What is it?
Carbon dioxide (CO₂) is a gas present naturally in the atmosphere and produced continuously by the respiration of people and animals and by various combustion processes.
In indoor air quality it is mainly used as an indicator of how effective ventilation and air renewal are in occupied spaces.
Assessing it shows whether the indoor air is being renewed adequately for the intended use of the building.
Where can it be found?
CO₂ is present in every occupied indoor space.
Its concentration rises when air renewal is insufficient for the number of occupants or the activity taking place.
Certain combustion appliances can also contribute, although in most buildings the main source is people’s breathing.
How does it affect the space?
CO₂ is one of the most widely used parameters for assessing how a building’s ventilation performs: its concentration rises when air renewal does not keep pace with the occupancy or activity in the room.
A reading therefore says less about the gas itself than about how the space is working, and points to opportunities for improvement related to air renewal. On its own it is not equivalent to indoor air quality.
How is it assessed?
What the inspection looks at
The technical inspection examines the building, its occupancy and the existing ventilation systems.
What is recorded for each measurement
Equipment, quantity, unit, location, date, measurement conditions and duration, together with the relevant limitations and the interpretation criterion applied.
How this factor is measured
Measurements are taken with specialist professional instruments to record CO₂ concentrations under different conditions of use when the scope of the assessment requires it.
Interpretation takes into account room occupancy, available ventilation, the intended use of each space and the overall behaviour of the indoor environment.
In assessments intended as expert evidence, calibrated instruments are used to ensure the reliability and traceability of the measurements.
Criteria
Results are interpreted using recognised technical references for indoor air quality and guidance values applicable to carbon dioxide.
The assessment takes into account the function of the room, the time occupants spend there and the other parameters assessed during the technical inspection.
This guide does not publish values or thresholds. Technical criteria, legal limits and recommendations are different things and are not presented as equivalent.
Improvement measures
Work always begins by understanding and, where possible, reducing the source, before acting on the path or on the space. Measures are prioritised by expected effect, feasibility and proportionality, and no products are recommended by default.
The action taken depends on the characteristics of the building and the results obtained. Options that may be considered include:
- Improving natural or mechanical ventilation.
- Optimising air renewal.
- Checking how heating and air-conditioning systems are working.
Recommendations are always made after an individual assessment.
How Cemprotecta helps
This factor is not assessed on its own. It is measured as part of an assessment that treats the space as a system, because what it describes is not so much a pollutant as how the ventilation is working.
What an assessment gives you is knowing what is there, where it is and what can be done about it, with an ordered sequence of measures rather than a list of problems.
- Inspection of the space and of accessible installations.
- Measurement or sampling in the rooms where people spend most time.
- Combined interpretation with the other factors assessed.
- A report with measures ranked by their expected effect on exposure.
Request an assessment
If this factor concerns you in your home or workplace, tell us about your case. The prior inspection will determine whether it is worth measuring and what else should be assessed alongside it.