VENTILATION: CONTINUOUS EXTRACT
July 24, 2023
In our second post of this series on ventilation, we will look at another method that uses trickle vents as the basis for overall building ventilation.
Q: What is continuous extract ventilation?
A: Ventilation is provided via continuous mechanical mechanism either via individual room extracts, a central extract system or a combination of both. Trickle vents or bespoke wall-mounted vents deliver cold, unfiltered make-up air into the dwelling; and warm air will be lost from them. Window openings normally need to be sized accordingly to accommodate them.
Q: Who calculates the required amount of ventilation?
A: The calculation is complex as it includes things like typical wind speeds and should be carried out by a specialist consultant or subcontractor. The rate of extract is set by Building Regulations.
Q: How is moist and stale air extracted from the building?
A: Moist air is typically extracted via a continuous fan from the wet rooms, utility rooms and the kitchen; and will be exhausted via a duct to the outside. Any heat in the air will be lost to the outside. The ducts are typically plastic and can be circular or rectangular.
Q: What is uncontrolled ventilation and why is it important?
A: Uncontrolled ventilation occurs through construction gaps in the external building envelope. It is often referred to as a building's "airtightness". It can contribute to drafts and results in the loss of internal heat gained through heating and occupying the house. Continuous mechanical ventilation is suitable for any level of airtightness.
Q: Can I open the windows?
A: The windows can be opened for comfort control and cooling.