Today in modern construction there are industries in which research is carried out to improve the technology of construction, also improve the quality during operation, the air exchange of premises in the building is no exception. Problems in this area are relevant and are solved by selecting the multiplicity for the ventilation system. Full-scale tests are carried out and standards are written on the basis of them. The most successful country in this matter is the United States. They developed the ASHRAE standard, using the experience of other countries, namely Germany, Denmark, Finland, and their scientific developments. There is also a developed analogue of such a document in the post-Soviet space. In 2002, AVOK developed standards for "air exchange rates for public and residential buildings."
The construction of modern structures is carried out with the expectation of increased insulation and high tightness of windows. Therefore, optimal air exchange is very important in such cases in order to comply with sanitary and hygienic standards and an appropriate microclimate. It is also important not to damage energy conservation, so that in winter all the heat is not drawn into the ventilation, and cool air from the air conditioner in summer.
To determine the calculation of air exchange in rooms other than hospitals, a new method was created and described in ASHRAE publication 62–1–2004. It is determined by summing the values \ u200b \ u200bof the value of fresh outdoor air, which is supplied directly for breathing, taking into account the area of \ u200b \ u200bthe room falling on one person. As a result, the value turned out to be significantly lower than the later edition of ASHRAE.
Air exchange rates in residential buildings
When carrying out the calculation, it is necessary to use the data in the table, provided that the saturation level of harmful components is not higher than the MPC standards.
| Premises | Air exchange rate | Notes (edit) |
| Living sector | Frequency rate 0.35 h-1, but not less than 30 m³ / h * pers. |
When calculating (m 3 / h) by the multiplicity of the volume of the room, the area of the room is taken into account |
| 3 m³ / m² * h of residential premises, with an apartment area of less than 20 m² / person. | Rooms with air-enclosing structures require additional hoods | |
| Kitchen | 60 m³ / h for electric cooker | Air supply to living rooms |
| 90 m³ / h for using a 4-burner gas hob | ||
| Bathroom, toilet | 25 m³ / h from each room | Same |
| 50 m³ / h with a combined bathroom | ||
| Laundry | Multiplicity 5 h-1 | Same |
| Dressing room, pantry | Multiplicity 1 h-1 | Same |
In cases of non-use of premises for housing, the indicators are reduced in this way:
- in the living area for 0.2h-1;
- in the rest: kitchen, bathroom, toilet, pantry, wardrobe for 0.5h-1.
In this case, it is necessary to avoid the ingress of running air from these premises into the living quarters, if it is present there.
In cases where the air entering the room from the street travels a long distance to the hood, the rate of air exchange also increases. There is also such a thing as delayed ventilation, which implies a lag in the ingress of oxygen from the outside before the start of its use in the room. This time is determined using a special diagram (see figure 1), taking into account the lowest air exchange rates in the above table.
For instance:
- air consumption 60 m³ / h * person;
- housing volume 30 m³ / person;
- lag time 0.6 h.
Air exchange rates for office buildings
The norms in such buildings will be much higher, because ventilation must effectively cope with the large amount of carbon dioxide emitted by the office staff and the equipment located there, remove excess heat, while supplying clean air. In this case, natural ventilation will not be enough; the use of such a system today cannot provide the required hygienic and air exchange standards. During construction, hermetically closed doors and windows are used, and the panoramic glazing device completely restricts the ingress of air from the outside, which leads to stagnation of air and deterioration of the microclimate of housing and the general condition of a person. Therefore, it is necessary to design and install special ventilation.
The main requirements for such ventilation include:
- the ability to provide a sufficient volume of fresh clean air;
- filtration and elimination of used air;
- no excess of noise standards;
- convenient control;
- low energy consumption;
- the ability to fit into the interior and be small in size.
In conference rooms, additional air inlets must be installed, and the hood must be installed in toilets, corridors and copy rooms. In offices, a mechanical hood is installed in cases where the area of each office exceeds 35 sq. m.
As practice shows, in case of incorrect distribution of a large air flow in offices with low ceilings, a feeling of draft is created, and in this case people demand to turn off the ventilation.
Organization of air exchange in a private house
A healthy microclimate and well-being depend largely on the correct organization of the supply and exhaust system in the house. Often, during the design process, ventilation is forgotten or paid little attention, thinking that one hood in the toilet will be enough for this. And often the air exchange is organized incorrectly, which leads to many problems and poses a threat to human health.
In the case when there is insufficient outlet of polluted air, then the room will have a high level of humidity, the possibility of infection of the walls with fungus, fogging of the windows and a feeling of dampness. And when there is a poor flow, there is a lack of oxygen, a lot of dust and high humidity or dryness, it depends on the season outside the window.
Properly arranged ventilation and air exchange in the house looks as shown in the figure.
The air entering the dwelling must first pass through the window or open sash of the window, the supply valve is located on the outside of the wall of the dwelling, then, passing through the room, it penetrates under the door leaf or through special ventilation holes and enters the bathrooms and the kitchen. Longer comes out through the hood system.
The way of organizing the exchange of air differs in the use of ventilation systems: mechanical or natural, but in all cases the air is supplied from residential areas, and goes into technical areas: a bathroom, a kitchen and others. When using any system, it is imperative to arrange ventilation ducts in the inner part of the main wall, this will avoid the so-called overturning of the air flow, which means its reverse movement before as shown in Figure 2. Through these ducts, the exhaust air is discharged outside.
What is air exchange for?
Air exchange is the flow rate of the supplied outdoor air, m3 / h, that enters the building through the ventilation system (Figure 3). Environmental pollution in living rooms comes from sources located in them - it can be furniture, different fabric, consumer products and human activity, household products. This also happens by gas formation from the effects of the exhalation of carbon dioxide by a person and other vital processes of the body, various technical vapors that can be present in the kitchen from the combustion of gas on the stove and many other factors. Therefore, air exchange is so necessary.
To maintain normal air readings in the home, the CO2 saturation should be monitored by adjusting the ventilation system based on the concentration. But there is a second method, the more common one - this is a method of controlling air exchange. It is much cheaper and in many cases more efficient. There is a simplified way to estimate it using Table 2.
But when designing a mechanical ventilation system in a house or apartment, you need to make a calculation.
How to check if the ventilation is working?
First, it is checked whether the hood is working, for this you need to bring a sheet of paper or a flame from a lighter directly to the ventilation grill in the bathroom or kitchen. The flame or leaf should bend towards the hood, if so, then it works, and if this does not happen, then the channel may be blocked, for example, clogged with leaves or for some other reason. Therefore, the main task is to eliminate the cause and provide traction in the channel.
In cases where the draft is unstable from the neighbors, the air flow can pass to you, while bringing in extraneous odors to your apartment, this is a sign of the occurrence reverse thrust... To eliminate it, it is necessary to mount special shutters that will close when a reverse draft appears.
Classification and calculation of ventilation systems at home
In this article we will introduce you to the concept of ventilation and the method of calculating the required air exchange for residential premises. This article will give you a clear idea of what ventilation systems are for and what kind of ventilation systems are, and also, from it you will learn the algorithm for selecting ventilation systems for a cottage.
Classification of ventilation systems
Ventilation systems for residential and public buildings can be classified into three categories: by functional purpose, by the method of inducing air movement and by the method of air movement.
Types of ventilation systems by functional purpose:
- supply ventilation system (ventilation system that supplies fresh air to the room);
- exhaust ventilation system (ventilation system that removes exhaust air from the room);
- recirculation ventilation system (ventilation system that supplies fresh air to the room with partial admixture of extract air).
Types of ventilation systems by the method of inducing air movement:
- with mechanical or artificial (these are ventilation systems in which air is moved using a fan);
- with natural or natural (air movement is carried out due to the action of gravitational forces).
Types of ventilation systems by the way of air movement:
- duct (air movement is carried out through the network of air ducts and channels);
- channelless (air enters the room is not organized, through non-density of window openings, open windows, doors).
What is the threat of poor-quality ventilation?
If the flow in the house is insufficient, then the room will have a lack of oxygen, high humidity or dryness (depending on the season) and dustiness.
Misting windows due to insufficient ventilation
If the hood is insufficient in the house, then there will be high humidity, greasy soot on the walls of the kitchen, fogging of the windows in winter, fungus is possible on the walls, especially the bathroom and toilet, as well as walls covered with wallpaper.
Fungus on wallpaper with insufficient ventilation.
And as a result, an increased risk of cardiovascular disease and respiratory system... In addition, most furniture and decoration materials constantly release hazardous chemical compounds... Their maximum permissible concentration (maximum permissible concentration) in sanitary and hygienic conclusions for this furniture and finishing materials is set from the conditions for compliance with ventilation standards. And the worse the ventilation works, the more the concentration of these harmful substances in the air at home increases. Therefore, the health of the residents of the house directly depends on the provision of proper ventilation.
How to check if your ventilation is working?
First of all, you can check if the hood is working. To do this, bring a lighter or a piece of paper to the ventilation grill installed in the bathroom wall or kitchen. If the flame (or a piece of paper) bent towards the grate, then there is a draft, the hood is working. If not, then the channel is blocked, for example - clogged, with leaves through the air duct. If you have an apartment, then neighbors could have blocked it, redeveloping the premises. Therefore, your first task is to provide traction in the ventilation duct.
Checking ventilation for draft
If there is a craving, but it is not constant, and neighbors live above or below you. In this case, air can flow to you, carrying smells from neighboring premises. In this situation, it is necessary to equip the hood with a non-return valve or an automatic shutter, which closes with a reverse draft.
How to check if you have a sufficient cross-section of the hood, we will consider further.
Calculation of air exchange
In order to choose the ventilation system we need, we need to know how much air must be supplied or removed from a particular room. In simple words, it is necessary to find out the air exchange in a room or in a group of rooms. This will make it possible to determine the system, select the type and model of the fan and select the cross-section of the air ducts. There are many types of calculation of air exchange, for example, to remove excess heat, to remove moisture, to dilute contaminants to the maximum permissible concentration (maximum permissible concentration), all of them require special knowledge, the ability to use tables and diagrams.It should be noted that there are state regulatory documents, such as SanPins, GOSTs and SNiPs, which clearly define what ventilation systems should be in certain rooms, what equipment should be used in them and where it should be located. And also, how much air, with what parameters and by what principle should they be supplied and removed. When designing ventilation systems, each engineer makes calculations in accordance with the aforementioned standards. To calculate the air exchange in residential premises, we will also be guided by these standards and use the two simplest methods of finding air exchange: by the area of the room, by sanitary and hygienic standards, and by air exchange rates.
Calculation by the area of the room
This is the simplest calculation. It is done on the basis that for residential premises, the norms regulate the supply of 3 m3 / hour of fresh air per 1 m2 of the area of the room, regardless of the number of people.Calculation according to sanitary and hygienic standards
According to sanitary standards for public and administrative buildings, 60 m3 / hour of fresh air is needed for one person permanently staying in the room, and 20 m3 / hour for one temporary person.Frequency calculation
Table 1. Frequency rate of air exchange in the premises of residential buildings. |
||||||
| Premises | Design temperature in winter, ºС | Air exchange requirements | ||||
| Inflow | Hood | |||||
| Common room, bedroom, study | 20 | 1-fold | -- | |||
| Kitchen | 18 | - | According to the air balance of the apartment, but not less, m 3 / hour | 90 | ||
| Kitchen-dining room | 20 | 1-fold | ||||
| Bathroom | 25 | - | 25 | |||
| Restroom | 20 | - | 50 | |||
| Combined bathroom | 25 | - | 50 | |||
| Pool | 25 | By calculation | ||||
| Room for a washing machine in the apartment | 18 | - | 0.5x | |||
| Cloakroom for cleaning and ironing clothes | 18 | - | 1.5x | |||
| Lobby, common corridor, staircase, apartment hallway | 16 | - | - | |||
| The premises of the staff on duty (concierge / concierge) | 18 | 1-fold | - | |||
| Smoke-free staircase | 14 | - | - | |||
| Elevator machine room | 14 | - | 0.5x | |||
| Waste collection chamber | 5 | - | 1-fold | |||
| Parking garage | 5 | - | By calculation | |||
| Switchboard room | 5 | - | 0.5x | |||
The air exchange rate is a value that shows how many times the air in the room is completely replaced during one hour. The multiplicity directly depends on the specific room (its volume). That is, a single air exchange is when fresh air was supplied to the room within an hour and the "exhaust" air was removed in an amount equal to one volume of the room; 0.5 tap air exchange - half the volume of the room. In this table, in the last two columns, the multiplicity and requirements for air exchange in the premises for the supply and exhaust air, respectively, are indicated.
The required amount of air is calculated by the formula: L = n * V (m3 / hour), where n is the normalized rate of air exchange, hour-1; V is the volume of the room, m3. When we calculate air exchange for a group of rooms within one building (for example, a residential apartment) or for a building as a whole (a cottage), they should be considered as a single air volume. This volume must meet the condition ∑ Lpr = ∑ Lexpired That is, how much air we supply, the same must be removed.
Thus, the sequence of calculation by multiplicities is as follows:
- We calculate the volume of each room in the house (volume = height * length * width).
- We calculate the volume of air for each room according to the formula: L = n * V.
- To do this, we pre-select from table 1 the rate of air exchange rate for each room. For most rooms, only the inflow or only the exhaust is standardized. For some, for example, the kitchen-dining room is both. A dash means that it is not necessary to supply (remove) air to this room.
- For those rooms for which in the table, instead of the value of the air exchange rate, the minimum air exchange is indicated (for example, ≥90m3 / h for the kitchen), we consider the required air exchange equal to this recommended one. At the very end of the calculation, if the balance equation (∑ Lpr and ∑ Lexhaust) does not agree with us, then we can increase the air exchange values for these rooms to the required figure.
- If there is no room in the table, then we consider the air exchange rate for it, given that for residential premises, the norms regulate the supply of 3 m3 / hour of fresh air per 1 m2 of the area of the room. Those. we consider the air exchange for such rooms according to the formula: L = S rooms * 3.
- All L values are rounded up to 5, i.e. values must be multiples of 5.
- Let us summarize separately L of those rooms for which the air flow is standardized, and separately L of those rooms for which the exhaust is standardized. We get 2 digits: ∑ Lpr and ∑ Lout
- We compose the balance equation ∑ Lpr = ∑ Lout.
- If ∑ Lpr> ∑ Lexhaust, then in order to increase Lexhaust to the value L, we increase the air exchange values for those rooms for which we at point 3 took the air exchange equal to the minimum allowable value.
Example 1. Calculation by multiplicities
There is a house with an area of 140 m 2 with premises: kitchen (s 1 = 20 m 2), bedroom (s 2 = 24 m 2), study (s 3 = 16 m 2), living room (s 4 = 40 m 2), corridor (s 5 = 8 m 2), a bathroom (s 6 = 2 m 2), a bathroom (s 7 = 4 m 2), height h = 3.5 m. It is necessary to draw up the air balance at home.- We find the volumes of premises according to the formula V = sn * h, they will be V 1 = 70 m 3, V 2 = 84 m 3, V 3 = 56 m 3, V 4 = 140 m 3, V 5 = 28 m 3, V 6 = 7 m 3, V 7 = 14 m 3.
- Now we will calculate the required amount of air in terms of multiplicities (formula L = n * V) and write it down in the table, having previously rounded the unit part up to five upwards. When calculating the multiplicity n we take from Table 1, we obtain the following values of the required amount of air L:
Thus, L ave living room = S living room * 3 = 40 * 3 = 120 m 3 / hour. Let us summarize separately L of those rooms for which the air flow is standardized, and separately L of those rooms for which the exhaust is standardized.
∑ L intake = 85 + 60 + 120 = 265 m 3 / hour
∑ L ext = 90 + 50 + 25 = 165 m 3 / hour
Let's compose the air balance equation. As you can see, ∑ L at> ∑ L at, therefore we increase the value of L from the room where we took the value of air exchange equal to the minimum allowable. We have such all three rooms (kitchen, su, bathroom). We will increase L exhaust for the kitchen to the value of L exhaust kitchen = 190. Thus, the total ∑ L ext = 265m 3 / hour. The condition of Table 1 is fulfilled. ∑ L pr = ∑ L ext. It should be noted that in the rooms of the bathroom, bathroom and kitchen, we organize only an exhaust hood, without an inflow, and in the rooms of the bedroom, study and living room, only an inflow. This is to prevent the spill-over of harmful odors into living quarters. Also, this can be seen from Table 1, in the inflow cells opposite these premises there are dashes.
Example 2. Calculation according to sanitary standards
The conditions remain the same. Just add the information that 2 people live in the house, and we will carry out the calculation according to sanitary standards. Let me remind you that according to sanitary standards, 60 m 3 / hour of fresh air is needed for one person constantly staying in the room, and for one temporary 20 m 3 / hour.We get that for the bedroom L 2 = 2 * 60 = 120 m 3 / hour, for the office we will take one permanent resident and one temporary L 3 = 1 * 60 + 1 * 20 = 80 m 3 / hour. For the living room, we accept two permanent residents and two temporary (as a rule, the number of permanent and temporary people is determined by the customer's specifications) L 4 = 2 * 60 + 2 * 20 = 160 m 3 / hour, we will write the obtained data into the table.
Composing the equation of air balances ∑ L pr = ∑ L ext: 360<525 м 3 /час, видим, что количество вытяжного воздуха превышает приточный на ∆L=165 м 3 /час. Поэтому количество приточного воздуха необходимо увеличить на 165 м 3 /час. Поскольку помещения спальни, кабинета и гостиной сбалансированы то воздух необходимый для санузла, ванны и кухни можно подать в помещение смежное с ними, к примеру, в коридор, т.е. в таблицу добавится L прит.коридор =165 м 3 /час. Из коридора воздух будет перетекать в ванную, санузлы и кухню, а оттуда посредством вытяжных вентиляторов (если они установлены) или естественной тяги удалятся из квартиры. Такое перетекание необходимо для предотвращения распространения неприятных запахов и влаги. Таким образом, уравнение воздушных балансов ∑ L пр = ∑ L выт: 525=525 м 3 /час - выполняется.
Example 3. Calculation based on the area of the room.
We will make this calculation, taking into account that for residential premises the norms regulate the supply of 3 m 3 / hour of fresh air per 1 m 2 of the area of the room. Those. we consider air exchange according to the formula: ∑ L = ∑ L pr = ∑ L out = ∑ S premises * 3. ∑ L ext 3 = 114 * 3 = 342m 3 / hour.Comparison of calculations
As we can see, the calculation options differ in the amount of air (∑ L out1 = 265 m 3 / hour< ∑ L выт3 =342 м 3 /час < ∑ L выт2 =525 м 3 /час). Все три варианта являются правильными согласно норм. Однако, первый и третий более простые и дешевые в реализации, а второй дороже, но создает более комфортные условия для человека. Как правило, при проектировании выбор варианта расчета зависит от желания заказчика, точнее от его бюджета. Selection of the duct cross-section
Now that we have calculated the air exchange, we can choose the implementation scheme for the ventilation system. In ventilation systems, two types of rigid air ducts are used - round and rectangular. In rectangular ducts, to reduce pressure losses and reduce noise, the aspect ratio should not exceed three to one (3: 1). When choosing the cross-section of the air ducts, one should be guided by the fact that the speed in the main air duct should be up to 5 m / s, and in the branches up to 3 m / s. The dimensions of the duct section can be determined from the diagram below.In the diagram, the horizontal lines represent the air flow rate and the vertical lines represent the speed. The oblique lines correspond to the dimensions of the ducts. We select the cross-section of the branches of the main air duct (which go directly into each room) and the main air duct itself for supplying air with a flow rate of L = 525 m 3 / h. On the left and right in the diagram, the costs are indicated, we choose ours (525 m 3 / hour). Further, we move horizontally until the intersection with the vertical line corresponding to the value of 5 m / s (for the maximum duct). Now, along the speed line, we go down to the intersection with the nearest section line. We got that the cross-section of the main air duct we need is 160x120 mm or Ø200 mm. To select the cross-section of the branch, we move from about a flow rate of 525 m 3 / hour in a straight line to the intersection at a speed of 3 m 3 / hour. We get a branch section of 250x250 mm or a diameter of 300 mm.
Note. In our example, it was not, but special attention should be paid to the indoor swimming pool when it is in the house. The pool is a room with an excess amount of moisture and an individual approach is required when calculating the required air exchange. From practice, I can say that the flow rate is at least eight times. This is a rather large consumption and if we take into account that the supply air temperature should be 1-2 ° C higher than the water temperature in the pool, then the cost of heating the air in winter is very high. Therefore, it is more logical to use dehumidification systems for indoor swimming pools. These systems work according to this scheme - the dehumidifier takes moist air from the room, passing it through itself, removes moisture from it (by cooling it), then heats it up to a predetermined temperature and feeds it back into the room. Also, there are air dehumidification systems with the possibility of adding fresh air.
The ventilation scheme is purely individual for each house and depends on the architectural features of the house, on the wishes of the customer, etc. Meanwhile, there are some conditions that must be met, and they apply to all schemes, without exception. In the meantime, there is no need to know about it. ”
General requirements for ventilation systems
- Exhaust air is thrown out above the roof. With natural exhaust ventilation, all ducts are removed above the roof. With mechanical exhaust ventilation, the air duct is also taken out above the roof either inside the building or outside.
- Fresh air intake with a mechanical supply ventilation system is carried out using an intake grille. It must be placed at least two meters above ground level.
- The movement of air must be organized in such a way that the air from the living quarters moves in the direction of the premises with the release of harmful substances (bathroom, bathroom, kitchen).
Air exchange rates
Despite the fact that mankind has been interested in ventilation issues for a long time, articles on the topic “how much air does a person need?” Are still periodically appearing in construction magazines. This interest is based on the search for a possible compromise between two opposing tendencies: you want to have the largest possible air exchange in order to bring the composition of the internal air closer to the outside, but you do not want to spend money on heating the supply air in the cold season and moving it along the route atmosphere - living quarters - atmosphere year-round.
There is quite a lot of information about the ratio of the purity of the external and internal air in the literature, but the conclusion is general: the inside is always worse than the outside. Indeed, the internal air appears in the apartment not from cylinders, like drinking water, but from the street and, in addition to the existing dust and gas impurities, it receives dust and impurities generated already inside by the residents themselves. A modern city dweller spends 90% of his time indoors. According to environmentalists, the air in the house is 4-6 times dirtier and 8-10 times more toxic than the outside air. About 10% of infectious and colds are acquired outside walls, and 90% indoors.
If you do not arrange from an apartment an analogue of a submarine with oxygen generators, carbon dioxide absorbers, if in mass residential housing for various reasons it is impossible to use fine air filters and carbon filters on the inflow, you will have to admit that the only real way to make the internal air usable is ensuring the necessary air exchange with the environment.
Air exchange standards
Today, in the standards and recommendations, one can find the binding of the amount of air exchange to the area of living quarters, their volume (multiplicity) or the number of people. Despite the fact that people in different countries breathe about the same, the standards can vary quite significantly.
The air exchange rate, 1 / hour, is: in Ukraine 1.2 before 1996 and 1.0 after 1996, in the USA - 0.35, Germany - 0.5, Great Britain - 0.4, Sweden - 0, 2. The standards in the UK and Sweden are reduced to a density of apartment occupancy of 20 sq.m. / person. It can be seen where and how much heat energy is valued.
During the USSR and post-Soviet times, air exchange rates in residential buildings were also defined in various documents.
So, according to SNiP 2.08.01-89 * "Residential buildings", the air exchange of the apartment must be at least one of two values: the total exhaust rate from toilets, bathrooms and the kitchen, which, depending on the type of stove, is 110-140 cubic meters / hour, or the inflow rate equal to 3 cubic meters ./hour/sq.m. living space. Since this norm for large apartments leads to unreasonably high ventilation air consumption, in Moscow regional norms MGSN 3.01-96 "Residential buildings" air exchange of living rooms is provided with a flow rate of 30 cubic meters per hour per person.
In one of the latest regulations TR AVOK-4-2008 it is proposed to calculate air exchange for all three parameters (area, volume, number of people) in this form (for a residential area): air exchange rate 0.35 1 / hour, but not less than 30 cubic meters / hour / person. or 3 cubic meters / hour / sq.m. living space, if the total area of the apartment is less than 20 sq.m. / person.
It should be noted that all these fixed norms do not take into account the obvious fact that quite often living quarters are empty, in the morning people usually go to work, and children go to school. In an empty apartment, the normative air exchange is not needed and the fulfillment of these standards leads to irrational waste of heat energy for heating the ventilation air, in other words - “to heating the street”.
The absurdity of the requirements for fixed air exchange in rooms with variable occupancy, which are apartments in modern multi-storey residential buildings, was taken into account in SNiP 31-01-2003 "Residential apartment buildings", where the concept of "inoperative mode" and "service mode" appeared, in which the amount of air exchange can (and should) vary within a fairly wide range. So, for bedrooms, common and children's rooms, it is recommended to set the air exchange rate at least 0.2 and 1.0, respectively.
To date, TR AVOK-4-2004 is a regulatory document, perhaps the most appropriate to the requirements for the simultaneous maintenance of the necessary parameters of the microclimate of residential premises and the maximum reduction of heat losses for heating the ventilation air. So, the minimum air exchange in the apartment is set at a level of at least 25% of the calculated one, regardless of the will of the residents. The fact is that even in their absence, there is constant pollution of the internal air with radon, gas emissions from building and finishing materials, furniture and other interior elements.
On the other hand, in these TR, it is recommended to design ventilation systems for residential apartments with the possibility of individual regulation of the amount of air exchange, for which purpose, adjustable devices for the supply and removal of air are used. In this case, the adjustments can be both manual and automatic. Sensors of differential pressure, humidity of internal air, illumination, presence of people, etc. can be used as control sensors in automatic mode. It is recommended to ensure energy efficiency of ventilation systems by reducing the amount of air exchange depending on the intensity of operation of individual rooms and the apartment as a whole, as well as using the heat of the exhaust air for heating the supply air (in supply and exhaust mechanical ventilation systems). For these positions, this standard is fully consistent with the current level of European rule-making.
Technical solutions
Usually, in urban apartment buildings, natural supply and exhaust ventilation systems are used. At the same time, such a scheme of air movement through the premises is planned: exhaust air is removed from the utility rooms (kitchens, bathrooms, toilets, laundry rooms) through the exhaust openings of the exhaust ducts. For normal operation of the hood, of course, it is necessary to replace the outgoing air with the same amount of incoming air. Fresh supply air penetrated into the premises usually through the leaks of the existing old wooden windows, as well as through the doors, transoms and vents manually opened by residents as needed. The operation of such a ventilation system is based on the difference in the specific gravity of cold air outside and warm air inside a dwelling; wind also participates in creating traction in the exhaust ducts. To ensure air exchange, the internal doors in the entire apartment must have an undercut of the leaf of 1.5… .2.0 cm, facilitating the flow of air, special cross-flow grids or be constantly open. Only in this case the apartment can be considered as a single air volume with the same pressure.
Design development overview
As for the design of the exhaust ducts, the schemes used in housing construction have changed several times over the past decades. In residential buildings built at the very beginning of mass housing construction, individual ducts from each exhaust grille were used. With the increase in the number of storeys in residential buildings, this scheme has been improved. To save space, every 4-5 floors, the vertical channels coming out of the apartments began to be connected with horizontal ones, and from it the air was directed to the mine along one vertical channel. Since the 70s of the last century, in almost all series of residential buildings above five floors (P-44, P3, etc.), a ventilation scheme has been used, which includes a prefabricated vertical duct with side floor branches - "satellites". Moreover, each vertical line of apartments, depending on the series of the house, can have one or two prefabricated channels. In any case, the air leaving the room first enters the "satellite" channel, from which it enters the "trunk" not immediately, but only in the interfloor overlap above the next floor or even two floors above. As a result, the hood scheme becomes like a “herringbone”.
Such a scheme of exhaust ducts has both undeniable advantages and disadvantages. The main advantages of natural ventilation are its simplicity and low cost, as well as the almost complete absence of the need for its maintenance.
It is much more compact than a system with individual channels and takes up significantly less useful space. The disadvantages are related to the dependence on atmospheric conditions (air temperature, wind), which leads to unstable system operation.
So, for example, in the already mentioned work N.I. Vatina and T.V. Samoplyas An analysis of the efficiency of ventilation with natural motivation was carried out under the usual assumptions adopted in Russia: the outside air temperature is +5 degrees, calmness, the inside air temperature is equal to the calculated one, the windows are open. It was shown that in almost 50% of the time ventilation is less than the calculated one (for +5 degrees), in 13% of the time ventilation is half or more less than the calculated one, and in 5% of the time there is no ventilation at all. Although the calculations used climatic data for St. Petersburg, the figures for Moscow and cities in central Russia will be similar.
Thus, if we take not the heating period, but the whole year, it is clear that the natural ventilation systems with which already built houses are equipped and continue to be equipped, as a rule, new residential buildings, do not provide the air exchange necessary according to sanitary standards with all the ensuing consequences for health. working capacity and life expectancy of the country's population.
So, the natural ventilation systems currently available in residential buildings include the following main elements: supply "devices" in the form of windows, interior and sanitary doors with undercut sheets or transfer grilles for the passage of air to utility rooms, exhaust grilles and the exhaust ducts themselves, which in the most favorable situation, they will not be able to provide the standard air exchange for six months.
Nevertheless, generations of Russians have lived in such residential buildings for many years and there have been no mass deaths due to poor indoor air quality. Why?
In many ways, oddly enough it sounds, due to the poor quality of the old Soviet "carpentry".
Here is what he writes about this AVOK President Y.A. Tabunshchikov on the emergence of a new regulatory document SNiP 23-02-2003 "Thermal protection of buildings"“… Requirements for improving the thermal efficiency of buildings, which are the main end-user of energy, are becoming one of the important components of legislation in most countries of the world. These requirements are considered, first of all, from the point of view of the security of the nation, environmental protection - as a means of ensuring the rational use of non-renewable natural energy resources and reducing the emission of carbon dioxide and harmful substances into the atmosphere, supplying food to the country's population. Approved building codes and regulations develop requirements for thermal protection of buildings in order to reduce energy requirements for maintaining optimal microclimate parameters in premises. These requirements are harmonized with the requirements of similar foreign standards for developed countries.
The new document retains the contradiction of the previous SNiP, that windows with the recommended air permeability in buildings with natural ventilation do not provide the necessary sanitary and hygienic air exchange. Indeed, consider the following simple calculations.
The basic principle of natural ventilation in multi-storey residential buildings is that air enters the apartments through leaks in window fillings. However, due to the increase in city noise and dustiness of the outside air, they tried to reduce the air permeability of the windows. The requirements for the air permeability of windows at the level of the 1st floor of a residential building have changed in different years as follows:
- 1971 - Gн = 18kg / sq.m. x hour
- 1979 - 10 kg / sq.m. x hour<
- 1998-2003 - 5-6 kg / sq.m. x hour.
Consider a two-room apartment with a total area of 75 square meters, living rooms with a total area of 40 square meters, a volume of 200 cubic meters, the number of residents - 3 people, three windows with a total area of 8 square meters. Calculation of air exchange by inflow gives the following results: in terms of frequency - 200 x 0.35 = 70 cubic meters / hour, according to the standard - 30 x 3 = 90 cubic meters / hour. The calculation of air exchange for the hood gives the following results: 60 + 25+ 25 = 110 cubic meters / hour. Therefore, the required air exchange is 110 cubic meters / hour, and then 110/8 = 14 cubic meters / hour should flow through one square meter of the window. Thus, the norms of 1971 made it possible to provide the required air exchange, while the norms of 1979 and subsequent years do not allow this ... .. "
Thus, in the past, residents somehow adapted to find a compromise between windows and ventilation. In the cold period of the year, with a constantly available draft in the channels of natural exhaust, a completely acceptable air flow was provided. If the inflow increased significantly and the temperature inside the premises began to drop, the cracks in the vestibules were sealed with improvised materials. In the summer, the vents and sashes could be kept open, providing ventilation.
Influence of plastic windows on air exchange
Everything changed dramatically with the advent of new PVC, wood and aluminum windows with double-glazed windows and 2-3 sealing contours. Their massive appearance in Europe in the 70s of the last century was largely initiated by the global energy crisis. In energy audits of residential buildings, it was not difficult to verify that uncontrolled infiltration of cold air through the windows is too much of a luxury in terms of energy savings. SEALED windows appeared. In addition, sealed double-glazed windows made it possible to significantly increase the resistance to heat transfer of window blocks due to the use of low-emission glasses and noble gases, which was difficult or even impossible to do when glazing with sheet glass.
But it turned out that two good goals - creating a favorable indoor climate and energy saving - contradict each other. This is how ventilation specialists write about it in TR AVOK-4-2004: “... The high tightness of modern windows made natural ventilation systems practically inoperative. The comfort of living in apartments has deteriorated: there is high humidity and low air quality, the probability of fungal infections of structures increases ... ".
So, maybe we should go back to the "good old carpentry"? Such proposals appear periodically in articles on construction topics.
"For modern translucent structures (not important from PVC or glued wood), air permeability has decreased tenfold. The windows really stopped" blowing. "But here another problem arose in full growth - the need for frequent ventilation or a sharp decrease in air exchange in the premises. leads to an increase in relative humidity, condensation on the glazing, the appearance of mold, persistent odors, etc. In this regard, in recent years, even a new term has appeared - “sick buildings syndrome.” Moreover, the increased tightness of window structures also turned into unexpected consequences for the systems themselves ventilation - overturning the movement of air in the ducts, the flow of dirty air between apartments on different floors.
With sealed windows and sufficiently sealed entrance doors, due to the lack of an organized air flow in the apartments, a certain vacuum will be created, and for a number of reasons one of the ventilation ducts may start to work on the inflow - "topple over" (or due to the fact that the mouth of this duct is higher than the others, either due to a higher air temperature in one of the rooms, or due to the difference in wind pressures). The consequences are no less sad than the increased humidity of the air - freezing of the canal walls, damage to the finish, drafts, etc. In this regard, claims are often made against modern windows - "they do not breathe", "uncomfortable", "unsuitable for operation in our conditions" etc. And "solutions" are proposed - to bring the air permeability of the windows to their previous limits by removing the gaskets, holes in the window frames, to return to the old double-stitched bindings, etc. It is not difficult to predict the consequences - local freezing of the bindings due to cooling by filtered air, uncontrolled heat loss for heating the supply air, etc. Without dwelling on a detailed analysis of such "solutions", I would like to emphasize (although this may sound somewhat paradoxical) that it is wonderful and very good that we have learned how to make such sealed windows. And there is no need to depressurize them.
It is necessary to properly operate them and use the advantages that these structures allow to realize. It is the high tightness of modern translucent structures that opens up real opportunities for saving thermal energy - both in new construction and in the reconstruction of buildings or simple renovation of apartments - due to regulated, controlled air exchange, carried out with the use of appropriate ventilation systems ... ".
