The odors from the charcoal grill no longer disturb the offices

The Ozonetech RENA Pro ozone system enables up to 91.5 % odor removal

Nordstan is the main shopping mall in Gothenburg, Sweden’s second largest city. Its central location, easy parking and variety of restaurants, cafes, shops and boutiques makes it one of the most visited malls in Sweden. In the mall and nearby there are also plenty of offices. When tenants complained that they were disturbed by odors, the mall management reacted swiftly and contacted us.


  • Name:

    Nordstan shopping mall

  • Location:

    Gothenburg, Sweden

  • Industry:

    Restaurant, kitchen exhaust

  • Purpose:

    Odor control

  • Performance:

    72% VOC reduction and 78 % odor removal

  • Air flow rate:

    1,100 L/s


  • Ozonetech RENA Pro B4

  • Dimensions (HxWxD):

    800 x 600 x 1,800 mm

  • Input power:

    2.3 kW

  • Noise level:

    55 dB

Ozonetech rena pro system

The Ozonetech RENA Pro is skid-mounted and installed close to the ventilation duct where the ozone is injected. The operation is automatic and the installation includes closed-loop cooling system, oxygen concentrator, ozone sensors and remote monitoring.

The problem

One of the restaurants in the mall had been rebuilt recently to make room for a charcoal grill. The fumes had an intense odor and high grease content, disturbing the nearby offices when the wind was blowing towards them. With a ventilation flow rate of 1100 L/s, the odor problem became significant, causing frequent complaints from the office workers. In most kitchens, the air entering the ventilation contains odor compounds with low amounts of particles. Charcoal grills are a different story. The charcoal produces a lot of smoke and soot particles that protect the odor compounds from being treated. For this reason, charcoal grills are a very challenging task.

The solution

To minimize the odor emissions, an Ozonetech RENA Pro™ ozone system was chosen. The plug-and-play installation was done in the back of the restaurant next to the ventilation ducts, out of sight from customers. The RENA system is mounted on a skid fitting half EUR pallet standard. The ozone is injected directly into the ventilation.

The high-performance and remote monitored Ozonetech RENA system is oxygen-fed and liquid cooled. This is the only way to produce large quantities of concentrated ozone stable over time – which in turn is the only way to continuously and automatically remove grease from kitchen ducts with an absolute minimum of maintenance. The HELS™ technology, our electrode-less technology for ozone generation, produces up to 30 % more ozone compared to traditional Corona Discharge techniques. In addition, Ozonetech RENA produces no dangerous by-products such as NOx and HNO3. The safety is high. In case of an ozone leak or low duct air pressure the ozone generator is automatically shut off.


The Ozonetech RENA Pro delivered as promised, showing an average VOC (Volatile Organic Compounds) reduction of 72% and an average odor reduction of 78%, with a maximum of 91.5%. The performance was stable under various kitchen loads. Performance tests were done during both peak hours and low kitchen activity, ensuring reliable test results.

Thanks to the Ozonetech RENA Pro, people in the surrounding offices are not disturbed by odors, even during high kitchen activity. Nordstan and the restaurant owner can trust that the investment for a long time will keep the surroundings free from odors coming from the popular charcoal grill restaurant.

VOC reduction and Odor removal graph