By Cato Fagermo, NeoCortec
Background
When you want to measure something in a building – whether it is indoor air quality (IAQ) or occupancy – or to control something (such as thermostatic smart valves), you need to be able to communicate data between sensors, devices and controllers/gateways. However, this is not as easy as it may sound for large buildings such as commercial premises, multi-family homes, hospitals, industrial buildings and other large properties.
Measuring the data is easy: there are plenty of sensors on the market. Delivering that data into the building management system (BMS), a gateway or controller, or into the cloud, is, however, not that straightforward. If you are building a new property, it is simple: you can install a cabled fieldbus, such as ModBus, BACnet or KNX. But when it comes to an old building, without a cabled fieldbus, you will likely have a hard time convincing the building owner to install such cabling – unless they are already planning a major renovation of the building. The cost of installing the fieldbus, and the inconvenience for the users/tenants of the building, is simply too high, and the business case is too difficult to make.
In such cases, it seems obvious to go for a wireless solution – and there are many potential options. Examples include Zigbee, Thread, BLE and LoRaWAN, as well as many more. But common to most of these options is that they simply shift the challenge from one set of issues to another. Yes, you can install sensors in a building using these wireless solutions, and you can make it work. However, most such buildings are too large for these technologies to work seamlessly without installing many infrastructure devices, such as repeaters or gateways, throughout the building. Without these, you risk having some sensors with poor or no connection. And these infrastructure devices typically require cables. For sure mains power, but also most likely a fieldbus, depending on implementation. So, we are back to cabling the building – except that now the cables may not have to go into all rooms in the building.
A frequently overlooked challenge is that buildings are also dynamic. As tenants move in and out, the premises will have to adapt. Buildings will often be changed or remodelled over time, with walls raised or removed. As these changes incrementally happen over years, it is more likely than not that mistakes may happen, disconnecting infrastructure devices and thus consequently also disabling parts of the sensor network.
NeoMesh is alternative solution, designed for devices which can operate for years using standard AA batteries. NeoMesh is scalable to thousands of devices in the same network. As the devices are organized in a mesh network, they will communicate through one another without repeaters being needed, and the network can be scaled to cover almost any size building.
Embedded World 2024
Nürnberg Messe is a large exhibition centre in Nuremberg, Germany. Each year, the trade show, Embedded World takes place there, with NeoCortec exhibiting as one out of over 1,100 exhibitors. As a part of its display for the 2024 exhibition, the company showcased a full IOT (internet of things) solution based on NeoMesh. The purpose was to demonstrate how easy it can be to build a sensor network, and to communicate data generated by those sensors to an IOT platform for further processing.
Embedded World 2024 demo
For Embedded World, we decided that we wanted to measure IAQ (indoor air quality) data: temperature, humidity and carbon dioxide (CO2) levels. In addition, we wanted to count the number of Bluetooth devices which were near each node, in order to provide an estimate of the concentration of people across the area throughout the day. We wanted to use a fully battery-operated network, so that installation and deinstallation could be achieved in just a few hours.
The nodes were built using Click Boards from MikroElektronika (MikroE). For each node, three Click Boards were combined and mounted on a development board, together with a battery.
The devices were specified, assembled and programmed by a second year Danish Technical University (DTU) student. The IAQ sensor was a Sensirion sensor assembled on a Click Board and sampled by the Nordic microcontroller (nRF) onboard the BLE 10 Click. The same BLE 10 Click was used to scan for Bluetooth beacons nearby, using the nRF embedded 2.4 GHz radio. A small program was written for the nRF to sample the data. For the scanning of Bluetooth devices nearby, the purpose was to make a relative estimate on how many people were nearby the node. To take into account stationary Bluetooth devices, as well as exhibitor personal, beacons that had been visible for more than 10 minutes were discounted
he nodes were hung up at 35 locations across Halls 3 and 3A at Embedded World. Worth noting is that both halls have walls constructed out of metal. This makes radio communication through the walls exceedingly difficult, as the halls effectively function as Faraday cages. To show the flexibility of a mesh topology, some nodes were positioned outside of the halls, near the doors (see floorplan below in Figure 2).
As a gateway, a BeaglePlay board from BeagleBoard.org Foundation was used, equipped with a NeoMesh Click Board. The open source NeoMesh gateway software was installed, exposing two IP sockets where JSON-formatted packages could be sent into or out of the mesh network. The data was then uploaded to Avnet Abacus’ IOT Connect cloud platform, using Node-RED. Dashboards for visualization of the IAQ data, as well as the Bluetooth beacon heatmap, were then developed.
In addition, the NeoMesh monitoring tool was installed on the gateway. This tool provided a visualization of the mesh network, showing which nodes were connected to each other and flagging any problematic nodes.
Results
The results can be summarized into three categories:
Ease of developing: The MikroE Click Boards, together with the BeaglePlay board, provide a flexible platform for quick and easy manufacturing of nodes. The high number of Click Boards available provides a high level of flexibility in combining microprocessor-, sensor- and communication boards to build a wide range of devices. By downloading libraries for each Click Board, the application software can be developed with a minimum of coding needed. This keeps the time and cost for building a proof of concept very low.
Ease of installing and establishing a network: The agreement with the event organizer was to use only available ‘public’ locations, not being part of other exhibitors’ stands. This made it impossible in advance to plan the location for the nodes. Instead, their positions were identified by simply walking around in the halls. The nodes were adhered to columns and walls using self-adhesive tape, and then switched on. Since all nodes were battery powered, no mains power was needed. The NeoMesh protocol ensured that once switched on, the nodes would automatically be included in the network.
As the two halls were separated from each other, and each had metal walls, we expected that it could be challenging to establish communication between the halls. If this proved to be the case, then two islands would form. To mitigate this, extra nodes were installed around the two passages between the halls, to create a link between them. Similar was done for those nodes located in the foyers outside of Hall 3.
As can be seen from Figure 2, this proved sufficient to create a good connection between the halls. However, what we also saw was that at night, when the passage doors were shut, we did indeed lose connectivity between the two halls.
Data acquisition: IAQ data and people counter: Temperature, humidity and CO2 data were collected every two minutes from the sensors. As expected, we observed a steady increase in CO2, peaking around noon, which was in line with our perception of this being the busiest time of the day. The CO2 value peaked at around 1000-1100 ppm, unlike other exhibitions we have attended, where we observed CO2 values of up to 1500 ppm during the peak of the day. 1500 ppm is getting close to levels where the air quality is considered unhealthy. At evening and in the night, we saw CO2 levels fall to outdoor levels.
The people counting was not intended to represent a highly accurate estimate of people, as many people wear or carry more than one Bluetooth device (such as smartphones, smartwatches or wireless headphones), while some may have none. But we could see, just as expected, that during the morning there was a higher density of people near the entrance doors. Throughout the day this got more uniform, with people spreading out throughout the halls. With some refinement, this could provide an effective way, on a simple basis, to build a heatmap of people and a relative approximation of how many people were there.
Conclusion
NeoCortec has, together with Avnet and MikroE, built a sensor network of clickable modules, without any bespoke hardware developed. Installing these at Messe Nürnberg was very easy, since they run on batteries and can be mounted exactly where you want them to be. When switched on in an arbitrary sequence, the mesh network will form itself.
This ‘pop-up’ application installation was made to measure IAQ and create an approximation of where visitors were distributed across the two halls. Whereas the purpose of the test was not to create a qualitative analysis of the air quality, it did confirm the quality of the air was acceptable throughout all exhibition dates, as well as the hours when the number of visitors peaked.
About NeoMesh
At NeoCortec, we make NeoMesh. NeoMesh is a wireless communication protocol designed to be embedded in smart devices to enable communication between the devices, as well as to the cloud. NeoMesh is built completely from scratch to overcome some of the limitations found in, for instance, Zigbee, Zwave, Bluetooth, Thread and others: scalability in numbers of devices and range, while maintaining low power consumption.
At NeoCortec, we aim to help make non-smart and large buildings smarter by using NeoMesh, providing an easy upgrade without cabling.
We do not make sensors, we do not measure IAQ or count people. But we can enable those applications – and other modes of sensing – through collecting data. NeoMesh is available on communication modules, as well as on a license basis on various chipsets.
