Why Ventilation Matters.

Improving insulation and airtightness makes your home warmer and more energy efficient, but it also reduces natural airflow.

Without proper ventilation, you may experience:

• Condensation on windows.
• Damp patches or mould growth.
• Poor indoor air quality.
• Stale or stuffy air.
• Increased risk of respiratory issues.

Why does the ventilation matter, are we not just adding more draughts into our property?

Yes and no! The secret is “controlled ventilation” which means in basic terms that the person(s) living in the property can open, close or control that ventilation. Some ventilation like combustion vents are meant to be non-controllable, these are usually found in rooms with a open flue appliance like a fire.

Now bear with us!

If you fully unzip a thick winter coat on a cold, brisk walk, you’ll quickly feel the chill and end up zipping it back up again. Now if you open it just slightly, you let in enough fresh air to stay comfortable without overheating, even in cold weather.

Your home works in much the same way.

When insulation is added (like putting on the coat), the way the building behaves changes. It holds heat more effectively, which is great, but it can also lead to overheating and moisture build-up (like getting too warm on that walk).

That’s why you need a way to control.

Trickle vents or other forms of controllable background ventilation act like the zip on the coat. They allow you to regulate how much fresh air enters your home, which is especially important in rooms where everyday living and occupancy create moisture and stale air.

Now think a bit deeper about the coat itself.

What kind of material is it? Is it breathable like wool, or waterproof and less permeable? Does it allow moisture to escape, or does it trap it inside? And what about the person wearing it—are they jogging or just walking?

In this analogy, the person becomes the house.

Their activity represents how the home is used, and the fabric represents the building materials and insulation.
To keep everything comfortable and healthy, the “fabric” of the home, and how it breathes needs to be designed to suit how the space is actually lived in.

Energy upgrades and ventilation must work together.

Pre-Installation Checks.

• Existing extractor fans are working correctly and have sufficient extraction rates.
• Air bricks and vents are not blocked.
• There is adequate airflow in loft spaces.
• Any previous damp or mould issues are properly addressed.
• Air can move around property (door undercuts)

If ventilation isn’t considered before upgrades, problems often appear afterwards.

Post-Installation Considerations.

After insulation or airtightness improvements:

• Check that extractor fans are still effective.
• Monitor humidity levels (ideal indoor RH: 40–60%).
• Ensure trickle vents are open and functioning.
• Confirm other background ventilation hasn’t been removed or blocked and is controllable.
• Watch for new condensation or mould spots.

Improved airtightness means ventilation becomes more important — not less.

Mechanical Ventilation Options.

Depending on the level of upgrade, you may need:

• Intermittent extractor fans (IEV) (Coming Soon).
• Continuous mechanical extract ventilation (MEV) (Coming Soon).
• Positive input ventilation (PIV) (Coming Soon).
• Mechanical ventilation with heat recovery (MVHR) (Coming Soon).

The right system depends on your property type, airtightness level, and occupancy.

Ventilation should never be an afterthought If you’re:.

• Planning insulation upgrades.
• Installing a heat pump.
• Improving airtightness.
• Experiencing condensation after works.

Make ventilation part of the conversation — before problems start.