The Norwegian construction industry is responsible for approximately 1.2% of national GHG emissions during the construction phase. Consequently, there is a growing interest in addressing construction emissions. Therefore, this article aims to comprehensively document and analyse construction phase emissions from a Norwegian ZEB construction site, and compare estimated and actual data in embodied construction emission calculations. Construction site activities considered include transportation and installation of building materials, construction machinery, temporary works, energy use, waste management and person transport. The environmental performance is calculated in terms of GHG emissions weighted as carbon dioxide equivalents (CO2eq). The embodied construction emission results are 1.1 kgCO2eq/m 2 /yr for estimated data, and 2 kgCO2eq/m 2 /yr for actual data. The results show a 44% increase in emissions when using actual data instead of estimated data. The largest contributors to emissions are the operation of construction machinery (47%), energy use (17%), transport of building materials to site (15%) person transport (10%), installation of building materials (10%), followed by temporary works (0.8%) and construction waste (0.3%). This study highlights the importance of embodied construction emissions in Norwegian ZEBs, and recommends paying more attention to the construction phase in the future. These results may be used in future Norwegian construction projects, to help measure, evaluate and compare the environmental performance of construction activities.