Blog 1: Beneath the Surface: Underfloor Expertise for a Smart Retrofit Solution

Continuous v Purge Ventilation; less is more

Less is More: Why Purge Ventilation Works Better for Homes

When people first hear about AirEx Floorvent, they sometimes assume that by closing vents it reduces the amount of ventilation a home receives. After all, the system is designed to shut when conditions are unfavourable, so surely that means less airflow? In reality, the opposite is true. Floorvent doesn’t reduce ventilation, it makes it smarter, more effective and far more energy efficient.

To see why, it helps to compare two different approaches: continuous ventilation and purge ventilation.

Continuous vs purge ventilation: a room analogy

Imagine you’re ventilating a living room. Continuous ventilation means keeping a small window open all the time. Fresh air comes in, but in winter heat constantly escapes, pushing up heating bills.

Purge ventilation is when you open the window wide for a short period. The stale air is quickly flushed out, then you close the window again to keep the warmth in. Both methods achieve fresh air, but the second is far less wasteful.

Less really can be more when airflow is targeted at the right moments.

Underfloor spaces: the forgotten battleground

Suspended timber floors rely on air bricks to stop moisture from building up under the floor, preventing damp, mould and timber decay. Traditional air bricks provide this ventilation, but continuously whether it’s needed or not.

The result is often a lose-lose situation. Draughts rise into living spaces, wasting energy and leaving homes colder. Heat escapes into the void, driving up bills. And paradoxically, during high external humidity, air bricks allow unhelpful conditions to enter the structure.

This is where AirEx Floorvent makes a fundamental change.

More capacity when it counts

One common misconception is that because Floorvent closes at times, it must reduce airflow compared with a traditional air brick. The truth is that when open, Floorvent delivers far more capacity.

A standard air brick provides around 1,300 mm² of free ventilation area. Even a double size one only gives 2,900 mm². A single Floorvent offers 4,300 mm². At the moments when ventilation is really needed, Floorvent clears the void much more effectively.

Selective, not restricted

The advantage of Floorvent is selectivity. The system closes when conditions mean ventilation would simply waste energy, and opens when the void needs fresh air.

When shut, it helps form a warm air blanket under the floor, cutting draughts and reducing heat loss. When open, it purges the void quickly and effectively. In this way, Floorvent converts crude continuous ventilation into efficient purge ventilation.

Guided by real conditions

What makes this possible is sensing. Floorvent units monitor temperature and humidity, adjusting in real time to the conditions of each home. If humidity rises, the vents open. If the outside temperature drops, they close to protect warmth.

Rather than assuming what a property might need, Floorvent knows. The result is healthier homes with lower bills and greater comfort for residents.

Confidence for designers

For specifiers, one of the biggest challenges is deciding how much ventilation to allow for in a suspended floor. Too much and residents suffer unnecessary heat loss. Too little and there is a risk of damp and structural damage. Traditionally it has been a compromise.

Because Floorvent moderates itself, designers can confidently over-specify ventilation capacity to ensure resilience. The system will then scale airflow up or down as conditions demand, protecting both the building and the household budget.

Less really is more

Ventilation is vital to healthy homes, but how it is delivered matters. Continuous ventilation wastes energy and often fails to protect the building. Purge ventilation, intelligently controlled, achieves better outcomes for residents, landlords and the housing stock itself.