The American National Standards Institute and the Building Owners and Managers Association publish the “Office Buildings: Standard Methods of Measurement” (“BOMA Office Standard”). The BOMA Office Standard, previously the “American National Standard Method of Measuring Floor Area in Office Buildings”, has been the leading method used for floor measurement for many years.

Adopted in May 2010, the new BOMA Office Standard (the “2010 Standard”) updates and addresses issues posed by the last edition of the standard that was published in 1996 (the “1996 Standard”). Responding to the mandates of their respective organizations, BOMA and the International Facility Managers Association (“IFMA”) created a working group to develop a unified set of measurement methodology and terminology that both organizations could share. Published in 2008, the resulting document, “A Unified Approach for Measuring Office Space for use in Facility and Property Management”, was a driving force behind many of the changes made in the 2010 Standard.

Other factors included the need to create the new “occupant storage” class of space for separately leasing certain occupant areas in a building based solely on usable area without application of a load factor (such as basement occupant storage), and to respond to regional leasing practices, particularly in tropical climates. These regional leasing practices have been incorporated into the 2010 Standard to allow for enclosure requirements and limited (unenclosed) circulation.

Prior to May 2010, the BOMA Office Standard had a single methodology of floor measurement that calculated the “Rentable Area” of leasable premises as the sum of “Basic Rentable Area” and its pro rata share of the “Building Common Areas”. “Basic Rentable Area” comprised of the “Usable Area”, or space actually occupied by tenants, and its share of the “Floor Common Area”, areas on a floor such as washrooms, janitorial closets, electrical rooms, telephone rooms, mechanical rooms, elevator lobbies and public corridors. “Building Common Areas” comprised of those areas in a building that provide services to tenants but are not included in the area of any specific tenant; including lobbies, atrium spaces at the level of the finished floor, concierge or security desks, conference rooms, fitness centres and the like.

The 2010 Standard introduces the “Single Load Factor Method” or “Method B” to compute rentable areas in multi‐story, multiple occupant buildings using a single load factor. The Single Load Factor Method, previously not permitted by the 1996 Standard, has been added as an alternative to the general 1996 Standard “Legacy Method” or “Method A”. Users may choose to apply either the Legacy Method or Single Load Factor Method to measure a building, but whichever is chosen must be applied to the entire building. Both methods may not be applied to the same building simultaneously.

Prior to 2010, the Legacy Method (Method A) could result in different rentable areas for each floor of a building. The Single Load Factor Method (Method B), however, allows for an identical load factor on all floors of the building. To allow this, it introduces a new class of space, “base building circulation”, and a revised global summary of areas to redistribute the rentable area of the building across its floor levels. “Base building circulation” is defined as “the minimum path on a multi‐occupant floor necessary for access to and egress from: occupant areas; access stairs, escalators and elevators; rest rooms, janitor’s closets and water coolers; required areas of refuge; life safety equipment; and building service and amenity areas”.

The 2010 Standard changes many of the terms users of the 1996 Standard are familiar with, as a result of the tandem effort with IFMA. The areas known as “Building Common Area”, “Floor Common Area” and “Floor Rentable Area” are now referred to as “Building Service & Amenity Areas”, “Floor Service & Amenity Areas” and “Preliminary Floor Area”, respectively. A summary of the terminology changes are provided in an appendix to the BOMA Office Standard.

The 2010 Standard also represents a more specialized standard method than its predecessor. Since the publication of the 1996 Standard, BOMA spun‐off “Gross Areas of A Building: Standard Methods of Measurement” in 2009, eliminating the need to define “Gross Area” in the BOMA Office Standard.

June 2010 also brought the introduction of a new standard, “Retail Buildings: Standard Methods of Measurement” (“BOMA Retail Standard”) to provide a uniform methodology to calculate and communicate the measurement of retail buildings. The BOMA Retail Standard offer three measurement methods: the “construction gross area” includes “exterior gross area” and other areas that have a structural floor or are covered by a roof or canopy that are typically enclosed but within the building perimeter; the “exterior gross area” or the sum of all the enclosed floor areas of all floors of a building contained within their measure lines, excluding voids, interstitial space, unexcavated space and crawl space; and “gross leasable area” which is the total enclosed floor area designed for the exclusive use of an occupant, including basements, mezzanines or upper floors.

2010 brings a number of important changes to the BOMA standards. Most notably, the 2010 Standard introduces the alternative Single Load Factor Method (Method B) that calculates the rentable area of a floor identically across each floor of a building and was not previously permitted by the 1996 Standard. Also, the introduction of a new retail building‐specific standard provides a uniform and unequivocal direct measure of the floor area of a retail building.

What does this mean for landlords and tenants? Reference in a lease to measurement in accordance with “BOMA Standards” is not clear enough, as there are now several alternative methods of area calculation available. A lease should clearly indicate whether the measurement method is the Office Building Standard, Method A, the Office Building Standard, Method B, or one of BOMA’s non‐office measurement standards, which now include the BOMA Retail Standard. Reference should be made to the detailed publications of BOMA so that landlords and tenants can familiarize themselves with the revised standards.