EXIGENCE project is committed to reducing the overall energy consumption and carbon-footprint of ICT service delivery. Contrary to existing approaches, which address individual domains, EXIGENCE takes on the behemoth by improving the energy consumption and considering the type of energy sources used by not only the individual tenants in each heterogeneous domain of the ICT value chain but the energy/carbon footprint of the entire ICT ecosystem. The project will conceive a system and define suitable metrics and inter-domain data exposure means for assessing end-to-end ICT service delivery. The insights from this work will be formulated as pivotal sustainability requirements and brought into authoritative standardization bodies (3GPP and ETSI) so as to shape the emerging next-generation mobile system (6G)