Background

Extreme heat is rapidly becoming one of the most pressing challenges in Southeast Asia, driven by the combined pressures of urbanisation, climate change, and rising energy demand. The urban population in the region is expected to grow significantly, increasing exposure to prolonged periods of extreme temperatures, with some cities projected to experience up to 120 days annually above 35°C by mid-century. These risks are intensified in dense urban areas, where heat-retaining materials, limited green spaces, and inadequate ventilation contribute to severe indoor heat conditions.

The impacts are highly unequal. Vulnerable groups, including women, children, the elderly, and low-income communities, are disproportionately affected, often facing unsafe indoor temperatures or working in heat-exposed environments. At the same time, increasing reliance on mechanical air conditioning is driving up electricity demand, greenhouse gas emissions, and pressure on energy systems, reinforcing a cycle that exacerbates climate warming.

Passive cooling presents a practical, cost-effective solution to these challenges. By prioritising strategies such as natural ventilation, shading, reflective materials, thermal mass, and climate-responsive design, buildings can significantly reduce indoor temperatures and energy consumption. These approaches can lower temperatures by several degrees and reduce energy use substantially, while also offering scalable benefits at the regional level by limiting future cooling demand, reducing emissions, and lowering infrastructure costs. Importantly, passive cooling provides an accessible pathway to improve thermal comfort for populations that currently lack adequate cooling solutions.

About the Roadmap

The ASEAN Passive Cooling Strategies Roadmap has been developed through a collaborative, multi-stage process involving research, stakeholder engagement, and regional consultation. It provides a strategic framework to integrate passive cooling into policy, regulatory, and investment landscapes across the region, aligning with broader climate and energy commitments.

The roadmap translates regional heat challenges into actionable recommendations, including policy directions, financing approaches, and capacity-building pathways that can be adapted at the national level. It promotes a “Passive First” approach, encouraging building design that minimises cooling demand through orientation, envelope performance, shading, and ventilation before relying on mechanical systems.