With the increasing awareness on energy efficiency and the constant rise of energy prices, Communications Service Providers (CSPs) are focusing on reducing their CO2 footprint and operational costs by altering the setup of Base Transceiver Stations (BTS) on their networks [1] [2]. This paper describes a system developed by Fraunhofer Portugal - AICOS within the scope of the SavEnergy project [3], which aims at improving the energy efficiency of the Optimus' (a major Portuguese CSP) BTS sites. The developed system - the Energy Box (EB) - can be interfaced with several BTS site components - creating the Energy Box Ecosystem (EBE) - and managing its internal operations by using the principles of the Autonomic Computing philosophy. The EB presents a modular architecture, easily adjustable/extensible to the possible conditions found in different BTS sites. The EBE was built according to requirements defined by the CSP for five different BTS prototypes, and was configured to fulfill them. The EBE is currently under evaluation as part of the implementations of the aforementioned five prototypes, consisting in active and modified BTS sites on Optimus' network infrastructure. The preliminary results are presented in this paper.