Air changes per hour
The air exchange rate n is a measure of the supply airflow of the indoor air in relation to the volume of construction of buildings. It plays a role in ventilation technology and heating technology.
Definition
The air exchange rate in the unit [ 1 / h ] indicates the multiple of the spatial volume, which is supplied as supply air.
This statement is, strictly speaking, only for the Displacement ventilation. Dilution ventilation rate effectively exchanged air is much lower.
For outdoor air flow
The outdoor air rate is determined by the number of those living in the areas to be served and the people outdoor air rate per person according to the applicable regulations. Recommended outdoor air rates are per person, for example, for:
- Open-plan offices 50 m³ / h
- Restaurants 40 m³ / h
- Individual offices, conference rooms, auditoriums 30 m³ / h
- Theaters, halls, Halls 20 m³ / h
If it is to be expected with an additional odor nuisance, these levels are increased by about 20 to 50%.
Examples supply airflow
For the determination of the number of air changes the type of land use is responsible. Recommended air exchange rates are for example:
- Office space 3 to 6 times per hour
- Guest rooms, meeting rooms 5 to 10 times per hour
- Lecture halls 8 to 10 times per hour
- Department Stores 4 to 6 times per hour
- Cinemas, theaters 4 to 6 times per hour
- Swimming pools 3 to 4 times per hour
- Toilets 4 to 6 times per hour
- Laboratories 8 to 15 times per hour
- Kitchen 20 to 30 times per hour
Regardless of the air exchange rate, however, is to take care that is recognized and changed the entire volume in the affected areas.
Air change rate n50 as a density measure
The air change rate n50 is a measure of the air tightness of a building. This number is obtained from the air flow, the sets in an hour, when a pressure difference of 50 Pa is maintained, divided by the volume of the building. The smaller the number, the thicker the building. For normal buildings without air-conditioning systems is an air exchange rate of, from those with air-handling equipment is required. For passive houses. The measurement is achieved, for example, with the blower door test (differential pressure method ).
Hygienic minimum air exchange rate
The minimum hygienic air change rate is about 0.3 / h Can you be a minimum for the freezing of fresh air below which occur odor problems, dust and Mikrorganismenbelastung and radon concentrations.