In certain professions the performance concept is familiar. Within the electronics or optics fields, for instance, products are evaluated based on their performance. In the building construction field, the performance concept is new. Building codes and construction regulations often exist without clear guidelines for how a structure should be constructed. The amplifier is evaluated based on performance.
Nobody asks about what's inside.
The word requirement is used here in a broad sense. In some cases it is the absolute requirements of government agencies, and in other instances requirements are determined by needs or wishes. However, users can also be animals. In storage and industrial structures the users are also machines, industrial processors, or other industrial items. 13 User requirements The structural design of a building is optimal when the users, free and unhampered, can carry out the activities for which the structure is designed.