The ubiquity of information and communication technologies (ICT) results in substantial amounts of energy consumption and thus, CO2 -emissions. Since software induces the energy consumption of hardware, some reliable procedures and tests for measuring software are necessary. We present such a method and prove our measurement concept by applying it to two software product groups: word processors and content management systems. Even though the two groups are very different in terms of their requirements, we were successful in the creation of a measurement environment that supports the production of reliable, verifi able results, allowing the comparison of the energy consumption induced by software systems with similar functionality. The method shows viable results for desktop and client-server systems, paving the way for further setups like e.g. mobile and embedded devices.