As the ZEB/ZEH of buildings progress, environmental load at the time of construction of buildings would account for a large portion of the environmental load in the entire building lifecycle. Therefore, the energy consumption and CO2 emissions at the time of manufacturing building components and construction of a building itself would become issues. In order to examine methods for reducing the embodied energy (EE) and embodied CO2 equivalent (EC) in buildings, it is important to calculate and determine the EEC in the early stage of design. Accordingly, this paper will discuss a simple EEC calculation method undertaken at an early stage of the design process. This method proposes applying appropriate intensities to major selected building items. It also indicates that setting intensities per quantity of major materials/equipment, per gross floor area and per estimated cost would enable calculation of the EEC with relatively high accuracy. The EEC of the sample building was obtained by both the simple calculation and detailed calculation methods, in order to confirm the accuracy of the former calculation. Utilizing this simple calculation method, roughly 96% of the entire building has been counted, which would allow calculation of the EEC by identifying quantities in a relatively simple manner.