Leveraging the information – physical framework of the Internet of Things (IoT) sensor network, this research paper develops a carbon emission monitoring system for the building construction phase. It devises various types of sensors to gather environmental data during building construction and incorporates a MySQL database to store the diverse data sets. The scope of carbon emission calculation for the building construction stage is re – delineated. A carbon emission calculation approach for the construction stage is formulated from three aspects: human resources, building materials, and construction machinery. The T project is selected as the case study. The carbon emissions during its construction phase are computed, and the functionality of the carbon emission monitoring system is validated. The findings indicate that the average relative deviation rate of the calculated carbon emissions from construction machinery is 8.43%. Moreover, the carbon emission monitoring system enhances the calculation efficiency by nearly 15 times when compared to the conventional manual calculation method. In conclusion, a comprehensive integration of IoT sensors with building construction can notably enhance the carbon emission monitoring capacity during the building construction stage and contribute to the advancement of green buildings.