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DIN Standards Committee Heating and Ventilation Technology and their Safety

Overview

This part of ISO 16000 specifies the planning of carbon dioxide (CO₂) indoor pollution measurements as . In the case of indoor air measurements, the careful planning of sampling and the entire measurement strategy are of particular significance since the result of the measurement can have far-reaching consequences, for example, with regard to ascertaining the need for remedial action or the success of such an action. An inappropriate measurement strategy can lead to misrepresentation of the true conditions or, worse, to erroneous results. Before indoor air measurements are carried out, the purpose of the measurement shall be clearly defined. In the case of determination of carbon dioxide, the following objectives, which are described in detail, are chiefly of interest: - Investigating compliance with a guide value - Investigating the ventilation situation in a room. Carbon dioxide is a natural constituent of atmospheric air, where it is present on average at a content of a little over 0,03 % (volume fraction) (equal to about 600 mg/m₃). Carbon dioxide plays a central role in the processes of life on Earth. In the case of humans, the amount released depends on the extent of physical activity. CO₂ is frequently used as a general indicator of indoor air pollution of human origin. Particularly in rooms to be ventilated naturally which are regularly occupied by a relatively large number of people, for example, in school rooms or auditoria, this value can sometimes be considerably exceeded without the required ventilation. In a classroom having an interior volume of just 200 m³, when occupied by 45 people, with closed windows and an air change rate of around 1 h^-1, after 1 h a CO₂ concentration of about 0,3 % (volume fraction) resulted. From such findings, there resulted the recommendation to ensure sufficient ventilation. When the CO₂ concentration of a room is being reported, it is assumed that the air in the room is uniformly mixed and is thus of the same quality at all points, that is to say also has the same CO₂ concentration. However, this need not necessarily be the case, particularly in the case of mechanically ventilated rooms. Especially in very large rooms, for example, in auditoria, open-plan offices or angular rooms, depending on the position of the orifices for supply air and extract air or else on the type of mounting of installations, "dead zones" can be formed in which the air exchange is reduced. The indoor air pollution shall be limited to an extent safe for health. The value has been used for decades as a criterion of good air quality indoors and for calculating the design of room conditioning systems for ventilating indoor areas; for this purpose, based on an ambient air level of approximately 0,035 % to 0,04 % (volume fraction). The topics measurement objective and boundary conditions, when to measure, measurement location and period as well as measurement uncertainty and quality assurance are dealt with in detail. In Annex A, the calculation of the ventilation requirements of a room is described. Whereas CO₂ is removed continuously from indoor air in the case of mechanical ventilation, its removal is best achieved in rooms with natural ventilation by rapid air change by opening as many windows as possible at regular intervals. This applies in particular to most school rooms. Examples of screening tests and of continuously registering measuring devices for CO₂ and CO are described in informative Annex C. The sampling strategy procedure described in this part of ISO 16000 is based on VDI 4300 Part 9. This part of ISO 16000 is applicable for the measurement strategy for carbon dioxide (CO₂) but not carbon monoxide (CO) in indoor air. The International Standard has been prepared by Working Group 15 "Sampling strategy procedure for CO₂" of ISO/TC 146/SC 6 "Indoor air", the chairmanships and secretariats are each held by DIN. The responsible German committee is NA 134-04-04-01-01 AK "Planung von Innenraumluftmessungen" ("Planning of indoor air measurements").

Document: references other documents

Responsible national committee

NA 134-04-04-01 UA - Planning of indoorair analyses  

Responsible european committee

CEN/TC 264 - Air quality