Ventilation replaces the dirty air in your apartment with new, fresh air. The air in your apartment gets dirty when you e.g. cook food. Dust from clothes, rugs, pets and various chemical substances from plaster and wood are some of the pollutants that need to be removed. The ventilation system also removes moisture that builds up as a result of you showering, doing your laundry and preparing food. To ensure a healthy indoor environment, it is important for you as the tenant to know how the ventilation system works.

Natural ventilation

Natural ventilation is the oldest form of ventilation. The system works using what is known as the 'chimney effect'. External air comes into the building when you open the window as well as through the air vents and porous sealant material. The internal air is heated up, rises and disappears through the waste air vents in the kitchen, bathroom and clothes closet. This type of ventilation works better during the winter than in the summer, when the temperature outside is higher.

Waste air ventilation

Waste air ventilation is the commonest form of mechanical ventilation. An extractor fan sucks out the waste air from the apartment via air vents in the kitchen and bathroom. External air comes into the apartment via airing panels, slot air valves and porous sealant material.

Combined waste and intake ventilation

In this kind of ventilation system, both waste and intake air are mechanical forced out/in using fans. It is often used together with a heat recovery system in residential housing.
Intake or external air is filtered and heated to the right temperature before being mechanically forced into the apartment. The air comes in through intake channels, that are located next to the radiators or high up on the wall close to the ceiling. Waste air vents are located in e.g. the kitchen, bathroom and clothes closet.

Air vents

There are different types of vents. In the shower and bathroom, there are waste air vents with a fixed air flow. These must never be completely closed. In the kitchen there are waste air vents with a variable air flow, which can be opened fully when cooking food, by adjusting the dial on the cooker-top. The dial returns to its default position after a certain length of time. There are also waste air vents in kitchenettes, with either a variable or fixed air flow.

The vents are pre-set by a fitter and you must not readjust or cover them. This will cause the ventilation system to malfunction. Fresh air enters the apartment via the intake air vents. Common types of vents include disk valves, airing panels and slot air valves. Slot air valves are often located above or under the windows. Windows may also be fitted with airing panels.

Checking the ventilation

Here's how you check that the waste air ventilation is working:
Hold a piece of thin paper, e.g. toilet paper, up against the waste air vent. If the paper stays there when you let go, waste air is being sucked out of the vent and the system is working properly. If the paper falls down and the vents are clean, you can try opening a window. If the paper is then sucked against the vent, you need to open the slot air valves or airing panels above or under the windows to allow intake air to come into the apartment. If the paper still falls away from the vent, it probably needs cleaning.

Cleaning the air vents

The air vents must be wiped clean occasionally. One way of cleaning them is to try and remove the dust with a piece of bent steel wire. Then vacuum-clean and wipe the vents.

Get into the habit of cleaning all the vents twice a year. Use lukewarm water and a mild detergent.

How to air your apartment

The most effective way of getting rid of damp and dirty air is to ventilate your apartment. Creating a cross-draught for about five minutes will ensure your apartment is adequately aired.

Don't open the kitchen window when trying to get rid of the smell of cooking. The fresh air will build up excess pressure in the kitchen and force the smell into the rest of the apartment. Open a window in an adjacent room instead and keep the door to the kitchen closed. Air is then forced into the kitchen through the gap under the door, preventing the smell of cooking spreading to the rest of the apartment.

The extractor fan above the cooker

Many of our apartments have a fan encased in a cover above the cooker. The type of cover you have depends on the ventilation system in the rest of the building.

There is a grease filter attached to the fan and this must be cleaned at least once a month. A dirty filter also increases the risk of fire. You can wash the filter in normal washing-up liquid and hot water. If it is very dirty, you may need to soak it for a few hours. Many grease filters can be washed in the dishwasher.

Condensation

If you often get condensation on the inside of your windows, the apartment is probably insufficiently ventilated. Severe cold can also cause condensation on the windows without there being a problem with the ventilation. Similarly, if the window seals/dust seals between the panes of glass are too tight, condensation may build up under certain weather conditions. It is important that the warm air from the radiator has free passage past the window. You should therefore avoid putting something there that may hinder the air circulation around the window.

Damp and mould

Be on the alert for signs of damp and mould. Tell us if the bathroom or shower-room seems to be unusually damp and starts to smell or if it looks like the floor and walls aren't sealed well enough or have become discoloured.

Moisture in the air is formed when you have a bath or shower, when you wash up or do the laundry. We, as human beings, also produce a fair amount of moisture! Good ventilation is needed in order to avoid excess moisture which can cause damp damage and mould.