Greenhouse gas (GHG) reduction from the campus is of considerable concern for every university across the world. In response to this concern, Kyoto University commenced an experimental project involving the use of regional renewable energy including wood pellets made of forest thinning for an air conditioning (AC) system in 2011. The aim of this study was to clarify the effects of the energy savings, GHG reduction, and energy cost of this regional renewable energy. Uji-North Bldg. No. 4, one of the buildings in the Uji campus in Kyoto University, was selected as the object building. Wood pellets and solar heat were used as the regional renewable energy sources. A pellet fired absorption heater chiller (PF-AHC), and a solar heating absorption heater chiller (SH-AHC) using urban gas as supplemental fuel, were introduced in conjunction with an air-cooled heat pump chiller (AC-HPC). This configuration, referred to as ‘the renewable AC system', was compared to ‘the previous AC system' using only a direct-fired absorption heater chiller between FY2005 and FY2009.
   Our results show that the renewable AC system reduced 50.8% of fossil energy consumption, 52.8% of CO₂ emission, and 36.9% of energy cost compared to the previous AC system. The AC system operations in summer had more impact on these results than winter operation, because the cooling load accounted for 72.9% of the annual load. PF-AHC and SH-AHC (SH), which used renewable energy sources, contributed to only 7.4% of annual CO₂ emission while they supplied 16.9% of the annual cooling and heating load. However, our analysis also implies that PF-AHC must be managed carefully because the cost of wood pellets created a trade-off relationship between environmental and economical aspects. Going forward, optimal planning of summer operations of the renewable AC system will be considered.