Do you dream that the house had a healthy microclimate and in no room did it smell of musty and damp? To make the house truly comfortable, it is necessary to conduct a competent calculation of ventilation at the design stage.
If during the construction of the house you miss this important point, you will have to solve a number of problems in the future: from removing mold in the bathroom to new repairs and installing an air duct system. You must admit that it is not too pleasant to see black seedlings in the kitchen on the windowsill or in the corners of the children's room, and to plunge into repair work again.
In the article we presented, useful materials for calculating ventilation systems, reference tables are collected. Formulas, illustrative illustrations and a real example for rooms for various purposes and a certain area, shown in the video are given.
Causes of ventilation problems
With proper calculations and proper installation, ventilation of the house is carried out in a suitable mode. This means that the air in the living area will be fresh, with normal humidity and no unpleasant odors.
If the opposite picture is observed, for example, constant stuffiness, mold in the bathroom or other negative phenomena, then you need to check the condition of the ventilation system.
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Private loft ventilation
Ventkanal in the overlapping frame house
Supply and exhaust system components
Ventilation paired with air conditioning
Ventilation grille and exhaust outlet
Exhaust fan in the bathroom
Roof ventilation
Basement supply pipe
A lot of problems are caused by the absence of the finest gaps characteristic of windows and doors, provoked by the installation of sealed plastic structures. In this case, too little fresh air enters the house, you need to take care of its influx.
Clogging and depressurization of ducts can cause serious problems with the removal of exhaust air, which is saturated with unpleasant odors, as well as excess water vapor.
As a result, fungal colonies may appear in office premises, which is bad for people's health and can provoke a number of serious diseases.
Misty windows, mold and mildew in the bathroom, stuffiness are all clear signs that the living spaces are not properly ventilated
But it also happens that the elements of the ventilation system work perfectly, but the problems described above remain unresolved. Perhaps the calculations of the ventilation system for a particular house or apartment were carried out incorrectly.
It can negatively affect the ventilation of rooms, their alteration, redevelopment, the appearance of extensions, the installation of plastic windows already mentioned earlier, etc. With such significant changes, it does not place to re-perform calculations and upgrade the existing ventilation system in accordance with new data.
One simple way to detect ventilation problems is to check for draft. A lit match or sheet of tissue paper should be brought to the grill of the exhaust outlet. You should not use open fire for such a test if gas heating equipment is used in the room.
Too tight internal doors can interfere with normal air circulation around the house, special grilles or holes will help solve the problem
If the flame or paper confidently deviates towards the hood, there is draft, if this does not happen or the deviation is weak, irregular, the problem with the discharge of exhaust air becomes obvious. The cause may be blockages or damage to the duct as a result of inept repair.
It is not always possible to eliminate the breakdown, the solution to the problem often becomes the installation of additional exhaust ventilation equipment. Before installing them, it also does not hurt to make the necessary calculations.
To determine the presence or absence of normal draft in the exhaust ventilation system at home, you can use a flame or a sheet of thin paper
How to calculate air exchange?
All calculations for ventilation systems are reduced to determining the volume of air in the room. As such a room can be considered as a separate room, or a set of rooms in a particular house or apartment.
Based on these data, as well as information from regulatory documents, the basic parameters of the ventilation system are calculated, such as the number and cross-section of air ducts, fan power, etc.
There are specialized calculation methods that allow you to calculate not only the renewal of air masses in the room, but also the removal of thermal energy, change in humidity, removal of pollution, etc. Similar calculations are usually performed for buildings of industrial, social or any specialized purpose.
If there is a need or desire to perform such detailed calculations, it is best to contact an engineer who has studied such methods.
For independent calculations on residential premises, use the following options:
- by multiplicities;
- according to sanitary standards;
- by area.
All these techniques are relatively simple, having understood their essence, even a layman can calculate the main parameters of his ventilation system. The easiest way is to use area calculations. The following norm is taken as a basis: every hour, three cubic meters of fresh air for each square meter of area should enter the house.
The number of people who permanently live in the house is not taken into account.
The ventilation system in residential buildings is arranged so that air enters through the bedroom and living room, and is removed from the kitchen and bathroom
Calculation of sanitary standards is also relatively simple. In this case, not the area is used for the calculations, but the data on the number of permanent and temporary residents.
For each resident, it is necessary to provide an influx of fresh air in the amount of 60 cubic meters per hour. If temporary visitors are regularly present in the room, then for each such person you need to add another 20 cubic meters per hour.
A little more complicated is the calculation of the frequency of air exchange. During its implementation, the purpose of each individual room and the standards for the frequency of air exchange for each of them are taken into account.
The multiplicity of air exchange is called the coefficient reflecting the amount of complete replacement of exhaust air in the room within one hour. The relevant information is contained in a special regulatory table (SNiP 2.08.01-89 * Residential buildings, adj. 4).
Using this table, the calculation of ventilation at home is performed according to multiplicities. Corresponding coefficients reflect the rate of air exchange per unit of time depending on the purpose of the room
Calculate the amount of air that needs to be updated within an hour, using the formula:
L = N * V,
Where:
- N - the rate of air exchange per hour, taken from the table;
- V - volume of the room, cubic meters
The volume of each room is very simple to calculate, for this you need to multiply the area of the room by its height. Then, for each room, the volume of air exchange per hour is calculated according to the above formula.
The L indicator for each room is summed up, the final value allows you to get an idea of how much fresh air should enter the room per unit of time.
Of course, exactly the same amount of exhaust air must be removed through the exhaust ducts. In the same room do not install both supply and exhaust ventilation. Typically, air is supplied through “clean” rooms: bedroom, nursery, living room, study, etc.
Exhaust ventilation in the bathroom or bathroom is installed at the top of the wall, the built-in fan works automatically
They remove air from service rooms: bathrooms, bathtubs, kitchens, etc. This is reasonable, because the unpleasant odors characteristic of these rooms do not spread throughout the house, but are immediately brought out, which makes living in the house more comfortable.
Therefore, in the calculations they take the standard only for supply or only for exhaust ventilation, as reflected in the normative table.
If air does not need to be supplied to a specific room or removed from it, a dash appears in the corresponding box. For some rooms, the minimum value of the air exchange rate is indicated. If the calculated value is below the minimum, use the tabulated value for the calculations.
If ventilation problems are detected after the repair in the house has been carried out, you can install the supply and exhaust valves in the wall
Of course, in the house there may be premises whose purpose is not displayed in the table. In such cases, the standards adopted for residential premises are used, i.e. 3 cubic meters per square meter of room. You just need to multiply the area of the room by 3, take the resulting value as the standard rate of air exchange.
All values of the air exchange rate L should be rounded up so that they are a multiple of five. Now you need to calculate the sum of the multiplicity of air exchange L for the rooms through which the air flow is carried out. Separately summarize the air exchange rate L of those rooms from which the exhaust air is removed.
If the result of the calculation does not meet sanitary requirements, a supply valve, breather or hood is installed through the wall, the existing system is modernized, or it is cleaned.
Cold outdoor air can adversely affect the quality of heating in the house, for such situations use ventilation devices with a recuperator
Then you should compare these two indicators. If L by inflow is higher than L by exhaust, then you need to increase the indicators for those rooms for which the minimum values were used in the calculations.
Examples of calculating the volume of air exchange
In order to calculate for a ventilation system by multiples, first you need to make a list of all the rooms in the house, write down their area and ceiling height.
For example, in a hypothetical house there are the following premises:
- Bedroom - 27 sq.m .;
- Living room - 38 sq.m .;
- Cabinet - 18 sq.m .;
- Children's - 12 sq.m .;
- Kitchen - 20 sq.m .;
- Bathroom - 3 sq.m .;
- Bathroom - 4 sq.m .;
- Corridor - 8 sq.m.
Given that the ceiling height in all rooms is three meters, we calculate the corresponding air volumes:
- Bedroom - 81 cubic meters .;
- Living room - 114 cubic meters .;
- Cabinet - 54 cubic meters .;
- Children - 36 cubic meters .;
- Kitchen - 60 cubic meters .;
- Bathroom - 9 cubic meters .;
- Bathroom - 12 cubic meters .;
- Corridor - 24 cubic meters
Now, using the table above, you need to calculate the ventilation of the room taking into account the frequency of air exchange, increasing each indicator to a multiple of five:
- Bedroom - 81 cubic meters * 1 = 85 cubic meters .;
- Living room - 38 sq.m. * 3 = 115 cubic meters .;
- Cabinet - 54 cubic meters * 1 = 55 cubic meters .;
- Children - 36 cubic meters * 1 = 40 cubic meters .;
- Kitchen - 60 cubic meters - not less than 90 cubic meters;
- Bathroom - 9 cubic meters not less than 50 cubic meters;
- Bathroom - 12 cubic meters not less than 25 cubic meters
There are no information on the standards for the corridor in the table, therefore, the data for this small room are not taken into account in the calculation. For the living room, a calculation is made according to the area, taking into account the standard of three cubic meters. meters per square meter.
A properly organized ventilation system will ensure adequate air circulation in the living room. When designing, the requirements and norms of SNiPs must be taken into account
Now you need to separately summarize the information on the rooms in which air is supplied, and separately - the rooms where exhaust ventilation devices are installed.
Volume of air exchange by inflow:
- Bedroom - 81 cubic meters * 1 = 85 cubic meters / h .;
- Living room - 38 sq.m. * 3 = 115 cubic meters / h;
- Cabinet - 54 cubic meters * 1 = 55 cubic meters / h;
- Children - 36 cubic meters * 1 = 40 cubic meters / h;
Total: 295 cubic meters h.
Air exhaust volume:
- Kitchen - 60 cubic meters - not less than 90 m3 / h;
- Bathroom - 9 cubic meters - not less than 50 m3 / h;
- Bathroom - 12 cubic meters - not less than 25 m3 / h.
Total: 165 m3 / h
Now you should compare the amounts received. Obviously, the required inflow exceeds the exhaust by 130 cubic meters per hour (295 cubic meters per hour-165 cubic meters per hour).
To eliminate this difference, you need to increase the exhaust air exchange, for example, by increasing the performance in the kitchen. In practice, this is done, for example, by replacing air ducts with larger channels.
The rules for calculating the area of air channels for replacing or upgrading the ventilation system are given here. We recommend that you familiarize yourself with useful material.
After editing, the calculation results will look as follows:
Inflow air volume:
- Bedroom - 81 cubic meters * 1 = 85 cubic meters / h .;
- Living room - 38 sq.m. * 3 = 115 cubic meters / h;
- Cabinet - 54 cubic meters * 1 = 55 cubic meters / h;
- Children - 36 cubic meters * 1 = 40 cubic meters / h;
Total: 295 cubic meters h.
Air exhaust volume:
- Kitchen - 60 cubic meters - 220 m3 / h;
- Bathroom - 9 cubic meters - not less than 25 m3 / h.
Total: 295 m3 / h
The volumes of inflow and exhaust are equal, which meets the requirements in the calculation of air exchange by multiplicity.
Calculation of the ventilation system for the kitchen is also extremely important. Especially if you use gas cooking equipment there
Calculation of air exchange in accordance with sanitary standards is much simpler. Suppose that in the house discussed above, two people live permanently and two more are in the room irregularly.
The calculation is carried out separately for each room in accordance with the norm of 60 cubic meters per person for permanent residents and 20 cubic meters per hour for temporary visitors:
- Bedroom - 2 people * 60 = 120 cubic meters hour;
- Cabinet - 1 person * 60 = 60 cubic meters hour;
- Living room 2 people * 60 + 2 people * 20 = 160 cubic meters hour;
- Children 1 pers. * 60 = 60 cubic meters hour.
Total by inflow - 400 cubic meters hour.
For the number of permanent and temporary inhabitants of the house there are no strict rules; these figures are determined based on the real situation and common sense.
A sufficient amount of air entering the bathroom in a timely manner, as well as timely evacuation of the exhaust air, helps prevent the formation of stale air and the appearance of moldy mushrooms.
The hood is calculated according to the standards set forth in the table above, and increased to the total inflow rate:
- Kitchen - 60 cubic meters - 300 m3 / h;
- Bathroom - 9 cubic meters - not less than 50 m3 / h.
Total hood: 400 m3 / h.
Increased air exchange for the kitchen and bathroom. Insufficient exhaust hood volume can be divided between all rooms in which exhaust ventilation is installed. Or increase this indicator for only one room, as was done when calculating by multiples.
In accordance with sanitary standards, air exchange is calculated in a similar way. Let's say the area of the house is 130 sq.m. Then the air exchange along the inflow should be 130 sq.m * 3 cubic meters hour = 390 cubic meters hour.
It remains to distribute this volume into the rooms by hood, for example, in this way:
- Kitchen - 60 cubic meters - 290 m3 / h;
- Bathroom - 9 cubic meters - not less than 50 m3 / h.
Total hood: 390 m3 / h
The balance of air exchange is one of the main indicators in the design of ventilation systems. Further calculations are based on this information.
How to choose a duct section?
The ventilation system, as you know, can be channel or non-channel. In the first case, you need to choose the right section of the channels.If a decision is made to install structures with a rectangular section, then the ratio of its length and width should approach 3: 1.
The length and width of the cross-section of the ducts with a rectangular configuration should be correlated as three to one in order to reduce the amount of noise
The standard speed of movement of air masses along the main ventilation duct should be about five meters per second, and on branches - up to three meters per second. This ensures that the system works with minimal noise. The speed of air movement largely depends on the cross-sectional area of the duct.
To choose the dimensions of the structure, you can use special calculation tables. In such a table, you need to select the air exchange volume on the left, for example, 400 cubic meters h, and select the speed value on top - five meters per second.
Then you need to find the intersection of the horizontal line in air exchange with the vertical line in speed.
Using this diagram, the cross section of the ducts for the duct ventilation system is calculated. The speed of movement in the main channel should not exceed 5 m / s
From this intersection, draw a line down to the curve by which a suitable section can be determined. For a rectangular duct, this will be the value of the area, and for a round one, the diameter in millimeters. First, calculations are made for the main duct, and then for the branches.
Thus, the calculations are done if only one exhaust duct is planned in the house. If it is supposed to install several exhaust ducts, then the total exhaust duct volume should be divided by the number of ducts, and then carry out calculations according to the stated principle.
This table allows you to choose the cross section of the duct for duct ventilation, taking into account the volume and speed of movement of air masses
In addition, there are specialized costing programs with which you can perform similar calculations. For apartments and residential buildings, such programs can be even more convenient, since they give a more accurate result.
Normal air exchange is influenced by a phenomenon such as reverse draft, the specificity of which and the methods of dealing with it will be introduced by the article recommended by us.
Clip # 1. Useful information on the principles of operation of the ventilation system:
Clip # 2. Together with the exhaust air, the house leaves and heat. Here, the calculations of heat losses associated with the operation of the ventilation system are clearly demonstrated:
The correct calculation of ventilation is the basis of its successful functioning and the key to a favorable microclimate in a house or apartment. Knowing the basic parameters on which such calculations are based will allow not only to correctly design the ventilation system during construction, but also to adjust its condition if circumstances change.
Do you want to share your own experience in the calculation and construction of ventilation? Having questions while reading the information? Found flaws in the text? Please write comments in the block under the text of the article.