Building cooling by green roof is mainly dependent upon the plant performance, which maybe greatly influenced by plant species with the different photosynthetic and water use strategies. This study was conducted to investigate the different green roof cooling effects by C3 (Poa pratensis and Festuca arundinacea), C4 (Cynodon dactylon and Eremochloa ophiuroides), and CAM plant species (Sedum lineare and Callisia repens). The results showed that different plant species performed different strategies for green roof cooling. Green roof cooling with C3 and C4 plant species was mainly from their transpirations and C4 plants with higher transpiration rate performed the superior canopy cooling than C3 plants. CAM plants performed the lowest canopy cooling due to their stomata closure and lower transpiration during the daytime. All green roofs performed significant cooling in soil profile. The soil cooling by CAM green roofs could be from their canopy solar energy absorption and insulation. The significant night cooling was noticed only by the green roofs with CAM plants which could be contributed from their unique CAM energy fixation during the nighttime. Our results indicated that the green roofs with different plant species could deliver the different range of ecological and environmental benefits. (C) 2019 Elsevier B.V. All rights reserved.