Everything You Need To Know About Smart Building Sensors

Published Categorized as Innovative Technology
Motion Sensors

The global market of smart buildings is currently worth around $80.62 billion, poised to grow to ~$328.62 billion by the end of this decade. This new paradigm’s foundation is the fast-evolving combination of the Internet of Things (IoT) and smart building sensors.

Smart building sensors are integral to modern property management systems, especially commercial real estate. IoT-enabled sensors reduce energy, operating, and personnel costs while enhancing efficiency, sustainability, productivity, safety, and security.

Smart building sensors can transform both residential and commercial real estate beyond the traditional scope of climate control and energy efficiency. Keep reading to explore everything you need to know about smart building sensors and how they are changing our world.

What Are Smart Building Sensors?

Technology has evolved rapidly since Warren Johnson’s electric tele-thermoscope, also known as the electric room thermostat, and Samuel Bagno’s motion sensors. These first sensors were genius creations but not smart in the current context as the internet did not exist until the 60s.

Smart building sensors can detect and regulate temperature, humidity, lights, appliances, and air quality. Additionally, IoT sensors can monitor motion, proximity, contact, water quality, electricity, and security, thus automating various systems and providing valuable data.

Contemporary smart building sensors use different technologies and the Internet of Things to offer real-time automation. Most smart building sensors also assist in property management and essential operations, including preventive maintenance, security, and emergency services.

Types of Smart Building Sensors

By definition, all smart building sensors are IoT-enabled. However, a residential or commercial building does not necessarily use a fully integrated management system.

Some properties have an individual building management system (BMS). Such setups can have only one smart sensor or several standalone installations. However, in the latter scenario, the smart building sensors do not share a common or fully integrated IoT system.

In addition, some properties have a partially integrated building management system. Such setups do not require as much manual intervention as an individual BMS.

In contrast, a fully integrated IoT-enabled BMS covers all the smart building sensors installed at a property with real-time automation and actionable data.

The scope of a building management system depends on the objectives. Likewise, the scope and objectives decide the types of smart building sensors in a BMS. The following are the most prevalent types of smart building sensors in the United States and worldwide.

Motion Sensors

Samuel Bagno created the first motion sensor for non-military use. Bagno’s burglar alarm used ultrasonic waves to detect motion. Today, smart motion sensors use different methods to track and detect movement.

The most common types of smart motion sensors use passive infrared (PIR), microwave (MW), or both. Some motion sensors use ultrasound and radio waves. Motion detection systems are also known as occupancy sensors.

A dual technology smart sensor using passive infrared and microwave has a two-tier detection mechanism. Generally, the passive infrared sensor detects motion or occupancy, and then the microwave radar turns on. Any motion or occupancy must trigger both these sensors for the system to activate. Often, these systems are marketed as less vulnerable to false alarms.

Smart buildings with automated lighting, climate control, doors, and other such features rely on occupancy or motion sensors. These sensors may connect to imaging or video surveillance systems, thereby expanding the scope of automation, response, and data analysis.

A plethora of smart motion sensors is available now. Some advanced ones are programmable, so you can modify the coverage, exclude the movement of pets or small animals, or use image, video, or signal processing systems to customize the alarms, related actions, and other settings.

Temperature Sensors

You are probably familiar with smart thermostats like Nest. Moreover, almost all popular HVAC manufacturers have their own smart thermostats, including Carrier, Lennox, Honeywell, etc.

The temperature sensors used in smart building management systems are quite similar to those you may have used. These sensors have transistors, thermopiles, and thermocouples to detect temperatures, usually in the range of -67 to 302 °F (-55 to 150 °C).

Smart temperature sensors do not have the bimetallic strips used by Warren Johnson to make the first electric room thermostat. Instead, the recent versions have microelectromechanical systems (MEMS).

Most residential, commercial, and industrial properties require multiple temperature sensors, subject to the number of HVAC zones in a building. Accordingly, the temperature sensors can control the heating, cooling, and ventilation of each zone, typically with a +/- 1-degree accuracy.

Humidity Sensors

Humidity sensors are a type of hygrometer. While a hygrometer only measures the relative humidity in the air or inside a building, the smart sensors take it a step further and regulate the ambient moisture. Hence, many companies refer to these sensors as humidistat or hygrostat.

Some hygrometers or sensors can measure absolute humidity. However, the humidistats or hygrostats used in buildings are almost always relative humidity sensors.

The three prevalent types of smart humidity sensors are capacitive, resistive, and thermal.

  • Capacitive humidity sensors are suitable for residential and commercial buildings. Most HVAC systems, refrigerators, ovens, and automobiles use capacitive humidistats.
  • Resistive humidity sensors are not as accurate as capacitive humidistats. However, resistive humidistats are more affordable and thus a preferred option for large properties.
  • Thermal humidity sensors have a greater resolution and durability of the three, so these humidistats are preferred in pharmaceutical plants, drying kilns, and even clothes dryers.

Humidistat or hygrostat is one of the most important smart building sensors for large properties with little to no natural ventilation. Commercial buildings, such as offices, malls, hotels, or indoor restaurants, can have a distinct relative humidity inside when compared to the air outside.

Light Sensors

Occupancy or motion sensors can regulate connected smart lights. However, smart buildings also use light sensors or photoelectric devices. The photosensors are different from occupancy or motion detection devices.

Smart light sensors have photo-sensitive cells to regulate various lighting fixtures depending on the strength, presence, and absence of sunlight. Essentially, the cells scan the whole spectrum of visible light, and some may even detect infrared and ultraviolet wavelengths.

Modern light sensors use different technologies, such as photojunction devices, photodiodes, and photo-transistors. However, the most prevalent type of smart light sensor used in buildings is a photoconductive cell, also known as a photoresistor or light-dependent resistor (LDR).

A light-dependent resistor can turn the connected lighting fixtures on and off. You can also connect dimmable lights and automate them using such sensors. Furthermore, a fully integrated IoT BMS can sync lighting fixtures with light and occupancy or motion sensors.

Smoke Sensors

Smoke sensors or detectors have been around for decades, and they are an integral part of fire safety regulations for many types of properties. However, smart smoke sensors typically have a few failsafe features that traditional devices do not carry.

The fundamental concepts are still the same. Smart smoke detectors can have photoelectric sensors or use ionization. Dual smoke sensors use both for impeccable efficacy, and several variants can detect carbon monoxide.

In addition to these conventional features, smart smoke sensors compatible with IoT have onboard batteries for power backup to run during an outage. Some smart smoke sensors have Bluetooth to communicate with phones in the event the internet is down.

Many smart smoke detectors can run self-diagnostics to confirm if the system is working as expected. Thus, you will get a notification if such smoke sensors fail or malfunction.

Air Quality Sensors

Traditionally, air quality sensors have been essential in manufacturing and industrial facilities. Many commercial buildings have these sensors now to enhance the efficacy and efficiency of their air purifiers and HVAC. Air quality sensors are also necessary for health and safety.

Smart air quality sensors can detect the following, subject to the specifications:

  • Carbon dioxide
  • Carbon monoxide
  • Combustible gasses
  • Dust
  • Hydrogen gas
  • Hydrogen sulfide
  • Methane
  • Nitrous oxide
  • Nitric dioxide
  • Nitric oxide
  • Oxygen
  • Ozone
  • Particulate matter
  • Sulfur dioxide
  • Volatile organic compounds

Industrial facilities and commercial establishments dealing with hazardous substances need air quality detectors covering the entire spectrum of those fumes, gasses, or volatile compounds.

Additionally, air quality sensors have a specific detection sensitivity. Residential and public buildings need sensitive air quality sensors. Otherwise, the low levels of any harmful gasses, particulate matter, and volatile organic compounds may remain undetected.

An IoT building management system must connect such smart air quality sensors to the central infrastructure and control interface. Properties also need a sufficient number of these air quality sensors, like the zones for HVAC and purifiers.

Water Sensors

Smart buildings can have two types of water sensors. The simpler type is a water leak sensor. These varieties may use floats, bubblers, pressure transducers, or ultrasonic sensors. The other kind is a water quality sensor to detect ions, substances, suspended solids, and other elements.

Some facilities may have water quality sensors capable of measuring the pH, general hardness, carbonates, bicarbonates, and softness if these parameters are necessary for the intended utilities.

While the standard water sensors with smart features may use flow meters or acoustics, those assessing the quality are more sophisticated and thus expensive. However, water leak detection and quality sensors are essential in many smart buildings.

Like the other smart building sensors, water leak detectors and quality assessment systems can be synced with temperature, humidity, and air quality sensors. Detecting fluctuations in a zone’s temperature, relative humidity, and air quality can offer comprehensive and invaluable data.

Suppose there is a leak due to a pipe burst, but the property managers do not know the exact source. In such scenarios, collating the real-time data from multiple smart building sensors can be consequential in identifying the precise source of the problem and the extent of the damage.

Proximity Sensors

Proximity sensors in buildings are not very different from those used in cars and the automated sliding doors at malls and airports. The principle is identical, but proximity sensors are not the same as occupancy or motion detectors.

Generally, proximity sensors use ultrasonic or electromagnetic waves to measure the distance between the device and obstructions. Some proximity detecting devices may be area reflective sensors. Area reflective sensors use LEDs and active infrared to detect obstacles. Unlike the passive infrared in motion detectors, the LED emits active infrared to detect proximity.

Occupancy or motion detectors and proximity sensors can work in synergy. A highly efficient building management system may use a combination of these sensors and IoT to split a vast property into many smaller units. You can choose a zone as small as an office cubicle or desk.

Optical Sensors

Many smart devices or tools use optical sensors, such as motion or occupancy detectors. Even water leak and quality detectors can use optical sensors. However, optical sensors may be both hardware and software.

Optical sensors with image and video processing systems use hardware and software. However, the visible light spectrum is not the only domain of these devices. Optical sensors can scan the infrared, ultraviolet, or entire electromagnetic spectrum.

Furthermore, optical sensors are integral to many types of security systems, irrespective of the array of devices and detectors facilitating the first trigger.

Current Sensors

Current sensors can detect and measure electricity. Also known as CT or current transformer sensors, these smart systems can measure AC, DC, or both.

Generally, current sensors have a solid or split core. Some systems use Rogowski coils, which are closed loops. Such devices with inductive technology are used to detect or measure AC. A current sensor using open loops or conductive methods, such as the Hall Effect, is for DC.

Smart buildings can use current sensors not only to detect and measure electricity consumption but also in sync with power-off systems or protocols for efficient energy management.

Contact Sensors

Contact sensors are simple but multipurpose tools. Smart contact sensors contribute to security by alerting you if a door, window, or access point is open. Also, these notifications can prevent a significant waste of energy and probable damage to infrastructure.

Doors, windows, and main entrances & exits are not the only applications of contact sensors. A magnet-based contact sensor can be installed on machines, cabinets, and common appliances, like a fridge.

Security Sensors

Security sensors in smart buildings are not a particular type of device but a bouquet of systems. A security sensor may detect proximity, occupancy, motion, image, video, or contact. Thus, any technology that can detect unauthorized presence is eligible to be a part of a security sensor.

However, smart security sensors available today use infrared (passive and active), microwave, or both. The other prevalent methods are magnetic contact switches, photoelectric beams, and sound, including ultrasonic waves.

Tomographic motion detectors are still nascent, so the technology using radio waves to create 3D images without a line of sight may take a while to become commonplace. For places with a direct line of sight, video surveillance systems continue to be the default for building security.

Final Thoughts

Many benefits of smart building sensors are evident: energy conservation, resource utilization, cost reduction, space optimization, sustainability, and security. However, imagine the evolution that the data obtained through these IoT-based BMS using smart sensors can usher in.

Apart from the commerce of data analytics, smart building sensors can influence architecture, infrastructure planning, real estate development, and socio-technical activities. More importantly, data about any immediate surroundings can flag potential dangers, including health hazards.


By Giovanni Valle

Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.

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