Since I began my career in workplace, the measurement of rentable square foot (RSF) has always been a guide post measure for our teams. We measure everything from how much space you provide per employee, to calculating how much that space costs to fit-out based on this number.
Once I started doing international work I came to realize that RSF isn't a universal metric. There are two factors that are an issue with using this measurement. The first problem is the lack of a universal measurement system globally. Rentable Sq meters in Europe, Tsubo in Japan, etc are just a few of the measures used. The Second problem is how we calculate those numbers in the first place. Do we include elevators, shafts, stairwells in the number? It's pretty hard to hold a meeting in a shaft, though I've held a few in stairwells.
Unfortunately these systems of measurement are deeply entrenched in brokerage and commercial markets. So in order to provide the right experience for employees we must find a way to work around them. In order to circumvent this inefficient system one must take three steps.
Planning Around A Bad System
First, you must set your RSF and USF per employee early. This should really be among the first metrics you define as a workplace team if you plan to do any scaling. You need RSF to look at market spaces and then you need the USF number for doing test fits of those spaces.
Second, have a space planner or architect you trust on board to do test fits of any space you are seriously considering signing a lease for. Your planner will be able to take away all the space clutter that landlords put in their leasing number to show you how much space you can actually utilize for employees. A space may look great but if it's inefficient, you'll sacrifice a lot of money to the LL for space you can't use and the experience of your employees when you try to cram them into it later.
Third, codify your space planning standards into a living document. By defining the size of meeting rooms, desk areas, offices, kitchens, etc early in the process, you'll have an easier time doing test fits and will be happier with the amount of space you take. However, this shouldn't be a document you just make once to set it on the shelf or carve it on a block in the center of your office for all to see. It should be a living document that you continually update as your company scales and inevitably new spaces get added to the mix. The kitchen / training room / yoga area / speaker series space change all become separate spaces at scale.
Why Starting Early Makes Sense
In the end, I don't see a way for us to move from RSF to USF in every market. However, if you start to think strategically early, using the right methods, you will save yourself and your employees a lot of pain. If you're a 50 person company with plans to grow to 200, 500, etc—then the time to start is now. Your spaces will be more efficient, employees will be happier, and your finance team will appreciate you not spending money on shafts and other unusable spaces.