Humidity and mould

It is currently a trend to renovate old buildings or build new homes in a way that they consume about 30 % less primary energy than it is the case in traditional, conventional buildings, meaning that consumption is reduced by keeping the loss of energy at a minimum. However, this „air tight“ insulation cannot transport humidity from inside the house to the outside without any further means of ventilation, which has proven to be a main cause for mould and damage of building materials. The prime reason for installing a ventilation system is the prevention of high humidity by ensuring sufficient air exchange and transportation of humidity. It either functions as a support for regular airing with windows or as the only supply of fresh air in rooms without windows.

The formation of mould is more than just a visual problem: Resistant mould spores are extremely bad for your health, irritate your respiratory tract, provoke headaches and are suspected to cause cancer. The basic structure of the building can experience irreversible damage if mould penetrates the organic materials deep enough. Sometimes the infested wall becomes porous and the affected spots starts to disintegrate, which leads to the suffering of the complete construction. Spores already begin to form under a humidity level of 60 – 80%, particularly in places where warm indoor air meets a cold exterior wall or surface, for example in corners above the windows or directly on the window sill. Curtains, wallpapers and the beloved decoration on the window sill are often the victims. Mould stains and serpula are unfortunately not always formed in obvious places, but rather like to thrive and flourish behind closets and cover panels. Condensation and melting water on windows only become visible once they reach 100% humidity and are a sure indicator that humidity inside the house is too high! Especially rooms where laundry was drying over night and now have fogged windows should never be left to natural regulation alone. If you spot the first black spots on your wall you still have the possibility to easily remove them with cleaning agents from the supermarket, aggressive agents with clorine are available for tenacious stains. It is also imperative to change your ventilation and airing habits, prevent over 200 kinds of fungi with sufficient and regular ventilation through a modern system. 

Functionality of decentralised heat recovery

If supply and exhaust air is controlled by fans, heat recovery comes into play. That means the ventilation system takes the thermal energy from the used air that is transported to the outside and passes it on to supplied air. A heat recovering system for rooms that are being heated is a good investment, because, without too many extra costs, it kills two birds with one stone: On one hand you have a regular supply and exhaust air cycles in your premises and on the other hand reutilisation of thermal energy that was taken from air that has already been heated.

In our product range, with a ceramic unit for storage:

Tips for use in kitchens and bathrooms

Especially in rooms that are constantly exposed to high humidity, e.g. kitchen, bathroom, washing room and toilet, it makes sense to support ventilation with windows with a mechanical ventilation system. That way even rooms without windows can reach ideal air quality, a decentralised ventilation system is an excellent way of preventing mould, keep breathing air at a good quality level and extract smells.

Kitchens, bathrooms and toilets are rooms with so-called extract air. Inside these rooms we usually encounter a higher amount of humidity and heat, which means that they need to comply with stricter guidelines: If you are considering to use models in these rooms that work based on alternating operation (air extraction phase followed by air supply phase), you might be obligated to install two of those device in each room with extract air. A device that combines a heat exchanger and two integrated fans is also permitted. Extract air rooms without windows are a special case where the air needs to be exchanged sufficiently with a mechanical ventilation system, in a kitchen this can be done by regular airing. It should be made sure that all rooms inside the house without windows can be ventilated at the same time if necessary. Due to bad smells it can actually make more sense to install only extractor fans in these rooms that are complemented by decentralised systems in other rooms.

Heat recovery is also recommendable in cellar rooms if is being heated as well, for example when it is used as a hobby room or laundry room. 

Measures in summer and winter

On cold days and a high potential of heat recovery in winter (through permanent heating) condensation water can develop on the inside of the ventilation system. It is either collected in a container inside the device itself which needs to be emptied regularly, or the water is lead outside through a ventilation grille and can drip off with a safe distance to the exterior wall of the house. The manufacturer should always include the problem of condensation in the item description and offer an adequate solution for the particular product. If that is not the case for your system, we recommend a fitting grille for external walls in our accessory range.
During summer rooms tend to get hot and muggy, the cold air at night is a welcome change. A summer ventilation feature offers you the possibility to supply fresh air at night without heat recovery. This means you are reducing heat inside your home without an air conditioning system.

Tip: In order to let in a summer breeze that smells of flowers and grass or to feel the cold winter frost on your skin, you are of course allowed to open the window for a short time. If you are looking to permanently switch over to ventilation through opening the windows in summer, simply turn of the system.