This thesis explores the principles and practices of sustainable architecture, emphasizing the reuse, repurposing, and refurbishment of building facades. These strategies are crucial for reducing environmental impact while preserving the cultural and historical significance of structures. The research focuses on the unique challenges involved in refurbishing non-iconic architectural heritage buildings that possess distinct characteristics, with a particular focus on building envelope improvements, especially for mid-20th century buildings featuring curtain wall systems. The first chapter provides a broad exploration of the concept of building reuse, tracing its historical development and evolution across various architectural movements. The research examines different architectural discourses surrounding reuse, identifying critical points where restoration, preservation, refurbishment, and repurposing intersect.