Benchmarking A Website

This isn't really even specifically Drupal related... can I ask non-Drupally questions here? Let's find out...

So I'm currently writing a website specification for a public sector organisation. Because of this it's important to benchmark as many of the build requirements as I can.

However a lot of the website building world instinctively seems to be pretty subjective, and it would be good to find ways of making things as objective as possible, so there is a clear achievable target.

For instance, how do you benchmark responsive design? or website speed? or css quality? or even security?

There are some good guides in coding terms. There's the W3C compliance or WCAG for accessibility, but beyond that achieving objectivity in web specification is pretty hard.

This was more meant as a general discussion on whether anyone had tips on what objective benchmarking can be achieved in website design.

(As a justification this is Drupal related, the new website is being built off Drupal.)