.jpg?width=75&name=sigvardsson_220628_0008_small_webb%20(1).jpg)
.jpg?width=75&name=magnus%20andersson_550x550%20(1).jpg)
-4.png?width=75&name=MicrosoftTeams-image%20(3)-4.png)
For decades, one of the strongest selling points of chilled beams has been their simplicity. With no fans, no drainage pumps and no mechanical moving parts, chilled beams have built a reputation of being reliable, low in maintenance and offer a long product life. This passive design has made them a trusted solution in buildings worldwide. But as ventilation strategies evolve, so must the technology behind them. Our expert, Tobias Nordström, Product Manager Chilled Beams at Swegon, presents how.
There is a few reasons to why chilled beams work so well, their performance builds on two key physical phenomena: induction and the Coanda effect. Supply air is delivered through the chilled beams nozzles at relatively high velocity, created by a pressure difference between the duct and the room, typically between 50–120 Pa.
This pressure generates:
- Induction: the high air velocity from the nozzles creates an under pressure above the heat exchanger which draws room air into the chilled beam. As the room air passes through the heat exchanger it is cooled/heated before being mixed with supply air and return to the room. This is what enables high cooling/heating capacity without fans.
- The Coanda effect: the supply air attaches to the ceiling, which allows it to spread across the room and slow down before reaching the occupied zone. This ensures that air velocities remain below ~0.2 m/s, which prevents draughts and maintains comfort.
Together, these principles deliver a efficient, quiet and comfortable indoor climate control.
.png?width=2439&height=1237&name=bild%20(3).png)
The challenge: variable airflow systems
The simplicity of chilled beams suits constant air volume (CAV) solutions exceptionally well. However, modern buildings often need to meet stricter energy regulations and face higher expectations on presenting a good indoor climate. This is why buildings more often rely on variable air volumes (VAV) and demand controlled ventilation (DCV).
These systems continuously adjust airflow based on occupancy, CO₂ levels and/or temperature, and the result is a reduced energy consumption while comfort is maintained. Traditionally, airflow in such systems has been controlled by utilising a VAV damper upstream of the chilled beam. 
What happens when airflow is reduced?
Chilled beams are typically designed for peak conditions, meaning airflow and cooling/heating demands on a maximum level. Looking at a simplified example of a chilled beam with fixed nozzles and an upstream damper:
At design conditions:
-
Airflow = 288 m3/h
-
Pressure drop = 70 Pa
-
k-factor on chilled beam = 9,6
If airflow is reduced using an upstream damper:
- At 144 m3/h → pressure drops to ~17 Pa on the chilled beam
- At 72 m3/h → pressure drops to ~4 Pa on the chilled beam
This reduction in pressure has a direct impact:
- Lower induction → reduced cooling/heating capacity
- Weaker Coanda effect → increased risk of draughts and poor air distribution
In practice, this means the system may need to increase airflow to maintain performance, which negatively affect the intended energy reduction.
To address this challenge, there is an identified need to vary airflow without compromising pressure conditions in the system. The solution could possibly rethink the nozzle design and for example enable the nozzle to change in size. The need for upstream dampers and their associated pressure losses would then be removed.
Using the same example, this is could be the result in practice:
- 288 m3/h→ k-factor = 9,6 with pressure drop 70 Pa
- 144 m3/h → k-factor adjusts to ~4,8 maintains 70 Pa system designed pressure drop
- 72 m3/h→ k-factor adjusts to ~2,4 maintains 70 Pa system designed pressure drop
Here, instead of losing pressure with the upstream damper, the k-factor is adjusted to maintain the desired airflow.
More than performance: an easy to use system
This approach would not only improve performance, it would also simplify the entire system design and installation process.
Reduced system complexity
In VAV and DCV systems, there would be no need for a separate upstream VAV damper. Airflow is instead controlled directly in the chilled beam, reducing:
- Components in the duct system
- Installation time
- Cost
Smarter CAV installation
In CAV systems, this integrated functionality act as a built-in commissioning damper. Meaning:
- For most applications, no additional balancing damper would be required
- Commissioning would be faster and easier
- Fewer components would need to be installed and maintained
(Note: In systems with very high duct pressures 200Pa+, additional damping may still be required to reduce the pressure before the chilled beam to not create sound in the occupied space, this can be calculated with our free selection software’s.)
The result: consistent performance at any airflow
By maintaining pressure across the nozzles, this kind of nozzle functionality would ensure:
- High induction → sustained cooling/heating capacity, even at low airflow
- Strong Coanda effect → stable air distribution and reduced draught risk
- Lower required airflow to deliver cooling/heating capacity → improved energy efficiency
Enter Flow control
At Swegon, we let this not only be an idea or example, we have developed Flow control, which, by adjusting the nozzle geometry, actively control the k-factor. This allows the airflow to be regulated while maintaining a stable system pressure drop. The additional installation, commissioning and maintenance gains mentioned above are all included in this solution.
Further, choosing any of Swegon’s built-in control options, REACT, AWC or WISE, add the benefit of pressure-independent airflow control which ensures that the desired airflow is maintained even when duct pressures vary. This improves system stability and performance.
In real applications, this means a chilled beam with Flow Control can deliver the same comfort with less air, compared to traditional solutions with upstream dampers.
Below is an example showing the cooling capacity difference between an old Pacific unit with an upstream VAV damper and a REACT Pacific with built in flow control.
.png?width=2483&height=1258&name=bild%20(4).png)
From passive to adaptive
The absence of moving parts has long been a defining advantage of chilled beams, and still is in many applications. But as buildings become smarter and more dynamic, solutions must evolve. By integrating intelligent airflow control, designed and tested for long-term reliability, modern chilled beams combine the best of both worlds:
- The reliability and simplicity of passive systems
- The performance and efficiency of adaptive, demand-driven control
Looking ahead
Chilled beams are no longer just passive components in an indoor climate solution, they are becoming active contributors to enhanced building performance. Innovations like Flow Control, ensure that buildings are equipped to meet the demands of modern buildings and deliver on the following parameters: comfort, energy-efficiency and performance, aligning with regulations such as EPBD while making sure people feel good inside.
