Design of ventilation ducts for better ventilation

The design of ventilation ducts is crucial in any ventilation project. In many cases, decisions focus on what solutions are best for each case and the efficiency of each system. However, something as simple -yet complex- as the paths through which air will travel is essential for ventilating a room correctly.

The ventilation ducts are the internal paths through which air will pass from one room to another. They are designed to ventilate spaces but have some complexity, as there can be air intake or exhaust ducts. Likewise, the design of the ducts must be intelligently done to avoid unnecessary costs and ensure that the air flow is efficient.

Depending on the size of the air ducts and their length, we will need more or less power in our mechanical ventilation systems. Longer air paths require more power, which affects energy expenses.

Therefore, it is necessary that the design of the ventilation ducts is done strategically, considering all factors from the beginning of a project. Because they will be responsible for transporting air and thus maintaining comfort at home.

Depending on the project being carried out, one can opt for ventilation ducts made from different materials and diameters. They can also be insulated or not. And in addition to needing to adapt efficiently to the project they are intended for, they must comply with current regulations. We could say that, depending on where they will be installed and their function, it is essential to calculate the following:

1. Air flow. Depending on the diameter and distance they cover, they can provide a specific flow.
2. Air velocity. It will also depend on their design and the power of the ventilation systems that will be used.
3. Air pressure losses. The total air load lost due to the duct's pathway and diameter must be calculated, as well as other causes such as bends in the path or unnecessary turns.

How to create an appropriate design of ventilation ducts?

The first step for a correct design of ventilation ducts is to calculate the necessary flow in each room. From there, we can determine the dimensions of the ducts and their path. Along with the flow, we can determine the speed at which the air will travel inside the ducts.

For flow calculation, it is necessary to follow current regulations, in this case, the Technical Building Code. This text specifies the required flow for each home, as well as the maximum permissive air passage to avoid uncomfortable noises. Specifications for parking lots and storage areas, as well as public buildings, commercial places, and hotels, are also written.

After flow, in the design of ventilation ducts, the next step is to determine the air passage velocity, which is probably the most important parameter to know how long the ducts should be.

High velocities are only recommended in the industrial sector, as they lead to a lot of noise and expenses. These velocities would be more than 10 meters per second. The Technical Building Code specifies that the air speed should not exceed 4 meters per second. In other cases, such as offices or public buildings, it may be increased to 6 meters per second.

If the duct's diameter is larger, the passage speed will be lower, which directly influences noise and pressure losses. The higher the speed, the greater the noise.

The third element to consider is pressure losses in the design of air ducts. In this case, higher speeds will also make it more difficult to avoid pressure losses.

It is very important to avoid pressure losses, as this would mean that the fans would not be able to renew the air or would require more power. This would translate into increased energy expenditure.

Considering that it is ideal to have low speeds to avoid noise and require less power, what can we do to reduce pressure losses? Make the air circulate more efficiently, create a pathway without unexpected turns, with fewer bends and reductions. The cleaner the air passage, the fewer pressure losses there will be. Similarly, we will need less power and can have less noise.

In the case of air ducts, we can also apply the keys to silent ventilation, which will help us achieve greater comfort at home. It is essential to have a good installation and enjoy a great design of the air ducts to be much more efficient in ventilation.