This study aims to develop a design for a sustainable healthcare centre through passive energy efficiency measures to improve the thermal comfort, cooling, lighting and ventilation requirements for primary healthcare centres in Nigeria. The methodology adopted for the study included both primary and secondary data collection. Primary data were collected from the administered questionnaire (5-point Likert scale closed-ended), a total of 350 sets of questionnaires administered and 87% were valid. A case study research strategy was adopted to ascertain the effectiveness and efficiency of building design with an emphasis on sustainable architectural design principles. A significant regression equation was revealed (F (2,257) = 33.619, p <.000, with an R2 of 0.294, which revealed that implementing passive measures for energy optimization has a significant and positive effect on designing sustainable healthcare centres. It further recommends the integration of passive design, design for deconstruction, adaptive reuse, and design for human comfort as part of architectural design principles that would result in sustainable energy optimization should be adopted in every design of primary healthcare centres by architects.