In recent years more and more sophisticated devices are created including an, in the "worst" case, exponential growth of functionality: In current versions mobile phones are not just telecommunication devices, but also a camera, music player, browser, email interface etc., resulting in new terms like smart phones. A television device can also be used as a browser using a wireless internet connection and washing machines contain more programmable functions than customers will ever need and use. This dissertation presents an approach integrating end user requirements into product development process as a simulation but also as recommendations for designers during early development stages.