Smart Building Sensors Explained

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Why do we need smart building sensors?

How we work has changed due to the arrival of agile working. Nowadays, employees no longer operate a 9-5 and sit in the same workspace all day long. The shift in workplace practice presents two challenges for space managers. Firstly, how to create a workplace delivering the experience employees expect. Secondly, how do you redeploy workspace to match modern work styles with minimal cost?

Smart building sensors might answer those questions. Using sensors aims to measure occupancy and utilization across workspace, neighborhoods, and shared spaces. They come in all shapes and sizes, using various technologies.

Naturally, the available technology comes with its relative strengths and weaknesses. Moreover, Data reliability and accuracy play critical roles when selecting occupancy sensors. With this in mind, let’s review the types of sensors most commonly found in workplaces to track people’s movement driving more effective space planning.

What types of smart building sensors are there?

The facility manager’s job is constantly evolving. However, they must continually provide a safe, comfortable experience to building users while meeting financial and operational targets. Knowing when, where and how many people use the space makes this more achievable. There are several different types of smart building sensors to capture the movement patterns of people. Technology includes:

  • Passive Infrared (PIR) sensors,
  • video counting sensors,
  • Bluetooth Low Energy (BLE) sensors,
  • thermal counting sensors, and
  • beam counting sensors.

With the rise of the Internet of Things (IoT) and Machine Learning, sensor technologies can drive additional value.

Passive Infrared Sensors

Passive Infrared (PIR) technology’s primary use is in motion detectors. The term passive refers to the fact that PIR devices do not spread energy for detection purposes. Instead, they work by detecting infrared radiation emitted by or reflected from objects. But, because they see heat reflected from surfaces, PIR sensors cannot capture who is in the space.

However, as a smart building sensor, PIR sensors have varied use throughout facilities. From triggering alarms and lighting by detecting movement in space to capturing space utilization.
Nevertheless, because PIR’s only detect general movement, they cannot tell how many people are within its field of view. As a result, they are better used to track workspace utilization levels.

In addition, PIR sensors typically sit beneath the desk, detecting when and for how long the workspace is in use. This data alone helps identify areas of underutilized space. Furthermore, combining workspace utilization data with business hierarchy data enables Space Planners to re-evaluate workspace allocation.

Where are they mounted?

  • Under desktops

What data does it collect?

  • Workstation utilization – capturing occupancy and length of time

Strengths

  • Cost-effective
  • Relatively easy to set up
  • Anonymized data (only captures whether a workspace is in use)

Weaknesses

  • Because PIR sensors sit under a workspace, they can be interfered with easily. Previously, we have experienced employees pulling them off.
  • Unable to count the number of employees.
  • PIR sensors cannot give insight into what departments are using the workspace.
Smart Building Sensor - Passive Infrared Sensor
Passive Infrared Sensor

Video Counting Sensors

Video counting sensors are mounted to the ceiling, capturing occupancy and utilization data across different space types. Therefore, Video sensors work by counting the number of employees that pass beneath them. Crucially, Video sensors filter objects based on height, shape, and size, meaning the sensor can tell the difference between what is and isn’t a person and how many people are within the frame.

Space Planners can use video counters to understand how people interact with a building from entry to exit, floor usage, neighborhoods, and individual workstations. Unfortunately, these smart building sensors are video-based, potentially causing privacy issues. However, video counting sensors are not security cameras. Often, the video captured is not high quality, and privacy shields are applied to anonymize employees. Whether anonymized or not, employees often get the sense that “big brother” is watching.

Check out this article by Sensource for more information on privacy concerns.

Where are they Mounted?

  • Ceiling mounted over an area of interest – banks of workstations, meeting rooms, common spaces.

What data does it collect?

  • The number of people in a space and how long.

Strengths

  • Possible to achieve up to 95% accuracy
  • Versatility – able to capture occupancy and utilization in multiple space types
  • Robust analysis – Macro and Micro level

Weaknesses

  • Complicated setup
  • Costly
  • Privacy concerns
Smart Building Sensors - Video Counting Sensor
Video Counting Sensor

Bluetooth Low Energy (BLE) Sensors

Bluetooth Low Energy (BLE) sensors capture utilization and occupancy data across various space types. In general, BLE’s work by installing a beacon in a shared space or zone, which sends a signal out over an area. In addition, employees either download an app that runs in the background on their phones or carry a wearable BLE device.

The app or wearable interacts with the BLE’s signal and responds depending on its programming. For example, a response can be a simple notification that a person is in the beacon’s range and length of time they stayed. Furthermore, employees can be fed information based on their location. For instance, when stepping off the elevator, the BLE beacon can inform people in the lobby which workstations are available on that floor. Thus enabling them to book a workstation quickly, easily navigate to the area and get to work easier.

Where are they Mounted?

  • Typically on ceilings throughout facilities

What data does it collect?

  • Utilization and occupancy data – when spaces are being used and by how
  • many people

Strengths

  • Configurable goals/ outcomes when interacting with beacons
  • The advantage over WiFi and GPS is that BLE’s can reliably pinpoint locations.
  • High accuracy levels
  • Data capture is anonymous.

Weaknesses

  • Employees/ building visitors would need to install an app to run in the background on their phones or carry a BLE wearable receiver while on site.
Smart Building Sensor - Bluetooth Beacon
Bluetooth Low Energy Sensor

Thermal Counting Sensors

The primary use of thermal counters is to track people as they enter or leave a space. For example, counters are mounted around a door and count people by detecting their body heat. These sensors can tell the difference between a person moving in or out of space.

Thermal counters thrive when used in high footfall areas. They are ideal for counting the number of people coming into a building, floor, or open space and where they go. Moreover, thermal counters remain popular amongst retailers, co-working spaces, and large facilities. Furthermore, thermal counters have the bonus of anonymous data, as these sensors do not rely on video or mobile data. However, anonymous data means you can’t examine who is coming and going or how they interact with the workspace.

Where are they Mounted?

  • Above doorways (at entrances – to a building, floor, common area, or meeting room)

What data does it collect?

  • General occupancy data – indicating how many people are in a space and footfall direction

Strengths

  • Anonymized data at collection – no privacy or security issues
  • Devices powered over Ethernet (PoE)

Weaknesses

  • Can have issues with tailgating – not differentiating one person following closely behind another
  • Calibration during setup is difficult
Smart Building Sensor - Thermal Sensor
Thermal Counting Sensor

Beam Counters

Beam counters are a simple and cost-effective way of capturing footfall.
Entranceways contain an emitter on one side and a reflective plate on the other. The reflective plate returns the infrared beam. When the beam breaks, a count is registered.
However, several variables can affect accuracy – a wide or busy entrance, a lack of differentiation between people and assets, and even sunlight. In addition, beam counters are not able to capture the direction of travel. Also, they can’t differentiate between multiple people! For instance, two people could walk past a counter at the same time. However, to the beam counter, this is one person. Furthermore, someone wheeling a chair down a corridor could count as two people.

Where are they Mounted?

  • At entrance ways

What data does it collect?

  • Elementary occupancy data – indicating how many people are in a space

Strengths

  • Data capture is anonymous
  • Cost-effective

Weaknesses

  • Simple metrics – will not indicate footfall direction and does not differentiate individuals in groups.
  • Inanimate objects counted as people
  • Accuracy is also affected by environmental conditions.
Beam Counting Sensors
Beam Counter Sensors

Summary

Employees demand comfortable, safe facilities that are easy to use in this agile, flexible working age. However, organizations must strike a balance between building optimization, cost-efficiency, and user needs.
Monitoring how, when, and where users interact with facilities through sensor technology is one solution.

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