##### Будем рады ответить на все Ваши вопросы.

**What amount of air must get inside a building?**

A grown-up person has lungs with a volume of 4.5-5 litres.

In free, inactive state, such as sleep, a person's shallow breath has a volume of 1 litre making one cycle of inhale-exhale every 6 seconds. Thus, breath capacity per hour of the adult is 10 litres

When breathing is active the volume of air is 3 liters per 4 seconds, therefore the volume of air that must be replaced is 45 litres. Average volume of air is considered to be 22, 6 litres/hour.

The amount of air required indoors for one person every hour is called volume of ventilation.

It can be determined by humidity, temperature, yet for providing for the vital needs it is determined according to carbon dioxide.

**Procedure:**

Air contains 0.4% of carbon dioxide. As it has been mentioned earlier, in buildings requiring high level of hygiene (hospital wards, operation room) the level of carbon dioxide can't exceed 0.7%, which means that the difference in concentration must not be higher 0.3%. For ordinary buildings acceptable concentration is 1%, which means that the difference in concentration must not exceed 0.6%.

Then we use the following formula:

V = (К * N) / (Р – Pa)

где

V – volume of ventilation (м )

N – number of people indoors

P – maximum permissible contents of carbon dioxide indoors (0.7% for buildings with high level of hygiene and 1% for ordinary ones).

Pa – contents of carbon dioxide in atmospheric air (0.4%). As a result, buildings requiring high level of hygiene: V=22,6л x 1/(0,7-0,4)=**75 м3****For residential accomodation:**

V=22,6л x 1/(1-0,4)=**38 m3**

This figure is multipled by a number of people inside a building.