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Types of smart building sensor and how they work

The world of smart building sensors can be a confusing one. Perhaps you’re a building or facilities manager looking to meet environmental targets or increase efficiency. Perhaps you’re a landlord or hotel proprietor looking to save money or provide a safer living environment. Or perhaps you’re just intrigued by the idea of a smart home and want to know what technology is available. Where do you begin?

There are lots of different options out there and there’s a whole lot of information too – ranging from the very basic to the impossibly technical. We’ve put this list together to introduce the various types of sensor available and explain the main benefits of each.

Smart building technology - different types of smart sensor

Temperature sensors

Simply put, temperature sensors measure heat to detect changes in temperature. They’ve been used for years to control things like heating and air conditioning but, thanks to the emergence of the Internet of Things, have found many more uses.

For example, many machines used in manufacturing and computing are sensitive to temperature and have to be protected from overheating. With smart temperature sensors, businesses can automate heating, ventilation and air conditioning controls to maintain ideal conditions and automatically detect failure or faults as they happen.

Not only is the right temperature vital to people’s comfort, it can also prove dangerous. Anyone in control or a business premises or renting out a property has a responsibility to reduce the risk of exposure to legionella. The bacteria can spread in hot and cold water systems and can thrive if water in any part of the system is between 20 and 45°C.

Humidity sensors

Humidity, also known as relative humidity, is defined as the amount of water vapour in the atmosphere. Just as many machines don’t tolerate certain temperatures, humid conditions also present difficulties. Too much moisture in the air causes condensation, which can cause some machinery to corrode.

Humidity sensors let you maintain ideal conditions and take action straight away if there’s a change. In homes and businesses they’re used to control heating, ventilating, and air conditioning systems. They’re used in manufacturing plants, hospitals, museums, greenhouses and weather stations – any environment that’s sensitive to moisture.

Motion / occupancy sensors

Motion sensors pick up on physical movement – whether that’s a person, animal or object – in a given area and transform that information into an electric signal. Motion detection has been used in the security industry for years to alert businesses to intruders. They’re found in appliances we use every day, like automatic doors, toilet flushes and hand dryers. And they can also be used to automate building controls like heating and lighting depending on whether or not a space is occupied – helping to reduce both energy consumption and running costs.

Lately though, they’ve found a further use: helping businesses understand how rooms and spaces are used. By detecting the presence of people or objects in real time, occupancy sensors allow organisations to understand which spaces get the most use, or know which desks or meeting rooms are available at any one time. In a large organisation, being able to use space more efficiently can lead huge cost savings, not to mention increased productivity.

Motion or occupancy sensors work by detecting infrared energy or by sending out ultrasonic waves or radio waves and measuring their reflection off a moving object. We currently supply under-desk passive infrared (PIR) motion sensors. This small, wireless device two slots made of a material that’s sensitive to infrared light. When the sensor is idle, both slots detect the same amount of ambient infrared radiation. When a person enters the sensor’s field of view, the movement reaches one half of the sensor before the other. It’s this change between the radiation detected by the two slots that tells the sensor someone is present.

Contact sensors

Contact sensors are also known as position or status sensors, or building monitoring sensors. Contact sensors are a simple way to tell whether a door, window or other similar mechanism is open or closed.

The sensors come in two pieces ­– one that’s fixed to the door or window and another that’s fixed to the frame. The two parts use magnetic fields to detect when they’re touching (meaning the door or window is closed) and when they’re moved apart (as the door or window is opened).

For a range of reasons, including safety, security and energy efficiency, it’s useful to know what’s going on around your building at any one time. Building monitoring using contact sensors lets you see the live status of doors and windows around your building, including doors on cupboards, cabinets and fridges. You can automatically detect unlocked doors or cabinets, open or broken windows or a presence in a room, and automate building controls based on live occupancy.

Gas / air-quality sensors

Gas sensors are used to monitor changes to air quality and detect the presence of various gases. They’re used to monitor air quality, detect toxic or combustible gases, and monitor hazardous gases in manufacturing, pharmaceutical, petrochemical and mining industries. Depending on use, you could monitor carbon dioxide, carbon monoxide, hydrogen, nitrogen oxide, oxygen, air pollution or gas.

While many applications are concerned with safety, the effects of poor air quality aren’t always severe, or even that easy to spot. In today’s well-insulated buildings, rising carbon dioxide levels can lead to stale, stuffy air and complaints like tiredness and headaches. It can affect people’s comfort and wellbeing as well as productivity. And seeing as employers have a responsibility to provide a healthy working environment, it’s not surprising more businesses are using environmental monitoring to maintain temperature and air quality.

Electrical current monitoring sensors

Electrical current (CT) sensors measure real-time energy consumption at a circuit, zone or machine level. Knowing how much energy is being used has two main uses. Firstly, you can identify where you use and waste the most energy, allowing you to make savings. You can also automatically switch off assets when they’re not in use.

Secondly, if you can recognise normal operating conditions you can also see when machinery isn’t functioning as well as it should. For example, a higher-than-average operating current could tell you that a motor has been overloaded. This insight means you can schedule maintenance when it’s actually needed rather than pay for routine inspections. You can also fix potential problems straight away and keep unplanned downtime to a minimum.

Other types of sensor

While we don’t currently offer these sensor types as off-the-shelf products, we can work with you to develop bespoke solutions – read up on our design and manufacturing capabilities to find out more or use our contact form to get in touch.

  • Optical sensors measures electromagnetic energy including electricity and light. They’re used in industries such as healthcare, energy and communications to monitor variables including light, radiation, electric and magnetic field and temperature.
  • Proximity sensors, much like motion sensors, detect the presence of an object and measure how close it is. One of the most familiar uses is reverse parking sensors in cars.
  • Pressure sensors detect pressure and alert the system administrator of any deviation from the standard pressure range – similar to machine monitoring. This is useful in manufacturing as well as in water and heating systems.
  • Water-quality sensors are used in environmental management to measure chemicals, ions, organic elements, suspended solids and pH levels in water.
  • Chemical sensors detect the presence of chemicals in water or air. They’re used to track air and water quality in cities, to monitor industrial processes and to detect harmful chemicals, explosives and radioactive materials.
  • Smoke sensors detect levels of airborne particulates and gases. While they’ve been around for a while, the development of IoT means they’re now able to notify users of problems immediately.
  • Level sensors determine the level of fluids, liquids or other substances in an open or closed system. They’re mainly used to measure fuel levels, but are also used to measure sea and reservoir levels and in medical equipment, compressors and hydraulics.
  • Image sensors can be found in digital cameras, medical imaging and night vision equipment and biometric devices. They’re also used in the car industry and play an important role in the development of driverless cars.
  • Accelerometer sensors detect vibration, tilting and acceleration in an object. Uses include anti-theft devices, vehicle fleet monitoring, aircraft and aviation industries and consumer electronics, including smartphones and pedometers.
  • Gyroscope sensors are used together with accelerometers and measure angular velocity, defined as a measurement of speed of rotation around an axis. Their main applications include car navigation systems, game controllers, robotics and consumer electronics.


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