Sensors have been used in buildings since the invention of air conditioning to understand how buildings are performing, from in-room temperature sensors, to sensors on plant equipment, motors, ductwork and pipes. The Internet of Things (IoT) has enabled more sensors of different types to be deployed in more locations throughout the building easier than ever before.

The point of installing and using IoT sensors is to gain deeper insight into how buildings are performing, and ensure buildings are healthier, more productive for people to work in, more effective to run and more energy efficient.

This article looks at in-room sensors, such as temperature, air quality and occupancy, and how IoT sensors can help improve building performance. The benefits of IoT sensors is that they are easy to install, both physically and from a commissioning perspectiveThe benefits of IoT sensors is that they are easy to install, both physically and from a commissioning perspective.

Cabling is usually minimal or not required at all: IoT sensors are battery powered, or require simple USB power (from a plug socket) or utilise Power over Ethernet (PoE). IoT sensors use low power wireless protocols (such as Bluetooth, Mesh etc) to send data, and thus can be placed anywhere within a building and do not require multiple physical IOs for integration.

Unprecedented amounts of data

IoT sensors are usually cost-effective such that thousands of sensors can be deployed throughout the building without much effort. This gives an unprecedented amount of data to building managers, which comes with its own challenges – How to make use of this data?

There are two ways to utilise this data to improve building health, performance and efficiency:

  1. Use an effective monitoring platform or data analysis tools to turn raw data into actionable insights. This can provide the building and facilities team with insights to be more pro-active, and spot temperature, air quality, overcrowding, etc issues even before the users or tenants begin to notice e.g. it’s too cold, too drafty, too stuffy, etc.
  2. Integrate the live data from the IoT sensors straight into the Building Management System (BMS) and create new control strategies to automate the building further. This requires a bit more integration and commissioning work upfront, but the performance and efficiency benefits through automation will give a fast Return on Investment. The key here isn’t the sensor integration itself, but the building control strategy that will be the logic to which the building automation fucntions.

Some use cases of IoT sensors are:

Temperature and HVAC

A common problem I’ve heard from many buildings is that existing temperature sensors that connect to the BMS have been placed in the ceiling, and not at head height. Using battery powered IoT temperature (and humidity) sensors, and sticking them to the wall at head height, is a quick and easy way to measure temperature where it actually matters.Data can be used to plot temperature heatmaps, find hot or cold spots, or analyse the solar heat gain

Data can be used to plot temperature heatmaps, find hot or cold spots (e.g. if two nearby FCUs are working against each other, one heating one cooling); or analyse the solar heat gain, and adjust internal loads. The IoT temperature sensors can be connect to the BMS to provide more accurate temperature data to FCUs instead of the sensors in the ceiling.

In general, IoT senors can easily be reconfigured and moved, e.g. during a fit out. But care needs to be taken to keep a close eye on the sensors and which room/space they relate to.

Battery will need to be changed every 5 years. The IoT temperature sensors are cheap enough that they can simply be replaced with new ones e.g. the sensors element need recalibrating.

Indoor air quality sensors and HVAC

Accurate CO2 level sensors (which use duel channel NDIR technology) with IoT connectivity are getting cheaper and can also be used to do ‘heatmapping’, of the building, and provide accurate insights on indoor air quality. Similarly, heatmaps can be done with particulate matter sensors (PM10, PM2.5, PM1), VOC sensors and others embedded in an IoT connected sensor.

CO2 level sensors in Accurate CO2 level sensors  with IoT connectivity are getting cheaper and can also be used to do ‘heatmapping’particular are important as the level of CO2 indoors affects our cognitive ability. High indoor CO2 levels hinder our productivity. Indoor CO2 levels of 900ppm to 1400ppm and higher, which are seen in buildings with poor ventilation, reduce our ability to make decisions and use complex information by 15% to 50% and higher, respectively.

Indoor CO2 levels are also a good indication of the risk of infection, as people breathing are usually the main source of CO2 in buildings. So being able to monitor CO2 levels in every space inside the building will provide building owners, tenants and users with reassurance with regard to COVID-19 related challenges.

‘eCO2’, a derivative from VOC sensors, should NEVER be used as a measure of CO2 levels. All CO2 sensors elements need to be recalibrated every 3-5 years.

Occupancy level and HVAC

Knowing the occupancy on every floor of the building can be used to control HVAC systems. Through BMS integration, controlling the flow of ventilation dynamically, based on real-time floor-by-floor occupancy, allows the building to ‘breathe’ with actual demand.Employing an occupancy-based, dynamic control strategy on the BMS reduces the energy consumption for buildings that rarely see full occupancy This balances the building from a technical perspective, and improves air delivery by opening up more ventilation capacity.

Employing an occupancy-based, dynamic control strategy on the BMS, not only improves the indoor air quality, but also reduces the energy consumption for buildings that rarely see full occupancy, or have dynamic use (which will only be more common as we begin to work-from-home more often)

Measuring the number of people is difficult, which usually means expensive. One way to count people is using PIR sensors places under each desk. This can get expensive for 1,000 desks even if one IoT PIR sensor is relatively cheap. Another way is to use a less accurate, but cheaper method, e.g. using long-range sensors that count the number wireless devices in a vicinity / floor, and using that as a proxy for percentage occupancy levels.

Summary

1,000s of IoT sensors can be easily installed anywhere throughout any building. To get the best out of an IoT system a clear use case (or set of use cases) is necessary. By understanding the use cases and benefits, the right design, UI or integration can be used to maximise the cost-benefit ratio for the specific use cases, for example:

  • BMS integration for IoT temperatures sensors;
  • Relevant platform UI and analysis to extract actionable insights for the Facilities Management team from the raw IoT sensor data; or
  • Correct HVAC control and automation strategy based on occupancy level data.
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Author profile

Alex Bak Co-Founder, LightFi

As LightFi’s building control expert, working with clients, integrators and engineers, Alex drives the implementation of sensor driven automation to make commercial buildings healthier and sustainable for clients such as British Gas, Heathrow, TfL. He graduated from Oxford and has a Physics PhD from Imperial College.

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