The carbon emission intensity of BHIP and ZSBT buildings at different stages of the life cycle and different materials. (a) The carbon emission intensity of BHIP and ZSBT buildings at different stages of the life cycle, (kg CO₂/m²); (b) The carbon emission intensity of different materials of BHIP and ZSBT buildings, (kg CO₂/m²); (c) The ratio of carbon emission intensity of BHIP building in different stages; (d) The ratio of carbon emission intensity of ZSBT building in different stages; (e) The ratio of carbon emission intensity of BHIP building materials; (f) The ratio of carbon emission intensity of ZSBT building materials. Note: * means a significant level, and ** means an extremely significant level.