What We Do: GLHN is an employee-owned firm established in 1963 and has a professional staff of over 60. We are a full-service design firm with Architecture, Civil, Mechanical, and Electrical Engineering, with offices in Tucson and Phoenix. Staff includes LEED Accredited Professionals in all disciplines, Registered Communications Distribution Designers, Certified Energy Managers, Building Energy Simulation Analysts, Certified Commissioning Authorities and Technicians, and a Lighting Certified designer.