Oulun Kosteustutkimus Oy Wiistie concrete sensors:

“The accuracy of the humidity data is impeccable”

Oulun Kosteustutkimus Oy uses Wiistee concrete moisture sensors, for example, in the A section of the city's renovated university hospital under construction. According to the company, Wiistee's sensors and cloud service reduce the need for borehole measurements on an average construction site by 5–10 measurements.

Oulu's extensive hospital renovation will be completed in its entirety in the 2030s. The scale of the project is evident from its budget of 1.61 billion euros.

Wiistee sensors are currently being used to monitor the moisture content of the concrete structures in the new A-section of the hospital, which is part of the first phase.

– Moisture is monitored actively and for a long time at the nuclear hospital. The data from all sensors is reviewed 1–2 times a year. The locations are marked on large floor plan sheets that can be seen in addition to Relia, says Juha Yliniemi, a structural moisture meter and AHA expert from Oulu Moisture Research.

Oulu Moisture Research is a certified expert in building health and a specialist in moisture measurement.

The accuracy of the sensors was compared to borehole and sample measurements

The company first became familiar with Wiistee humidity sensors in 2014.

– At that time, SRV was building a new Mehiläinen hospital building in the center of Oulu. We first learned about the new sensors from the site's foreman, who had heard rumors about Wiiste's solutions.

– He asked us to investigate the matter. So Mehiläinen's project became the first construction site where we used Wiisteen concrete sensors.

Juha Yliniemi admits that he was initially skeptical about the accuracy of the new sensors.

– We did a lot of comparative measurements then and have done so since. Based on these experiences, I can say that the accuracy of wireless sensors is beyond reproach. The measurement accuracy of the sensors is good. It is often between the results of a borehole measurement and a sample piece measurement.

– It is extremely rare to find a difference of more than two percentage points in relative humidity compared to borehole measurements. If this is the case, the conditions of both measurements must be examined and which measurement result is actually more accurate, says Juha Yliniemi.

Image: Wiistee's concrete IoT moisture sensors installed in the casting. The sensors' batteries have a service life of up to 10 years. After that, the results can be read with a hand-held reader.

Benefit: 5–10 fewer borehole measurements per jobsite

– The biggest benefit of Wiistee's sensors for us is that they clearly reduce unnecessary measurement visits. We don't have to take wet samples. We don't have to take 5–10 borehole measurements at one construction site. This saves a lot of time, which allows us to handle more sites.

Juha Yliniemi sees that switching from manual measurements to automatic remote monitoring will not “eat the company’s own bread”.

– The new technology will give us more competitiveness and also more sales. When Wiiste sensors are on a construction site, our other services are usually also needed.

“Remote targets make the most sense for IoT sensors”

Oulu Moisture Research still uses a lot of concrete sensors that can be read on site with a hand-held scanner. In addition to them, Wiistee's thin SH3 sensors have also been used, which are suitable for moisture measurement, for example behind a vapor barrier or under waterproofing.

Image: Wiistee SH3 sensor.

IoT sensors are also used. – From our perspective, remote sites make the most sense for IoT sensors, as remote monitoring avoids several long driving distances. They have been used in sites such as Haapavesi, Ylivieska and Pudasjärvi.

Yliniemi considers Wiistee's sensors and measurement data user interface in the Relia cloud service to be easy, as long as you take the time to familiarize yourself with the idea.

– We also have sites in Northern and Southern Finland, and we have recently held many Teams training sessions on Relia for the responsible foremen on construction sites – starting with how to export data from sensors to Relia.

Already over 1000 sensors in various concrete structures

Yliniemi believes that it is of primary importance that the end customer also understands what the measurement result means and what actions it makes sense to take based on the results. The expertise of Oulu Moisture Research is useful in drawing conclusions.

The sensors installed in the concrete casting will naturally remain permanently in place for future use in the property. Juha Yliniemi estimates that over 1,000 Wiisteen “concrete sensors” have been installed in Oulu Moisture Research sites to date.

– At Relia, we currently have 68 sites under monitoring, but not all sites are there. Most often, monitoring ends when the building is completed, but in some sites, data is monitored later.

– A few contractors have wanted this themselves. For example, the NCC foreman requested moisture data a year after the carpeting on the Muhos school building had been installed. In the end, the data was monitored for 3–4 years.

Structural moisture monitoring on the rise

According to Juha Yliniemi, the professionals at Oulun Kosteustutkimus Oy are “quite measurement device freaks.” Wiistee’s sensors have earned their place.

- Quite often we are offered all kinds of measurement solutions, and we test potential ones. However, we have had no reason to change our current measurement solutions for others.

According to Yliniemi, interest in building health has grown. As part of this, post-construction moisture monitoring is increasing.

- The direction is right, but progress is slow.

New drying trailer: 5000 m3 of dry air per hour

Oulu Humidity Research is currently also strongly developing its drying service for construction sites. The company's new drying trailer is a solution for drying large new projects.

There is enough power, as the device produces 5,000 cubic meters of dry air per hour. If necessary, the air can also be heated if district heating is supplied to the site. At best, cost savings of almost 60 percent have been achieved in heating during construction.

There is also demand for the company's other expertise. According to Yliniemi, there are enough orders for at least a few years to come.

Oulun Kosteustutkimus Oy is a multi-skilled company founded in 1996, which mainly offers construction companies a wide range of new construction services: moisture measurements, moisture management, drying and heating, tightness measurements, dust management and thermal imaging. The company focuses on the latest knowledge, expertise and equipment in the field. Oulun Kosteustutkimus Oy employs over 10 experts.