Why is Cross Ventilation Important?

Why is Cross Ventilation Important?

Cross ventilation refers to a form of natural ventilation in a building. The main requirements for this type of ventilation are the presence of air inlet and outlet, and the pressure of the air entering the space must be different from the pressure of the air leaving it. In the simplest case, this pressure drop occurs when two windows in the same room are open and point in opposite directions.

The air inside the building must be replenished regularly. Stale air can trap moisture and cause mold. It can also smell bad and make the building uncomfortable for the occupant. Without fresh air, irritants and allergies in the air, such as dust or hair, can also adversely affect health.

A typical home contains several features that allow fresh air to escape. Windows and wall vents are the most common options. These air inlets and outlets are passive features of the building. Although vents and windows are traditional methods, engineers and architects can design them for optimum efficiency for a particular building.

The basis of cross ventilation is the special air pressure difference between the incoming and outgoing air. Since the interior of a building tends to be warmer than the outside in cold climates, indoor air is under low pressure as it expands when heated. The air from the cooler outside has high pressure, as it is colder. The wind is another source of pressure drop that is important in both cool and hot climates.

The wind provides the outside air with more force than the air inside the building. Both of these pressure sources tend to drive air into buildings. Air enters through an inlet, which is a window or vent on the side of the building facing the wind. Mutual ventilation comes into play – these are areas where incoming air can force air out of the room and push it out of the building.

For this, the outgoing air must have an escape route. Typically, with transverse ventilation, these escape routes are located in the opposite direction to the air inlet or the left or right of the entrance. Architects with knowledge of ventilation mechanics can plan appropriate air outlets relative to air inlets for maximum efficiency.

Although cross-ventilation applies to individual rooms, it can also play a role in buildings with a large number of rooms. One problem with cross ventilation in a complex interior structure is that people who work or live inside buildings may block ventilation through closed doors or windows. To work around this problem, construction companies can install duct systems that direct fresh air around the building and serve as an outlet for stale air.

One of the advantages of designing cross ventilation in a building is that the process takes place without the need for any additional energy use, as in air conditioning. On the other hand, cross ventilation usually affects the temperature inside the building. This may require the use of central heating, which requires energy if the building is in the coldest part of the world.

Cross ventilation in homes?

There are many ways to ventilate your home, but how many are effective? It was generally believed that it was enough to open the windows and let the air in from the outside, but modern construction and the new rules of the Technical Building Code have shown the necessary renewal of indoor air, both for health reasons and for reasons of comfort. And if mechanical ventilation systems are not available, natural cross ventilation in the home is a good option.

Achieving indoor air exchange through natural cross ventilation is something to think about before starting a construction project, as it is also possible to implement in almost any home, especially in homes, as it can be more difficult in apartments. It is cheap and effective in many cases.

How to identify natural cross ventilation? We can say that exactly two openings in the same space or room are located in opposite or adjacent walls, which will make it very easy for air to enter and exit. Obviously, this type of ventilation is ideal for places with high temperatures, as the main benefits of natural cross ventilation are twofold:

High air renewal. Although there are no automatic mechanisms that read the specific needs of space in real-time and act accordingly, the reality is that with this type of natural ventilation, air inflow and return is achieved. This is why renewal is a great success.

Improved thermal comfort in hot climates. The fan effect makes people in the same room feel much more relaxed. If the wind is in constant motion, they will surely notice a better thermal sensation. Similarly, by changing the air heated in the room, the temperature should be lowered.

The natural lateral ventilation effect is achieved by the opposite positions of the two openings in the same room. On one floor, this can be more difficult to do, but sometimes it can be done by opening the living room window and opening the door if it encounters another draft. In these cases, we can find various ways to achieve good airflow.

It is certainly much easier to achieve this type of natural ventilation in a home because next to windows that open to other places, you can find doors that open outward. Is this effect always as effective? Not at all. There are several concepts to keep in mind in order to maximize the effectiveness of natural cross ventilation. For example, consider the following:

The hottest air currents come from the south side of the houses;
The air rises when the temperature rises.

Thus, if we want to plan a construction site that takes advantage of natural cross-ventilation, it is important to place doors and windows on the south façade, as this is where we want warm air out of the interior. From now on, we can choose to install fans that send air out of the house through these vents.

Likewise, the windows from which we want the outside air to enter the house should be located in the northern position of the house. And simply by implementing these solutions, we will undoubtedly achieve a lot in terms of ventilation in our home, without relying on mechanical systems or traditional air conditioning.


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