© Vilpe

Every­thing in the dry range: roof venti­lation with EC tech­nology

Vilpe Sense from Finnish company Vilpe detects water damage in roofs before it occurs. The system dissi­pates excess mois­ture to the outside, by using an EC centrifugal fan from ebm-papst.

Some­times the smallest things can have a big effect. A tiny hole in the bitumen felt on a flat roof, for example. If it remains unde­tected, mois­ture will pene­trate the building. By the time it’s noticed, the water damage is already done, and fixing it will entail costly reno­va­tion work. To stay one step ahead of mois­ture Finnish company Vilpe has devel­oped a system that moni­tors mois­ture in build­ings and dries them as needed.

Vilpe Sense detects even the smallest leaks in the roof and dries the building auto­mat­i­cally – thanks to RadiCal EC fan. (Graphic | Vilpe)

Vilpe Sense is the name of the solu­tion and it works as follows: A sensor measures the temper­a­ture and rela­tive mois­ture in the insu­la­tion layer, while another sensor records these values for the outside air. A control unit sends the data to the Vilpe cloud, where it is analyzed. If the system detects exces­sive mois­ture in the insu­la­tion layer, two things happen: The building manager is informed via an app and the fan installed on the roof starts auto­mat­i­cally and runs at the required speed until the mois­ture in the building enve­lope is back within an accept­able range.

Even a small crack in the roofing felt can cause great damage to flat roofs. That’s what Vilpe Sense is for. (Image | Vilpe)

Dry building enve­lope = no chance for mold

Veli-Pekka Lahti is Director Research and Devel­op­ment at Vilpe. “In Finland, we have snowy winters, which increases the risk of damage to roofs,” he explains. “There is also a lot of tech­nical equip­ment installed on them these days, such as solar panels, cooling and venti­lation systems. This means that damage to rooftops can happen quickly.”

But Vilpe Sense not only detects damage to existing roofs, it also helps dry out new builds: “During the construc­tion phase, mois­ture is natu­rally intro­duced into the building. Reli­able venti­lation is essen­tial here, other­wise mold will quickly form,” explains Lahti. “It is diffi­cult to provide good air in living spaces if the building enve­lope isn’t healthy.” This is why Vilpe Sense is avail­able not only for rooftops, but also for crawl­space venti­lation.

If mois­ture pene­trates the insu­la­tion layer over a longer period of time, mold quickly forms. (Image | Vilpe)

The Vilpe Sense system uses sensors to detect mois­ture. It informs the person in charge of the building and starts venti­lating the building. (Image | Vilpe)

Roof venti­lation – demand-based and effi­cient

What is special about the solu­tion is that it works according to demand. An intel­li­gent algo­rithm controls the speed of the fan installed on the roof. The fan only starts when the sensors in the building enve­lope detect mois­ture. But that’s not all: “When temper­a­tures outside are cold, the system auto­mat­i­cally reduces the speed of the fan because we don’t want to remove heat from the inte­riors,” explains Lahti, adding: “On the other hand, when the black roofs heat up a lot in the summer and the mois­ture evap­o­rates, Vilpe Sense detects this as well and increases the flow rate. Along with the mois­ture, it then blows the heat out.”

Tests at the Vilpe lab between May and August 2021 found a total of about 692 kWh of excess heat energy dissi­pated by the system. “This saves energy that would other­wise be used to cool the inte­riors. So we are oper­ating in a very energy effi­cient way,” says Lahti.


The system measures rela­tive humidity and temper­a­ture in the insu­la­tion layer and compares these values with those of the outside air. It inde­pen­dently regu­lates the rota­tion speed of the fan and always auto­mat­i­cally adjusts it to the demand. (Image | Vilpe)

RadiCal for extreme condi­tions

The effi­ciency of the compo­nents used was of corre­sponding impor­tance. Lahti and his team opted for size 190 EC fans from ebm-papst’s RadiCal series. They had already had good expe­ri­ences with these prod­ucts in the past. They operate econom­i­cally and are also extremely robust. An impor­tant crite­rion, as Lahti explains.

In cold outdoor temper­a­tures, the system auto­mat­i­cally reduces the speed of the fan. Thus we do not extract heat from the inte­rior.Veli-Pekka Lahti, Director Research and Devel­op­ment at Vilpe

“The climate in Finland is very harsh. We have temper­a­tures ranging from minus 40 to over plus 50 degrees Celsius from the insu­la­tion layer. Our prod­ucts and their compo­nents have to with­stand this. With ebm-papst fans, we know they are robust enough. We’ve put them through numerous tests and have been using them for many years.” Another plus: They operate very quietly. Since they do their job on the roofs of resi­den­tial and office build­ings, loud fan noises would be unac­cept­able.

Water damage is a thing of the past

The Vilpe Sense system is now in use on an increasing number of factory and school roofs in Finland. As Lahti explains: “Water damage due to flat roof degra­da­tion is much more common than many people think. This is also true for new build­ings. In work­shops, I often ask if anyone has ever seen a janitor place a bucket under a leak. Usually, half of the partic­i­pants then put up their hands. With Vilpe Sense, no janitor has to put a bucket down anymore.”

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