Carbon Footprint of King Saud University’s Main Campus: Challenges Toward Carbon Neutrality

Campuses in hot–arid regions are under-represented in the literature on the carbon footprint of higher education institutions. This study quantifies the 2025 greenhouse gas (GHG) footprint of the main campus of King Saud University (KSU), Riyadh, Saudi Arabia, under the operational-control approach of the GHG Protocol. The inventory covers stationary combustion and on-site wastewater treatment (Scope 1), purchased electricity (Scope 2), and mobility, municipal water and solid waste (Scope 3), with every emission factor disclosed. The inventory estimate of gross emissions was 579,000 t CO2e (5.88 t CO2e per daily equivalent user, 8.14 per student), close to the Monte Carlo median of 576,000 t CO2e (90% interval 550,000–610,000). Purchased electricity contributed 79.7% and private vehicle mobility 14.6%. Across published Saudi grid factors, the total ranged from 455,000 to 599,000 t CO2e. Green infrastructure irrigated with treated sewage sequesters only 390–1780 t CO2e/yr (0.07–0.31% of the total). A planned photovoltaic retrofit of existing car parking would avoid 29,600–37,000 t CO2e/yr without new land, whereas a 29.7 ha green-area expansion would add 79–361 t CO2e/yr; together they would avoid 5.1–6.4% of gross emissions. For the sources quantified, carbon neutrality therefore depends on grid decarbonization, electricity demand reduction and modal shift, not on-campus greening.