© Janosch Abel

Happy hemp thanks to perfect ventilation

Since cannabis with THC content under one percent was legalized in Switzerland, the sector has been booming. BioCan AG got in on the ground floor of hemp cultivation. Thanks to good ventilation, its harvest is better than that of its competitors.


Philipp Schennach and Jorma Lori look proudly over the fruits of their labor: several thousand hemp plants swaying back and forth in the artificial wind and illuminated by 170 lamps simulating the sun. In about three weeks, the harvest can begin. And none too soon; demand for the plant is huge. Hemp truly has many functions. Its fibers can be used in textiles and even in the automobile industry, and the compounds in its flowers relieve pain, relax muscles and stimulate the appetite, so the plant is gaining acceptance in the medical community. And the oil from its seeds can even be used as fuel.

But the consumption of hemp is off limits in almost all countries. However, in Switzerland a decision by the Federal Office of Public Health (FOPH) in 2016 really stirred up the market. The sale of hemp is now legal as long as the concentration of the psychoactive substance tetrahydrocannabinol, better known by its initials as THC, is under one percent. In this case, hemp counts as a tobacco substitute. Schennach and Lori have had lots to do since then. They work at BioCan AG, the first Swiss company permitted to produce and sell cannabis legally as a tobacco substitute.

BioCan AG

The founder of the company, which is headquartered in Thayngen, Switzerland, is Markus Walther, a pioneer in hemp production who was advocating its legalization for sale as long ago as the 1990s. Through numerous hybridizations, he was able to breed a hemp plant with a THC concentration below one percent. When the Federal Office of Public Health gave its approval in 2016, he and his company got to work. In addition to hemp for smoking, BioCan AG also supplies hemp oil and tablets.

The decision by the FOPH was a huge opportunity for Schennach and Lori. Lori, actually a carpenter by trade, is one of the founders of BioCan AG. He is the facility manager for cultivation at its site in Bassersdorf. Schennach heard from an acquaintance that the company was looking for investors. Since he had some savings to spare, he invested. “But soon I wanted to be involved in hemp cultivation myself, so I got involved in the operational side of the business.”

Schennach is actually a trained brewer. “There is common ground with beer, because hops are also a member of the hemp family.” At BioCan AG, he took the position of technical director for indoor production, one of three production methods along with greenhouses and fields. “That way we spread the risks. Out in the fields, crop failures can happen frequently. Indoors we’re independent of the seasons.”

Hemp likes it windy

Schennach and Lori approached their new task with enthusiasm. In the industrial park in Bassersdorf, a small community near Zurich, they rented two floors in an office building, a total of 3,000 square meters. Then they were able to begin designing their facility. A crucial component of their planning was the ventilation. “Good ventilation is very important for the plants,” says Schennach. Hemp plants are actually very undemanding.

“Good ventilation is very important for the plants.”

Philipp Schennach, BioCan AG

The valuable part is the buds on the female plants; the bigger they are the better. But the stems have to be strong enough to bear the weight of the buds. In the wild, the wind strengthens the plants. “We try to simulate nature as well as we can indoors, so there should always be a light breeze there. To do that, we need good technology,” explains Lori.

Hemp background

Cannabis is the scientific name for hemp. The valuable part is the buds on the female plant, which are host to over 80 cannabinoids and over 400 active substances. The most important cannabinoids are the intoxicating tetrahydrocannabinol (THC) and the non-intoxicating cannabidiol (CBD). Hemp with a THC content of less than one percent is also called CBD hemp. Medicinal effects are attributed to CBD. It’s important to keep the blossoms from being fertilized by pollen, which would make them worthless.

A constant breeze also inhibits the growth of mold and mildew in the humidity arising from the plants’ transpiration. “We don’t need any pesticides at all.” One advantage of indoor production is that the growth period can be controlled. “Hemp is actually an annual plant. In spring and summer, it puts all of its energy into growth. When the days get shorter in the fall, the plant knows it’s time to reproduce and it forms flowers.

By controlling the lighting, we can shorten this process and get up to six crops per year instead of just one.” But the lamps with 600 or 1000 watts each generate a lot of heat, so cooling is another important function of the ventilation system.

Planning for the facility

With these ideas in mind, Schennach and Lori got to work on the design and began drawing up plans. They thought about how the fans had to be positioned for optimum air flow and calculated pressure losses and the required air performance. They did research in the Internet to find suitable fans for their requirements. When they saw the product video for the RadiPac centrifugal fan on the ebm-papst website, they knew: “That’s the one!” So Schennach got in touch with ebm-papst.

It was a somewhat unusual inquiry for Daniel Schefer at ebm-papst in Switzerland. “It’s not every day that our products are used for hemp production.” During an on-site visit, Schennach explained to him that he was still looking for a solution to generate air flow over the entire 30-meter length of the room. For that, he needed fans with high air throw.

“We have a facility that’s superior to many others, simply because we have good fans.”

Jorma Lori, BioCan AG

Right away, Schefer thought of the AxiCool axial fans, which are normally used in cold stores but were a perfect fit for the requirements. “They were much more compact than the fans I’d seen elsewhere, and easier to install,” says Schennach. That was important, because the two did everything themselves. They installed a total of 20 units on the ceiling, and two RadiPacs each for intake and exhaust.

Schennach and Lori are very satisfied with the results. “We have a facility that’s superior to many others, simply because we have good fans,” says Lori. And the next ordered fans are already waiting to be put to work on the remaining floor space. Of the 3,000 square meters in Bassersdorf, BioCan is only using about 1,000, and the demand for legal hemp – not only from private consumers but also from wholesalers – isn’t slowing down.

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