Software engineers make decisions about the design of the software they are creating on a daily basis. These decisions may impact the application in terms of efficiency, usability, flexibility, etc. Different competing design decisions are therefore often evaluated in terms of their projected impact on quality metrics prior to implementation. Recently energy has become a concern for software systems, ranging from mobile devices to large data centers. Additionally, it has been recognized that the software executing on a computing device can have a significant impact on the device's energy consumption. This raises the obvious question of whether or not it is possible to reduce the energy consumption of a software system by the means of software design decisions.