WHY YOU NEED TO MEASURE THE CARBON DIOXIDE IN YOUR BUILDING  

Each time you exhale, you’re releasing between 35,000 and 50,000 parts per million (ppm) of the asphyxiate gas carbon dioxide (CO2). While carbon dioxide is a trace gas, occurring naturally in our atmosphere, concentrations of 7 percent to 10 percent (70,000–100,000 ppm) can cause headaches, dizziness, vision or hearing impairment, and even suffocation. However, it’s rare for the indoor concentration of CO2 to reach harmful levels. In fact, carbon dioxide is often used to help indoor air quality experts calculate the IAQ of a building at any given time.

Indoor Air Quality (IAQ) is influenced by a complex mix of gasses and particles. Measuring CO2 levels can be a quick way to help experts determine if a building has adequate ventilation, and if enough outside air (OSA) is being delivered to the conditioned space.

Current guidelines from the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) recommend indoor CO2 levels not exceed the outdoor concentration by more than about 700 ppm. Carbon dioxide levels outside a building can range from 380 to 450 ppm, though this can vary according to traffic, nearby industry emissions, and weather conditions. For a building in an area with an average outdoor concentration of 400 ppm CO2, the ASHRAE maximum recommended indoor level of CO2 would be 1,100 ppm.

Measuring the levels of CO2 is the easy part — it’s when the numbers are interpreted that mistakes can be made. A low CO2 reading doesn’t automatically indicate quality ventilation. If a measurement is taken early in the morning, before occupants have spent hours inside, CO2 has not had a chance to accumulate. Likewise, if an “expert” calculates a high CO2 measurement, but fails to factor in the already high CO2 levels occurring naturally outside, they could needlessly recommend that unnecessary changes be made to the ventilation system or occupant density in the space.

This is why you should only enlist the help of a professional who doesn’t just know how to measure IAQ, but also has experience interpreting the data. We want you to breathe easy knowing that you are moving forward with the right information.