Standards for air exchange rates in various rooms + calculation examples

If you are building a private home or a building for your business, you have probably encountered many standards and would like to forget about them.But safety has to come first, right? If you are thinking of starting construction or making artificial ventilation for a finished facility, then take a look at the norms for the air exchange rate in rooms that we have given in this article. Achieving a high-quality result is not so difficult if you pay due attention to everything. Do you agree?

From the article you will learn what air exchange is, how it is measured and what regulatory documents exist in this area. Read also about the norms for specific premises. Here you will find examples of calculating the air exchange rate.

Air exchange rate and its significance

Air exchange - a quantitative value reflecting the operation of the ventilation system in a closed space.

Multiplicity — an indicator of air mass replacement per unit of time, included in the design of buildings and ventilation systems. Before choosing a multiplicity indicator, you should familiarize yourself with the rules and understand the calculation methods.

A simple scheme of air exchange in an apartment/house: for technical rooms, air removal is more important, for residential rooms - inflow, and the flow between rooms replenishes the missing amounts of air

The air exchange rate is a sanitary indicator of the state of the air mass in the room. The safety and comfort of people depends on this parameter. Acceptable values ​​are regulated by the state - in building codes and regulations (SNiP), codes of practice (SP), sanitary rules and regulations (SanPiN) and GOSTs.The air exchange rate shows how many times during an hour the air was replaced with a new one.

SNiPs for air replacement are based on the following nuances:

• purpose of the building/premises;
• air temperature and humidity;
• quality, intensity and throughput of natural ventilation;
• the number of residents, workers and other people permanently or temporarily located in the premises;
• heat output of operating appliances;
• number of household appliances.

There are 2 types of air exchange: natural and artificial. The natural way exchange consists in the movement of air masses due to pressure differences. From points with high pressure to places with less. Artificial air exchange involves the operation of fans, air conditioners and other electrical devices.

The formula for the air exchange rate looks like this:

N = Q air / V room, Where:

N or n - frequency (once per hour);
Q air - the required amount of fresh air per hour, m³/h;
V room - volume of the room, m³; if the room has a complex shape, the volume should be determined together with specialists.

Natural air replacement is limited to 3-4 times, so its movement sometimes has to be enhanced by mechanical ventilation.

Supply and exhaust ventilation device (from 1 to 10): air intake, cleaning, air ducts, supply fan, air supply device, air removal device, exhaust fan, dust and gas collectors, filters, air exhaust device

Ventilation systems operate according to 2 schemes: they displace old air with new air or mix both of these masses.

For systems operating only to remove air, the basic formula for the expansion ratio is as follows:

N = V y. V. /V pom, Where:

V y. V.— volume of air removed, m³/h;
V room is the volume of the room, m³.

The volume removed should include thermal emissions and volatile harmful substances.

For supply and exhaust ventilation, separate multiplicity indicators are also calculated.

For example, for a supply system it is defined as follows:

N pr = L pr / V room, Where:

L pr - productivity of the supply system, m³/h;
V room is the volume of the room, m³.

A separate multiplicity rate for exhaust ventilation is usually 1 or 2 units per hour higher than for supply ventilation, but in some medical premises it is the other way around. The total multiplicity is always measured by the larger index.

The air exchange rate given in SNiPs and sanitary standards has 4 expressions:

• number of times per hour;
• cubic meters per hour - usually for standard-sized rooms;
• cubic meters per hour per person;
• cubic meters per hour per square meter.

The last two indicators are specific air exchange rates for rooms where the presence of people plays a large role. Calculation per person can be useful in production workshops, shops and hospitals. At these sites, the number of people can be counted and the average number of visitors can be established.

60 m³/h should be allocated for one employee, and 20 m³/h for a temporary visitor. The specific multiplicity acts as an informative indicator, provided that the dimensions of the room are close to standard.

Air exchange in the room: Q ex - excess heat generation, G - harmful gases or vapors, V - room volume, q pr - concentration of harmful gases or vapors in the incoming air, q ex - the same, but in the exhaust air, t pr - incoming air temperature air, t out - outgoing

There is also an air exchange coefficient, determined by the formula:

E = T / (2 × Y) × 100%, Where:

T is the volume of the room or incoming air;
Y is the air replacement time.

The coefficient can also be called air replacement quality. The indicator reaches 100% in ventilation that removes old air, and 50% in a ventilation system that mixes air masses.

According to the air exchange rate standards, the required ventilation performance is determined.

The formula looks like this:

L = n × V room, Where:

L—productivity, m³/h;
n — standard frequency (once per hour);
V room is the volume of the room, m³.

The default multiplicity standard is 1-2 times for living rooms and 2-3 for office premises. For bathrooms, the air change rate starts from 3-5, and for kitchens - from 5-10.

Norms of air exchange rate for premises

The insulated and sealed construction of houses leads to a decrease in the air replacement rate. As a result, harmful microorganisms multiply more intensively, and general hygiene deteriorates.

The norms and regulations display critical values ​​for air exchange, failure to comply with which will definitely lead to problems.

Air exchange using the example of a basement: to achieve the required expansion ratio, you need several inlet openings and a deflector on the outlet pipe to enhance the outflow

For apartment buildings, various rooms and buildings have established air exchange rate standards - in SP 54.13330.2016.

The following requirements apply to individual rooms:

• kitchen with gas-using equipment - 80-100 m³/h;
• kitchen with electric stove and without gas appliances - 60 m³/h;
• bath/shower/toilet – 25 m³/h;
• combined bathroom - 50 m³/h;
• general washing, drying, ironing - 7;
• hall or corridor in an apartment building - 3;
• living room in an apartment (children's room, bedroom) - 3 m³/h per 1 m²; 30 m³/h per person, but not less than 0.35 times per hour of the volume of the room;
• staircase - 3;
• wardrobe in the dormitory - 1.5;
• elevator machine room - 1;
• a room with a heat generator with a heating capacity of up to 50 kW - 1 m³/h for a closed combustion chamber and 100 m³/h for an open one;
• pantry for household items, sports equipment - 0.5.

If you install a gas stove in a room with a heat generator, you will need an additional 100 m³/h of air exchange.

For premises for different purposes, the multiplicity is selected according to SP 60.13330.2016, SP 118.13330.2012 And SP 44.13330.2011.

To measure the air exchange rate in rooms and technical rooms with non-standard layout or dimensions, use Sanitary Regulations and adjust the result based on your own calculations.

In restaurants, it is worth placing both supply and exhaust ventilation above each heat source, and if these air ducts are located at the top, then the temperature contrast between the internal and incoming air should not exceed 6 ° C

Modern buildings are equipped with autonomous air valves, which eliminate stagnant air masses. Apartment owners can regulate them.

Additional ventilation devices resolve issues with maximum permissible concentrations of harmful substances. In residential buildings and public institutions, acceptable values ​​are considered to be 0.1 mg/m³ for ozone and 0.005 mg/m³ for chlorine-containing compounds.

Residents will be even safer if they have strong mechanical ventilation.

Workshops and industrial premises

In industrial premises, conditions are more difficult and sometimes harmful. The air exchange rate in workshops should be several times higher than the parameters for other rooms.

Industrial premises require high-power air exchange with a high frequency rate, and it is calculated based on excess moisture, excess heat, explosive and harmful substances, and emissions from personnel

Factors in selecting the correct workshop ventilation rate:

1. Humidity percentage, excess moisture in the air. This primarily concerns enterprises that use liquids in technological processes.
2. Thermal energy generated by equipment. Excess heat from industrial machines must be eliminated through natural and mechanical ventilation.
3. Level of pollution and features of technological processes. For each chemical compound there is a maximum permissible concentration. Air exchange is designed to ensure that the main harmful substances are present in the air in minimal quantities.
4. Labor intensity. Heavy physical activity and intense mental work will become easier and more manageable with a high content of fresh air. In the case of physical labor, it is also about safety.
5. The number of people working in the room at one time and throughout the day.Each employee should be provided with air based on the average requirement for 1 person.

The shape of the workshop and its volume are also important. The first parameter affects the movement of air masses, the second - the need for air.

You will have to take into account air stagnation and turbulence.

Shops can be painting, welding, mechanical assembly and mechanical: from these rooms it is necessary to remove convective and radiant heat, smoke, compounds with inert gases and various impurities

For industrial facilities with hazardous and volatile chemicals. connections require 45-fold exchange. Dyeing shops - 40. In rooms where workers significantly use physical force, the air needs to be renewed 35 times per hour.

On production sites where the work process does not include complex work and frequent use of physical effort - 30. In workshops where work involves light physical activity - 25.

The air exchange rate for industrial premises is indicated in SP 118.13330.2012, as well as in SP 60.13330.2012 and SP 60.13330.2016 - updated editions SNiP 41-01-2003.

Medical organizations and hospitals

In healthcare organizations, the quality of air affects the lives of patients and the speed of their recovery. In children's hospitals, even more attention should be paid to this. The frequency of air changes for medical institutions is regulated by SP 158.13330.2014.

Rooms for infectious patients are in greatest need of air replacement. The required air exchange rate for them is 160 m³/h per person. Wards for other patients (children and adults) require an air exchange rate of 80 m³/h per person.

Indicators in m³/h per person provide more guarantee that this air exchange rate will be enough to maintain and improve the health of those being treated.

For doctors' offices and laboratory assistants, 60 m³/h per person is enough. The same amount of new air is required in rooms for acupuncture and manual therapy, gyms for physical therapy, as well as in offices with permanent workplaces.

If the frequency of air replacement in a hospital is correct, then the ideal chemical and microbiological composition of the air will be ensured with a minimum level of noise and vibration

In many cases, it is possible to do without high-intensity air exchange, as well as without specific standards. In tomography rooms and treatment rooms for administering radiopharmaceuticals, 6 air changes are sufficient.

Five times an hour it is necessary to refresh the air in dirty areas of the DSO/CSO, rooms for sanitary treatment of patients, rooms for storing disinfectants, sorting used linen, processing and washing dishes.

In rooms where drugs and sterile materials are stored, a 4-fold change of air is needed. The same amount of new air is needed in treatment rooms and rooms equipped for fluorographic and x-ray diagnostic examinations.

Renewing air three times is considered the norm for small workshops for servicing medical equipment, clinical laboratory rooms, and clean areas of the sterilization department.

The same standards apply to rooms for sorting tests, halls, functional and ultrasound diagnostic rooms.

In the resuscitation and intensive care department, air exchange is designed to prevent the spread of combustion products, and fire dampers also help with this

For buffets and eating areas in hospitals, a 2-fold air exchange is required. Just 1 air update per hour is enough for small offices where there is not a single permanent workplace.

The same amount is enough for small warehouses with equipment and clean materials, lobbies on the ground floor, archives, reference rooms, dressing rooms and storerooms.

Offices and business centers

Offices and administrative buildings require more fresh air than individual housing. The reason for this is the large amount of office equipment, intense mental activity and customer service standards.

Criteria for ventilation in offices:

• large size of ventilation ducts;
• availability of mechanical and natural ventilation;
• effective aeration with low energy consumption;
• flexible control of the ventilation system: the ability to adjust and configure it to suit external weather conditions;
• convenient placement of mechanical and natural ventilation elements for carrying out repair and installation work of various types;
• the use of silent equipment or sound insulation;
• high-quality exhaust and forced ventilation;
• constant supply of fresh air, ideally from the street.

The new air must effectively remove vapors. It is worth paying attention to humidifying and purifying the air, cooling or warming it before supplying it to the premises.

In large office rooms, a developed system of general and local ventilation is installed with valves, air distributors, heaters, thermal insulation and automatic control

In a workroom, 1 employee needs at least 20 m³/h. In conference rooms the same amount is allocated for each visitor. Intensive air exchange should be ensured in washrooms and sanitary rooms - up to 15 air updates per hour.

Smoking areas will require a 10-fold exchange. In the office of the manager/managers, the air exchange rate is required at level 3, in technical rooms - 1, in rooms with filing cabinets and storage rooms - 0.5. The standards for offices are in SP 118.13330.2012 and the international standard ASHRAE 62-1-2004.

Examples of calculating air exchange rates

Let's take as an example a room with a height of 3.5 m and an area of ​​60 m², where 15 people work. We believe that the air is polluted only from an increase in the concentration of carbon dioxide due to breathing.

First we find room volume: V = 3.5 m × 60 m² = 210 m³.

Consider that the average person emits 22.6 liters of carbon dioxide per hour.

We get that harmful secretions can be calculated by the formula B = 22.6 × n, where n corresponds to the number of people in the room.

B = 22.6 l/h × 15 = 339 l/h

For indoors, the maximum permissible concentration of carbon dioxide is 1/1000, or 0.1%. Let's convert this to 1 l/m³. There is about 0.035% carbon dioxide in pure air. Convert to 0.35 l/m³.

Let's calculate how much fresh air will be needed for all 15 people:

Q = 339 l/h: 1 l/m³ – 0.35 l/m³ = 339 l/h: 0.65 l/m³ = 521.5 m³/h. In this case, cubic meters became the numerator, and hours, on the contrary, became the denominator.

In addition to the calculation of harmful substances, the air exchange rate is important when regulating the amount of moisture and heat in the room: the corresponding formulas are shown in this image

We define air exchange rate:

N = 521.5 m³/h: 210 m³ = 2.48 times per hour.It turns out that with an air change of 2.48 times per hour, the concentration of carbon dioxide will remain within normal limits.

Let's find it now specific air replacement rate for 1 person and 1 m². The volume of the room must be at least 210 m³, and the ceiling height must be at least 3.5 m.

521.5 m³/h: 15 people. = 34.7 m³/h per 1 person

521.5 m³/h: 60 m² = 8.7 m³/h per 1 m² area

Harmful secretions (B) is also calculated using the formula:

B = a × b × V × n, where:

a is the infiltration coefficient;
b—carbon dioxide concentration, l/m³ for 1 hour;
V—room volume, m³;
n is the number of people.

The content of substances can be measured in grams rather than in liters - this will be better for safety.

Conclusions and useful video on the topic

Air exchange rate for different store premises + drawing:

Application for calculating air exchange for various rooms:

Basic values ​​for the ventilation system, air flow:

The air exchange rate reflects the room's need for the amount of air at which it functions normally. Air changeability is expressed in the number of times per hour or cubic meters for the same period. There are also specific values ​​for 1 person and 1 square meter.

The greatest need for fresh air is in hospitals, hazardous industries and public places. Life sometimes depends on the minimum air exchange rate, so use not only the standards, but also calculate everything yourself and invite specialists.

Do you have questions about the air exchange rate or related parameters? Submit them in the form below the article. You can also exchange valuable information with other readers. Perhaps your personal experience in this matter will be useful to someone.