This chapter delves into the principles of Environmental Architecture, focusing on the integration of sustainable design for efficient and sustainable building facilities. It explores how sustainable design optimizes building performance, minimizes negative environmental impacts, and balances cost, environmental, societal, and human benefits. The chapter highlights key strategies such as optimizing site potential, minimizing non-renewable energy consumption and waste, using environmentally preferable products, protecting and conserving water, improving indoor air quality, and enhancing operational and maintenance practices. It emphasizes the holistic approach of sustainable design, which positively impacts all phases of a building's life cycle, encouraging compromise and trade-offs for a more sustainable future.