Although the movement of ventilation air usually takes place in a natural way, nothing stands in the way of forcing it using fans in this way. This kind of forced ventilation is commonly known as mechanical ventilation.
If the fan is limited to removing used air while fresh air comes in through window or wall ventilators, we can speak of exhaust ventilation. However, if it provides not only the exhaust of used air, but also the supply of that which is fresh, the subject of analysis is the supply-exhaust ventilation. When we are dealing with exhaust ventilation, we can usually find it on the example of bathroom fans and those installed in kitchen hoods. It is most often used as a complement to gravity navigation, as it is not very efficient. In detached houses, exhaust ventilation is already rare today.
Mechanical ventilation - advantages
Mechanical ventilation has a number of advantages, so it is worth mentioning that it allows for relatively precise control of air exchange. Most often it does not consist of one, but at least several independent fans, and each can have its own sensor to control it. The fact that the fan can actively work with the timer also seems to matter. Exhaust ventilation is not very complicated in construction, so you do not have to decide on a large network of horizontal ducts and very high chimneys. When dealing with supply-exhaust ventilation, we have to reckon with the fact that its construction will be more complex. It must guarantee the exhaust of part of the rooms and a controlled supply of fresh air. In single-family houses, exchangers are increasingly used as a solution. It is these that make it possible to recover the heat from this air, which is extracted to the outside. The gravity ventilation system can be relatively easily converted to exhaust ventilation, but if you want a supply and exhaust system, it is good to think about its creation already at the stage of house construction. The later we start to design it, the more awkward it gets. It is also expected to be much more expensive than supply air ventilation. Of course, a lot depends on the quality of the materials we use, but the total cost can be up to 5000 PLN. Fortunately, the costs incurred compensate for its effectiveness. The installation of mechanical ventilation is carried out by e.g. Prestigevent.com.pl from Krakow.
Gravitational ventilation - what is it?
In single-family houses, gravity ventilation is usually regarded as a standard solution. However, it turns out that the demand for its mechanical version is also growing. It is therefore worth analysing the similarities and differences characterising such solutions. Gravity ventilation draws attention to itself primarily because it is a fairly simple system. The exchange of indoor air is therefore based on its natural movement. Warmer air is lighter than cool air, so when it is warmer in the house than when it is outside, the force of buoyancy makes the warmer air leave the room. A vacuum then appears, and these contribute to the influx of fresh air. Gravity ventilation is to some extent also dependent on wind. Depending on the direction in which it blows, it can not only support the air exchange, but also make it more difficult.
If this type of ventilation is to work properly, vertical flues are also required in those rooms from which the air is to be removed and the air vents in the rooms. Of course, the greatest effectiveness of gravity ventilation can be achieved when the outside temperature is no more than a dozen or so degrees. If it is warmer, it is necessary to open windows. Also, a large temperature difference both inside and outside can make the air flow too intensive. Of course, this is not an impossible problem, the most effective are the exhaust grilles and diffusers with manually or automatically controlled moving dampers. If we want to make the air exchange independent of the weather conditions at a given moment, we should be interested in mechanical ventilation. This ensures a constant airflow and at the same time makes it possible to increase it at any time even without having to open a window for this purpose. When dealing with mechanical exhaust ventilation, we should consider using fans for this purpose. Their action creates a vacuum in the rooms. Most often they are installed in the inlets to the ducts by which the air is removed, although it is also possible to install them at the outlets. Nothing stands in the way of the wires being led to the roof or wall. Another interesting solution is mechanical supply-exhaust ventilation, which allows for a significant reduction of energy demand.
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