Carbon emissions from construction sites exhibit distinct traits of spatial concentration and temporal intensity, which underscores the pressing need for effective monitoring and regulation of their environmental impacts. However, many construction site carbon assessments are carried out before or after project completion, with little attention paid to monitoring environmental performance during the construction process. This paper develops a performance assessment model called Earned Carbon Value Management (ECVM) based on construction quota theory, internet of things technology and earned value theory to assess the performance of carbon emissions during construction and improve the accuracy and efficiency of the carbon emissions management at construction sites.The model links construction carbon emissions with project completion volume and resource consumption, proposing three key parameters and four key indicators.The development model was applied to a construction project of a building in Shanghai, and the evaluation revealed that at the 20-day mark of construction, the project had an emission variance (EV) of -105.46 kgCO₂e, while the schedule variance (SV) was -215 kgCO₂e. This indicates significant delays in the current construction progress, with carbon emissions exceeding the allocated limit. However,when construction progressed to 30 days, the EV and SV of the project were -2 603.18 kgCO₂e and 555.39 kgCO₂e, respectively. This demonstrates the positive impact of a moderate progress adjustment, resulting in effective control of the construction schedule. Nevertheless, the carbon emissions still exceeded the allotted limit, necessitating further measures to mitigate carbon emissions.The case demonstrates that ECVM can analyze the relationship between construction progress and carbon emissions during the construction process analyze the causes of deviations and propose targeted corrective measures based on carbon emission performance indicators. The model presented in this paper is generic and can be used for any construction project that aims to reduce carbon emissions.