The study of the impact of the zero-emissions scenarios of several countries on the electrical demand is relevant to analyze the feasibility of the sustainable energy transition. This paper presents a structured method to assess the effect of the 100 % renewable scenario on the hourly electrical load profile of a country taking Italy as reference case study. The hourly discretization is a fundamental approach to evaluate the contribution of the intermittent renewable sources during the day and the proposed methodology can be easily applied to several countries' scenarios. Numerous decarbonization scenarios consider the adoption of electricity in several sectors. Consequently, the primary energy reduction (40 % in the scenario considered) is usually accompanied by a relevant increase of the annual electricity demand (94%–124 %). In this paper, each sector's contribution is estimated separately, and the results show demand peaks above 100 GW and a baseload above 50 GW, which is more than double that of recent years. Electricity consumption is higher in the colder months and hydrogen and synthetic fuel production impacts significantly on the total electricity demand (26%–32 %). The results of this work will be used to verify the feasibility of net zero scenarios with hourly discretization in further research analysis.