Office occupancy rate: measuring real use of offices, shops and meeting rooms

Office occupancy rate is the share of your capacity that is actually in use: occupied desks, rooms or hours divided by the desks, rooms or hours available, multiplied by 100. Measured with sensors rather than booking data, it is one of the few figures a facility manager should be able to defend in front of both management and the board. Here is why that matters. It is Tuesday, 10.15. Outlook says all eight meeting rooms on the third floor are booked. Walk the floor and three of them are empty, and in a fourth one person sits alone with a laptop. Meanwhile the department on the ground floor complains that they can never find a free room. That is not a space problem. It is a measurement problem.

Why booking data and access cards lie

Most offices already have two data sources they believe can replace measurement: the calendar system and access control. Both are systematically wrong, just in opposite directions.

• Bookings overestimate. Recurring weekly meetings are never cancelled, even when half of them have moved to Teams. A room for twelve is used by three and counted as full.
• Access cards underestimate. People walk in behind a colleague, and the card says nothing about which floor or zone they ended up on. You know how many arrived, not where they sat.
• Both lack duration. A desk that is occupied from 8 to 9 and again from 15 to 16 looks used in a snapshot, but in reality it sits empty for six hours in the middle of the day.

If your office occupancy is calculated from either of those sources today, the figure is not off by a couple of percent. In busy periods it can be off by a wide margin, and that is expensive when the decision is whether to give up a floor or extend a lease.

How to calculate occupancy rate so the number holds

The occupancy rate formula is simple: occupied desks or rooms as a percentage of capacity. Three choices decide whether the result is worth anything:

• The time window. Measure only during the hours the building is actually in use, typically 8 to 17 on weekdays. Include nights and weekends and the average drops, handing you an artificial argument for cutting space.
• The unit. Meeting rooms need two dimensions: how much of the time the room is occupied, and how many people are in it relative to the chairs. As an illustration, a twelve-person room with 90 percent time occupancy and three people on average is not a successful room. It is a room that should be split in two.
• Peak versus average. Always report both. An average office space utilization of 45 percent can hide 85 percent on Tuesday and Wednesday and 15 percent on Friday. Those are two different problems with two different solutions.

A hypothetical example: if a company with 200 desks measures 130 occupied at peak, that gives 65 percent. But if the split is 90 percent on two days of the week and under 40 percent on the others, the answer is not to remove 70 desks. The answer is to work out which teams have home-working days when. The measurement has to be granular enough to show that.

Which occupancy sensor for which room

There is no single sensor type that solves everything. In practice a good installation combines several technologies, and the choice depends on what you need the number for.

• Counting sensors at entrances and between floors. They measure flow in and out of a zone and give the total number of people in the building or on the floor. That is the basis for calculating occupancy in larger areas and for comparing capacity with real presence.
• Occupancy sensors at desk level. They register whether a specific desk is taken. Necessary if you want to change space utilization in an activity-based office where desks are not personal.
• Room sensors in meeting rooms. Here the number of people matters more than whether the room is in use. A sensor that only detects motion cannot tell two participants from twelve.

Be honest about accuracy. A professional counting system is typically delivered with a contractual minimum 96 percent, typically 98 to 99 percent in practice, but only when lighting, room layout and behaviour allow it. An entrance where people stand and talk in the doorway, or a glass front with strong backlight, pulls the figure down. So always ask the supplier how they verify the number after installation, not just what the brochure promises.

The shop: same metric, different purpose

For a shop or a shopping centre, occupancy rate is not about cutting square metres but about knowing when and where capacity comes under pressure. The number of customers in the store relative to the floor area decides whether there are enough staff at the tills, whether the fitting rooms are a bottleneck, and whether a zone with high traffic but low sales should be laid out differently. Property managers in shopping centres also use occupancy per zone when negotiating rent with tenants who argue that a location by the back entrance does not justify the agreed price. Here a verified counting figure is considerably stronger than a feeling.

Occupancy and indoor climate belong together in reporting

This is where many companies are now discovering that occupancy data has an extra value. The CO2 level in a meeting room follows the number of people almost one to one. Measure both in the same platform and you get two things: documentation that the ventilation is actually sized for real use, and a basis for running ventilation and heating by presence instead of by the clock. Vemco Group's reporting already shows occupancy alongside indoor climate measured on CO2 and temperature, and VemSpace is designed to bring that and ESG data together in one place, so the facility manager does not have to merge spreadsheets from three systems when the sustainability report is due.

The practical point is that the energy saving rarely lies in measuring. It lies in connecting the measurement to the controls. A room that stands empty three days a week should not be ventilated as if it were full, and that only happens if the building management system gets data from the sensors.

What most people only learn after installation

A lesson from implementation: the first thing that happens when employees know they are being counted is not that behaviour changes. It is that cleaning, security and contractors suddenly appear in the numbers and wreck the overnight average. So set up time filters from day one, and treat the first two to three weeks as a calibration period before anyone presents figures to management. The second lesson is to involve employee representatives early. Occupancy sensors count people, not identities, but if that is not explained clearly, the project is met as surveillance instead of as a tool for better rooms. Communication is as important as the choice of sensor.

Frequently asked questions

What is office occupancy rate? Office occupancy rate is the share of used desks or rooms as a percentage of total capacity. It is typically measured with occupancy sensors and counting sensors over a defined period, so that both the average and the peak can be read.

How do you calculate occupancy rate for an office? Divide the number of occupied workstations by the total number of workstations and multiply by 100, measured within working hours. Do it per day and per zone, so you can see the difference between Tuesday and Friday and between departments, instead of one overall number that hides the problems.

Which sensors measure occupancy? Counting sensors at entrances measure people flow in and out of a zone, while occupancy sensors on desks and in meeting rooms register whether a specific desk or room is in use and by how many. Most installations combine the types, because each covers a different need.

What is a good occupancy rate for offices? There is no single right number, because it depends on the way of working and how much flexibility the organisation wants. What matters is knowing the relationship between average and peak: a very low peak points to surplus space, while a peak close to 100 percent means people genuinely lack space on busy days.

How are occupancy rate and indoor climate connected? The number of people in a room directly drives CO2 level and temperature, so occupancy and indoor climate should be measured together. When the data is connected to ventilation control, the system can run on real presence, which improves comfort and documents energy use in ESG reporting.

If you have a lease up for renegotiation or a floor you are considering reorganising, it is better to measure for three months than to guess for three years. Contact Vemco Group via vemcogroup.com/contact-us to book a demo and get a concrete assessment of which sensors and which setup will give you an occupancy figure you can make decisions on.