To be able to discuss occupancy, there must first be a shared vocabulary so that the terms being used are consistently understood and interpreted. In most organizations this is the first and largest challenge.

For example, the people within most organizations will have many different interpretations of what “occupancy” means – some will think it means the total leased space, others the space assigned to various business units, others how much is being used on an average day. Some people will think occupancy is measured as an area; others as a headcount; and others as a ratio or percentage.

This variety of interpretations – none of which are “right” or “wrong” – leads to misunderstandings and miscommunications. It is no surprise that there is so much caution and mistrust of occupancy reports.

To ground these conversations about occupancy, there must be a set of definitions that can be adopted to remove these variations and allow people to understand consistently the language being used. Definitions will be introduced that are summarized in the appendix as a glossary.

According to the Oxford English Dictionary, Occupancy is defined as the action or fact of occupying a space. This is helpful in distinguishing both the fact of occupancy (i.e. the space is or is not occupied) but also that occupancy may also relate to an action. For our purposes, we will use this as the basis for our definition:

It also requires clarity about what being “occupied” means. It might mean a person’s physical presence in the space, having an implicit (e.g. permanent assignment) or explicit reservation for the space, or leaving belongings in the space (for example a laptop or coat).

The following definition provides a starting point for considering utilization:

However, immediately there is hidden complexity in our apparently straightforward definition: these measurement dimensions – space, time and occupancy – have different characteristics that must be understood if the measurement of Utilization is going to be understood.

What is meant by a space may seem obvious, but when defining terms that will ultimately lead to measurements being taken and metrics established, it is vital that the definitions be explicit and unambiguous.

The term “space” is intentionally extremely generic. In the context of Utilization, there are three common measures that build on Space:

Examples:

1. A workstation has a Capacity of one person, even if that workstation is used by two people at different times during the week as part of a job share or is used within a neighbourhood of unassigned or short-term reservable workstations.
2. A conference centre comprising ten rooms designed for eight people that are intended to be used boardroom-style and a theatre that seats two hundred people would have a Resource Count Count of eleven rooms.

Given these definitions, all measurements of space are relatively static: they will not change without some explicit action – e.g. refitting the space, changing its use, or switching to a new measurement standard. This property of space is useful in ‘reasonability testing’, discussed in ‘error detection and correction‘.

In some cases, measurements are taken at a point of time. This is typically the case for ‘clipboard surveys’, which take a point-in-time sample of the use of space. This is called a Snapshot:

However, such measurements are of limited use when trying to understand the overall pattern of use of space, as they typically provide too little information to safely generalize or use as sample data in a statistical analysis.

Therefore, it is necessary to clearly define continuous measurement times:

A period may be within a single day (e.g. “the 3-hour period from 09:00 to 12:00”) or may be a collection of discrete periods aggregated in some meaningful way. The two most common discrete period aggregations in workplaces are defined below, but other definitions will be required in other space types.

Examples:

1. In a typical office, normal business hours might be 08:00 to 17:00. The Business Hours for February would include the aggregate of 08:00 to 17:00 on all days during February when the business was operating (i.e. excluding any days when the business was closed – for example weekends or public holidays).
2. The Core Hours for the same office might comprise 10:00 – 12:00 and 14:00 – 16:00 each day as these are often the times when both workstations and meeting rooms are busiest. However, if the space being analysed were catering space, then the Core Hours Periods might instead be 07:00 – 09:00 and 12:00 – 14:00 (breakfast and lunch time).
3. A call centre may operate a shift system to provide 24/7 service, and in this case ‘Business Hours” might be 24 hours per day. Core Hours may also be 24 hours a day but are not necessarily so – for example, if the call volumes have significant and consistent peaks (say between 12:00 and 14:00), and the call centre operations increases the staffing during these periods, then these might be considered the Core Hours.
4. A Stadium would likely have Core Hours related to game or match times.

Whenever Business Hours of Core Hours are not 24 hours a day, then each also defines its complement: i.e. the hours that are not included. Analysis of this complement is sometimes useful, and this is discussed later.

It is sometimes helpful to consider multiple uses and Business and/or Core hours for each. For example, a corporate conference suite may be used during the company Business Hours for meetings but may be made available during evening and weekends to community groups. In this case the predominant use for meetings by the company would be considered the primary use, with a secondary use as community meeting space. These uses would in turn lead to differing Primary Business Hours and Secondary Business Hours, and corresponding Core Hours.

It is also very important to understand that whilst these definitions of time are reasonable, the constraints that arise due to methods of measurement mean that error margins and corrections may need to be employed when they are used for establishing measurements.

Having defined what is meant by Space, and how time can be specified, the final element of utilization is defining what is meant by “occupied”. Given that Occupancy is the fact or action of occupying a Space, there are several legitimate definitions of Occupancy provided below which are in common use today (or very similar variations of them):

A particular case in establishing Trace Occupancy is Space subject to a reservation. This may or may not be considered Trace Occupied, depending on the extent to which the reservation creates a “belief in any observer that the Space is in use”. A reservation that includes digital (or other) signage on the Space itself indicating it is reserved is likely to meet this test and be considered Trace Occupied. A reservation that can only be identified by checking in a system may not meet this test, although this will depend on the cultural reliance on the reservation system, and the extent to which the reservation system proactively informs the occupant of Space reservation status – for example using location based services (e.g. indoor positioning or IPDD) to determine a user’s location and then prompting them with free/busy availability about the Space(s) they are in or near.

Space that is either physically occupied or has trace occupancy is sometimes referred to as “apparently occupied”, because both of these forms of occupancy are based on what can be seen by observing the Space:

In addition to the types of Occupancy above that can be established by observation, there are also two types of Occupancy that are defined in terms of Space being dedicated to either individual people or organizational units:

To help explain how these various types of occupancy interact, the Venn diagram below shows how Space can belong to multiple occupancy types:

NOTE: Although the diagram above suggests Space can have Assigned Occupancy without Allocated Occupancy, this combination is unusual as it indicates a Space that is assigned to specific people but not to any organizational unit. This is unusual because Space that is not Allocated is typically Vacant, and therefore by definition not Assigned. However, some organisations may choose to have Space that is for the equal benefit of everyone (regardless of their organizational unit) left unallocated with business rules that take such Space and use a secondary re-allocation process to recover the associated costs (for example split the costs in proportion to organizational unit Headcount). If the shared Space is capable of being assigned – for example it is possible to make a reservation for some part of the shared Space – then this Space could be Assigned but Unallocated.

Whichever type of Occupancy is used, the occupied Space is measured using the same units as Space itself (defined above), namely: Area, Capacity and Resource Count. When measuring occupancy based on Capacity, this involves counting the actual number of people present. This is a form of Headcount, and is also often called a Census.

To help understand the difference between the four basic types of Occupancy, see the types of occupancy in offices worked example.

Many analytics depend on Headcount either to contextualize a situation (“small”, “medium”, “large”) or more commonly to provide comparable ratios (area per head, workstation per head etc.).

A particular type of criteria that is often required is that of Activity. People that would otherwise be in a group are often included/excluded based on their Activity. For example, if the Headcount in question were the occupants of a building, most analyses would legitimately exclude from this Headcount people providing facility services – for examples cleaners, maintenance engineers, or receptionists – because their presence does not impact the occupancy, behaviour, availability or demand.

It is also the case that the analysis Period may be relevant when establishing Headcount. For example, in an environment where there are shifts, the Headcount may be considered the number of people in each discrete shift. However, during the transition from one shift to the next, the people from both shifts will likely be in the building at the same time for a short period, and this may be an important period to analyze in some circumstances (for example when considering the required parking capacity at the location). Another similar example is a railway station platform, where – for a brief period – the platform must accommodate all the people waiting to board a train and the people wanting to disembark.

Headcount is often treated as relatively static. However, Headcount can very quite significantly in several contexts. Not only do employees get hired and leave, but they visit other locations, or non-employee visitors may contribute to certain Headcounts (particularly contractors/contingent workers).

By combining these dimensions of space, time and occupancy, very specific types of Utilization can be named.

The diagram below provides a reference for these Utilization types following a three-step naming process – choosing first the type of space measurement being used, secondly the basis of occupancy and finally the type of period. Note that each of these types of Occupancy can be addressed to specific types of Space, for example open-plan workstations, small offices, or meeting rooms, and care must be taken if multiple space types are included in a single statement of space measurement.

NOTE: Because measuring Space based on Resource Count or Capacity usually requires a known fit-out, it is normally not meaningful to state Utilization based on Allocated Capacity or Allocated Resource Count. This is because measuring the total amount of Space used as the denominator in the Utilization ratio is not well defined as the unallocated Space may very well be empty (no furniture and possibly with interior walls removed or reinstated), or at best the furniture and fitout may be arbitrary.

Assigned Utilization stated in terms of Capacity [3] has historically been the most common basis used in Utilization statements. This is largely because:

(a)   it is readily available, as people need to be told where to work and assigned desks are often recorded in CAFM [4] systems;

(b)   it is not volatile, because assignments do not depend on a person using a desk each day, and are not affected by holidays/PTO, or traveling; and

(c)    when assignments do change, there are systems already in place that will be triggered by the change – even if not a CAFM system, then HR systems that identify joiners and leavers or internal transfers between offices or teams.

This type of Utilization is so common it has its own name, and so we formally define it here:

Note that the Assigned Occupancy of Space is also often talked about as a Headcount based on the criteria of who is assigned to the space. However, it is preferred to use the Assigned Occupancy of Space to make it clear that this is the group of people who are explicitly assigned to the space, and does not include other Headcount that nonetheless might use the space (for example visitors form other offices).

The definitions above provide everything needed to discuss Occupancy and Utilization. The worked examples below illustrate how these definitions can be put to use:

• Conference Suite point-in-time Utilization
• Utilization over a period

The diagram above  shows how the five types of Occupancy combine with Space and time measures to create sixty different types of Utilization. As noted above, some of these have little value, and while most have a role to play in certain analyses, the following are the most commonly used:

The diagram above  shows how the five types of Occupancy combine with Space and time measures to create sixty different types of Utilization. As noted above, some of these have little value, and while most have a role to play in certain analyses, the following are the most commonly used:

Density (Assigned Utilization of Capacity): most commonly used in unassigned workplaces, Density is used as a key metric representing the ratio of “people to desks”. The expectation is that this ratio will be greater than 1, indicating that there are more people than desks.

Apparent Utilization of Capacity: this is the measure that is established through observation, and so often when “Utilization” is discussed it is Apparent Utilization (i.e. Physical Utilization + Trace Utilization) of Capacity that is meant.

Physical Utilization of Capacity: similarly, this is measured using technologies like passive infrared sensors and as these have become more common over recent years, so this type of Utilization is increasingly reported and discussed (and, unfortunately, often coalesced with Apparent Utilization of Capacity).

Apparent Utilization of Resources: like Apparent Utilization of Capacity, this is often available through observational studies. Resource Count measurement is a particularly useful tool for meeting rooms, where rooms likely have a variety of different capacities.