Before knowing how many square metres you need per person, you need to know which square metres you are counting. A 500 m² space is not all the same: part is structure, part is circulation, part is surface genuinely usable for work. Without an objective measure, any calculation of efficiency or requirement is imprecise. The BOMA standard is that measure.
What the BOMA standard is and why it is objective
BOMA – the Building Owners and Managers Association – has defined an internationally recognised system for classifying office surfaces, codified as the ANSI/BOMA Z65.1 norm in 1996 and refined annually. The aim of the norm is simple: to establish a shared language among owners, managers, designers and companies, so that two spaces measured with the same method are directly comparable – regardless of who measures them or in which country they are located.
The objectivity of the standard comes from its precise definitions. Every metric has a measurement perimeter set by the norm. That is why, when analysing an existing space or assessing a new location, the BOMA method is the base on which ARCHIlabs works: it makes it possible to move beyond rough estimates and into verifiable quantitative reasoning.
The BOMA metrics: from gross surface to occupied area
The standard introduces five main metrics, arranged in a hierarchy that starts from the building's external envelope and descends to the space actually occupied by the workers.
GEA – Gross External Area: the entire footprint of the building measured on the external perimeter of the walls. It includes the structure and everything physically inside the building boundary.
GIA – Gross Internal Area: the total internal surface, measured net of the perimeter walls. From the GEA the thickness of the external masonry is excluded.
NLA – Net Lettable Area: the surface the owner can grant on lease. Excluded from the GIA are the common areas – technical rooms, shared stairs, the building core – that the tenant cannot use exclusively.
NIA – Net Internal Area: the surface measured within the tenant's walls, net of any internal structures, wall openings and restrooms reserved for the floor. It is the reference metric for assessing how much space is physically available within the property unit.
NOA/NUA – Net Office Area / Net Usable Area: the most operational metric. From the NIA the main circulation internal to the unit is subtracted, yielding the surface that can actually be dedicated to work areas and support areas. It is the figure on which the space planning project is built.
CORE
GEA
GIA
NLA
NIA
NOA/NUA
The BOMA metrics: from the gross external surface (GEA) to the net occupied surface (NOA/NUA), with the components subtracted at each level.
What it is really for: compare, assess, decide
BOMA measurement is not a technical exercise for its own sake: it enables three concrete operations that otherwise remain imprecise.
Comparing two candidate spaces. Two buildings with the same cadastral surface can have very different NOA/NUA, because the core, the circulation and the internal structures weigh differently. Without the BOMA method, the comparison is between apples and pears. With the BOMA method, you compare the share of surface that is genuinely usable.
Assessing the efficiency of an existing space. A company that wants to optimise its office needs to know how much of the available surface is NOA/NUA and how much is structurally subtracted from productivity. This analysis is the starting point for understanding what to look at first in an optimisation project.
Calculating the requirement per person on real data. As we explain in the article on per-person sizing, the number of m² per person is calculated on the NOA/NUA – not on the cadastral surface. Using the wrong metric leads to underestimating or overestimating the requirement, with direct effects on the layout and the budget.
How ARCHIlabs uses the BOMA method in the project
In the Community Based Design method, knowledge of the space – the second of the three pillars – rests entirely on the BOMA standard. During analysis, ARCHIlabs measures the existing space or assesses candidate spaces by applying the ANSI/BOMA Z65.1 definitions, producing a survey that distinguishes the different surface categories. This classification serves two parallel purposes: assessing the efficiency of the current layout against the organisation's needs, and providing the quantitative base on which to build the project scenarios.
The added value is not in the measurement itself – it is in the ability to cross-reference the BOMA figure with the work profiles gathered by the survey and with the desk sharing ratio derived from real attendance data. Only with all three levels of analysis is it possible to translate square metres into a space that genuinely works. It is this cross-referencing that ARCHIlabs' proprietary software performs automatically: it links the BOMA measurement to the benchmark built over more than twenty years and 2.7 million square metres designed and returns the sizing in workstations, work settings and effective square metres.