How an IoT company revolutionizes soil moisture monitoring for the construction industry: the case of Silverlight Ltd.

Soil moisture sensors have been developed using communication protocols introduced in the 80s. At this time, these sensors were usually read out by dataloggers and the data was either extracted manually or later transmitted using cellular technologies. With the rise of low power transmission technologies like LoRaWAN, the sensor data has been made available at a very low hardware cost, making big hardware installations obsolete.

Using state-of-the-art cloud technologies, the soil moisture can be analyzed and combined with other related data like weather conditions to provide additional value for the people working at the spot where the sensors are placed.

Silverlight’s aim was to facilitate the work at construction sites, allow for more accurate predictions or to schedule harvest operations at agriculture farms. This massively reduces the amount of manual fieldwork previously necessary. This is to protect the integrity of the soil as a valuable resource, as dictated by Swiss law.

How is it done?

Silverlight uses the tensIoT sensors (a tensiometer equipped with a radio unit) to measure the suction pressure of the soil. The value mentioned can be defined as the “complex energy state created by the interaction between the soil, water, and air present in the soil”. This creates negative pressure. Simply put, it is the amount of water that the soil can absorb.

Those sensors are buried at two heights inside the soil. At around 20cm lays the topsoil and at 35cm is the subsoil. The measurements are taken at different depths because the two layers absorb water differently.

A novel remote metering solution for the construction industry

The company works primarily for the construction industry. For each measurement on construction sites, it is recommended to install five tensiometers on an area of 2 square meters and take the median value of the measurements. The tensiometric measurement indicates from which moisture conditions the soil can be driven on, without the construction vehicles producing significant damages causing infertility. The result of the measurement allows determining whether the intervention is allowed or to be avoided and, if necessary, to indicate the method of moving the soil and the type of machine allowed (see recommendations from the Swiss Bundesamt für Umwelt).

Silverlight provides the graphics with the projected and processed data of the suction pressure and moisture in the soil. Based on this data, the planning office and the construction manager can make informed decisions on where construction vehicles and heavy machinery can operate.

Without this solution, the weight of the individual machines and measured values would have to be measured individually, based on the established guidelines, to see whether it is legal to start construction. These established guidelines are standard from the confederation, and are all the same in Switzerland.

Who is interested in Silverlight’s service?

Depending on the project, the end customer could be entrepreneurs, constructors, environmental specialists, or landlords. The cantons, for example, have pedological construction supervision, which entails a specialist determining whether the floor is fit for construction.

This is where Silverlight plays an essential role by equipping the land with sensors and transmitters. The new addition of LoRa tensometers, allows for the data to be collected continuously and transmitted in real-time to the end application without requiring human intervention. Additionally, the company has the ability to combine the values with precipitation values to see how those affect the state of the soil. This allows for the planners to work with weather forecasts and ahead of time with predictions.

The data can be projected in Grafana, as depicted in the visual below. The lower the curve, the damper the floor. In the visual, one can see five different sensors that are distributed over a particular area. The drops in the graphic depict rapid changes (f.e heavy rain). Simultaneously, there are three different colors in the background of the graphic: red, yellow and green. As soon as the values reach the green area, it is safe for the construction machinery to start its operations.

What are the benefits of the solution?

The automated measurement system provides valuable information and insights into the dynamic behavior of soil. It has the potential to reduce manual work by around 90%. The collected data allows for better predictions and resource planning for the involved company, regardless of whether in the field of construction or agriculture.

• The installation is small and autonomous: It uses very little space, runs autonomously for the entire season, and does not need any maintenance.

• Measurements visualization: Reports are generated with a single click and therefore quick and easy to provide.

• By working with LoRa sensors, little energy is used, which allows for the sensors to operate for years offering a sustainable solution.

"The akenza platform reduced the time for device onboarding and payload decoding, and has proven to be valuable for troubleshooting."

-Valentin Keller, General Manager at Silverlight, on how akenza facilitates his work with the sensors

What role does akenza play?

• The akenza platform massively simplifies the management of the IoT device fleet. New devices are easily added and removed, offering the ability to fully focus on the core business operations, the measurement technology.

• Data management and monitoring of the incoming data streams from the different sensors are performed on a single platform, allowing the development of fast and flexible solutions.

• The agnostic architecture of the platform allows for the quick replacement of any sensor and connectivity technology, as well as custom applications for data analysis and visualization.