Monitoring Earth Energy Imbalance (EEI) is absolutely fundamental to understand and prevent climate change as it corresponds to the Earth’s excess heat. In particular, measuring radiative forcing in an environment with a wide range of conditions entails a better understanding of its impact on the climate.The UltraViolet and infrared Sensors at high Quantum efficiency on-board a small SATellite (UVSQ-SAT) aims to improve measurements of those radiations at Top Of the Atmosphere (TOA). It becomes a pathfinder for Radiation Budget measurements on-board a CubeSat demonstrating a disruptive technology, implementing miniaturized sensors on a small satellite (twelve miniaturized thermopiles sensors and four photodiodes). This project is promoted by the University of Saint-Quentin-en-Yvelines with the support of the International Satellite Program in Research and Education (INSPIRE). The satellite will be launched and in-orbit in December 2020.One of the main purposes of the mission is to measure the Essential Climate Variables (ECV) more precisely using multi-point observation, in an effort to improve spatiotemporal coverage through future constellation. The scientific goals of the mission are first to observe incoming solar radiation and outgoing terrestrial radiations at Top Of the Atmosphere. The second purpose is to measure solar spectral irradiance in the Herzberg continuum. Finally, the third objective is to improve the technological readiness of a sensor.This session will focus on the ability to define the spatiotemporal accuracy required to monitor the variability of those Essential Climate Variables. Therefore, it will allow us to determine the number of satellites and characteristics of the future constellation meeting these specifications.