The simplest system there is. It still has to be designed rather than assumed.
Background, purge and extract. All three, correctly sized.
Natural ventilation uses pressure differences and buoyancy — wind across the building and warm air rising — to move air through a home, with no fans and no running cost.
It’s the system most Irish homes already have, usually in the form of wall vents, window vents and extract fans in the wet rooms. The trouble is that in most of those homes it was never designed, it’s been partly disabled by occupants blocking draughty vents, and it no longer does the job. Three mechanisms do the work:
All three have to be present and correctly sized. Background vents alone won’t clear a bathroom after a shower. Extract fans alone have nothing to draw in if there’s no background provision.
Appropriate on some buildings, and clearly not on others.
We specify and install natural ventilation where it’s the appropriate solution, and tell you straight when it isn’t.
From insulation to heat pumps, ventilation and more. Improve comfort, lower bills and increase your BER rating.
New builds, extensions and deep retrofits, fully managed from design and planning through to construction and completion.
High-quality solar panel systems for homes, farms and businesses. Lower energy costs and gain energy independence.
Energy upgrades and construction solutions for commercial, agricultural and public sector projects.
Be clear-eyed about the limits. Natural ventilation is weather-dependent. On a still, mild day the driving forces are weak and airflow drops — often at exactly the time humidity is highest indoors. On a windy day it can over-ventilate and pull heat out of the house. It also can’t recover heat: everything you extract, you’ve paid to warm.
Once a home has been insulated and draught-proofed to a meaningful standard, natural ventilation usually can’t keep up, and moisture problems follow. At that point DCV or MVHR is the appropriate system. We’d rather tell you that at survey than have you ring us about mould in eighteen months.
Almost every home we survey has at least one wall vent stuffed with a bag, taped over or plastered shut. The reason is always the same — it was draughty and someone was cold. That’s an understandable response to a badly specified vent, but it removes the ventilation the house depends on. The answer is controllable vents positioned where they don’t blow cold air directly onto people, sized properly for the room.
If your home is relatively leaky and you have no condensation problems, quite possibly. If you’re planning insulation and airtightness work, probably not for much longer. A survey settles it.
Common causes: vents blocked or undersized, no extract in the wet rooms, extract fans that don’t actually move much air, or a house that’s been tightened without the ventilation being revisited.
The system as a whole is usually described as natural ventilation with mechanical extract. The background and purge elements are passive; the wet-room extract is powered.
Yes. DCV in particular retrofits into existing homes without major disruption, which is why it’s the usual next step.
Call 051 850722 and we’ll assess it. The honest answer is sometimes that you need less than you think.
