Intermittent ventilation refers to a mechanical ventilation system that operates only during specific periods of increased indoor air pollution or humidity, rather than running continuously. This type of system is typically activated when there is a particular need, such as cooking, bathing, or showering.
In the UK house building sector, intermittent ventilation is commonly implemented using extract fans in kitchens and bathrooms. These fans may be manually operated by switches or automatically controlled by humidity sensors that activate the fan when moisture levels exceed a predefined threshold. For instance, an extract fan in a bathroom may run for 15 minutes after a shower to remove excess moisture, thereby helping to prevent mould growth.
In a typical UK home, an intermittent extract fan is installed in the kitchen. When cooking, the homeowner turns on the fan, which runs at a higher speed to effectively remove cooking odours and moisture. Once the cooking is finished, the fan can be switched off manually, or it may have a timer to continue running for a short period to ensure that the air is cleared of lingering pollutants.