The definition of economies of scale i was taught is "falling average cost of production as output increases".
Im not sure your going to get meaningful results by looking at how labor costs relate to land usage. For example Consider a hypothetical office company in which:
(1) All staff are paid the same
(2) All office space is used for desks
You would observe that labor costs increased proportionately with office space, but that doesn't tell you anything about the cost of producing each unit of the company's output.