Discusses the factors that influence overall building efficiency. Presents some of the major decision-making considerations for each of these factors in terms of the roles of the architect and engineer. Illustrates these considerations by a case study of an underground library, selected because an underground building represents a design solution that requires much cooperation between these professions if energy waste is to be minimised.

KEYWORDS: Buildings, designing, efficiency, energy consumption, architects, engineers, underground spaces, case studies, libraries, USA.