As climate change intensifies, rapidly urbanizing cities like Phnom Penh must adopt sustainable building practices to reduce energy use and emissions in line with global commitments such as the SDGs, the Paris Agreement, and IPCC guidance. With new buildings expected to achieve near-zero operational energy by 2030, Cambodia must pursue a holistic approach that combines energy-efficient and passive design, renewable energy, and low-carbon materials while addressing both operational and embodied carbon. These guidelines provide practical direction for practitioners and local authorities to support Cambodia’s transition toward a resilient, climate-neutral urban future.