Ventilation in your Home – a glossary of terms by RENOVA

 Air Changes per Hour (ACH)

Ventilation image 1

 Air changes per hour (ACH or ac/h), is a measure of the air volume added to or removed from a space, divided by the volume of the space. Simply put, ACH is the rate at which a space is ventilated. Certain places will require more air changes per hour, depending on usage and occupancy – for instance kitchens and bathrooms where there tends to be a high moisture content.

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Ducting

Ducting for Ventilation

Ducting is pipework through which air is channelled in a ventilation system. It is normally concealed behind walls and above ceilings.

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Natural Ventilation

passive ventilation

This is a basic form of ventilation which relies on ‘holes in the walls’ and is very common in most Irish homes. Incoming and outgoing air will vary depending on wind speed and wind direction. This can result in unwanted draughts at times and therefore is far from ideal.

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 Demand Controlled Ventilation (DCV) 

aeroco mechanical ventilation

Above is an image from aereco which illustrates how DCV operates. ‘Demand Controlled Ventilation’ (DCV), is a system which provides constant ventilation within a house. It links the amount of fresh air entering the building to the occupancy levels of a building. Energy savings are made when the need for ventilation is low, which can represent over half of the time. This system adjusts the amount of incoming fresh air based on humidity levels in the house, and therefore the need for replacement air. For example, if there is a lot of indoor air pollution from cooking, showering etc, then a greater airflow is generated to remove it efficiently.

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Mechanical Ventilation with Heat Recovery (MVHR)

MVHR Image

‘Mechanical Ventilation with Heat Recovery’  (MVHR) is a system which also provides constant fresh air within a home. The fans are ‘controlled’ so the ventilation is ‘mechanical’ as opposed to natural. Simply put, a fan draws fresh air into a building and distributes it via ducts, and other ducts draw stale air out. By using a ‘Heat Exchanger’ at the fan, fresh cold outdoor air is warmed up to a comfortable temperature by using the heat of the warm, stale indoor air as it is extracted. There is no pollution or contamination from the stale air – only the heat is exchanged. 

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 Positive Pressure Ventilation

positive pressure ventilation

With ‘Positive Pressure Ventilation’, a centrally located fan provides a constant stream of fresh air within the house. This air finds its way out through vents and other ‘gaps’ in the fabric of the building. In doing so, unwanted draughts are prevented from entering the house. 

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Blower Door Test

Blower door test

Above is an image of a Blower Door Test carried out during a RENOVA retrofit.  A Blower Door Test is an air pressure test undertaken at the end of a job to check for air leakage and to eliminate any draughts. The results provide a certified air tightness result.

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If you want to find out more about ventilation and for a free, no obligation consultation, call RENOVA today.

Click here to read another RENOVA blog about ventilation.

Click here to download our RENOVA brochure.

Tel: 01 2021122

Email: info@renova.ie

Web: www.renova.ie