The presence of a ventilation system is necessary to ensure air exchange inside the building by removing excess moisture, heat, harmful substances. Her presence is one of the main conditions for ensuring livelihoods.
If the room does not have any types of ventilation systems, it harms the human body, leads to the formation of fungi, because in the absence of air exchange, condensation forms.
We offer to understand the existing types of ventilation systems and the principles of their operation.
Classification of ventilation systems
Systems are classified according to different criteria:
- feed method;
- appointment;
- air exchange method;
- constructive execution.
The type of ventilation is determined at the design stage of the building. At the same time, both the economic and technical aspects as well as the sanitary and hygienic conditions are taken into account.
Types of ventilation system by feeding method
If you are based on the methods of supplying and removing air from a room, 3 categories of ventilation can be distinguished:
- natural;
- mechanical;
- mixed.
Carry out the design of ventilation, if such a solution is able to provide air exchange that meets the established standards.
When ventilation of a natural type does not satisfy the requirements of sanitary and hygienic standards, the second option is chosen - the mechanical way of activating the air mass.
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Ventilation systems are designed to supply fresh air and exhaust exhaust air from the room. If the natural system does not cope with the delivery, it is supplemented by a mechanical system or mechanical ventilation is built
Ventilation systems allow not only creating a favorable microclimate for residents, but also removing harmful building materials and finishing fumes from closed heated rooms, which significantly prolongs the operational life of facilities
In the production halls of the food, chemical, processing industries and many other areas of the national economy, certified ventilation systems are installed without fail
In multi-storey buildings with water heating, natural systems prevail, with steam - mechanical or combined, for which they often arrange common boxes with filtration and heating devices
You should consider an effective ventilation system in country houses with stove and fireplace heating. It should be noted that in rooms with a stove or fireplace, as well as in a boiler room with gas equipment, ventilation can only be natural
In residential high-rise buildings of the old type, designed for free air flow through leaks in window and door openings, exhaust openings are located in bathrooms, toilets, and mixed bathrooms. If there is a need to stimulate the movement of air flow, a fan is put into the hood, after which the system becomes mixed: with a natural inflow and mechanized exhaust
Actively operated kitchens of private houses and high-rise buildings are equipped with exhaust systems, so that ventilation, by analogy with a bathroom, becomes combined. Moreover, the combined type includes both hoods with access to the ventilation shaft, and recirculation types that simply drive the stream through the filter and return it back to the room
If window and door structures interfere with natural air exchange, as is the case with PVC windows, a supply valve is installed to supply fresh air. Among them there are devices with and without a fan
Ventilation system device
Air supply for ventilation of building materials
Industrial type of ventilation system
Mechanical ventilation paired with air heating
Country house with fireplace
Ventilation in bathrooms and toilets
Exhaust equipment in the interior of the kitchen
Supply valve under the windowsill
If it is possible, in addition to the second option of ventilation, to partially use the first, mixed ventilation is laid in the project. In residential buildings, air flows through the windows, and exhaust equipment is located in the kitchen and in the sanitary room. Therefore, it is important to establish good air exchange between the rooms.
Mixed ventilation. Apply it when natural ventilation may not be the only option. For high-quality air exchange in rooms with very polluted air arrange mechanical ventilation
Designated ventilation
Based on the purpose of ventilation, working ventilation systems and emergency ones are distinguished. Whereas the former must constantly provide comfortable conditions, the latter come into operation only when the former are turned off and an emergency occurs, when standard living conditions are violated.
These are sudden failures when air pollution occurs with toxic fumes, gases, explosive ‚toxic substances.
The types of ventilation systems for all types of rooms are almost the same. Having studied all their types and having weighed all the advantages and disadvantages ‚you can choose the best option for a particular building
Emergency ventilation is not designed for fresh air. It only provides a gas outlet and does not allow the air mass with hazardous substances to spread throughout the room.
Ventilation systems by the method of air exchange
By this criterion, ventilation systems are distinguished general and local. The first should provide the entire room volume with sufficient air exchange while maintaining all the necessary air parameters. Additionally, it must remove excess moisture ‚heat‚ pollution. Air exchange can be carried out both on the channel and channel-free system.
General exchange ventilation reduces the concentration of harmful substances remaining after the operation of the local and general exchange exhaust ventilation system
The purpose of local ventilation is to supply clean air to specific places and remove contaminated from the points where it is formed. As a rule, it is arranged in large rooms with a limited number of employees. Air exchange occurs only at workplaces.
Separation of systems by design
Based on this feature, ventilation systems are divided into channel and non-channel. Channel-type systems consist of a branched route ‚consisting of air ducts through which air is transported. The installation of such a system is advisable in large premises.
When there are no channels, the system is called channelless. An example of such a system is an ordinary fan. There are 2 types of channelless systems - ceiling and laid under the floor. Channelless systems are simpler to use and consume less power.
Natural ventilation
The movement of air masses during natural ventilation occurs naturally without additional motivation due to:
- temperature difference inside and outside the building;
- pressure differences between the room and the hood located on the roof of the building;
- under the influence of wind.
This is the simplest system. It does not require the installation of complex, expensive equipment that consumes a lot of electricity. Such a system cannot be called reliable due to the fact that its effectiveness depends on factors not controlled by humans.
The system can be organized and unorganized. An adjustable or organized system functions due to aeration or the presence of deflectors. Aeration is a general exchange process during which air enters and leaves through open windows, lamps, transoms.
Infiltration or unregulated ventilation. Natural ventilation is the ingress of air into a room through leaks in structures.
Despite the development of technology, natural ventilation is also used in modern buildings because of the simplicity and lack of operating costs. In addition to its dependence on environmental conditions, one cannot ignore the fact that there is a likelihood of the occurrence of a phenomenon that the term “traction overturning” is used to indicate. This is a very accurate definition - the air mass suddenly changes direction and begins to move back
In industry, aeration is used in the presence of processes where, according to technology, work is accompanied by the release of heat in large quantities. Its use is permissible provided that the supply air contains less than 30% of harmful emissions from the permissible concentration directly in the zone of their formation.
Do not use aeration if the air entering the room requires pre-treatment or condensation or fog may appear outside the air stream. By aeration, multiple air exchange occurs at scanty energy expenditures. This is its main advantage.
The principle of operation of the ventilation system with the natural movement of air flows is based on the difference in their temperature and pressure:
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The location of the components of a natural-type ventilation system is taken into account and thought out at the design stage of the house. In contrast to the components of a mechanical system, it is problematic to make them upon completion of construction
Exhaust vents of natural ventilation systems are located at the highest point possible. A fresh stream coming from the street displaces the exhaust air mass exactly up
Supply air holes are located in the lower part of the room, outside they are located mainly on the basement of the house. Due to the exhaust air inside the building, a vacuum is created, which is rapidly filled with a fresh portion from the street
In order for the air to move to the exhaust outlet within the apartment or house, the door leaf is equipped with a ventilation grill. If the grille is not installed, then the door leaf should be 1-1.5 cm above the floor
Natural ventilation canal and non-channel. Most often, the supply ducts, less often - exhaust ducts as in the photo
If the air flow does not move, there is no influx or the hood does not work, condensation can be seen on the windows. During normal operation of the system, it evaporates
A clogged exhaust duct or lack of supply can interfere with the movement of air in natural-type systems. It also happens in hot weather, when the apartment is cooler than the street
To check the operation of natural ventilation in the simplest way, a sheet of paper is applied to the exhaust grill. If it is not pressed against the grill, then measures must be taken to restore ventilation
Ventilation shaft construction
Location of exhaust vent
Supply unit in the basement of the house
Interior ventilation grille
Ducted Natural Ventilation System
Signs of ineffective ventilation
Airflow Return
Checking the draft of natural ventilation
In some cases, deflectors are mounted on the mouths of the exhaust ducts - special nozzles. They function through the use of wind energy. Deflectors do a good job of removing dirty and excessively heated air masses from small spaces. They are also used for local hoods.
The normal operation of the ventilation driven by the pressure difference ‚provides a minimum difference between the intake point and the exhaust outlet of 3 m.
For the effective functioning of ventilation, experts recommend not laying horizontal sections longer than 3 m when laying ducts. The air in them should move at a speed of no more than 1 m / s
Mechanical ventilation characteristics
The ventilation system, by means of which air is supplied and removed with the use of additional stimulators at impressive distances, is called mechanical. There are other names for this type of ventilation - forced and artificial.
They apply it both to ensure technological processes in various industries, and to create comfortable conditions for humans.
A device that is easy to install and use, which extracts exhaust air from bathrooms, kitchens and bathrooms of private houses, is a ventilation system with an automatic microprocessor:
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The device channels for the household system
CPU fan
Smart Fan Front Panel
Fan control panel
Mechanical ventilation, unlike natural ventilation, does not depend on external conditions. It is completely controlled and controllable. The air ‚supplied to the room‚ is processed and with a debugged system all its parameters meet the standards. Emissions also enter the atmosphere already cleared of harmful inclusions to the right degree.
The mechanical system includes devices and equipment - automation fans, dust collectors, air heaters, electric motors. All this consumes a lot of electricity.
The presence of a mechanical ventilation system allows you to optimally distribute the air with its supply to a specific place. With its help, harmful emissions are captured at the source of their formation, not allowing polluting the air of the entire room.
The disadvantage of mechanical ventilation is a large financial investment during its installation and operation. To take full advantage of it ‚you have to deal with channel pollution‚ regularly replace the filters.
If a ventilation filter with heat recovery function is installed, you must switch to the summer liner before the summer period. If you leave the winter option ‚it will reduce the efficiency of ventilation.
Mechanical ventilation can be either local or general exchange. The latter is implemented in 2 versions - channelless and channel. The air in the duct system is replaced by fans - centrifugal or axial, ejector installations.
In production, ejectors are often used for drawing, especially where explosive gases are present. The use of ordinary fans is unacceptable here, because they may spark in the event of a malfunction. Their installation is practiced when installing a supply or supply and exhaust system
General mechanical ventilation
Structures with a mechanical drive can be both supply and exhaust. Supply ventilation is sometimes performed in conjunction with central heating.
The air inlet in such a system may have the form of holes in the building envelope of a building, a freestanding or auxiliary shaft. When mounted outside the building, the air intake shaft is located above ground level or on the roof.
The layout of the air intake devices: in the building envelope (a) ‚near the outer wall (b)‚ on the roof (c). Extraction ducts and shafts are insulated from the outside; otherwise, ice will appear in them in winter
The choice of design and location of the air inlets is influenced by the requirements for the degree of purity of the outside air, as well as the architecture of the building.The bottom of the opening through which clean air enters should be located at a distance of at least 2 m from the ground, and in the case of a building located in the green zone - 1 m. External air inlets can not be placed where there are harmful emissions.
Air masses enter the shaft through a fan. Passing through the air heater, they heat up, moisten, or vice versa, are dried and enter inside through air ducts with openings.
Air can also be supplied through branches ‚equipped with nozzles‚ guiding the supply air masses. The air volume is regulated by the gates or valves located in the branches.
Mechanical local ventilation
Local mechanical ventilation, operating in a confined space, is called air showering. This type of ventilation is used in those working areas where the radiant heat is more than 300 kcal / h. or production involves the release of toxins that cannot be removed using a local extract.
Scented installations are mobile and stationary. The first, when providing the workplace with clean air, take it from the room. Sometimes water is supplied to the atomized air mass. Its drops when it enters the human body become an additional cooler. The second through the choking nozzles serves clean external air or pre-processed.
Exhaust ventilation
Removing exhaust air from the room is the task of exhaust ventilation. Removal of used air from the room occurs by lowering the pressure in it. Thus, conditions are created for air to enter from outside or from an adjacent room.
The design of exhaust ventilation includes a cleaning device (1) a fan (2) air ducts - a central (3) suction (4). When there is no other type of ventilation in the room, except for exhaust ventilation, the pressure in it drops to a mark lower than in adjacent rooms or lower than outside
When designing exhaust hoods of a general exchange nature for production shops, the moment is taken into account that the elimination of dirty air should be carried out directly from the primary source of formation of harmful emissions in the direction of their natural trajectory and not pollute clean areas. Such places are biological laboratories ‚workshops with harmful conditions.
Mechanical supply and exhaust ventilation
The base of supply and exhaust ventilation are 2 flows, moving towards each other. It consists of two independent systems - supply and exhaust or one unit. It has built all the equipment necessary for work on the inflow ‚and the exhaust hood.
If there are 2 separate systems, ventilation works without recirculation and is called open. The second type of ventilation system is called closed, and it works with recirculation.
The recirculation system saves energy spent on cooling or heating the air ‚because the air mass is not fully heated, but only its volume that comes from the outside. The removed air in the recirculation system is returned to the room repeatedly with an admixture of fresh air, comprising 10-15% of the total air mass.
Such ventilation is possible in places where there is no hazardous pollution. In regions with a cold climate, a closed system is inefficient because recirculation and external air masses do not mix well enough.
Accident mechanical ventilation
In case of unusual situations, in addition to the working version, emergency ventilation is arranged. Invariably, it is always exhaust. Mechanical emergency ventilation is installed in rooms where there is a risk of breakthrough of explosive vapors or gases. In this case, explosion-proof and spark-proof fans are mounted.
The axial explosion-proof fan contains an engine in a flameproof enclosure. It is fixed so that if necessary it can be quickly replaced
There are dangerous components that cannot be removed with the fans. Then the system includes an ejector. Emergency ventilation should start automatically as soon as the main ventilation stops working. Opening of openings through which dirty air will leave needs to be carried out remotely.
Pipes and grilles designed for air outlet during emergency ventilation are placed in places of the most probable concentration of hazardous substances in a large volume. Apertures through which air is removed in an emergency ‚should not be in areas where people are constantly. Umbrellas must not be mounted on pipes and shafts of the emergency system.
Emissions ‚accidentally emitted into the atmosphere‚ should be dispersed as much as possible and not allowed to fall into the closed zones of the territory adjacent to the building. MPCs are monitored by means of gas analyzers adjusted accordingly.
Smoke ventilation
The main task of smoke ventilation is to remove smoke from a room or building as quickly as possible ‚to block its spread and thereby protect people during their evacuation.
In the photo - a scheme of action of smoke ventilation. It is mounted in addition to the main ventilation ‚to guarantee the evacuation of people in the event of a fire and to cut off the smoke paths
Such ventilation is installed where, with the constant presence of a large number of people, air flow is not possible in a natural way. These are elevators ‚stairwells‚ blind corridors and similar places. The basis of the work of smoke ventilation is the supply and exhaust circuit.
Channels, powerful fans included in the ventilation ‚have increased fire resistance and the ability to resist deformation under prolonged exposure to high temperatures.
Parts of the system are equipped with two types of valves - anti-smoke and fire-retardant. The components of the anti-smoke system are also durable, impervious to gases and smoke screens and doors.
To avoid troubles during the evacuation of people ‚two types of control - automatic and remote manual - are laid in the design of smoke ventilation.
The system must include elements that indicate a fire:
- detectors, when triggered by which, the automatic opening of exhaust fans and smoke valves occurs;
- “Fire” signal on the central console;
- manual activation of smoke ventilation.
Smoke exhaust valves are distributed evenly under the ceiling. Coverage should not exceed 900 m². The system is zoned into sections ‚and in addition to hatches and valves‚ are equipped with smoke exhausters.
It not only removes smoke ‚but also removes carbon monoxide‚ small suspensions formed during combustion. More information about installing a smoke exhaust system can be found in this material.
This video is a kind of educational program about ventilation. Here, the very concept of ventilation is considered in detail and all questions regarding its competent design are covered:
Workshop on installing a ventilation system:
Both enterprise managers and private developers should understand that the normal functioning of those for whom they are responsible depends on the effectiveness of ventilation. Sometimes the life of people is also called into question. You cannot miss this moment and save on it.
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