How ventilation is arranged in multi-storey buildings: main problems and features. Ventilation and shaft installation in multi-storey apartment buildings Ventilation riser in an apartment building
Organized natural ventilation in a residential building is an air exchange that occurs due to the difference in air density inside the building and outside, through specially arranged exhaust and supply openings.
For ventilation of rooms in residential apartment building a natural ventilation system is provided. Let's see how it works and how it works.
Natural ventilation device
Each entrance from the first floor to the last has a common ventilation duct that runs vertically from the bottom, up with access either to the attic or directly to the roof (depending on the project). Satellite channels are connected to the main ventilation duct, the beginning of which is located, as a rule, in the bathroom, kitchen and toilet.
Through these satellite channels, the "exhaust" air leaves the apartments, enters the common ventilation shaft, passes through it and is discharged into the atmosphere.
It seems that everything is extremely simple and such a mechanism should work flawlessly. But there are many things that can interfere with the normal operation of ventilation.
The most important thing in the work of natural ventilation is that air must be supplied to the apartment in sufficient quantities. According to projects, according to SNiP, this air should flow through "leaks" window openings, as well as by opening the vents.
Extract from SNiP 2.08.01-89 (minimum air exchange parameters for an apartment).
But we all understand that modern windows when closed, they do not let in any sounds, much less air. It turns out that you need to keep the windows open all the time, which of course is not possible for a number of reasons.
Causes of disruption of natural ventilation
- Re-equipment of ventilation channels
- Debris in the ventilation duct
- Not correct connection exhaust hoods
- seasonality
It happens that the ventilation stops working due to active neighbors who could simply break the ventilation duct to expand the living space. In this case, for all residents whose apartments are located below, the ventilation will stop working.
It often happens that something gets into the ventilation shaft and simply does not allow air to move freely. If this happens, then you need to contact the appropriate structure, it is forbidden to climb into the ventilation duct on your own.
It is also a common problem to connect kitchen hoods (exhaust hoods) of high power to a satellite channel that is not intended for this. And when such a hood is turned on, an air lock forms in the common ventilation duct, which disrupts the operation of the entire system.
Unfortunately for work natural system ventilation also has an effect temperature regime, in the cold season, it works better, and in summer, when the temperature rises outside, it works weaker. To this, several negative points described above are added, and the operation of the entire system comes to naught.
And of course, there are mistakes during construction made by the contractor for one reason or another ... Only the installation of supply and exhaust ventilation equipment will help here.
Natural ventilation works all year round 24 hours a day. Therefore, a round-the-clock supply of air to the room is necessary. If it is not, then in winter closed windows condensation is possible, an increase in humidity up to the formation of mold, to avoid this, install supply valves, this will improve ventilation in the room and get rid of excess moisture.
For the organization of good air exchange in the apartment all year round. A ventilator will be required. Thanks to this device, you do not have to open the windows, and the apartment will always receive fresh and fresh air.
Comfortable living of a person in an apartment is possible in the presence of all communications necessary for his life - water supply, sewerage, lighting, ventilation. modern building multi-storey buildings is aimed at minimizing their heat loss, so the facades are lined with high-quality heat-insulating materials, windows and doors are made as airtight as possible. This necessitates the organization of ventilation of the premises. What ventilation system to choose and how to properly equip it - you will learn from this article.
General rules for ventilation of apartments
According to SNiP, air exchange must be organized in each residential building. Therefore, the apartments are provided with a ventilation system designed to remove air from service premises, such as a bath, toilet, kitchen.
Scheme of organizing ventilation in an apartment building
Each member of the family uses these rooms several times daily, as a result of which the air in them is polluted, moisture accumulates in it. With proper ventilation, these consequences of human activity are invisible. But if the air exchange in the apartment is disturbed, this manifests itself:
- , the formation of condensate;
- the appearance of dampness in the corners, mold;
- air stagnation, spread unpleasant odors by premises.
All this negatively affects not only the state of furniture, decoration, but also human health. Excess moisture and heat is a favorable environment for the reproduction of pathogens.
We check the performance of ventilation in the apartment
How efficiently is your home ventilated? This can be found out on your own. It is necessary to open the window in one of the rooms and attach thin sheet paper to the air vent. If it starts to be sucked in, the ventilation works, if not, there are problems with air exchange in the housing.
Note: the thrust is checked in the same way if a lit match is presented to the hole.
Ventilation can be measured with an anemometer. This device shows the speed of movement of air through the channels. The resulting value, together with the cross-sectional indicator of the ventilation hole, is entered into a special calculation table, and as a result, they find out how much air passes through the grate in 1 hour (m 3 / h).
Ventilation work in the house, check
How ventilation works in a typical apartment
In all high-rise buildings forced-air and exhaust ventilation of natural type is organized. On its basis, air exchange rates for city apartments are calculated. According to this system, air should enter the housing through door, window openings / leaks, open vents, and be removed through the ventilation ducts.
This principle of air exchange worked before the appearance on the market of PVC windows equipped with sealed double-glazed windows, and metal doors equipped with rubber seals. On the one hand, they strengthen, but on the other hand, they block the flow of fresh air into the rooms. Opening windows (especially in winter) is impractical, since heat leaves the apartment, and cold air and dust enter from outside.
The problem of ventilation is especially acute on the upper floors. In order for the air to be effectively removed from the room, it must pass through a vertical channel of at least 2 m. This is possible on any floor except the last one (because there is an attic above it).
Bottom line: supply and exhaust apartments, based on natural air supply, are ineffective today. It needs to be improved by using additional devices.
Supply and exhaust ventilation of apartments
How to organize the ventilation of the apartment
Determination of air exchange rates
The choice of ventilation system is based on the calculation of air exchange rates for different rooms. To determine the optimal volume of inflow, it is necessary to compare the norms of ventilation of the apartment with its area and the number of inhabitants. For 1 m 2 of housing, 3 m 3 of air should flow in 1 hour. One adult needs 30 m 3 of air for every 60 minutes. The air exchange rate is:
- for a kitchen with a gas stove - 90 m 3 / h, with an electric one - at least 60 m 3 / h;
- for - 25 m 3 / hour,
- for a toilet, or a combined bathroom - 50 m 3 / hour.
Air exchange
Ways to organize ventilation in the apartment
There are two methods for installing ventilation in an apartment building:
- natural (natural) way - based on the use of traction resulting from the temperature difference inside and outside the structure;
- forcibly - when traction is organized artificially, mechanically. It can be supply, exhaust, or combined.
To achieve the indicators of the optimal microclimate in the apartment, it is necessary to analyze the parameters of each system.
How Masses Circulate Naturally
This is the simplest, low-cost method of organizing ventilation, which is used in most multi-storey buildings. Air enters the premises through vents, gaps in windows and doors, and is removed through ventilation ducts arranged in the walls of the building.
But since modern technologies construction exclude the formation of gaps for air supply, they must be equipped additionally. To do this, special valves are installed in the walls or windows to let air in from the outside. These devices do not spoil appearance design, and, thanks to sound-reflecting visors, do not let in noise from the street.
Install supply valves in the walls, at the level of radiators. Pre-make a hole of the required diameter (50-100 mm). A valve is inserted into it, the gaps between it and the wall are sealed. All work takes about 15 minutes.
Note: by placing the supply valves near the radiators, you will provide partial heating of the air coming from the street.
Air circulation naturally
The main advantages of this type of ventilation are low cost, ease of installation and maintenance. But the effectiveness of the functioning of the valves depends on how well the ventilation ducts in the house work. The system provides high-quality air exchange in winter, when the temperature difference inside and outside the building is large, and the draft is stronger. In summer and when the temperature difference is less than 15˚С, its work is almost imperceptible. A significant drawback of natural ventilation is the lack of control over the volume of incoming and outgoing air, the microclimate in the apartment.
Arrangement of forced-type exhaust ventilation
When the removal of exhaust air from the premises in a natural way is not possible, it is pumped out mechanically. For these purposes, fans are used, which are built into the ventilation shafts of bathrooms and kitchens. They create a rarefaction of air in the premises, due to which it is drawn in from the outside (through open windows or supply valves).
The disadvantage of such a system is the uncontrolled volume of inflow coming naturally. It may not be enough for the needs of people living in the apartment. To prevent part of the heat from being spent on heating fresh air, supply valves are installed near radiators. Also, supply devices can be equipped with special electric heaters.
forced ventilation
Influx organized forcibly
If the amount of air coming from the street is not enough for the needs of the residents, it can be forced in. For this, special supply units are used. They consist of:
- fan;
- filter;
- shut-off valve;
- air heater;
- silencer.
To install equipment in the main wall of the building, make a hole corresponding to the diameter air handling unit. After installing the system, it is connected to a power source. It begins to supply fresh air into the room, and the exhaust is removed by natural draft through the ventilation ducts. In order for air to be supplied to all rooms, to the lower part interior doors install gratings, or cut them by 1.5-2 cm.
Forced supply ventilation in the apartment useful in that clean air enters the apartment in any weather all year round. The unit operates silently, and due to the heating of the inflow, condensation and mold do not form in the room. The disadvantage of the system is an uncontrolled air outlet. If exhaust channels do not cope with the load, or there is no traction, the exhaust air begins to stagnate in the apartment.
Supply ventilation in the apartment
Full forced air exchange
To ensure the comfort of people living in the apartment, to create a microclimate favorable for their health, it is necessary to constantly supply fresh air from the outside and regularly remove processed masses. Forced-air ventilation is designed to ensure this. With the help of special installations, air is not only supplied / removed, but also undergoes multi-stage purification.
by the most effective way ventilation of the apartment is a forced-air supply and exhaust system with heat recovery. The air supplied from the street is heated by the masses removed, which saves 70-80% of the heat that could be used to heat it. IN summer time the fresh stream is cooled, which reduces the load on the air conditioner.
Forced supply and exhaust system
Forced supply and exhaust ventilation consists of:
- air ducts - networks of pipes and connecting elements, through which the masses enter and exit the premises;
- fans providing forced air supply and output;
- air intake grilles through which outdoor air enters the building;
- an air valve that prevents the entry of masses from the outside when the system is turned off;
- filters that ensure the quality of the supplied air;
- heater - a device that heats the flows entering the premises;
- recuperator - a special cylinder with many channels, where the supply air is heated by the heat of the exhaust;
- silencer;
- air intakes and distributors (vent grids);
- control systems - mechanical (represented by a switch), or automatic (consisting of hygro- and thermostats, pressure gauges that respond to changes in weather conditions in a certain area).
- safety system to prevent equipment overheating.
The power of the units is selected to ensure optimal air exchange in all rooms of the apartment. The equipment is installed in suspended ceilings, or a separate utility room (pantry, insulated balcony).
Stages of arranging the ventilation of an apartment
To organize ventilation, you must:
- analyze the feasibility and possibility of its use in the apartment. This will require expert judgment. The specialist will be able to evaluate the operation of the existing ventilation system, give recommendations on improving its operation, or installing forced installations, analyze the possibility of laying additional ventilation ducts;
- make calculations to determine the optimal air exchange in different rooms;
- determine the type of ventilation system that meets the conditions of a particular apartment;
- draw up a ventilation scheme, including network wiring, indicating the length and cross-section of air ducts, locations and dimensions of installations;
- buy necessary equipment, materials;
- install and configure the system.
Tip: the type of ventilation system, its calculation, selection and installation of equipment should be carried out by experienced specialists - this is a guarantee of arranging effective air exchange in the apartment, health, well-being of all inhabitants.
Air exchange in the apartment
Arrangement of exhaust ventilation in the kitchen
The kitchen room is designed for cooking, so it often has high humidity, various odors accumulate. To neutralize them, an exhaust hood is provided above the stove. But does it manage to ventilate the room?
Using a range hood
There are two ways to arrange the removal of used air from the kitchen room using an extractor hood:
- by changing the air. Fresh flow enters the room through leaks, or supply valves, and the exhaust is removed by the hood into the ventilation duct;
- by cleaning the air in the exhaust device and returning it back to the room. For this, recirculation type hoods are used.
These methods have one drawback - the hood removes only the exhaust air above the stove and nearby it, it cannot cover the entire kitchen space. Therefore, in addition to the exhaust hood, it is necessary to additionally organize the removal of exhaust air in the cooking room.
Other ways to organize kitchen ventilation
Ventilation ducts in apartments have a cross section of 130x130 mm, so their throughput is on average 130-180 m 3 / hour (maximum 300 m 3 / hour). If the exhaust power is higher, this will disrupt the functioning of the air exchange system in all apartments connected to this shaft (stagnation of air will appear, odors will spread).
It is possible to equip the ventilation of the kitchen natural way. To do this, the room must have two exhaust ducts - to remove the exhaust air above the stove and for the rest of the room.
Tip: if the system does not work naturally, it is forced to organize it by installing a fan in the ventilation duct.
Apartment ventilation is an important factor in ensuring a healthy and comfortable life for all its inhabitants, maintaining the integrity, presentable appearance of furniture and premises. Well-coordinated, thoughtful work of air exchange, air conditioning and heating systems will create a favorable microclimate in housing with minimal energy consumption.
The easiest way to ensure air exchange in the premises is natural ventilation. It does not require energy consumption and finds wide application both in private and multi-storey buildings. The comfort of living in the house depends on the quality of ventilation.
Human life is associated with various processes in which water vapor, carbon dioxide, unwanted odors, tobacco smoke and other pollutants. Due to the lack of ventilation, the humidity in living spaces becomes excessive, resulting in mold and an unhealthy atmosphere with stale air. Without ventilation, gas heaters, a fireplace or a stove cannot be installed.
Natural ventilation works due to the difference in pressure inside and outside the premises. Polluted air exits through the ventilation duct, and fresh outside air enters through leaks in windows and doors.
In apartment buildings, natural ventilation is predominantly used. In houses with less than 5 floors, each apartment has its own ventilation duct. Sometimes these channels can be common, but unite the apartments through the floor. Such ventilation ducts have access to the roof.
In multi-storey buildings with more than 5 floors, there is simply not enough space on the roof to locate all the ventilation outlets from each apartment on the roof. Therefore, all individual ventilation ducts are combined into one common one, which, in turn, goes to the roof. Such a system complies with fire regulations and is also more compact than an individual duct system.
Most often, the ventilation ducts in the attic go into a box of gypsum slag boards, from where the exhaust air is released into the atmosphere. For effective work natural ventilation, the attic must be warm enough, otherwise the air will cool and condense, which will cause the so-called. reversal of circulation.
IN brick walls ventilation ducts are made in the form of shafts specially left in the masonry. Their cross section is usually a multiple of half a brick. Wherein minimum cross section considered 140×140 mm. Some projects do not allow you to execute channels during internal walls, therefore, it is necessary to build attached structures, the minimum section of which is considered to be 100 × 150 mm.
In panel and block houses, ventilation ducts are placed in a special ventilation panel with round or square holes inside. The diameter of the circular channels is 150 mm.
Each functional room (in apartments - this is a kitchen, bathroom and toilet) should be equipped with a separate ventilation duct. Unite them common hood not recommended, because air distribution will be disturbed. The beginning of the channel is drawn up ventilation grill, adjustable (with valve and movable shutters) or unregulated.
One of the main advantages of natural ventilation is the lack of energy consumption during its operation. To maintain such a system, you only need to keep the channels clean. The disadvantage is the need for a relatively large cross-section of ventilation ducts compared to forced exhaust, as well as dependence on weather and wind. It is believed that the range of natural ventilation is limited to 6-8 meters.
The condition for good draft in the ventilation duct is a lower outside temperature compared to the temperature in the ventilated room. When outside temperatures rise above +5°C, the intensity of ventilation gradually begins to decrease and disappears at +25°C. Further growth outside temperature can cause reverse draft, but in the warm season, when the windows are open, this is not dangerous - the main thing is that air exchange is present.
The draft in the ventilation duct is also affected by the air permeability of window and door porches, the height of the house, the floor of the apartment, the layout and connection with the staircase and elevator assembly.
Natural ventilation works best in apartments oriented on two opposite sides, provided that the system is installed without errors. Moreover, it will work most of the year, and not just the most cold period. And yet, on hot summer days, only a strong wind can provide natural ventilation. Otherwise, all kitchen odors will have to be vented through open windows. The downside to ventilation is that odors can end up in living spaces where they are undesirable.
Some multi-storey buildings are equipped with a fan located in technical floor. The motor of this fan is spring-loaded, and due to this it does not cause concern to the residents of the upper floors. The presence of forced exhaust does not allow us to call such ventilation natural.
In developed countries, mechanical ventilation in multi-storey buildings is the rule rather than the exception. Such a system does not depend on weather conditions and seasons. But it requires the mandatory installation of supply air valves on window frames. In Russia, houses with roof fans are also available. These are houses of the I-700A series. However, during operation, they did not show themselves with better side. Basically, the problem of air exchange is noted there due to non-working roof fans. However, shortcomings in the design and installation of the system were also identified. 
The problem of insufficient draft in natural ventilation ducts can be solved by installing an axial fan in place of a conventional ventilation grill. However, such fans are not allowed to be used in rooms with geysers and boilers with an open combustion chamber. Forced exhaust can cause back draft in the chimney.
Calculation of the ventilation system
The dimensions and cross-section of ventilation ducts are calculated based on the standards for air exchange in residential and utility rooms. Thus, the air velocity in the channels during natural ventilation is no more than 1-2 m/s. This allows you to determine the required section of the ventilation duct, knowing that according to the standards, 60 m³ (electric stove) and 90 m³ (gas stove) should be removed from the kitchen; 25 m³ per hour should be removed from the toilet and bathroom, and if the bathroom is combined, then at least 25 m³ per hour. However, if at least one of the ventilation ducts is equipped with a fan, then the operation of the system will be unbalanced. And although the regulations do not directly prohibit this, nevertheless, it is better to consult with specialists when installing the hood.
Organization of air flow
The traditional wooden joinery, which is known to many from the Soviet past, was leaky, due to which it let out a sufficient amount of air necessary for normal air exchange. But after the mass replacement of the old wooden windows complaints about poor ventilation in housing and management companies have become more frequent. And this is not surprising, because natural ventilation cannot function without inflow. A plastic windows with double-glazed windows in the absence of ventilators and participation from the residents, they practically do not allow air to pass in either direction.
The reason for this problem lies in the fact that sealed double-glazed windows were originally developed for houses with mechanical ventilation
. As a result, a very contradictory situation develops, when we are first told that it is necessary to replace windows with energy-saving ones, but in the end it turns out that their tightness becomes unnecessary. But there is a way out - you need to order windows with built-in aeromats - special supply valves. These valves, working on the inflow, make it possible to regulate the incoming air flow up to its overlap. Aeromats should be embedded in window frames kitchens and other rooms connected through a doorway with hoods. There is no need to install them on glazed balconies, since the balcony block will interfere with the regulation of the inflow.
The airmat is mounted at the top of the window so that the cold incoming air is directed to the ceiling and mixed with the warmest air. If you install supply valves at the bottom of the window, then cold air will flow down the window sill and form a cold layer near the floor.
Air valves, as a rule, worsen the sound insulation of a window with sealed double-glazed windows. But there are special valves with increased sound insulation.
The need for ventilation of premises mainly arises when there is an excess of humidity. Therefore, in addition to conventional valves with manual adjustment, window companies are also ready to offer valves with automatic adjustment that respond to an increase in humidity. Such valves contribute to the conservation of heat in the house, since they are covered when no one is at home, and, accordingly, water vapor is not released.
Number of valves. For a room of 15-20 m², one supply valve with ceiling heights up to 3 m. With an increase in area for every 15 m², one more valve should be added.
Ventilation communication problem
Surely the residents apartment buildings Soviet development is familiar with the situation when “neighborly” smells get into the apartment. This is especially felt if people do not smoke, and tobacco smoke enters their apartment; or if they are not engaged in cooking, and the neighbors below are standing at the stove.
The reason for the penetration of odors lies in the presence of combined ventilation ducts and poor draft in them. If the draft is insufficient, and the neighbors below also have a kitchen hood inserted into the ventilation duct, then, of course, you will have all the smells. In this case, you can turn off your own hood, but this is not the best option. In accordance with building codes, it is impossible to combine the ventilation ducts of the last two floors, and the lower ones - only through the floor. If this norm is not violated, and the smells still go, then the cause of this may be the depressurization of the ventilation duct, as a result of which it began to communicate with the neighboring one. Exhaust air at certain conditions can penetrate through the holes that have appeared between adjacent ventilation ducts, and from it into your house.
Dealing with this phenomenon is quite difficult, but possible. It is best to contact specialists who inspect the ventilation duct of your apartment using a Ridgid-type inspection camera. If damage to the walls is found in the channel, then the designated places are repaired. If the channels are in order, then the matter is most likely in the incorrect design of the ventilation system. To get rid of other people's odors in your apartment, along with which it can also penetrate carbon monoxide, you will have to take drastic measures - to arrange a separate ventilation duct or, at worst, to combine the ventilation of the kitchen and bathroom.
Description:
The book reveals the basic principles of designing ventilation systems for multi-storey buildings, it presents methods for determining the required air exchange in rooms and calculations of air infiltration through fencing leaks, describes and evaluates ventilation systems in multi-storey residential buildings, and provides technical, economic and operational indicators of these systems.
Features of ventilation of high-rise residential buildings
The report was based on the materials of the book by I. F. Livchak a “Ventilation of multi-storey residential buildings”, which was published in 1951 by the State Publishing House of Architecture and Urban Planning.
The book reveals the basic principles of designing ventilation systems for multi-storey buildings, it presents methods for determining the required air exchange in rooms and calculations of air infiltration through fencing leaks, describes and evaluates ventilation systems in multi-storey residential buildings, and provides technical, economic and operational indicators of these systems.
Despite the fact that the book was published in 1951, it remains relevant to the present - because today issues related to the quality of indoor air, comfortable microclimate parameters of buildings and premises are of particular importance.
In this issue of the journal, we publish one of the chapters of this book - "Ventilation features of high-rise residential buildings", which was written by I. F. Livchak together with engineer T. A. Melik-Arkelyan.
High-rise buildings include houses above 15 floors, which, as a rule, have technical floors that divide the building in height into zones up to 10–12 floors high.
Technical floors have hermetic ceilings and partitions with hermetic doors on the stairwell, preventing air from flowing from the floors of the lower zone to the floors of the higher zone.
The high height of the building and its planning and operational features have a significant effect on ventilation performance. The main factors to be considered in the design of high-rise residential buildings include the following:
1. The possibility of increased air flow in winter from the lower floors to the upper ones due to the high height of the building and the influence of zones located one above the other. This position creates an increased infiltration of outside air into the lower floors of the zone.
2. Increased wind speeds at high altitudes from the ground. This creates increased outdoor air infiltration in the windward spaces of the upper floors.
3. Increased gravity pressure in the ventilation system due to the high height of the building, reaching up to 20 mm of water in 30-storey buildings. Art. at t n \u003d -15 ° C and falling to 7 mm of water. Art. at t n \u003d 5 ° C against 5–2 mm of water. Art. in multi-storey buildings of mass construction.
The magnitude of the available pressures makes it possible to use them as a good traction stimulator at low outside temperatures. At the same time, significant pressure fluctuations can create significant uneven ventilation.
4. The considerable length of the air ducts and, as a result, large hydraulic losses in them, which causes a decrease in the efficiency of the deflectors in the exhaust shafts.
5. The impossibility of airing sanitary facilities in the summer due to the lack of windows in them, as a rule.
It should be added to the noted factors that high-rise buildings, unlike ordinary mass construction buildings, are equipped with complex engineering equipment: vacuum cleaners, own telephone exchanges, garbage disposal, elevator facilities, water supply and heating pumping units, etc.
It's complicated engineering equipment necessitates the maintenance of technically qualified operating personnel, which can also be used in the operation of the ventilation systems of a residential building.
Therefore, for the buildings under consideration, mechanical ventilation is quite possible.
1. Choosing a ventilation system
Sanitary units
The inability to ventilate sanitary facilities through windows and the inefficient operation of deflectors lead to the need for mechanically driven exhaust ventilation in the sanitary facilities of high-rise buildings, because otherwise for a long period, at outdoor temperatures of 10-15 ° C and above, when gravity there is no pressure, these rooms will remain without ventilation.
So, for example, in Moscow, the average number of days with temperatures above 15 °C, according to long-term climatological observations, is 75.72; they occur mainly in May, June, July, August, September and partly in October. (In April, only 0.3 days have a temperature above 15 °C, and in October - 3.5 days.)
Kitchens ventilated by a common ventilation system with sanitary facilities are the main source of harmful emissions. These emissions, when opening kitchen windows located on the windward side, can spread into living rooms. Therefore, kitchens should also be equipped with mechanical ventilation.
Ventilating the kitchen and sanitary facilities with common exhaust systems will only simplify the ventilation system of the building as a whole.
Mechanical excitation in exhaust ventilation will make it possible to design ventilation systems with increased resistance to air passage, which will reduce bad influence changes in gravitational pressure.
So, for example, considering the performance of the ventilation system as proportional to the square root of the magnitude of the current pressure and the estimated resistance of the system is 30 mm of water. Art., we get an increase in productivity for a 30-storey building when the outside temperature changes from +5 to -5 ° C in
| 30+20 | =1.15 times | |
| 30+7 |
If the calculation was carried out only on the natural impulse at outdoor temperature 5 °C, then a corresponding increase in system performance would be
| 20 | =1.7 times | |
| 7 |
Such an increase in productivity (if the pressure is not regulated by throttling) would lead to excessive air exchange in the rooms, excessive fuel consumption or hypothermia of the premises.
The significant resistance of the mechanically driven exhaust ventilation system will also help to reduce excessive infiltration in windward rooms. With low resistance in the system, the outside air infiltrated into the rooms will relatively freely go into the exhaust ventilation, as a result of which the pressure inside the room will drop, and the pressure difference on both sides of the windward window will increase, which in turn will increase the infiltration of outside air.
Such a system will be most effective in windward apartments without through ventilation, located on high altitude, at high wind speeds.
Thus, the need for mechanically driven exhaust ventilation from kitchens and sanitary facilities is quite obvious.
living rooms
When analyzing work ventilation devices in mass construction houses, it was found insufficient to have exhaust ventilation with natural induction only from sanitary facilities (if not in living rooms).
If there is a guaranteed mechanical impulse on the hood from the sanitary facilities, a fan that develops a sufficiently large pressure can create the necessary vacuum in the apartment, suck in outside air through the slots of window openings and thus provide the required ventilation air exchange in the living rooms.
However, with such a system, blast from windows is inevitable, especially when low temperatures outside air.
In addition, the absence of special ventilation devices in living rooms can lead to a violation of normal temperature conditions.
In rooms with more breathable window sashes, air exchange will increase by reducing air exchange in rooms where sashes are less breathable.
Thus, stable air conditions in living rooms cannot be ensured, and they will depend on many random causes. Therefore, living rooms in high-rise buildings should not be left without special ventilation devices for inflow.
The simplest ventilation device for an organized flow of air into living rooms is the installation of crackers in the outer walls under the ceiling of the room. However, this does not exclude air blast in the room, and, in addition, cracker holes coming out of each room to the outer surface of the wall will spoil the facade of the building.
A more advanced device is the so-called window sill device, shown in Fig. 1 and 2.
Here, air is taken in through a slot under the 2.5 cm high fender metal shield of the window opening. Such a slot is completely invisible from the outside.
The air passes over the heater through a duct 3 made of thin stainless steel measuring 60 x 2.5 cm at the end of the duct, the air hits the vertical wall of the movable valve 2 and exits into the room from top to bottom. When entering the room, the supply air mixes with currents of ascending warm air from the heating device, as a result of which the blast is significantly reduced.
The advantage of the supply window sill is the ability to control the amount supply air, achieved by changing the width of the gap through which air enters the room. The gap is adjusted by a valve that moves in one direction or another when the adjusting screw 1 in the rack 4 is rotated.
On fig. 3 shows another device for a decentralized inflow of outside air into a room heated by a heater.
Air intake is also carried out under the metal canopy of the window. Further, the air is directed downwards, here it mixes with the air of the room, rises up, in contact with the radiator, heats up and exits the room.
On fig. 4 shows the possible positions of the control valve, with which (if necessary) you can adjust the degree of heating of the incoming air.
The inlet window sill device is much simpler than the device for air inflow discussed above with heating by its heating device (Fig. 3).
The weak point of the latter is a narrow valve through which air descends. It is possible to form dampness in it; in addition, this channel will become clogged over time, and cleaning it will be impossible.
Cleaning the supply window sill from dust (Fig. 2) does not cause any particular difficulties.
All considered options for decentralized inflow have common disadvantages: in them, the supply air enters the premises without the necessary purification. Cleaning is needed even for the upper floors, because in large industrial centers, even at high altitudes, the outside air, especially in winter period, turns out to be very dusty.
The second disadvantage of a decentralized inflow is the unevenness of its operation due to the action of the wind.
The overpressure and underpressure that occurs under the influence of wind at the outer surface of the building and, consequently, at the intake openings of the supply units, will increase and decrease the amount of supply air.
To reduce the effect of wind speed, special visors are installed on the ventilation openings from the outside. However, this measure does not bring significant results, since the ventilation hole remains unprotected from the static pressure that occurs under the influence of the wind.
Uneven air flow can be greatly reduced by increasing the resistance to air passage through the opening.
So, if the resistance of the inlet is taken equal to 0.5 mm of water. Art., then the additional pressure on the outer surface is about 0.25 mm of water. Art., formed, for example, by a wind speed of 3 m / s with an aerodynamic coefficient of 0.5, will increase the amount of supply air through the hole in
| 0,5+0,25 | =1.15 times | |
| 0,5 |
Thus, in a room where there is a decentralized inflow, a vacuum of about 0.5 mm of water should be maintained. Art., which is usually achieved by exhaust ventilation. Exhaust ventilation and decentralized air supply must be adjusted to this value.
The operation of a decentralized supply air device at a higher resistance is undesirable, since this causes an increase in vacuum in the apartment, which leads to a significant unorganized suction of air through the window slots.
Here it is appropriate to note that in order to ensure the suction of supply air through window slits in living rooms, in buildings equipped with exhaust ventilation and decentralized inflow, it is necessary to achieve the greatest possible sealing of windows, especially in kitchens.
More perfect is the centralized supply system, because it is free from the indicated disadvantages of a decentralized air supply to living rooms. It is centralized forced ventilation with mechanical stimulation that should be recommended for living rooms of high-rise buildings, although the construction of such a system is more expensive than a decentralized inflow device.
Mechanical drive in supply ventilation makes it possible to provide centralized cleaning of outdoor air in the supply chamber.
The increased resistance of the supply ventilation system, which is possible with mechanical stimulation, will reduce the adjustment required with a variable difference in the temperatures of the outdoor and indoor air.
The possibility of equipping living rooms with supply and exhaust ventilation, which provides inflow and exhaust from centralized supply and exhaust systems in each room, is not ruled out. However, such a solution cannot be considered economically feasible, since, in addition to a significant increase in one-time costs for the construction of ventilation and its complication, it will also increase operating costs due to an increase (approximately twice) in the total air exchange in the apartment.
2. Features of the calculation
The amount of fresh air entering the premises of high-rise residential buildings with the same population density should be the same as in residential buildings mass construction. However, the infiltration of fresh air, due to the increased wind speed at high altitudes and the influence of zones located one above the other, in high-rise buildings is different.
The intensity of infiltration depends on the wind, temperature difference, tightness of enclosing structures and many other factors, and for each building, depending on its planning features, the intensity of infiltration will be different.
According to the approximate calculations made by the authors, for three-four-room apartments without through ventilation, equipped with supply and exhaust ventilation and double apartment doors, in a 30-story building divided into three equal zones, the infiltration of outdoor air at an outdoor temperature of -5 °C and average wind speeds is expressed by the following average values:
The first zone (up to 40 m from the ground): wind speed 2–3 m/s; the average exchange rate created by the infiltrating outside air is 0.25, with an increase in the lower floors up to 0.3 and a decrease in the upper floors up to 0.2 rpm/h.
Second zone (40–80 m): wind speed 3–4 m/s; the average rate of exchange is 0.35 rpm/h, with an increase in the lower ones up to 0.4 and a decrease in the upper ones up to 0.3 rpm/h.
Third zone (80–120 m): wind speed 4–5 m/s; the average exchange rate is 0.45 rpm, with an increase in the lower floors up to 0.5, and in the upper floors up to 0.4 rpm.
The frequency of air exchanges in living rooms, created by supply and exhaust ventilation (with the above data), should be as follows:
In the first zone:
On the lower floors:
1.25 - 0.3 \u003d 0.95 rpm / h;
On the upper floors:
1.25 - 0.2 \u003d 1.05 rpm / h.
In the second zone:
On the lower floors:
1.25 - 0.4 \u003d 0.85 rpm / h;
On the upper floors:
1.25 - 0.3 \u003d 0.95 rpm / h.
In the third zone:
On the lower floors:
1.25 - 0.5 \u003d 0.75 rpm / h;
On the upper floors:
1.25 - 0.4 \u003d 0.85 rpm / h.
In all intermediate floors of each zone, the exchange rate can be determined by interpolation, rounded up to 0.05 rpm/h. Thus, the value of air exchange for living rooms of a multi-storey high-rise building is determined within the range of 0.75–1 rpm / h, which is recommended by the temporary technical conditions.
The frequency of exchange in kitchens and sanitary facilities should be taken the same as in residential buildings of mass construction. The amount of air extracted and supplied to the apartment should be the same.
The initial value for determining the cross section of the supply and exhaust ventilation ducts in high-rise buildings should be considered the air velocity, which is taken in such a way that, in the event of the fan being inactive, the system can operate on a natural impulse. For these reasons, the range of the ventilation system is desirable to have no more than 10–12 m.
To increase the resistance of the ventilation system during normal operation with an operating fan, a damper or throttle valve should be installed on each supply and exhaust duct. These control devices are installed in close proximity to the ventilation grill or at the junction of a group of channels.
Selection of fans for supply and exhaust ventilation is carried out according to pressure depending on the height of the building: at 20 floors, at least 20 mm of water. Art., at 30 floors not less than 30 mm of water. Art. etc.
Otherwise, the calculation of ventilation devices has no special features and is carried out in the usual way.
3. Design of the system
To reduce the number of ventilation chambers in high-rise buildings, it is allowed to connect apartments located in different zones to one chamber.
For ventilation to work on a natural impulse, the supply chamber is located below, and the exhaust chamber is located above the serviced premises. The location of the ventilation chambers can be the basement, technical floors and attics. In order to prevent tipping of the draft when the system is operating on a natural impulse, the exhaust air from the exhaust systems serving the rooms that communicate with each other must be at the same level.
The device of independent ventilation ducts from the chamber to the ventilated room and high-rise buildings with a large number of floors causes serious difficulties. Therefore, the following combinations of supply and exhaust channels are allowed:
a) serving living rooms - into one horizontal channel within one apartment;
b) serving bathrooms and toilets - into one horizontal channel within one apartment;
c) vertical channels - into one collection channel within the same zone.
It is also allowed to combine vertical exhaust ducts from homogeneous rooms into one duct with a gap through two floors within the zone, as is schematically shown in the section of the building shown in Fig. 5. Such a combination can be allowed in exceptional cases, since under adverse conditions air can flow from one apartment to another. In any case, such a combination of channels serving rooms overlooking opposite sides should not be allowed.
Vertical supply and exhaust ducts are recommended to be located mainly in walls or in special shafts made of fireproof materials.
As materials for air ducts, the use of cinder concrete is allowed - for channels large sections and gypsum - for dry air in a dry place; asbestos-cement channels are allowed provided that they are protected from destruction in case of fire.
The use of metal ducts is not recommended. On fig. 6, 7 shows an example of a solution supply and exhaust ventilation 48 apartments located between two stairwells 24-storey building, divided into three zones.
The heating of the supply air, carried out in the supply chamber, can be carried out by a plate heater or a heater from smooth radiators or pipes. A plate heater is more compact than a heater made of smooth radiators or pipes, but the resistance in it is much greater, which eliminates the possibility of heating the air when the fan is inactive, when the ventilation system works on natural impulse.
The installation of heaters should be done in such a way that it is possible to clean its entire surface from dust.
Air purification from dust is carried out using oil paper or cloth filters. The first, more difficult to operate, give better cleaning than the latter, which are easier to use.
It should be noted that the air resistance when passing through the filters reaches 10 mm of water. Art., which excludes the possibility of normal operation of the system when the fan is idle.
If outside air is taken for ventilation at a height of more than 50 m, then special cleaning of it from dust is not necessary.
In the duct layout of both the supply and exhaust ventilation systems, it should be possible to pass air, in addition to the fan, through the bypass valve, so that when the fan is inactive (an accident or a temporary break), the system can work on natural impulse.
To reduce noise, it is recommended to install fans with a motor on the same axis, and in case of impossibility - on a textrope gear. The circumferential speed of the wheel of centrifugal fans should not exceed 18 m/s when installed in the basement and 15 m/s when installed in technical floors.
In addition to the above restrictions, to prevent noise transmission, it is recommended to install an independent foundation under the fan and motor, not connected to the walls of the building, install sound and vibration insulating pads between the foundation and the fan, and connect fans to air ducts using flexible pipes. To eliminate the transmission of sound through the air path, it is planned to install silencers in the air ducts.
To facilitate maintenance a large number located in different places ventilation units it is recommended to concentrate the push-button starters of all electric fans in one control center. In the same place, it is necessary to include devices for controlling the operation of fans in the electrical circuit.
It is desirable to have instruments in the control center that show the temperature and humidity of the supply air entering the chambers.
For inspection and cleaning of ventilation ducts, it is recommended to install special inspection hatches in them.
It is most expedient to place hatches in the technical floor, in the attic or in the lower floor, at the point where the vertical ducts are connected to the common collection duct.
Mounting adjustment dampers are installed on the vertical ducts at the point of their connection to the collection duct.
The laying of ventilation ducts and the installation of supply exhaust grilles in high-rise residential buildings is carried out in the same way as for residential buildings of mass construction.
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