The Penang International Airport Extension and Upgrading Project, targeting GBI Gold certification, sets a benchmark for sustainable airport development. Energy performance is optimized through high-efficiency chillers, zoned LED lighting, and a 6 MW solar PV system that reduces grid reliance by 20%. Water savings of over 50% are achieved with low-flow fixtures, rainwater harvesting, and reclaimed water use. Sustainable materials and a construction waste plan diverting 75% from landfill reinforce circular economy goals. The project also enhances indoor environmental quality with low-VOC materials, daylight access, and CO₂-based ventilation, while cool roofs, reflective hardscape, and stormwater management strategies reduce heat gain and runoff. Together, these measures align operational efficiency with environmental responsibility, positioning Penang Airport as a regional leader in sustainable infrastructure.