Several organizations carry out the execution of their systems and data processing services in local processing centers, i.e., data centers (DC). However, small to medium — sized organizations usually do not have technical and financial conditions to monitor the climatic conditions of their DC. Thus, this may imply from excessive energy costs, drastic reduction of the life spam of the equipment and the incorrect processing of data and systems. In this paper we present the open source based solution GreenHop that aims to perform environmental monitoring of the DC server room. This paper presents four tests with different temperature settings, which is also included the application of free cooling method. We present a comparison of the energy impact of all settings. Thus, we aim to provide ambiental monitoring of the DC server room while we keep the system customizable to implement and replicate.