I am reading around functional and performance requirements and have found they are associated, where the performance requirement is the 'how well' for the functional requirement.

Does anybody know in more detail what the connection between a particular functional requirement and some TBD performance requirements is?

For example: the user may specify a functional requirement for a new TBD product that it must "be able to heat water", what would the associated performance requirements be for this?


  • I have never understood why "performance" is used as an example for non-functional. If a product is supposed to heat water, it surely is meant to heat it in a reasonable amount of time with a reasonable amount of energy. You would never say a water heater that needs it's own powerplant and then takes 20 years to heat a liter of water would be a perfectly fine product, just with some drawbacks in it's secondary characteristics. That piece of s*** doesn't work. Period.
    – nvoigt
    Jun 6, 2022 at 5:48

1 Answer 1


There may not be direct associations between a given functional requirement and non-functional requirements (also called quality attributes, which is my preferred term), of which performance is one type. Both types of requirements describe the system.

If you have a system that heats water, then some of the quality attributes may be around things like efficiency (energy consumption, how much energy is lost by the system), performance (how long it takes to heat a given volume of water from one temperature to another temperature), reliability (how long the system should last before needing maintenance or replacement), safety (preventing burning, splashing water), and usability (measuring how long people take to use the system and perform key activities).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.