Hygienic requirements for residential ventilation

As a result of human activity in the air of residential and public premises increased content of carbon dioxide, water vapor, increased air temperature. Decomposition of sweat on the body surface, organic dust contained in the garment, leads to the appearance of unpleasant smells. Together with the dust in the air fall into a variety of microorganisms, including pathogenic. This so-called room smell reduces efficiency, affects overall health. Hygienic criteria of the air pollution of residential premises is the content of carbon dioxide, which must be in the air not more than 0,07-0,1%.
Under the ventilation understand replacement of air pollution areas fully or partially clean outdoor air.
The number of ventilation air, which must be submitted to the room in unit time, depend on a number of factors - cubic capacity of the premises, the number of people, the nature of the work, the number of impurities contained in the air. In accommodations for one person should enter 30-35 m3 of air per hour, children under 10 years need 12-20 m3, over 10 years - 20-30 m3 (volume ventilation).
For areas where heavy physical work (enterprise, gyms), hospital rooms, etc. the number of ventilation air per hour per person should be increased, because in these areas due to intensive breathing, sweating, and so on, change the state of the air environment more significant. So, in sports and gymnastic halls needs 90 m3 ventilation air per person per hour, in production areas - 70 m3 or more depending on the nature of production.
The ventilation rate is the number of times an hour fully shares the air. Determining the required ratio of air in premises may be made by dividing the amount of ventilation air cube (cubature space per person). For example, when area of 9 m2 per person, and the height of 3 m air cube will be equal to 27 m3 (9X3). The ventilation rate will be 35:27= 1,3; with less air Cuba necessary air exchange rate of increase.
Due air filtration through the pores in building materials, cracks in the Windows, etc. almost an hour in room is provided only a single exchange.
There are natural and artificial ventilation. Under natural ventilation understand sharing room air on the outside through the vents, transoms, ventilation ducts, window supply air devices, furnace openings furnaces, the pores of building materials. Natural ventilation is carried out under the influence of temperature differences between the outdoor and indoor air, and also due to the pressure difference.
The value of infiltration (leakage) of air through the pores in the walls is very small and practically neglected.
It is most expedient to arrange a transom. Transoms open a 45-degree angle to the surface of the window, which contributes to pre-heat the cold air. This allows even in the winter to keep transoms open for a long time in the presence of people. To ensure satisfactory ventilation total area panes and transoms should be not less than 1/50 of the floor.
More reliable effect through ventilation, which complete change of air in the room you can provide for 3-5 minutes
In areas where there is a large concentration of people or air pollution, natural ventilation is not able to provide adequate ventilation. In such cases, resort to artificial, mechanical
ventilation. Artificial ventilation can be local (for specific rooms) and Central (for the entire building).
Mechanical ventilation is not dependent on fluctuations of temperature and pressure of external air, operates continuously and evenly.
Central ventilation is more perfect and quiet operation. It can be of exhaust and combined (supply and exhaust). When ventilation is fed into the room air, but polluted removed through vents or transoms. Exhaust ventilation mechanically removes the air from the room and the flow of air through Windows, cracks, pores walls. When the ventilation and the inflow and exhaust air is realized by mechanical means (Fig. 20).

scheme of mechanical supply and exhaust ventilation
Fig. 20. The General scheme of mechanical supply and exhaust ventilation

Recently spread air conditioning. It is the most perfect type of artificial ventilation. Air conditioning indoors artificially create the necessary microclimate conditions (temperature, humidity, air movement, certain smells others). This eliminates the need in heating appliances.
Air conditioning is widely used in medical institutions, at enterprises, theatres, clubs and other areas that require a stable climate.