How Fabric Ducting Supports Uniform Air Distribution

Insights

A ventilation system can deliver the correct total amount of air and still leave parts of a room feeling uncomfortable. One area may feel draughty while another remains too warm, particularly where a few conventional grilles are expected to serve a large space.

Fabric ducting approaches air distribution differently. Instead of carrying air to a small number of separate diffusers, the duct itself can release air along much of its length. This gives designers more freedom to control where the air enters the room and how quickly it travels.

 

Why Can Traditional Air Distribution Become Uneven?

When a large volume of air is delivered through a limited number of outlets, the areas closest to those outlets can experience stronger air movement than locations further away.

Room shape can add to the problem. Racking, machinery, partitions, lighting and changes in ceiling height can all interfere with the intended airflow.

Simply increasing the fan speed may make matters worse because people close to an outlet experience an even stronger draught while distant areas remain poorly served.

Uniform distribution therefore depends on how the air enters the room as much as the total volume being supplied.

 

How Does Fabric Ducting Spread Air Across a Larger Area?

Fabric ducting can operate as both the air transport system and the diffuser.

Prihoda systems use outlets positioned along the fabric, allowing supply air to enter the space at many points rather than only at several grilles. A larger distribution area can provide more controlled air velocity across the room.

The exact outlet arrangement is designed for the particular application. Nozzles and perforations can be positioned on different parts of the duct depending on where the air needs to travel.

This is especially useful in long classrooms, production halls, warehouses and other spaces where occupants or equipment are spread across a wide floor area.

 

How Do Micro-Perforations Help Create Even Airflow?

Micro-perforations are tiny laser-cut openings in the fabric. Prihoda typically uses holes around 0.2mm in diameter, with the quantity calculated according to the available airflow and pressure.

Because there can be a large number of these openings, significant volumes of air can be released at very low velocity.

Their position can also be controlled. Rather than allowing cool air to fall directly underneath the duct, micro-perforations can be arranged in bands around its sides to spread air across a wider part of the room.

This can help reduce obvious hot spots, cold spots and concentrated draughts.

 

Can Different Areas Receive Different Airflow From the Same Duct?

Yes. One advantage of fabric systems is that different diffuser types can be combined. Micro-perforations provide short, gentle air movement, while larger perforations or fabric nozzles can throw air much further.

At the Eden Project, for example, Prihoda used larger perforations to direct air towards one occupied seating area while blocks of micro-perforations supplied a high volume at low velocity to staff working nearby.

This means uniform air distribution does not necessarily mean identical airflow everywhere. Different parts of a room can receive the type of air movement appropriate to how that area is being used.

 

Why Does Duct Sizing Matter for Uniform Distribution?

The duct itself needs to be sized correctly for the amount of air passing through it.

If a duct is too small, internal air velocity may become excessive. Our sizing calculator warns when velocity moves outside its recommended range and suggests reducing airflow or increasing the duct size.

Available pressure also matters because it needs to support both inflation of the fabric and the intended discharge through the outlets.

This is why fabric ducting is normally designed around known airflow and pressure figures rather than selecting a duct purely according to the physical space available.

 

Does Heating Need a Different Air Pattern From Cooling?

Often, yes. Cool air is denser and naturally falls, while warm air tends to rise. A high-level system that distributes cooling effectively may therefore need a different outlet arrangement when supplying warm air.

Large fabric nozzles can project air over much greater distances than micro-perforations, making them useful where warm air needs to reach the occupied zone from a high ceiling. Large nozzles can achieve throws of up to around 30 metres in suitable conditions.

Designers therefore need to consider supply temperature alongside air volume.

 

How Is Uniform Air Distribution Designed Before Installation?

The starting point is understanding the room. Designers need to know the dimensions, ceiling height, airflow, available pressure, supply temperature and where people or equipment will be located.

At Prihoda, we provide airflow graphics alongside our designs and can also use computational fluid dynamics, or CFD, for more demanding applications where additional modelling is useful.

This allows likely air direction, travel distance and velocity to be considered before the system is manufactured.

Uniform airflow therefore comes from the combination of correct duct size, carefully positioned outlets and an understanding of how the room will actually be used.

 

FAQs

Does Fabric Ducting Deliver Air Along Its Entire Length?

It can. Perforations and nozzles can be positioned along different parts of the duct so air is released across a much larger area than with a small number of conventional grilles.

What Are Micro-Perforations Used For?

They are very small laser-cut holes used to distribute relatively high volumes of air at low velocity, making them particularly useful where gentle air movement is required.

Can Fabric Ducting Be Used in Large Warehouses?

Yes. Different nozzle and perforation arrangements can be designed to provide both short and long air throws according to the height and layout of the building.

Can One Fabric Duct Produce Different Air Patterns?

Yes. Different types and sizes of outlets can be placed on the same duct to serve areas with different airflow requirements.

Does Fabric Ducting Guarantee Even Room Temperatures?

No. Duct design is only one part of the HVAC system. Heat gains, insulation, building layout, airflow volume and supply temperature also influence conditions throughout the space.