The building sector significantly contributes to global energy use and CO2 emissions, emphasizing the need for sustainable green building practices. University buildings, as high energy-intensive facilities, require systematic sustainability assessments. This study evaluates the sustainability performance of buildings at UNU and UNISA using the Greenship Existing Building rating system and examines indoor environmental comfort parameters, including temperature, humidity, CO2 concentration, and lighting intensity. The methodology includes document assessments, field observations, and direct measurements of indoor comfort across multiple rooms and floor. Data were quantitatively analyzed and spatially visualized using GIS-based IDW interpolation to illustrate horizontal and vertical comfort distribution. Results show that UNISA scored 58 points (49.57%) and UNU 56 points (47.86), both achieving Silver certification. UNISA performed better in site development, water conservation, and material cycles, while UNU excelled in energy efficiency, indoor comfort, and environmental management. The study highlights the need for further sustainability improvements.

The building sector significantly contributes to global energy use and CO2 emissions, emphasizing the need for sustainable green building practices. University buildings, as high energy-intensive facilities, require systematic sustainability assessments. This study evaluates the sustainability performance of buildings at UNU and UNISA using the Greenship Existing Building rating system and examines indoor environmental comfort parameters, including temperature, humidity, CO2 concentration, and lighting intensity. The methodology includes document assessments, field observations, and direct measurements of indoor comfort across multiple rooms and floor. Data were quantitatively analyzed and spatially visualized using GIS-based IDW interpolation to illustrate horizontal and vertical comfort distribution. Results show that UNISA scored 58 points (49.57%) and UNU 56 points (47.86), both achieving Silver certification. UNISA performed better in site development, water conservation, and material cycles, while UNU excelled in energy efficiency, indoor comfort, and environmental management. The study highlights the need for further sustainability improvements.