Contents
Even at the stage of designing a house, you need to think about fresh air in the rooms. Moreover, it may be that self-designed ventilation will work no worse than professionally designed. Perhaps the solution will not be so elegant – the main thing is that it be workable.
Definition and severity of the problem
Ventilation is understood as a specially organized movement of air masses. It is necessary to create comfortable and healthy living conditions for a person. In general, the system is very complex in the calculation. There are simply no standard solutions that suit everyone or at least a certain group of users. Each project is individual. Even the location of one grid, the fan, plays a role. A lot depends on the position of the house relative to the wind rose and many more little things. In order for self-designed ventilation to work well, you need to seriously understand.
For you to understand how serious it is
According to sanitary standards, one person at rest processes about 30 cubic meters of air per hour. If the air is not renewed, there will be less and less oxygen, and more and more carbon dioxide and other waste products. As the amount of oxygen decreases, well-being worsens. Prolonged lack of oxygen provokes the development of diseases.
A few figures, physiologists, showing the effect of CO2 carbon dioxide levels on a person’s condition:
- High quality air – up to 800 ppm, cheerfulness, perfect well-being.
- Medium quality air – 800 – 1000 ppm. At the upper limit, half of the people feel drowsiness, lethargy, decreased concentration and deterioration in the quality and speed of information processing.
Carbon dioxide levels affect well-being - Low quality air – 1000-1400 ppm. Lethargy, lethargy, problems with information processing, a feeling of “stuffiness”.
- Unfit for life air – ppm above 1400. Inability to concentrate, severe drowsiness, fatigue, sleep problems, dry mucous membranes.
Physiologists consider the content of carbon dioxide in the air at the level of 1400 ppm – the lowest point for relatively normal human functioning. All indicators with a large amount of carbon dioxide are already beyond.
A good example
To assess the severity of the situation without ventilation, here is a graph of CO2 levels. It was filmed as an experiment. To assess how much ventilation is needed in a modern house / apartment with plastic windows and thermal insulation measures taken.
Experiment conditions. Bedroom 13 squares (37 cubes), one person and one medium sized dog. The house has exhaust ventilation, a riser in the kitchen and in the boiler room. An exhaust fan is installed in the boiler room, which runs half the night and half the day on a timer. There is no supply, fresh air access through windows that have the function of ventilation and micro-ventilation.
Information to explain the graph:
- Point 1. From 20:XNUMX – work at the computer, the doors are ajar, the window is closed.
- Point 2. The window was opened, the doors were ajar, everyone left the room.
- Between 1-2 they returned to the room, the window was closed, then opened. All this can be tracked by fluctuations in CO2 levels.
- Point 3. At 3-35 the doors and the window are closed, the man and the dog are sleeping.
- Point 4. 9-20 am, the man woke up. The level of CO2 is 2600 ppm, which is well below the extreme norm. The window was opened, carbon dioxide levels returned to normal in less than an hour (Point 5).
As you can see from the graph, most of the night passes with very high concentrations of carbon dioxide. This can be the cause of fatigue, poor health in the morning. In general, everything is clear. If you wish, you can conduct a similar experiment yourself. Only a weather station with the ability to measure the level of carbon dioxide (with memory) is required. Looking at the results of the experiment, it is difficult to overestimate the importance of the ventilation system. Let’s understand how it works.
The principle of operation of ventilation of the house and apartment
All ventilation systems are divided into two types – with natural air movement and forced.
Air always moves from an area of higher pressure to an area of lower pressure. This property is used in natural ventilation systems. The higher pressure zone is usually located in an apartment / house. If there are ventilation ducts / openings, the air from the premises tends to get into the street. But a new one must take the place of the “gone”, otherwise the movement will stop. That is why for the normal operation of the ventilation system, both the outflow of exhaust air and the inflow of fresh air are necessary. And this is worth taking care of. Only then will ventilation – made / developed by one’s own hands or not – work effectively.
Keep in mind that “breathing” walls have nothing to do with air exchange. At best, they help regulate humidity. But only. Similarly, conventional air conditioning does not add oxygen. It only maintains the set parameters of the already available air. It removes only excess moisture, and has nothing to do with air exchange. Air inflow must be provided in the same way as outflow, using windows (not the most efficient way) or special devices.
Inflow problems
Here, it would seem, what is easier – make a hole in the wall – here you have an influx of oxygen. Maybe somewhere this is true, but not in our climate, when the temperature outside is far from comfortable for most of the year. What’s wrong? A number of unpleasant moments:
- Even at not very low temperatures, unheated air causes acute discomfort. Therefore, heating elements are placed in the supply channels or a recovery system is used.
- The air carries dust and exhaust gases with it. Therefore, a cleaning system is needed – filters.
- Just a hole in the wall – a source of extraneous noise. In cities, noise can interfere with life. That’s why noise reduction is needed.
One of the options for organizing the flow of fresh air is a valve in the wall - Outside air conditions are constantly changing, so humidity control is desirable – with dehumidification / humidification, depending on the need. This item is not a necessity, as you can make a separate system for maintaining the humidity level.
- When cold air enters, condensation forms on the walls of the supply duct. If no action is taken, it soaks into the walls, freezes / thaws – depending on the weather, thereby destroying these walls. Therefore, supply devices are made thermally insulated.
As you can see, a “simple” hole in the wall becomes a very complex device. And few of this list can be neglected. Existence will be too uncomfortable.
Exhaust ventilation
The exhaust ventilation in an apartment building is a large pipe that runs through all the floors and out to the roof. All apartments “in the riser” are connected to it. Under normal conditions, due to the difference in pressure in the apartment and on the roof, a “draught” is formed, which draws air from the premises (it also works if there is an inflow).
In apartment buildings, risers are usually located in the kitchen and/or bathroom. All other rooms are ventilated through these hoods. For normal air exchange in the bathroom door and in the kitchen, it is necessary to provide ventilation gaps (under the door or make overflow holes in the wall) or install grilles.
In a private house, everything is organized in much the same way: in the kitchen or bathroom, the main ventilation duct is installed, which leads to the roof. Don’t finish it in the attic. Even if the attic is cold and ventilated. With temperature differences and high humidity of the exhaust air, a large amount of condensate is formed. Even with good ventilation in the attic, it does not have time to be removed, the ceiling “gets wet”, the walls become damp. In general, this is a bad idea.
Duct material
A few words about the material from which the exhaust ventilation duct is made in a private house. Most often, galvanized pipes are used, and – round section. They have minimal airflow resistance. The second place in popularity is occupied by plastic air ducts. There are more problems with them – they accumulate static, which contributes to the accumulation of dust, they are less resistant to fire. The advantages include simpler installation, the presence of ready-made shaped elements, with which it is easy to create any system. In the case of these materials, the choice is yours – what you like more, then use it.
What you should not do is to drive the exhaust duct out of the brick. Firstly, it is expensive (you also need a foundation for it), and secondly, it is the most problematic in operation, as it has uneven walls, which contributes to the accumulation of dust. In brick walls that are not covered with a metal sleeve, condensate accumulates, due to which the brick quickly collapses. In general, brick exhaust ducts are the last century.
Additional devices
What else may be needed in an exhaust system is check valves. They prevent the air from moving in the opposite direction, which occurs when the thrust is overturned. When the pressure in the apartment / house becomes lower than on the street. Also, non-return valves prevent the spread of odors from the kitchen / toilet to other rooms connected to the channel.
In general, the device of the exhaust system is simpler. But only if the cross section of the ventilation duct is correctly calculated, the route is correctly drawn up and the installation is correct.
natural or forced
There are two types of ventilation – natural and forced. What’s better? It’s hard to say for sure. Everyone decides for himself, taking into account all the advantages and disadvantages of both types.
Natural ventilation in the house works due to the difference in pressure in the room and on the street (due to the existence of the very “natural draft”). Its advantages are noiselessness, independence from electricity. Cons – low productivity, which requires large pipes, the inability to control / regulate the intensity of work, dependence on the state of the external environment. In summer, natural ventilation often does not work, and sometimes it works in the opposite direction. This is when hot air is “pulled” into the room through the exhaust ventilation duct.
In forced ventilation, fans provide air movement. It can be adjustable, works in any weather, but only if there is electricity and efficient fans. And this is a minus. Even two. The first is volatility, the second is the noise that fans make during operation. Therefore, in forced ventilation systems, many prefer to use plastic air ducts. Precisely because they are “quiet”.
Ventilation schemes for a private house and apartment
The simplest option is implemented in small houses and apartments. Supply air openings are located in the living rooms, hoods – in the kitchen and bathroom. The air entering the premises through the cracks under the doors enters the kitchen and bathroom, where it is removed. This scheme works with an area of u100buXNUMXbnot more than XNUMX squares.
In houses with a total area of more than one hundred and fifty squares, organizing two separate systems – supply and exhaust. Each of them has its own duct system. With such a device in each room there are exhaust and supply openings in each of the rooms. In this case, the intensity of air inflow and outflow can be adjusted in each room – you can adjust the atmosphere to the requirements of its inhabitants.
With a centralized supply ventilation system, it is easier to prepare the air taken from the street – you can make a single cleaning and heating system. Prepared air can already be diluted throughout the premises. In this case, each room has two ventilation openings – one supply, one – exhaust. They are located in opposite corners, closed with grilles or diffusers.
Even with a large area of uXNUMXbuXNUMXbthe house, the supply ventilation system can be made decentralized, as in the first scheme. With the right selection of equipment, it will work no less efficiently. The question is what will be economically more profitable, since it will be necessary to solve the problem of air preparation for each supply channel. And the equipment is not cheap.
Do-it-yourself ventilation: an action plan
To independently design a ventilation system, you will have to perform a number of actions. It’s easier if the sequence is known.
Preparatory work
The collection of information and elementary calculations – this is where the independent creation of a ventilation project begins.
- Calculate the frequency of exchange in the entire house / apartment. It depends on the volume of the premises (you need to calculate the cubic capacity of each room), their purpose, the number of residents. According to sanitary standards in residential premises, the air must be changed once per hour, in technical premises (kitchen / bathroom / toilet) – at least three times per hour. The norms for boiler rooms are their own and must be taken into account (depending on the type of heating). Adding all the numbers, we get the required performance of the system, according to which the cross section of the exhaust duct is calculated, the performance of the ventilation equipment is selected.
First you need to draw how the air will move – from the inflow to the exhaust - Draw a diagram of the movement of air currents. At the same time, you immediately have to estimate the position of the supply and retraction channels.
- Draw a duct diagram. So far without dimensions and details, just following the rules and trying to fit the system without complicating the design too much. Everything is complicated here, since you can hide the air ducts only behind a suspended or stretch ceiling. Otherwise, they will be open.
Preliminary data is ready. Think about where and what devices should be located for some more time.
Parameter calculations and detailing
When all the questions on the scheme are resolved, it has taken its final form, we proceed to the detailing. First, there are also calculations, then you have to look for the components of the system, decide which company to use the equipment and reduce the budget.
- Calculate the cross-section of air ducts based on the exchange rate, the volume of the room and the speed of “silent” air movement. Otherwise it will be impossible to live.
- Enter the dimensions on the diagram (you can redraw).
- Carry out detailing. That is, make a list of the necessary elements of the systems, indicating the type and section.
Detailing – a detailed list of all required components with dimensions, performance, speed - Calculate the resistance of each section of the system, select fans (according to the operating point in the characteristic, taking into account the obtained system resistance). Take into account the noise level from the operation of the fan, take measures to reduce it (choose a low-noise model).
- Calculate the cost of system components. Try to combine “cash” with desires. Here you have to change the components several times, moving from what you want to what is real.
- We draw a final project with full details. We must also remember about the nodes of the passage of ventilation ducts through the walls / ceiling / roof, consumables and insulation materials, ventilation grilles and diffusers, fasteners and all other “little things” that result in a decent amount.
Installation and setup
“It remains” to find, buy, mount. Little has been written, but it will take a lot of effort, time, and nerves to implement this item. Only after that can we say that do-it-yourself ventilation is completely ready.
But that’s not all. Do-it-yourself ventilation must be started and adjusted. This is also not the easiest process – to achieve consistent operation of the system as a whole. Then, during operation, reconfiguration has to be done often. With a change of season, a change in the number of residents, a change in weather conditions. In general, adjusting the ventilation system is another responsibility of the home owner.
By the way, we advise you to think. Do-it-yourself ventilation (meaning installation) will cost less, but it requires more knowledge and time. Knowledge can be gleaned, and if there is a shortage of time, you will have to look for and hire performers, then accept their work.
Other solutions
The market does not stand still, and new solutions are being offered today. For example, there are recuperator systems that immediately, through one hole in the wall, remove the exhaust air and supply fresh air. This is an ideal solution if ventilation is taken care of after renovation or if it is necessary to solve the problem only in some rooms. The main thing is that these rooms have at least one wall facing the street.
The disadvantage of this method of organizing ventilation in a house or apartment is the price of such equipment. The cost of one such device is more than $400.