitals and Health Care Facilities, and the Advisory Council on Sustainability for the NYC Department of Buildings. An expert in sustainability, she is also on the steering committee for the Green Guide for Health Care, which she helped author, and the LEED for Health Care Core Committee.