Standards for air exchange rates in industrial premises: description and calculation. Sanitary and hygienic requirements for ventilation Supply and exhaust ventilation Sanpin standards

Work ability office worker directly depends on the indoor microclimate. According to the data medical research, the air temperature in the office should not exceed 26 degrees, whereas in practice in buildings with panoramic windows and with the abundance of technology it can go off scale beyond 30 degrees. In the heat, the reaction of employees is dulled, and fatigue increases. Cold also has a bad effect on work ability, causing drowsiness and lethargy. Lack of oxygen and high humidity create unbearable conditions for employees, reducing labor productivity, and hence the profitability of the enterprise.

To maintain optimal temperature and humidity conditions, an office ventilation system is installed.

Office ventilation requirements

Ventilation in an office building must meet the following requirements:

ensuring an influx of fresh clean air;
removal or filtration of exhaust air;
minimum noise level;
accessibility in management;
low power consumption;
small size, the ability to fit harmoniously into the interior.

The load on office climate systems is significantly higher compared to household ones. It is required to efficiently remove excess heat and carbon dioxide generated by equipment and employees, and supply clean and filtered air at a given temperature.

Previously used natural systems office ventilation today is not able to provide the conditions regulated sanitary standards. The operation of natural ventilation cannot be controlled; its effectiveness is highly dependent on the air parameters outside. In winter, this method threatens to cool the room, and in summer it causes drafts.

Widely used in the construction of office buildings, modern hermetically sealed windows and doors and continuous panoramic glazing prevent the passage of air from outside, causing it to stagnate and deteriorate people’s well-being.

All ventilation requirements office premises indicated in SanPiN ( Sanitary rules and standards) 2.2.4.

According to the document, the humidity in the premises should be:

at a temperature of 25 degrees – 70%;
at a temperature of 26 degrees – 65%;
at a temperature of 27 degrees – 60%.

The following ventilation standards in offices have been developed, taking into account the purpose of the room, in cubic meters per hour per person:

manager's office - from 50;
conference room – from 30;
reception - on average 40;
meeting room – 40;
employee offices – 60;
corridors and lobbies - at least 11;
toilets – from 75;
smoking rooms – from 100.

SanPiN for ventilation of office premises also regulates the speed of air movement of 0.1 m/s, regardless of the time of year.

As a rule, ventilation of small office premises is implemented using several. If during the hot season the office supply ventilation is not able to lower the air temperature below 28 degrees, additional air conditioning is required.

Separate air handling units are needed in conference rooms. Additional exhaust devices– in toilets, smoking rooms, corridors and lobbies, copy rooms. Mechanical exhaust from office rooms is necessary if the area of each office is more than 35 square meters. meters.

If the total area is not more than 100 sq. meters and there are 1-2 toilets, natural supply ventilation is allowed in the office through the vents. Supply- exhaust ventilation installed in medium and large sized offices.

Office ventilation system project

The ventilation system of an office building has a number of functions. Therefore, when designing, many factors are taken into account, regulated by SNiP rules for ventilation of office premises No. 2.09.04.87 and 2.04.05.91. The system is assembled from units of varying cost, functionality and design. The task of designers is to choose them correctly.

The following points are agreed upon with the customer:

location of the ventilation unit;
location of ventilation ducts;
power of the electrical system, possibility of water supply;
the need and ways of the drainage system;
access to equipment after installation;
possibility of design changes.

Design of ventilation systems for offices includes:

calculations of heat inflows for each separate room depending on the architectural features, appointments taking into account terms of reference to the project;
calculation of air exchange;
axonometric diagram of communications;
aerodynamic calculation, which makes it possible to determine the cross-sectional area of air ducts and pressure losses along the network;
selection of all necessary equipment to complete the ventilation system in the office;
calculation of heater power in the air handling unit;
preparation of a package of project documents.

Technical equipment is selected simultaneously with the preparation of the project and takes into account all the customer’s requirements. A properly designed ventilation system for any office increases employee productivity by 20% or more.

Components of office ventilation systems

Air is delivered to the room and removed through an air duct system. The air duct network directly contains pipes, adapters, splitters, turns and adapters, as well as diffusers and distribution grilles. The diameter of the air ducts, the resistance of the entire network, the noise from the ventilation operation and the power of the installation are closely interrelated. Therefore for optimal performance ventilation during the design process, it is necessary to balance all indicators. This is a difficult job that only professionals can do correctly.

Air pressure is calculated taking into account the total length of the air channels, the branching of the network and the cross-sectional area of the pipe. Fan power increases when large quantities transitions and branches. The air speed in office ventilation systems should be about 4 m/s.

Air ducts are assembled from flexible corrugated pipes or rigid metal or plastic. Flexible pipes are easier to install. But they resist air movement more strongly and hum. That's why flexible pipes used in small offices. Sometimes the main channels are made of rigid pipes, and the branches to the cabinets are made of flexible ones. But large systems are assembled from rigid pipes.

Air intake grilles

They are installed at the point where air enters the ventilation duct from the street. The gratings protect against the penetration of insects, rodents, and precipitation into the pipe. Made from plastic or metal.

Air valves

Prevents wind from blowing when the ventilation system is turned off. Often an electric drive controlled by automation is connected to the valve. To save money, they use manual drives. Then a check spring valve or “butterfly” is attached to the valve in order to block the outlets of the ventilation ducts for the whole winter.

Air filter

Cleanses supply air from dust. As a rule, coarse filters are used that retain up to 90% of particles with a size of 10 microns. In some cases, it is supplemented with a fine or extra fine filter.

Periodically filtering surface ( metal grid or man-made fibers) must be cleaned. The degree of filter contamination is determined by pressure sensors.

Heater

Used to heat street air in winter, they can be electric or water.

Electric heaters have some advantages compared to water heaters:

simple automatic control;
easier to install;
does not freeze;
easy to maintain.

Main disadvantage– high price of electricity.

Water heaters operate on water at a temperature of 70 – 95 degrees. Flaws:

complex automatic system management;
bulky and complex mixing circuit;
behind the mixing circuit is required special care and supervision;
may freeze.

But with proper operation it provides significant cost savings compared to an electric heater.

Fans

One of the most important components of the entire ventilation system. The main parameters when choosing: performance, pressure, noise level. There are radial and axial types of fans. For powerful and extensive networks it is preferable radial fans. Axial ones are more productive, but produce weak pressure.

Silencer

Installed after the fan to suppress noise. The main source of noise in an office ventilation system is the fan blades. The muffler filler is usually mineral wool or fiberglass.

Distribution grilles or diffusers

Installed at the outlets of air ducts into rooms. They are in plain sight, so they must fit into the interior and ensure distribution air flow in all directions.

Automatic control system

Monitors the operation of ventilation equipment. Usually installed in the electrical panel. Starts fans, protects against freezing, notifies about the need to clean filters, turns fans and heaters on and off.

Climate control equipment for offices

Office supply and exhaust ventilation

Duct ventilation of the supply-exhaust system is used for rooms up to 600 sq. m. meters, since the office supply and exhaust ventilation capacity is up to 8 thousand cubic meters per hour.

According to SanPiN standards for ventilation of office premises, 60 cubic meters of air per hour must be supplied per person.

SNiP ventilation of office premises requires air exchange:

inflow 3.5 times per hour;
outflow 2.8 times per hour.

The equipment is usually hidden behind suspended ceiling utility room. Air is distributed throughout the offices by a system of ventilation ducts, the outlets of which are hidden behind diffusers or grilles.

Air flow from the street at supply ventilation office is carried out at a height of two meters above the soil surface. The air is passed through a cleaning system, and if necessary, its temperature is lowered or increased (by an electric or water heater).

The exhaust air is discharged into a ventilation shaft or through a pipe, the end of which is located 150 cm above the roof.

To reduce energy consumption, the supply air is heated by a recuperator. It is a heat exchanger in which heat from exhaust air is transferred to fresh air. Recuperators for office ventilation are rotary and plate. The former have an efficiency of more than 75% and operate in bitter frosts. But during operation, about 5% of the exhaust air enters the room.

Plate recuperators are inexpensive, their efficiency is no more than 65%. But they become icy, and we have to provide heating.

All necessary equipment for air treatment in the supply and exhaust system is located in one relatively small housing. Duct ventilation of office premises is a combination of several modules.

To ensure the required air temperature in the office space, supply and exhaust ventilation is supplemented with air conditioners. Depending on the characteristics of the building, these can be several split systems or multisplits.

Office ventilation

Ventilation of a small office building can be provided by a ducted air conditioner. In addition to cooling and heating the air, duct systems supply some fresh air from the street into the halls. To implement this function, the duct air conditioner is equipped with additional equipment mixing air. That is, the equipment both air-conditions and ventilates the office in accordance with the standards.

This scheme works like this:

Outside air is supplied to the mixing chamber located in front of the air conditioner, here it is mixed with exhaust air. The mixture is fed into the conditioner, cleaned, and brought to required temperature and is sent through ventilation ducts to the offices. The air from here moves into the mixing chamber and further in a circular cycle.

The air conditioner housing is hidden above a false ceiling or in a utility room.

The advantage of a duct ventilation scheme for office premises is its invisibility. But it eliminates the possibility of varying the air temperature in different rooms.

Air handling units in combination with VRF systems for the office

In large areas, installation of ducted equipment is difficult, so large buildings are serviced by supply and exhaust ventilation units for offices in combination with chiller fan coils and VRF systems.

The power of such equipment can reach 60 thousand cubic meters per hour. Ventilation and climatic equipment installed on the roof of a building or in separate rooms.

The installation consists of many modules, which are assembled depending on the needs of the enterprise and taking into account office ventilation standards. The kit may include:

fan chamber;
recuperator;
sound absorber;
mixing chamber;
block with filters.

Air movement is carried out through an extensive system of air ducts. The air temperature in the building is maintained by chiller fan coils or VRF systems.

VRF is a multi-zone climate system, capable of maintaining the microclimate of an entire building. It is possible to differentiate the temperature in various rooms. An internal module is installed in each room to keep the temperature within the specified limits. There are no temperature changes typical for household air conditioners. Internal modules can be of any type (floor-standing, cassette, ceiling).

The chiller warms or cools the refrigerant - ethylene glycol. Which is supplied to the heat exchanger - fan coil with forced air movement. Fan coil units are located directly in office rooms. In order for the coolant to move at a given speed, the system is supplemented with a pumping station. Many offices and halls can be connected to one ventilation and air conditioning scheme. And not all at once, but as the need arises.

Central air conditioners for office ventilation

Central air conditioners belong to industrial climate control equipment. They are installed in accordance with SNiP and provide ventilation and air conditioning for office premises. In the air conditioner module, the air is brought to the required temperature and humidity parameters. Air is recirculated (mixing exhaust and fresh), including partial air recirculation. After treatment, the air is supplied to the premises through an air duct system.

The advantage of central systems is the absence of internal modules. At the same time, the air conditioner itself is a rather bulky structure that requires a separate room. The air ducts are also quite voluminous. In this case, the temperature throughout the building will be maintained at the same level.

In any office space there are people and computer equipment that is almost constantly turned on. Each room must be equipped with a basic ventilation system to ensure optimal air exchange and microclimate. This point is very important for any company that wants to run its business successfully and not pay sick leave.

Arrangement effective system ventilation in the office - key moment necessary for its effective work

In a poorly ventilated room, the risk of spreading infection increases, not to mention oxygen starvation, which has a very bad effect on brain activity. That is why the established “project” must be maintained in accordance with the established rules.

Indication of the need for air exchange

Office ventilation is not as simple a task as it seems at first glance. The air exchange rate for each room is indicated separately, taking into account:

room area;
number of persons;
humidity level;
presence in the air harmful substances.

The formula for the air exchange rate, if the nature and quantity of harmful impurities cannot be determined: L=Vroom. *Kр (m3/h).

Designations: V – office area, K – minimum air exchange rate. Quantity required air depending on the number of people, it is determined by the following formula L=L1*Nl, where L1 is the volume of air required by one person; Nl – number of people in the room.

The amount of air required is measured in cubic meters. Its minimum is directly related to the degree physical activity employees and is prescribed in SNIP standards:

20–25 cubic meters - with minimal physical exertion;
45 – required for light physical work;
60 – with intense physical work.

Formulas are used to determine the amount of air with excessive humidity, with excess heat, when the air is determined harmful impurities. From these multiplicities we derive average and based on this data, they make an office ventilation project.

How to design an air exchange system?

Office ventilation is thought out in advance. Ventilation design is directly related to the characteristics of the rooms. Ventilation of office premises can be of several types:

supply and exhaust;
supply ventilation in the office.

The ventilation system in the office can be centralized or decentralized. In the first case, the system supplies air to the entire building, in the second, a separate system is installed for each room. To ensure normal air exchange in office premises, it is impossible to connect the ventilation systems of bathrooms with general ventilation systems.

A decentralized system is installed mainly in rooms where there are no large crowds of people. For each separate group of rooms, small supply or supply and exhaust structures are used.

They are mostly installed in warehouses, corridors. To increase the indoor air temperature, electricity is used, because the supply thermal pipeline from the boiler room significantly increases the cost of installation.

Requirements for ventilation systems

Ventilation standards must be observed. Hygienic requirements to the microclimate are described in SNIP. Office ventilation will differ at different times of the year: in summer, the air temperature should be 19–21 degrees, and in winter 23–25. Indoor humidity in warm time year should not exceed 60%, and in winter - 65%. Air flow speed in winter and summer is 0.2–0.3 m/s.

The specified air exchange rates are presented for rooms of categories 2-3. The microclimate can be regulated naturally or by a forced central ventilation system.

Security optimal microclimate and maintaining sanitary and hygienic standards involves maintaining the required temperature during the hot period at 28 degrees or lower. Otherwise, ventilation and air conditioning must be planned.

SNIP requirements are based on the design of premises and their purpose. The heat transfer rate is calculated using special formulas and tables. The power of air flow will depend on the occupancy of the room and household appliances. The most commonly used centralized ventilation system.

When designing an office air conditioning system, subsequent ventilation repairs are taken into account. An autonomous hood is equipped in bathrooms, smoking rooms, and in rooms with a large concentration of equipment. According to SNIP, individual exhaust filters can be located in conference rooms.

Maintaining an optimal microclimate is achieved due to the fact that the air flow passes into each individual room. Part of the air is supplied to corridors and rooms equipped only with an exhaust system.

Removal carbon dioxide from the premises occurs due to its displacement by air into a room equipped with an exhaust hood. According to the requirements of SNIP, in rooms with an area of 35 square meters and above, it is assumed that supply and exhaust pipelines will be installed simultaneously.

Simultaneous installation of supply and exhaust air ducts is required in office premises with an area of more than 35 square meters

How to install the equipment?

When installing ventilation systems in offices, it is necessary to rely primarily on the requirements of SNIP for sanitary standards. Initially, calculate the area of the room. Then they move on to drawing up a project. After determining the effectiveness of projects in maintaining the microclimate, they move on to the selection of materials and installation of fans.

According to SanPiN, a supply and exhaust ventilation system is installed in office premises.

The main installation is mounted to the ceiling of the hall, together with exhaust fan and an air vent line. A distribution pipeline is installed in the offices.

Air exchange is adjusted and the microclimate is maintained by the penetration of fresh air from the street through openings covered with grilles. Inside supply system Filtration, heating or cooling takes place as needed, and after distribution along the main line to the premises.

At the same time, carbon dioxide from the offices enters the hood and goes out into the street. If before installation everything was planned in accordance with the rules of SanPiN, then the room after installation will not even have to be ventilated using window openings. This way you can maintain silence inside the office and avoid air polluted by cars from entering the room.

Most common ventilation devices Let's look at it in more detail below.

Mechanized supply and exhaust structure - can be located on the roof or in the basement. The system involves the installation of shafts through which clean air from the street enters a separate floor. When ventilation equipment is installed on the roof, it is necessary to further strengthen it, and when installed in the basement, there is no possibility of using it for any other purpose.
Mini supply- exhaust systems– ensure microclimate maintenance and air circulation. They are installed on each floor. There are practically no downsides to this system.
Multi-split air conditioning unit with air supply can be used as natural or exhaust ventilation. The outflow of air masses will be carried out through the main line, and the inflow will be organized by a split system. Such systems are installed only in rooms with a small area.

For large office centers or if the building contains numerous offices that are not equipped with a powerful air exchange system, it is recommended to install multi-zone split equipment.

How to heat or cool indoor air using a ventilation system?

In cold weather, the room cools down very quickly, so there is a need to heat the supply air. The most popular heating method is a heater built into the ventilation system.

A heater built into the ventilation system is the most effective way to heat the supply air

The air temperature regulation system significantly reduces heating costs in buildings, but only in the case of a room of 150 square meters. If the room has more dimensions, you will have to use a heater with higher power, which is quite expensive.

Ventilation with recovery can greatly reduce heating costs. The recuperator has proven itself well in supply and exhaust types of ventilation. The supply air is heated by the removed hydrocarbons. With such normalization of the temperature regime, up to 80% of the heat is transferred from the exhausted air masses.

If you need to heat the air for an office space with large area, use a water heater. The main disadvantage of this type of ventilation is the complexity of installation and repair in case of breakdown.

Instrument servicing

Maintenance of the ventilation system includes scheduled inspections, as well as scheduled preventative renovation work, during which disassembly, inspection and replacement, if necessary, of worn parts are carried out.

To ensure high-quality ventilation of the room, all kinds of planned work is carried out to prevent breakdowns, which are divided into several types:

current repairs;
renovation work medium difficulty;
overhaul.

When a breakdown requires partial replacement and dismantling, we are talking about work of medium complexity. Depending on the nature of the breakdown, work can be carried out on site or a decision is made to send the device to the factory.

If, during inspection of the devices, multiple damage to components and systems is detected, defects in the operation of the air conditioner that affect the quality of ventilation require major repairs. Working with ventilation after installation is a complex process consisting of a set of measures that can extend the life of the device.

Setting up and regulating devices

Regulating devices is an important issue. Office ventilation systems are controlled using automation. Such a system implies the presence of an electrical panel with a built-in control panel for the ventilation system.

An elementary option is a lever that regulates turning the device on and off.

The most popular option, which greatly simplifies the control and regulation of serviceability, is industrial automation. Such a regulation system allows you to set the level of contamination of fans, filters, and, if necessary, turns off the system, etc. To implement this complex process built-in thermostats, pressure sensors, hydrostats are used.

One of such devices that monitors the condition of the ventilation system is a microprocessor controller. This device has a screen with a simple interface. All signals about pressure and temperature fluctuations are given temperature sensors and pressure regulators.

Microprocessor controller - a device that allows you to monitor the condition of the ventilation system

Temperature sensors are divided into devices for rooms and ducts. Some are used to control the temperature in the main line, while others determine the temperature of the air flows in the rooms themselves. The work is carried out as follows: the device sends a signal to the control panel, where the received data is compared with the programmed ones and a change occurs in the operation of the ventilation system.

Pressure regulation sensors allow you to monitor the speed of air flow along the line. It regulates the operation of the heater, protecting against false starts and allows timely detection of contamination of filters and heaters.

Conclusion

Installation of ventilation in an office space important process. In any such room, ventilation must be designed in advance. Even if you ventilate the room very often, it does not give the same effect as a good supply and exhaust system.

Normally, in a room where people and household appliances are located, it should be maintained temperature regime below 28 degrees in summer, with relative humidity not higher than 65%. During the design of the system, they are guided by the sanitary standards prescribed in SNIP.

The speed and volumes of supplied air will directly depend on the area of the room, the number of people, equipment, the level of physical activity of those in the room, and the level of permissible amount of impurities in the air.

Ventilation systems are adjusted using automation, which allows, through the use of temperature and pressure regulation sensors, to detect changes in a timely manner and adjust the operation of the system.

Basic sanitary and hygienic requirements for ventilation of industrial premises have been determined sanitary standards, and building codes and rules (SNiP) “Heating, ventilation and air conditioning”.

For effective operation of ventilation, it is important that a number of sanitary, hygienic and technical requirements are met even at the design stage. The volume of required air must be sufficient. The amount of air required to ventilate production premises and ensure the required parameters air environment in the working area, installed by calculation. The calculation is carried out accordingly according to the excess of sensible heat or moisture or the amount of harmful substances released (dust, gases, vapors). With the simultaneous release of heat, moisture and harmful substances (or their various combinations) the required air exchange should be determined according to the prevailing harmfulness.

In accordance with sanitary standards, the amount of outside air supplied to the room per worker must be at least 30 m 3 / h when working in a room less than 20 m 3 per person and at least 20 m 3 / h when the room volume is more than 20 m 3 per person. In rooms with a volume of more than 40 m 3 for each worker, in the presence of windows or windows and lanterns and in the absence of the release of harmful or unpleasantly smelling substances, it is allowed to arrange periodic ventilation. In rooms without natural ventilation, the air supply per person should be at least 60 m 3 /h.

The balance of supply and exhaust air must correspond to the purpose of ventilation and the specific conditions of its use. In classic cases, the amount of supply air must correspond to the amount of air removed, the difference between them should be minimal. However, sometimes a special organization of air exchange is necessary with a predominance of one or another amount of air in the overall balance. For example, when designing ventilation in two adjacent rooms, in one of which there is the release of harmful substances, it is necessary to create a negative balance in it (a slight predominance of the exhaust over the inflow), thereby preventing the possibility of polluted air entering the room without its own sources of harmfulness.

In some cases, such air exchange organization schemes are required when excess pressure is maintained in the entire room relative to atmospheric pressure, i.e., the volume of supply air must be greater than the volume of exhaust air. This, for example, is necessary in electric vacuum production workshops, so-called clean rooms, to prevent outside air from penetrating through leaks in enclosures. A positive air balance is necessary when organizing ventilation with excessive dispersed moisture release to prevent the formation of fog and condensation due to the penetration of cold air from outside.

The volume of air removed from the premises by exhaust ventilation units must be compensated by an organized influx of clean air. Unorganized influx of outside air to compensate for exhaust air cold period years, it is allowed to take in a volume of no more than once per hour, if there is no hypothermia of the air and the formation of fog.

Supply and exhaust systems must be correctly placed. The influx should ensure maximum purity and optimal microclimatic parameters of the air in the working area. The hood should remove harmful emissions as much as possible. The ventilation system should not cause overheating or hypothermia of workers. The noise of ventilation units should not increase production noise above the level permitted by sanitary standards. The ventilation system must be effective at all times of the year under all climatic and weather conditions. The ventilation system should not be a source of pollution environment. The ventilation system must be simple in design, reliable in operation and meet the requirements of electrical, fire and explosion hazards.

Methods for reducing noise and vibration of ventilation units.

The operation of ventilation units is usually accompanied by more or less noise. In industrial enterprises with low noise levels from production equipment noise generated by ventilation units can be one of the main unfavorable factors in the working environment.

The noise of ventilation units can be mechanical and aerodynamic. Mechanical noise is created mainly by fans and electric motors as a result of poor damping, poor balancing of rotating parts, poor condition of bearings, etc. Mechanical noise spreads through the air of the room, ventilation ducts and often through the foundations of the ventilation unit to the building envelope, the so-called structural noise . Aerodynamic noise occurs as a result of vortex formation during rotation of the fan wheel, air movement in ventilation networks with high speed, when air escapes through the supply openings, etc.

Reducing the mechanical noise of ventilation units is achieved by special technical solutions: to eliminate vibration of the fan, it is recommended to mount it on vibration-isolating bases in a separate ventilation chamber. Careful dynamic balancing of the rotating fan mechanisms and taping of the fan casing are required soundproofing materials; To prevent the spread of mechanical noise through the air ducts, flexible non-metallic (tarpaulin, etc.) inserts are made between the latter and the fan.

Reduction of aerodynamic noise is ensured by such measures as correct selection fan (it must create the required pressure at a minimum number of revolutions of the impeller), the correct choice of air speeds in the air ducts; The cross-sectional area of the air ducts and nozzles must correspond to their purpose, not create unnecessary turbulent movements of air flows, and if necessary, noise silencers are installed.

Ventilation in rooms with excessive heat generation.

Many production processes associated with heating, smelting, casting metal, production of building materials (cement, bricks, ceramics), chemical raw materials, at thermal power plants are accompanied by the release of a significant amount of heat into production premises.

If heat release into the room is greater than heat loss, then their difference is called excess heat. According to sanitary standards, industrial premises with excess sensible heat with a heat intensity of more than 20 kcal/m3 per 1 hour are classified as premises with significant heat release or so-called hot shops.

Calculation heat balance, i.e. entering workroom and the heat leaving it, is one of the main and rather difficult tasks when designing ventilation to combat excess heat.

Sources of heat generation include: heating furnaces for smelting, heating metal or other materials; cooling materials; heated surfaces of apparatus, pipelines; working machines and mechanisms; solar radiation; lighting sources; People.

The heat is used to heat the building, which is cooled through external enclosures; heating in cold weather transport and materials entering the workshop; carried away by heated air through leaks in the building enclosures or removed by local suction, etc. Appropriate methods and calculation formulas have been developed to determine the required air exchange. They are set out in special manuals and reference books. General principles Organizations of air exchange in workshops with large excesses of sensible heat provide for aeration in combination with mechanical ventilation.

Ventilation in workshops with excess moisture.

For removing excess moisture, the release of which cannot be prevented technological means, first of all, local exhaust ventilation units should be provided. Recommended air intakes include fume hoods; at temperatures of evaporating water above 80 °C can be used exhaust hoods; display cases are suitable; baths are equipped with side suction.

In a number of industries, with diffuse intense release of moisture, where it is technically not possible to completely cover the sources and remove all moisture using local exhaust devices, they additionally use general exchange supply and exhaust ventilation, designed to remove humidified air and assimilate excess moisture with supply air. In this case, the following is recommended circuit diagram ventilation: most of(approximately 2/3) of the overheated and overdried supply air is supplied to the upper zone of the room, and vapor-saturated air is also extracted from the upper zone. If the room height is at least 5 m, it is allowed to overheat the supply air to 35 °C, and if the height is higher. 6 m to 50 - 70°C.

The inflow must prevail over the exhaust in order to avoid unorganized entry of cold outside air into the premises and the formation of fog.

At the same time, a number of architectural and construction conditions are imposed on rooms with significant moisture releases: their height must be at least 5 m to avoid overheating of the air in the workplace with hot supply air; to eliminate the possibility of condensation forming on inner surface fencing of the building (ceiling, walls, ceilings), they must be made of low thermal conductivity materials.

Ventilation in workshops with the release of toxic gases and vapors.

Preventing the release of toxic substances into the air of working premises must first of all be resolved by the rational organization of technological processes, reliable sealing equipment, etc.

Among the means of ventilation, preference should be given to aspiration. If it is impossible to equip it to localize and remove harmful substances directly from the place of their formation and release, the most rational option is local exhaust ventilation with shelters like fume hoods, on-board suction, umbrellas, etc. For effective ventilation, it is necessary to ensure such speeds of air suction into open openings and create such vacuums inside ventilation shelters that would contribute to the maximum extent to the removal of gases and vapors from the room. Local suctions designed to remove technological equipment hazardous substances of hazard classes 1 and 2, should be interlocked with this equipment in such a way that it cannot operate when local exhaust ventilation is inactive.

In a number of cases, when for technological, design and other reasons it is not possible to use local exhaust ventilation, general exchange ventilation is used, designed to dilute toxic substances to maximum permissible concentrations.

In accordance with technological design standards and departmental requirements regulatory documents In certain cases, emergency ventilation is provided. There should also be provision for blocking emergency ventilation with gas analyzers set to permissible concentrations of harmful substances.

Calculations are somewhat difficult required air exchange. Experience shows that sharp fluctuations in the concentrations of gases and vapors are often observed in individual points of the room, and sometimes their concentrations, even when ventilation is operating at full design capacity, can potentially reach dangerous levels. In this regard, when calculating air exchange, it is recommended to introduce a safety factor. This applies to toxic substances with maximum permissible concentrations greater than 1 mg/m3.

When toxic substances are released, the maximum permissible concentration for which is set below 1 mg/m 3, the use of general ventilation is unacceptable.

Dust control ventilation.

Among the measures aimed at preventing dust pollution in the air environment of industrial premises, the leading role should also belong to measures of an architectural, planning and technological nature.

When choosing methods to combat dust through ventilation, it should be borne in mind that local dust extraction ventilation installations are of decisive importance. The use of general ventilation, operating on the principle of dust dilution, is irrational, uneconomical and insufficient effective way, since increased air mobility prevents the settling of the fine dust fraction, and it is indefinite long time may be suspended.

Only in exceptional cases is it permissible to resort to general ventilation to reduce dust levels in the air by diluting the aerosol. For example, during arc welding at non-fixed workplaces in mechanical assembly and other shops, when it is not possible to equip local suction. Active ventilation aimed at removing dust is resorted to in the blind faces of mine workings. In this case, the supply air is supplied at strictly calculated relatively low speeds (0.4 - 0.7 m/sec).

Rice. 29. Installation of ventilation suction, a - incorrect; b - correct.

The optimal method of dust removal using local exhaust ventilation units is aspiration - complete covering of equipment combined with an exhaust hood. To prevent dust from being knocked out through leaks in the suction shelters, it is necessary to ensure sufficient air vacuum. The suction units should be correctly positioned (Fig. 29).

When choosing the design of the suction (dust collector) and the exhaust unit itself, a number of conditions must be observed:

It is possible to ensure complete cover of the source of dust formation, while at the same time not interfering with the free performance of labor operations;

Bring the suction hole as close as possible to the source of dust emission;

Provide a tight connection of the air duct to the dust receptacle to prevent dust from being knocked out;

Ensure that the dust collector is positioned in such a way that the dusty air being sucked out does not pass through the worker’s breathing zone;

Air ducts must be equipped with holes for periodic cleaning of settled dust;

Dust extraction ventilation systems should be as decentralized as possible, i.e., consist of several independent installations. This makes it possible to avoid laying long air ducts and clogging them with dust;

It is not allowed to combine dust extraction units into one system with units for removing excess moisture.

Local exhaust ventilation designed to combat dust must be equipped with dust cleaning devices that guarantee a degree of air purification in accordance with the requirements of sanitary legislation.

Sanitary supervision of ventilation.

The design specifications must address the principles and patterns of ventilation. When considering a project, it is necessary to carefully familiarize yourself with its technological part, check the basic calculations, heat-air balance, etc.; assess the compliance of the designed local suction with the nature of the equipment that is the source of the release of harmful factors. It should be borne in mind that in a number of cases, when considering projects, there are complex technical calculations and tasks that require special training to solve them. In these cases, the sanitary officer involves ventilation engineers.

Whenever controversial issues or if the project is particularly complex, it may be sent for sanitary or technical examination to research institutes.

Current sanitary supervision of existing ventilation systems industrial enterprises is based on periodic monitoring of the state of the air in the work area at permanent workplaces, as well as at the locations of air intake devices. In the event of a discrepancy between the air in the working area and the existing regulatory requirements The question arises about the efficiency of industrial ventilation.

Monitoring the operation of ventilation involves technical and sanitary tests of ventilation systems and installations.

Technical tests of the ventilation unit are carried out before putting it into operation during new construction or reconstruction in order to check the overall compliance with the design and the quality of its installation; existing ventilation - in order to check the technical condition of the installation.

At technical tests determine the speed of the fan and electric motor, the pressure in the network (static, dynamic, total); the overall performance of the installation and the distribution of air among its individual elements; the presence of leaks leading to air leaks or leaks; temperature and relative humidity supply and exhaust air; heater performance.

The correct distribution of supply air throughout the ventilated room and its removal, taking into account the volumes and required speeds, is also determined.

After eliminating the identified defects, ventilation is adjusted. The operating efficiency of the ventilation unit or the entire ventilation system is assessed based on sanitary and hygienic tests.

They provide for assessing the state of the air in work areas based on instrumental measurements and conducting the necessary chemical studies:

a) compliance of the air in the working area with the requirements of regulations (MPC) for the content of harmful vapors, gases and dust;

b) microclimatic regime indoors and in workplaces;

c) the degree of purity of the supply air, as well as its temperature and humidity;

d) the efficiency of purification of air removed from the premises into the surrounding atmosphere.

Each ventilation unit must have a passport, which, along with its description, contains technical test data.

Brief summary of SNiP on ventilation (sanitary norms and rules).

Sanitary norms and rules, abbreviated as “SNiP”, clearly and unambiguously describe where and when certain air conditioning means should be used and are mandatory throughout the Russian Federation. Here we list the main requirements that SNiP for ventilation impose on objects and structures proposed for installation various types ventilation and

In what cases do SNiPs provide for the installation of forced ventilation?

according to SNiP it should be installed in two cases:

if it does not allow achieving the required microclimate parameters in terms of cleanliness, humidity and pollutant content;
if the building or structure has areas and rooms in which there is no natural replacement of air;

At the same time, SNiP for ventilation allows the use of a mixed option, when partially natural ventilation is used to supply or remove air, including the supply of fresh air through leaks, windows and doors.

SNiP ventilation on temperature standards.

If the building is operated in cold areas with an average annual temperature below minus thirty degrees, then SNiP ventilation is recommended for administrative, utility and domestic buildings. mechanical ventilation with compulsion.

When jointly designing, SNiP regulates the use of backup (duplicate) fans or the use of at least two heating devices. This is done in case one of the fans fails, and in this case, SNiP ventilation allows a temporary decrease in air temperature, but not less than twelve degrees Celsius.

Ventilation SNiP on backup fans.

Backup ventilation SNiP allows not to be installed in the following situations:

if during an emergency shutdown the operation of devices, units and equipment automatically stops, technological processes which involve the release of polluting vapors, gases and dust-air mixtures into the air;
if installed in the building includes emergency ventilation capable of providing a capacity of at least fifty percent of the capacity of the main system;

SNiP ventilation on fire safety.

To ensure fire safety, SNiP ventilation provides for the installation of common ventilation, heating and air conditioning systems for premises located within a single fire compartment. Local ventilation, intended directly for the removal of harmful components and explosive and fire-hazardous mixtures at the points of their release, SNiP ventilation recommends designing it isolated from common system general ventilation.

March 16th, 2017 y.geny

You can order a range of works for the calculation, selection and installation of a ventilation and air conditioning system for your premises, building, office from our company: .

The ability of an office worker to work directly depends on the microclimate in the room. According to medical research, the air temperature in the office should not exceed 26 degrees, while in practice in buildings with panoramic windows and an abundance of equipment it can go beyond 30 degrees. In the heat, the reaction of employees is dulled, and fatigue increases. Cold also has a bad effect on work ability, causing drowsiness and lethargy. Lack of oxygen and high humidity create unbearable conditions for employees, reducing labor productivity and, therefore, the profitability of the enterprise.

To maintain optimal temperature and humidity conditions, an office ventilation system is installed.

Office ventilation requirements

Ventilation in an office building must meet the following requirements:

ensuring a flow of fresh, clean air;
removal or filtration of exhaust air;
minimum noise level;
accessibility in management;
low power consumption;
small size, the ability to fit harmoniously into the interior.

The load on office climate systems is significantly higher compared to household ones. It is required to efficiently remove excess heat and carbon dioxide generated by equipment and employees, and supply clean and filtered air at a given temperature.

Previously used natural office ventilation systems today are not able to provide conditions regulated by sanitary standards. The operation of natural ventilation cannot be controlled; its effectiveness is highly dependent on the air parameters outside. In winter, this method threatens to cool the room, and in summer it causes drafts.

All requirements for ventilation of office premises are specified in SanPiN (Sanitary rules and regulations) 2.2.4.

According to the document, the humidity in the premises should be:

at a temperature of 25 degrees – 70%;
at a temperature of 26 degrees – 65%;
at a temperature of 27 degrees – 60%.

Office building ventilation diagram

The following ventilation standards in offices have been developed, taking into account the purpose of the room, in cubic meters per hour per person:

manager's office - from 50;
conference room – from 30;
reception - on average 40;
meeting room – 40;
employee offices – 60;
corridors and lobbies - at least 11;
toilets – from 75;
smoking rooms – from 100.

SanPiN for ventilation of office premises also regulates the speed of air movement of 0.1 m/s, regardless of the time of year.

As a rule, ventilation of small office premises is carried out using several air handling units. If during the hot season the office supply ventilation is not able to lower the air temperature below 28 degrees, additional air conditioning is required.

Separate air handling units are needed in conference rooms. Additional exhaust devices - in toilets, smoking rooms, corridors and lobbies, copy rooms. Mechanical exhaust from office rooms is necessary if the area of each office is more than 35 square meters. meters.

If the total area is not more than 100 sq. meters and there are 1-2 toilets, natural supply ventilation is allowed in the office through the vents. Supply and exhaust ventilation is installed in medium and large sized offices.

Office ventilation system project

The following points are agreed upon with the customer:

location of the ventilation unit;
location of ventilation ducts;
power of the electrical system, possibility of water supply;
the need and ways of the drainage system;
access to equipment after installation;
possibility of design changes.

Design of ventilation systems for offices includes:

calculations of heat inflows for each individual room, depending on the architectural features, purpose, taking into account the technical specifications for the project;
calculation of air exchange;
axonometric diagram of communications;
aerodynamic calculation, which makes it possible to determine the cross-sectional area of air ducts and pressure losses along the network;
selection of all necessary equipment to complete the ventilation system in the office;
calculation of heater power in the air handling unit;
preparation of a package of project documents.

Technical equipment is selected simultaneously with the preparation of the project and takes into account all the customer’s requirements. A properly designed ventilation system for any office increases employee productivity by 20% or more.

Components of office ventilation systems

Air ducts

Air is delivered to the room and removed through an air duct system. The air duct network directly contains pipes, adapters, splitters, turns and adapters, as well as diffusers and distribution grilles. The diameter of the air ducts, the resistance of the entire network, the noise from the ventilation operation and the power of the installation are closely interrelated. Therefore, for optimal ventilation performance, it is necessary to balance all indicators during the design process. This is a difficult job that only professionals can do correctly.

Air pressure is calculated taking into account the total length of the air channels, the branching of the network and the cross-sectional area of the pipe. The fan power increases with a large number of transitions and branches. The air speed in office ventilation systems should be about 4 m/s.

Air ducts are assembled from flexible corrugated pipes or rigid metal or plastic. Flexible pipes are easier to install. But they resist air movement more strongly and hum. Therefore, flexible pipes are used in small offices. Sometimes the main channels are made of rigid pipes, and the branches to the cabinets are made of flexible ones. But large systems are assembled from rigid pipes.

Air intake grilles

Air valves

Prevents wind from blowing when the ventilation system is turned off. Often an electric drive controlled by automation is connected to the valve. To save money, manual drives are used. Then a check spring valve or “butterfly” is attached to the valve in order to block the outlets of the ventilation ducts for the whole winter.

Air filter

Cleans the supply air from dust. As a rule, coarse filters are used that retain up to 90% of particles with a size of 10 microns. In some cases, it is supplemented with a fine or extra fine filter.

Periodically, the filter surface (metal mesh or artificial fibers) needs to be cleaned. The degree of filter contamination is determined by pressure sensors.

Heater

Used to heat street air in winter, they can be electric or water.

Electric heaters have some advantages compared to water heaters:

simple automatic control;
easier to install;
does not freeze;
easy to maintain.

Main disadvantage– high price of electricity.

Water heaters operate on water at a temperature of 70 – 95 degrees. Flaws:

complex automatic control system;
bulky and complex mixing circuit;
the mixing circuit requires special care and supervision;
may freeze.

But with proper operation it provides significant cost savings compared to an electric heater.

Fans

One of the most important components of the entire ventilation system. The main parameters when choosing: performance, pressure, noise level. There are radial and axial types of fans. For powerful and extensive networks, radial fans are preferable. Axial ones are more productive, but produce weak pressure.

Silencer

Installed after the fan to suppress noise. The main source of noise in an office ventilation system is the fan blades. The muffler filler is usually mineral wool or fiberglass.

Distribution grilles or diffusers

Installed at the outlets of air ducts into rooms. They are in plain sight, so they must fit into the interior and ensure the distribution of air flows in all directions.

Automatic control system

Climate control equipment for offices

Supply ventilation unit for office. Brings fresh air from the street directly into the office space. The outflow of air occurs by displacing it into corridors and lobbies. With an area of more than 40 sq. meters the air is evacuated directly from it. Air supply units for office ventilation are used for areas up to 100 square meters. meters;

Supply and exhaust office ventilation systems. This is the most widely used type of equipment that provides air outflow, purification and delivery. The kit may include cooling or heating devices, humidifiers. The equipment is very diverse, but the supply and exhaust ventilation of the office must be calculated and installed by professionals. Automatic control over functionality reduces energy consumption and increases efficiency;
Duct ventilation system in the office. Duct air conditioners with outside air are installed in small and medium-sized offices. Combined with supply and exhaust equipment that brings the outside air temperature to the required level. After which it is served to the rooms;
Central air conditioning and ventilation in a large office. In large office buildings, the climate is controlled by chiller-fan coil systems and multi-zone VRF systems. The latter consist of many indoor units that provide different temperatures and humidity in the rooms. Central air conditioners are supply and exhaust ventilation in offices with cooling and heating units. This type of climate system is suitable for large offices that are not divided into separate rooms.

Office supply and exhaust ventilation

Duct ventilation of the supply-exhaust system is used for rooms up to 600 sq. m. meters, since the office supply and exhaust ventilation capacity is up to 8 thousand cubic meters per hour.

According to SanPiN standards for ventilation of office premises, 60 cubic meters of air per hour must be supplied per person.

SNiP ventilation of office premises requires air exchange:

inflow 3.5 times per hour;
outflow 2.8 times per hour.

The equipment is usually hidden behind the suspended ceiling of the utility room. Air is distributed throughout the offices by a system of ventilation ducts, the outlets of which are hidden behind diffusers or grilles.

The influx of air from the street during office supply ventilation is carried out at a height of two meters above the soil surface. The air is passed through a cleaning system, and if necessary, its temperature is lowered or increased (by an electric or water heater).

The exhaust air is discharged into a ventilation shaft or through a pipe, the end of which is located 150 cm above the roof.

Plate recuperators are inexpensive, their efficiency is no more than 65%. But they become icy, and we have to provide heating.

All the necessary equipment for air treatment in the supply and exhaust system is located in one relatively small building. Duct ventilation of office premises is a combination of several modules.

Office ventilation

Ventilation of a small office building can be provided by a ducted air conditioner. In addition to cooling and heating the air, duct systems supply some fresh air from the street into the halls. To implement this function, the duct air conditioner is equipped with additional air mixing equipment. That is, the equipment both air-conditions and ventilates the office in accordance with the standards.

This scheme works like this:

Outside air is supplied to the mixing chamber located in front of the air conditioner, here it is mixed with exhaust air. The mixture is fed into the air conditioner, cleaned, brought to the required temperature and sent through ventilation ducts to the offices. The air from here moves into the mixing chamber and further in a circular cycle.

The air conditioner housing is hidden above a false ceiling or in a utility room.

The advantage of a duct ventilation scheme for office premises is its invisibility. But it eliminates the possibility of varying the air temperature in different rooms.

Air handling units in combination with VRF systems for the office

The power of such equipment can reach 60 thousand cubic meters per hour. Ventilation and climate control equipment is installed on the roof of the building or in separate rooms.

The installation consists of many modules, which are assembled depending on the needs of the enterprise and taking into account office ventilation standards. The kit may include:

fan chamber;
recuperator;
sound absorber;
mixing chamber;
block with filters.

Air movement is carried out through an extensive system of air ducts. The air temperature in the building is maintained by chiller fan coils or VRF systems.

VRF- is a multi-zone climate system capable of maintaining the microclimate of an entire building. It is possible to differentiate the temperature in different rooms. An internal module is installed in each room to keep the temperature within the specified limits. There are no temperature changes typical for household air conditioners. Internal modules can be of any type (floor-standing, cassette, ceiling).

Central air conditioners for office ventilation