Ventilation system

A good ventilation system reduces condensation, improves the indoor climate and increases sleeping comfort. We have developed our Helsport Airflow II® ventilation system to give you the best night’s sleep possible.



Ventilation should ensure an even supply of fresh air/oxygen (for both safety and sleep comfort reasons) and transport condensation out of the tent.

The ventilation system must be capable of doing this in two ways: ventilation and airing. This is best achieved through a constant and controlled flow of air through the tent. Airing can be likened to opening the windows of a house to achieve rapid and substantial air exchange for a good indoor climate, atmospherically and thermally.

Helsport’s various tents feature a range of vents and ventilation systems. These may be simple vents with cord closures, vents with zip closures, skirt vents or roof vents. The main principle is that we want to bring fresh air in at ground level and release warm and humid air high up in the tent. Warm air rises naturally, creating a natural flow of air through the tent.

Cold, oxygen-rich are is drawn in through air vents at ground level while warm, oxygen-depleted air rises and is extracted higher up.



How it works

  • Cold, oxygen-rich are is drawn in at ground level underneath the outer tent fabric and through circulation vents positioned low down in the tent, ensuring circulation and exchange of moist air both inside the inner tent and in the space between the inner and outer tent.

  • Warm, damp and oxygen-depleted air rises and is released via the netted vent in the inner tent door on the opposite side and transported out through the upper vent in the outer tent. The opening needs to be adjusted based on the number of people in the tent. It is important that the netted vent on the other inner tent door (if applicable) is closed, as having it open would inhibit the flow of air.

Atmospheric indoor climate

A high level of CO2 makes the air feel ‘heavy’. In order to prevent CO2 levels becoming too high in spaces where there are people, each person needs a supply of fresh air of at least eight litres per minute. Research conducted at the Norwegian University of Science and Technology and SINTEF has shown that Helsport’s Airflow II® ventilation system meets this requirement. Tests performed on tents that do not have this type of ventilation system show that there is an insufficient supply of fresh air, and therefore too high a level of CO2.

Thermal indoor climate

Helsport’s AirFlow II® ventilation system ensures a good thermal indoor climate by transporting damp air out of the tent. This largely helps prevent condensation. Damp resulting from condensation can reduce the insulation capacity of sleeping bags and clothing and make the air feel sticky and heavy. A good thermal climate thus improves tent comfort.

Ventilation in extreme conditions

All our tents (apart from those in the Superlight series) have a completely sealable ventilation system. The ventilation can be closed off completely during winter use and mosquito nets and fabric openings can be opened and closed independently of each other.

Storm flaps

All our X-Trem tents are fitted with storm flaps, which makes a system such as Airflow II® essential in order to ensure sufficient air inside the tent. So, if you buy a tent with storm flaps, or have these fitted later, it’s important that the tent has a circulation vent to ensure that air is allowed to enter at the bottom. When we sew storm flaps onto tents that didn’t have them originally, we always recommend adding an additional air supply vent.

This vent is also important in tents without storm flaps that are used in winter, because when tents are dug into the snow, they can easily become too closed at the bottom regardless. This is why the ventilation system in our Pro tents with 4-season ventilation is the same as that in our X-Trem tents with storm flaps.



Many tents are constructed in a way that assumes good circulation underneath the tent. When these tents are used on snow or dug into the ground or snow, it becomes more difficult to ensure good ventilation as the vital circulation vent is blocked.

On tents that are to be used in winter, the vents must be fitted high up to prevent them becoming covered by snow. Remember that you can use the inner tent door as a vent to provide additional air flow in the inner tent. Breathable materials are used to ensure a good indoor climate and to prevent condensation forming even when the vents are closed.


Tent condensation is caused by water vapour becoming liquid. It’s important to understand condensation, which occurs in all tents.

There are three primary sources of condensation in a tent:

  • the people in the tent (breath, sweat and wet equipment)
  • the air and ground
  • boiling and cooking

A human body releases roughly half a litre of water in a night. This moisture is partially absorbed by clothing and sleeping bags, but some of it is released into the tent.

The condensation problem becomes greater when air humidity is high and/or at low temperature. Condensation settles on cold surfaces, and in a tent the outer tent and the ground sheet are the most exposed areas. Condensation forms on both the inside and the outside of these surfaces.

When the outer tent moves due to wind or rain, the condensation that has settled on the inside of the outer tent will drop down, and it’s easy to think that this is happening because the tent fabric isn’t waterproof.

Condensation can also easily form between the ground sheet and roll mats. The kit area does not have a ground sheet, meaning that damp from the ground will settle on the inside of the outer tent.

Inner tent

In addition to the ventilation system itself, which has been optimised to reduce condensation, the inner tent also helps reduce condensation by reducing the temperature difference between the two sides of the outer tent fabric. The inner tent hanging system ensures the correct distance between the inner and outer tent, as well as good air circulation.

Skirt vent

Another effective way of limiting condensation is to use our skirt vent system which allows you to open up and allow even more air in at ground level. This provides maximum ventilation through the inner and outer tent to minimise condensation.


A footprint is a highly effective way of achieving minimum condensation on the ground sheet (and from the porch area which lacks a ground sheet). You can buy footprints for almost all our tent models.