The FACE project has allowed a set of rules/guidelines to be defined for the design of user interfaces of new and improved consumer electronic products. InterFACE is the application of these methods and tools to analyse user, task and environmental requirements, to develop and evaluate concrete user interface prototypes, and to implement these components into demonstrators, such as the programmable heating controller. The FACE rule book is the prime output from the project. The rules specify how a product designer should implement the various 'common elements' of the user interface. The main objective is to urge the designer to think 'common elements' for basic functions which are found in many domestic products. This is a way to standardization. These include: value setting, text entry, time setting, menu navigation and many general-purpose routines which occur in a wide range of consumer products. By standardizing the process, skills learned on one (perhaps frequently-used) product can be applied to another (less-used) product. Another objective is to provide designers with a methodology based on the most recent expertise in human-computer interaction: it is important that variations of user interface techniques be defined so that they may be applied to devices with different levels of hardware sophistication. These results are currently used by marketing and design offices for new products ranging from the time programming clock to building automation systems and have improved their usability.