Ventilation systems

Why invest in ventilation?

During the cold months of the year, the air inside your home is warm. It carries more water vapour than the colder air outside, especially when well insulated. Cooking, laundry, showers, and other activities contribute to increased water vapour levels.

Water vapour can pass through ceilings, insulation and wood. When it moves into the attic space it can condense into liquid water on the cooler structural members-rafters, trusses and cold roof sheathing. This leads to a higher risk of moisture-related defects which can be costly to repair.

Good ventilation helps to create a healthy environment and make your home more comfortable.

Benefits of proper ventilation

• Improves indoor air quality by removing stale air, moisture, harmful pollutants and odours
• Ensures that fresh air circulates throughout your home
• Reduces the chance of condensation or mould
• Keeps your home dry and protects your health

Depending on your particular home, there are several different options to choose from for ventilation. 

Natural ventilation with intermittent extract fans

This approach provides fresh outdoor air through purpose provided openings. It quickly removes water vapour from wet rooms like the bathroom and kitchen.

Background ventilation

This provides general ventilation through a secure opening in a wall or window. It uses a controllable ventilation grill known as a "hit or miss" cover, placed on the internal side of the vent. The cover can also be fully closed.

Intermittent extract ventilation

All wet rooms should be fitted with a mechanical extract fan. They can rapidly remove water vapour and other pollutants directly to the outside. If your wet room has no background ventilator or openable window, the mechanical extract ventilation should include an automatic 15 minute overrun. That means it will stay on for an added 15 minutes once switched off.

Purge ventilation 

Purge ventilation allows the movement of a large amount of air in a short time period. You'll use large adjustable ventilation openings, such as a window. It's particularly useful for occasional activities like painting and decorating.

Mechanical ventilation

Mechanical ventilation systems incorporate fans and control systems to drive the ventilation process. They extract bad air from the kitchen and wet rooms and let in good air in living rooms and bedrooms. They're able to provide ventilation regardless of the natural forces at play. Mechanical ventilation should be used in very airtight homes.

Two common methods are:

• Demand Controlled Mechanical Extract Ventilation (DCV) systems which adjust the ventilation rate to each room's demands
• Mechanical Ventilation with Heat Recovery (MVHR) systems which can recover heat from the extracted bad air to heat your home

Mechanical ventilation systems can be more energy efficient than natural ventilation. They provide a greater amount of control and limit heat loss.

Permanent ventilation

Permanent ventilation is required to supply air to an open flued (non-room sealed) combustion appliance. An open flued appliance is one that draws air from the room it’s located in. The room requires a vent to safely use the appliance. They include stoves, gas fires, some cookers and open fires.

Room sealed appliances have their own dedicated air supply. This is normally an air duct from outside, connected to the appliance. Room sealed appliances do not need permanent ventilation.

Permanent ventilation options

• A ventilator permanently fixed in the open position, generally located in the wall. These cannot be closed which eliminates airflow through the device.
• Proprietary ventilation systems which are the full package: an external vent cover, a drainage pipe and an internal push on vent. These systems are tested and certified, so they deliver a guaranteed volume of air. If you manually put an external and internal vent cover either side of a drainage pipe, you may not get the best quality of ventilation.