Helsport Airflow II® ventilation system

A good ventilation system prevents condensation, and dramatically improves both interior climate and sleeping comfort.

A ventilation system achieves this in two ways: through ventilation, and air exchange. Ventilation must ensure an even and steady flow of fresh air/oxygen through the tent (for reasons of both safety and sleep), and at the same time remove condensation. Best results come from a constant and controlled stream of air through the tent. Air exchange can be compared with opening windows in your home to get a quick exchange of air to ensure a good atmospheric and thermal inner climate.

Helsport’s many tent models have a variety of different vents and ventilation systems, from simple vents with bungee or zippered closure, to skirt and roof ventilation. The main method of ventilation is achieved by letting fresh air in at ground-level, and allowing warm humid air to escape higher in the tent. Warm air rises and, by warming the air inside the tent, a natural flow of air is created.


Cold air, rich with oxygen enters through vents at ground level, and the warm, oxygen-depleted air goes out through the vents higher up.

Atmospheric inner climate
High levels of CO2 feel like “heavy air”. To prevent overexposure to CO2, the human body needs approximately 8L/min of fresh air. Clinical studies with NTNU and SINTEF have shown that Helsport’s Airflow II® ventilation system surpasses these required levels of fresh air. Test results without this type of ventilation system show inadequate exchange of fresh air and thus higher levels of CO2.

Thermal inner climate
By transporting humidity out of the tent, our Helsport Airflow II® ventilation system ensures a good thermal inner climate and helps to prevent condensation. Humidity resulting from condensation can reduce the insulating abilities of clothing and sleeping bags, and the air can feel clammy and heavy. Therefore, a good thermal inner climate will improve your comfort level inside the tent.

This is how it works: 

  • Cold fresh air, rich in oxygen, enters under the outer fly tent and through vents at ground level. This ensures circulation and exchange of humid air in the inner tent, as well as the layer between the inner and the flysheet.
  • Warm, humid, oxygen-depleted air rises and escapes through the mesh door on the inner tent, and further through an outer flysheet vent. Regulate the opening, dependent on how many people are in the tent. If the inner tent has two mesh doors, keep one of them closed – this will ensure airflow continues.

This is how AirFlow® works in a tent

This is how Helsport AirFlow® works in a lavvo:

Ventilation under extreme conditions
The ventilation system is fully closable in all our tents (except the SuperLight-series), a useful feature for extreme conditions. Also, the mosquito mesh and fabric doors can be opened and closed independently.

Storm flaps

All X-TREM tents are equipped with storm flaps and, in these tents, our Airflow II®
ventilation system is critical for getting fresh air into the tent. When we add storm flaps to tents that don’t have them originally, we always recommend adding an extra air intake vent. This air intake vent is also important for tents without storm flaps because, during winter use, snow can pack around the tent and prevent air entering underneath the outer flysheet. Therefore, all our PRO tents have 4-season ventilation, like the ventilation on our X-TREM tents with storm flaps.

Many tents are made assuming good circulation under the tent. However, when these tents are packed with snow, good ventilation is harder to achieve without a vital circulation vent.

For tents that are meant to be used during wintertime, vents need to be mounted higher up on the tent wall to prevent snow from blocking them. Remember that you can use the inner door as a vent to contribute to better airflow.

Breathable materials are used to improve interior climate and to prevent condensation, even with closed vents.

Condensation is a result of water vapour in the air turning to liquid water. It’s important to understand how condensation occurs in a tent.


There are three main reasons why condensation occurs in a tent:
– from the people inside (breathing, body humidity, wet equipment)
– from the air and the ground
– from cooking

During the night the human body releases around 0.5L of water. This moisture is partially absorbed by clothing and sleeping bags, but some is also trapped in the tent. Condensation increases with high humidity and/or low temperatures, and forms on both the outside and inside of fabrics. It tends to collect on cold surfaces, making the outer flysheet and ground sheet most vulnerable. When wind and rain cause the outer fly to move, condensation can drop down from the inside of the flysheet, often misinterpreted as a leaking tent. Condensation can also easily form between the ground sheet and your sleeping mattress. Because there’s no ground sheet in the vestibule, condensation from the ground or from cooking can collect here on the inside of the fly.

Inner tent
In addition to the ventilation system, the inner tent also contributes to minimizing condensation: it reduces the difference in temperature on both sides of the outer flysheet. The connections between the inner and outer fly ensure correct distance between the two layers, and thus a good airflow.

Skirt ventilation system
Our “skirt ventilation system” is another system that reduces condensation, giving you the option of opening part of the outer fly. This creates more air intake at ground-level, maximizing ventilation between the inner tent and outer fly, and minimizing condensation.

To protect and minimize condensation from the ground sheet, and to increase comfort, we recommend using a footprint. These are sold separately to suit almost every tent model.