Operational phase assessment and design modifications for enhancing building energy efficiency towards carbon neutrality in tropical climates

Achieving carbon neutrality in tropical climates necessitates a critical balance between daylight utilization and solar heat gain control, which is particularly acute for the existing building stock. While energy standards for new constructions are vital, scalable retrofitting strategies remain underdeveloped. Addressing this gap, our study proposes a novel, tiered framework for selecting and optimizing building envelope retrofits to cut operational carbon emissions. Using detailed ClimateStudio simulations of a naturally ventilated academic building in Chiang Mai, Thailand, we systematically evaluated strategic modifications, including high-performance glazing and fixed shading devices on key performance metrics like Spatial Daylight Autonomy and cooling energy demand. The results demonstrate a clear trade-off: while daylight access reduces artificial lighting, excessive solar gain significantly increases cooling loads. Crucially, an integrated retrofit approach can reduce operational carbon emissions from the cooling demand by up to 67% without compromising visual comfort. We conclude that prioritizing Solar Heat Gain Coefficient of glazing and integrating passive shading are non-negotiable for tropical retrofits. These findings provide architects, urban planners, and policymakers with a performance-based decision-making framework, offering directly applicable, tiered strategies to enhance the energy efficiency of the tropical building stock and advance progress toward UN Sustainable Development Goals 7, 11, and 13.