Glossary of Domestic Ventilation Terms

Term Acronym Definition
Acoustics Noise.
Air Changes per Hour ACH Air Changes per Hour (ACH) is a measurement of how many times the air within a defined space, such as a room or building, is replaced with outside air in one hour.
Air Exchange Rate AER The Air Exchange Rate (AER) refers to the rate at which outdoor air replaces indoor air in a space, typically measured in air changes per hour.
Air Leakage Air Leakage is the unintentional loss of air from a building through cracks and openings, which can affect energy efficiency and indoor air quality.
Air Permeability Air Permeability is a measure of how easily air can flow through a material, often expressed in terms of a specific volume of air passing through a unit area over time.
Airflow Airflow refers to the movement of air within a space, typically measured in cubic metres per hour (m³/h), cubic feet per minute (CFM) or litres per second (L/s).
Airflow Rates Measurement of a flow of air through a ventilation unit or duct.
Airtightness Airtightness describes how effectively a building prevents air from leaking in or out, impacting energy efficiency and comfort.
Background Ventilation Background Ventilation is a low-level airflow introduced into a space to maintain indoor air quality without causing discomfort.
Background Ventilator Trickle vent.
Balanced System A Balanced Ventilation System supplies and exhausts equal amounts of air, ensuring consistent indoor air quality and pressure.
Building Regulations A minimum standard for design, construction and alteration of buildings.
Boost High speed fan mode.
Centrifugal Fan Type of impeller designed to cope with high pressures.
Carbon Dioxide CO2 Colourless odourless gas.
Condensation The point at which air releases moisture.
Decentralised Mechanical Extract Ventilation dMEV dMEV is a type of ventilation system that uses individual units to extract air from specific rooms, reducing reliance on a central system.
Damp An indication/problem with a building fabric.
Dew Point The point at which water is released by air.
Dust mites Microscopic mites found in household dust.
Equivalent Area EA The aerodynamic measurement of an opening.
Extractor Fan A unit designed to expel moist stale air from a room.
Fire Stopping A way of utilising products to prevent the spread of fire.
Filter Used in some units to filter particle matter from the air.
Free Area Calculation of an open area of a ventilator or grill.
Grille A vent used to aid air to or from a dwelling or room.
Heat Recovery Ventilation HRV Heat Recovery Ventilation (HRV) systems transfer heat from exhausted indoor air to incoming fresh air, improving energy efficiency.
Humidity Amount of moisture in the air.
Indoor Air Quality IAQ Indoor Air Quality (IAQ) refers to the condition of air within buildings, impacting health, comfort, and productivity.
Mechanical Ventilation Heat Recovery MVHR Mechanical Ventilation Heat Recovery (MVHR) systems use mechanical means to ventilate spaces while recovering heat from exhaust air.
Mechanical Extract Ventilation MEV A continuous running ventilation system.
Mould A type of fungus that thrives in damp areas.
Noise Rating NR A measurement of noise.
Purge Ventilation Purge Ventilation involves temporarily increasing airflow to remove pollutants or excess heat from a space quickly.
Passive Stack A type of ventilation that has no mechanical assistance and relies on atmospheric conditions.
Positive Input Ventilation PIV A ventilation system that pushes air into a property to reduce humidity and contaminants.
Radon Rn A harmful gas formed underground in rock.
Resistance Friction caused by ancillaries and components used in ventilation.
Sick Building Syndrome SBS Sick Building Syndrome (SBS) describes a situation where building occupants experience health issues linked to time spent in a building, often related to poor ventilation.
Single Room MVHR Single Room MVHR systems provide mechanical ventilation and heat recovery for individual rooms, often used in retrofitting projects.
Shock Ventilation Shock Ventilation refers to a brief but intense increase in ventilation rates to rapidly improve indoor air quality.
Stoßlüften Stoßlüften is a German term meaning “shock ventilation,” referring to the practice of opening windows wide for a short time to quickly refresh indoor air.
Trickle Rate The Trickle Rate is the minimum airflow rate provided by ventilation systems, ensuring a continuous supply of fresh air.
Trickle Vents Background ventilators – normally fitted in windows.
Ventilation Replacement of moist stale air with fresh air.
Ventilation Rate Ventilation Rate is the measure of how much air is supplied to or removed from a space over a specific period, crucial for maintaining indoor air quality.
Whole Dwelling Ventilation The continual ventilation rate within a dwelling.
Whole Dwelling Extract Ventilation A higher extraction rate of air to remove humid stale air.
Wireless Radio controlled operation of boost or fan speed.