Room cost
What you choose to define as the supplier building area will influence the cost per square meter. There are basically two different ways to view the problem and that is either taking the whole area of the building and distributing the costs over it, or just taking the area from production and warehouse as a base for costs. The second choice would then enable the area possible for production carry the costs for indirect functions such as offices and lunch areas. It is up to the buyer to decide which base that is suitable, if discussions with the supplier arise the easiest solution is to base it on production and warehouse area as this area is smaller and would produce a higher square meter cost.