CO₂ Breathing Emission Calculator
Calculation Result
Indoor air quality affects health, comfort, and productivity. Carbon dioxide (CO₂), a natural component of exhaled breath, accumulates indoors and signals how well ventilated a space is. Understanding and estimating CO₂ concentration in a room can help manage ventilation, reduce risks of headaches, drowsiness, or worse air quality effects.
This article breaks down how a CO₂ Breathing Emission Calculator works, guiding you through the factors influencing indoor CO₂ levels and how to use those to get reliable estimates.
What Is a CO₂ Breathing Emission Calculator?
A CO₂ Breathing Emission Calculator estimates the increase of carbon dioxide concentration in an indoor environment based on several variables—number of occupants, activity level, room size or volume, air exchange rate, and time spent inside.
Since people exhale CO₂ continuously, the indoor air’s CO₂ level tends to rise depending on how much fresh air replaces stale air (ventilation rate), making such a tool vital for classrooms, offices, and homes concerned with air quality.
Key Factors Affecting Indoor CO₂ Concentration
1. Room Type and Ventilation Rate (ACH)
- Air Changes per Hour (ACH) quantify how many times the air inside a room is replaced with fresh air every hour.
- Different rooms have typical ACH values:
- Classroom: 3 ACH
- Office: 2 ACH
- Bedroom: 0.5 ACH
- Living Room: 1 ACH
- Custom ACH values can also be entered for more precise control.
Higher ACH means better ventilation and lower CO₂ buildup.
2. Occupancy and Activity Level
- Each person exhales CO₂ at rates that vary by activity:
- Sleeping: 0.3 liters CO₂ per minute
- Resting: 0.5 liters CO₂ per minute
- Working: 1.0 liters CO₂ per minute
- The number of people in the room multiplies this emission.
More occupants or higher activity increase CO₂ production.
3. Room Volume or Floor Area + Ceiling Height
- The calculator accepts either total room volume (in liters) or floor area plus ceiling height to estimate volume.
- 1 cubic meter equals 1,000 liters; this conversion lets you translate room dimensions into volume accurately.
Larger volume dilutes CO₂ concentration more effectively.
4. Starting CO₂ Concentration and Room Status
- Outdoor CO₂ baseline is typically 0.04% (400 ppm).
- If the room was previously occupied, the initial CO₂ level can be slightly higher due to residual indoor air, approximated as +200 ppm above outdoor levels.
How the Calculation Works: A Simplified Explanation
The calculator finds the total CO₂ produced by all occupants during the specified time, divides it by the room volume to find the concentration increase, and then adjusts for ventilation.
Ventilation reduces CO₂ buildup following an exponential decay model based on ACH and duration spent.
The formula predicts the eventual indoor CO₂ concentration as a percentage and parts per million (PPM), helping users assess the air quality status quickly.
Interpreting CO₂ Levels: Safety and Health Implications
| CO₂ Concentration | Percentage | PPM | Health Impact |
|---|---|---|---|
| Safe | <0.1% | < 1,000 | Good indoor air quality |
| Moderate | 0.1%–0.5% | 1,000–5,000 | Slightly elevated; ventilation recommended |
| Risky | 0.5%–3.0% | 5,000–30,000 | Can cause drowsiness, headaches; improve airflow |
| Dangerous | >3.0% | >30,000 | Potentially life-threatening; immediate action required |
How to Use a CO₂ Breathing Emission Calculator Effectively
- Choose your room type or enter a custom ACH.
- Specify previous room occupancy (fresh or used air).
- Input the number of occupants (from 1 up to 50).
- Select the activity level matching occupants’ exertion.
- Provide duration in minutes.
- Set the outdoor CO₂ baseline (defaults to 0.04%).
- Enter the room volume directly or provide floor area and ceiling height.
- Submit to calculate the estimated CO₂ level and safety advice.
Frequently Asked Questions (FAQs)
Can I use this calculator for commercial buildings?
Yes, by inputting accurate ACH values and room volumes, the calculator applies to offices, classrooms, and similar indoor environments.
Why does ventilation reduce CO₂ concentration exponentially?
Ventilation removes stale air continuously, diluting CO₂ levels at a rate proportional to the air exchange—this process follows an exponential decay pattern rather than linear.
Is outdoor CO₂ concentration always 0.04%?
That’s the typical average (around 400 ppm), but urban or industrial areas may have slightly higher baseline CO₂, which you can adjust in the calculator for accuracy.
How often should I check indoor CO₂ levels?
Monitoring during occupancy, especially in crowded or poorly ventilated rooms, helps maintain healthy air quality and prevent discomfort.
