What extreme climates have taught us about functioning ventilation systems

Almost everyone who deals with composting toilets asks the same question first:

Does the system have a fan?

That's understandable—odors are the first thing that concerns most people. But this question doesn't go far enough. A truly effective ventilation system always results from the interplay of several components that must be coordinated with each other.

We experienced this ourselves while traveling through hot, humid and dry regions — and learned how much more there is to a functioning system.

If the fan question alone isn't enough

Anyone planning or already using a composting toilet usually thinks of the fan first when it comes to ventilation. However, it's not just about whether air is moved – it's also about how it's guided through the system, where it's extracted, and whether odors even have a chance to remain in the room.

In the end, simply venting the air from the vehicle to the outside wasn't enough. If the air isn't adequately cleaned beforehand, the problem simply shifts outside.

This applies to vanlife travelers as well as anyone who uses a composting toilet regularly in their daily life. Those who only look at the fan are overlooking what the system can actually handle.

Once you understand ventilation as a complete system, your perspective shifts. Fan performance, airflow, activated carbon quality, and the outer cover all interact.

If a link in this chain is missing, it becomes apparent—often only later, on warm days, after prolonged use. No single factor is decisive on its own: it's the interplay that makes the difference in everyday life.

Three factors that truly make a ventilation system work

The fan and airflow

A fan that's too weak keeps odors in the system longer; one that's too strong creates unnecessary noise. Incorrect airflow means air is moving, but odors remain noticeable.

Especially at night or in small vehicles, it quickly becomes clear how important noise levels actually are in everyday life. That's why we offer a range of different fan solutions — including the SETRENLO® Silent fan for particularly quiet ventilation systems.

Fan performance and airflow must be coordinated for the system to function reliably in everyday use. Only when both are perfectly matched will the system work as expected.

The activated charcoal

Activated carbon is not simply activated carbon. Temperature, humidity, and airflow greatly influence how well it actually works.

Unsuitable activated carbon often only filters odors in the short term or loses its effectiveness significantly under certain conditions — a difference that becomes particularly noticeable with longer use.

Choosing the right activated charcoal is therefore crucial for the overall system to function correctly. For most situations, SETRENLO® Vegan Activated Charcoal is a good choice.

The cover

One point that is rarely discussed is the external cover of the vent. In strong winds or while driving, an unsuitable cover can cause air from the outside to be forced back into the system.

This not only affects airflow but also causes odors to suddenly reappear where they are not wanted. Therefore, the fan, air duct, and cover must work together as a unit.

The SETRENLO® universal cover is specifically optimized for this purpose and integrates seamlessly into the system.

It was designed to allow air to be expelled from the system in a controlled manner — even under changing wind conditions or different installation situations.

Things you should consider from the beginning during installation

Anyone planning to use a composting toilet long-term should consider the ventilation system as a whole from the outset. Airflow, airflow rate, activated carbon quality, noise level, cover, and installation situation must all work together. No single factor is decisive on its own—it's the interplay of these elements that makes the difference in everyday use. Thinking this through early on saves you from having to make adjustments later.

During our travels through hot, humid and dry regions, we noticed that ventilation systems can behave completely differently depending on the climate.

High humidity, intense heat, or very dry air alter how activated carbon works and how odors behave within the system. It was precisely under these conditions that we realized different requirements for activated carbon arise.

It was precisely from these experiences that the SETRENLO® Expedition activated carbon was created — specially developed for demanding conditions, such as those that can occur on long journeys or in extreme climates.

Good ventilation is hardly noticeable — and that's the goal.

A good ventilation system should be barely noticeable: quiet, unobtrusive, requiring no constant thought – both inside and outside the vehicle. This is only possible if the fan, air duct, activated carbon filter, and cover function as a single unit.

With a well-designed composting toilet, the odor is extracted directly where it originates — before it can even spread throughout the room.

That is precisely why we at SETRENLO® have developed different ventilation solutions — tailored to various installation situations and everyday requirements.

From particularly quiet fan solutions to various activated carbon and ventilation systems, all these solutions pursue the same goal: to make the issue of odor disappear as much as possible in everyday life.

Anyone who considers this from the outset uses a system that feels natural — that is exactly our aim.