This study presents an integrated methodology to assess and reduce greenhouse gas (GHG) emissions in institutional buildings by combining organizational carbon footprint (CFO) analysis with rooftop photovoltaic (PV) system simulation. The HM Building at King Mongkut’s Institute of Technology Ladkrabang (KMITL), Thailand, was selected as a case study to evaluate carbon emissions and the feasibility of solar-based mitigation strategies. The CFO assessment, conducted in accordance with ISO 14064-1:2018 and the Thailand Greenhouse Gas Management Organization (TGO) guidelines, identified total emissions of 1841.04 tCO₂e/year, with Scope 2 electricity-related emissions accounting for 442.00 tCO₂e/year. Appliance-level audits revealed that classroom activities represent 36.7% of the building’s electricity demand. These findings were validated using utility data totaling 850,000 kWh/year. A rooftop PV system with a capacity of 207 kWp was simulated using PVsyst software (version 7.1), incorporating site-specific solar irradiance and technical loss parameters. Monocrystalline modules produced the highest energy output of 292,000 kWh/year, capable of offsetting 151.84 tCO₂e/year, equivalent to 34.4% of Scope 2 emissions. Economic evaluation indicated a 7.4-year payback period, with a net present value (NPV) of THB 12.49 million and an internal rate of return (IRR) of 12.79%. The integration of verified CFO data with empirical load modeling and derated PV performance projections provides a robust, scalable framework for institutional carbon mitigation. This approach supports data-driven Net Zero campus planning aligned with Thailand’s Nationally Determined Contributions (NDCs) and carbon neutrality policies.

This study presents the design and implementation of a prototype‐scale hybrid CO ₂ capture system that combines Wolffia globosa cultivation, mineral carbonation with waste seashell‐derived CaO, and real‐time IoT‐based monitoring. Waste seashells were calcined at 900°C to produce CaO, which was characterized by XRD and morphological FESEM and EDS analysis and was selected for mineral carbonation. The IoT system monitored changes in CO ₂ concentration above the W. globosa tank, which were influenced by photosynthesis and respiration cycles. It also tracked CO ₂ concentration after the mineral bed, where a consistent decrease of approximately 300 ppm relative to the inlet was observed under the tested conditions, with outlet readings approaching the lower bound of the sensor's specified accuracy (±[50 ppm + 5% of reading]). This decrease was attributed to CaO hydration and subsequent carbonation. Continuous measurements of CO ₂ , pH, and temperature provided useful diagnostic information for interpreting system behavior. The results demonstrate the feasibility of integrating locally available waste‐derived CaO with biological cultivation and IoT‐based monitoring in a small‐scale laboratory prototype. However, a full net carbon balance, including calcination emissions and operational energy demand, was not included in this study. Therefore, the observed CO ₂ decrease should be interpreted as local CO ₂ uptake during the mineral carbonation step rather than confirmed net carbon removal.