New tool measures ventilation and indoor air quality

A new online tool developed by a team of researchers from the U.S. National Institute of Standards and Technology (NIST) calculates target carbon dioxide (CO₂) levels based on data exclusive to individual buildings.

The Quick Indoor CO₂ (QICO2) tool from NIST uses CO₂ readings as captured by monitors in schools, residences and office spaces to measure appropriate levels of the gas — which is a hallmark of good ventilation and consequently, good indoor air quality.

Source: NIST

According to the tool’s developers, proper ventilation in buildings is oftentimes misunderstood. As such, the QICO2 has been designed to combine data about a user’s desired ventilation rate with information about a building and its occupants to arrive at ideal CO₂ levels in a building.

“By measuring CO₂, you can verify that you’re achieving the ventilation rate that your space was designed for, but you need to consider all the factors that impact CO₂ levels,” explained the researchers.

While a CO₂ level of 1,000 parts per million (ppm) or higher is largely considered an indicator of poor indoor air quality, developers of the QICO2 tool suggest that this number is misleading and that other factors influencing indoor CO₂ will differ from building to building — in other words, what translates to adequate ventilation in one space might prove inappropriate for others.

Instead, the researchers suggest that identifying the CO₂ level that aligns with a user’s desired ventilation rate is based on the collection of other factors including the number of occupants and their ages, weights and levels of physical activity — all of which impact the amount of indoor CO₂. Likewise, outdoor CO₂ levels, a building’s size and indoor temperatures are also factors that impact indoor ventilation. As such, the researchers determined the mathematical relationships between these factors and indoor CO₂ levels, and combined them together within the QICO2 tool.

This data, according to the tool’s developers, can be manually entered into the QICO2 which then calculates the CO₂ levels users can compare their readings against so that corrections to their ventilation system can be made if necessary.

The QICO2 tool is currently available for free on the NIST website and it is detailed in the article, Development and application of an indoor carbon dioxide metric, which appears in the journal Indoor Air.