Ikast Swimming Center, owned by Ikast-Brande Municipality, traces its origins back to 1959 when it began as an open-air pool. The modern facility, which replaced the original outdoor pool, was inaugurated in 1992.
Today, the center spans over 5,000 m² and features a variety of facilities including a sports pool with a large spectator stand, a diving tower, a children’s splash area with a slide, a training pool, a baby pool, wellness amenities, a sauna, a café, meeting rooms, offices, and a reception.
The center is not just popular among ordinary guests; it also serves as a vital resource for local schools and the swim club, hosting over 20 different teams weekly. Besides regular operations, it frequently hosts major events such as the Mid-Summer Cup, National Championships, and other competitions.
Kim Neigaard Larsen has been the Technical Manager since 2017, working alongside Center Manager Jesper Harder. Together, they have spearheaded numerous development projects aimed at reducing energy consumption.
In 2023, their main focus was on HVLS fans, and Kim has agreed to share their experiences with the technical aspects of the operations before and after implementing the HVLS project with Nordicco.
Time period: February 2023
Project Scope: 2 Nordicco HVLS fans and Northern Sky with sensor add-on modules
Results: Better air circulation and improved indoor climate. Savings on electricity due to optimized HVAC operations
The center is equipped with 10 ventilation systems, 3 of which are primary. These systems incl. rotor exchangers, cross exchangers, and counterflow exchangers.
However, the 3 main systems are designed as heat-pipe exchangers that incorporate a mixing chamber. Kim provides some insight into their primary system: ”The heat-pipe is energy-efficient, which is a significant advantage. However, it also presents a major challenge. The mixing chamber complicates controlling the intake of fresh air, as it obscures the precise measurement of fresh air incorporated during the mixing process.”
Despite these complexities, the installation of HVLS fans has not altered their fundamental ventilation principles.
– according to Kim Neigaard Larsen:
HVLS effectively mixes air within the aquatic center at a much lower cost than using a traditional ventilation system. In the case of Ikast, it wasn’t financially feasible to circulate the air near the ceiling without HVLS.
The chill factor can be a downside, requiring careful consideration of temperature settings and the placement of stationary guests, or opting to run the fan at a low speed (RPM).
Based on my experience, regardless of the ventilation system in place, HVLS will always make a positive difference. This is because the fan aids in air mixing and consumes almost no electricity.
Kim Neigaard Larsen originally trained as an air conditioning technician and has always been driven by technical curiosity. He also serves as a lifeguard judge in his spare time.
”I joined Ikast Aquatic Center in 2017 and quickly realized that both staff and guests occasionally found the air quality to be poor. It could often feel clammy and uncomfortable,” Kim recounts.
Managing relative humidity (RH) also posed a persistent challenge: ”We’ve never managed to keep the relative humidity low during peak times such as swim meets and holidays,” Kim explains, and he shares an anecdote about one of his experiments with the ventilation system:
”I once cranked our ventilation motors up to 100%. The result was quite dramatic— the hinges holding a 1m² inspection door in place couldn’t withstand the pressure, and the door blew off.”
In his quest to improve air quality and temperature control, Kim discovered a significant temperature differential within the center:
”I noticed that the temperature near the ceiling, about 9 meters up, was 38°C, while at 2 meters it was only 30°C. I wanted to harness that heat energy at ceiling level and redistribute it to where it would be more beneficial. After a lengthy search for a fan that could endure the challenging environment of a swimming pool, I came across Nordicco at a conference a few years back”.
Kim performed smoke tests in the aquatic center to see the air flow with and without HVLS fans.
Fast forward to February 2023, when Ikast Aquatic Center saw the installation of 2 large HVLS fans from Nordicco, expertly installed by a professional climbing team. Kim had high hopes for the project.
”I was optimistic that we could lower the temperature near the ceiling to utilize that air more effectively, improving the indoor climate overall,” he explains. ”I also expected better control over relative humidity, along with reductions in our district heating and electricity consumption. Additionally, we were dealing with slightly elevated THM levels in one of our pools, and I was hopeful that the fans would help mitigate that issue as well.”
Kim has followed the HVLS project closely throughout 2023 and made operational adjustments on an ongoing basis. He’s deliberately not done other projects at the same time, so as not to disturb the results. The following operational adjustments have been made after installation:
The improvement in indoor climate was particularly noticeable after the fans were installed. Before, the center often felt clammy and uncomfortable during busy periods, but this challenge was now solved. Kim highlights the positive feedback:
”There are no more complaints from guests. That’s really positive! Both staff and guests can feel the difference, and the improvement in the indoor climate has been remarkable.”
The main result regarding ventilation is an enhanced air flow and a more energy-efficient air circulation. They’ve followed before/after data closely in connection with operational adjustments.
They’ve achieved annual electricity savings of 12,183 kWh in Training and 9,738 kWh in Sport, corresponding to 34% and 21% respectively.
As far as electricity consumption is concerned, the project has thus exceeded expectations.
THM tests have confirmed that it’s been possible to reducte the ventilation operations without causing any significant changes in THM levels. The tables below show Ikast Aquatic Centers THM data for the two pools, Sport and Training, in 2022 and 2023:
On the heating side, Kim didn’t achieve the expected savings:
”We’ve used roughly the same amount of heat, but we have also raised the air temperature by 1.0° C in Training, as the guests on the side of the pool felt a little cold. We therefore raised the temperature to counteract a chill factor.”
In the end, heat consumption is therefore largely the same before/after HVLS – despite the now slightly higher air temperature.
Regarding water consumption, the data show that they used 85 m³ more water in 2023 compared to 2022 in the Training pool and 55 m³ more in the Sports pool.
Kim explains that this makes sense when comparing the years in detail, since in 2023 there were more guests and also an extra competition event than in 2022:
”The filters for water treatment have been rinsed more, but when we look at stand-by consumption (evaporation) of the pools, there’s no difference year to year,” he says.
After adopting the online management platform Northern Sky and installing indoor climate sensors, Ikast has significantly improved its ability to monitor CO2 levels in the air.
’I can now see the exact CO2 content, which is fantastic – I actually didn’t have access to this data before,’ Kim remarks about this feature. He adds:
”Before we installed the ceiling fans, I relied on guest feedback and my own senses to determine when the indoor climate in the swimming hall became unbearably poor. Now, with the CO2 sensors and ceiling fans integrated as one system, I can directly check the management platform to know when it’s time to circulate more fresh air.”