The assessment of energy use in buildings is widely incorporated into building energy regulations, energy certifications and standards. The majority of these assessments focuses on a building’s operational energy use and, sometimes, on the indirect energy embodied in building materials. However, there is little research on the energy use during the construction stage. Current interpretations, quantification and analysis procedures of energy used for onsite construction activities are unclear and real-life data are lacking. Further, due to the increased focus on lowering operational energy use, the relative share of energy used in the construction stage is increasing. This paper presents the results of an explorative study on energy use during onsite activities for the construction of... family houses. A protocol was developed to structure data gathering and was applied to several residential building projects. The data gathered were analyzed to explore relationships between project characteristics and energy use in onsite construction activities. In the analysis, the authors use scatter plots and statistics. Significant strong positive correlations were found between onsite electricity use and three basic project characteristics: construction period in working days, gross floor area and gross building volume. Based on the findings, this paper concludes with a proposed research agenda.