Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation

D6245-18: Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation

Unlock a deeper understanding of building performance and occupant comfort with ASTM D6245-18, an essential guide for engineers and facility managers seeking to optimize indoor environments. This authoritative standard provides proven methodologies for leveraging indoor carbon dioxide (CO2) concentrations as a powerful diagnostic tool for assessing ventilation effectiveness and overall indoor air quality (IAQ).

What is D6245-18?

ASTM D6245-18, the "Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation," is a comprehensive engineering document developed by ASTM International. It outlines established methods for interpreting indoor CO2 levels to gain critical insights into building ventilation performance and the perceived comfort related to human bioeffluents. Its primary purpose is to provide professionals with a reliable framework for utilizing CO2 data in IAQ assessments.

Scope & Purpose

This industry-leading standard governs the application of measured indoor CO2 concentrations in evaluating building ventilation strategies and indoor air quality. It details how to estimate CO2 generation rates from occupants based on activity levels and body size, and how these concentrations relate to occupant comfort perception regarding body odor. The guide specifically covers techniques such as mass balance analysis at air handlers to determine outdoor air percentages, and tracer gas methods (decay and constant injection) to estimate whole-building air change rates using occupant-generated CO2. Importantly, it does not prescribe specific CO2 measurement methods, nor does it directly address the control of outdoor air intake rates based on CO2 levels.

Who Must Comply?

• • Primary audience: Environmental engineers, HVAC technicians, building scientists, facility managers, and industrial hygienists.
• • Industries affected: Commercial real estate, education, healthcare, building construction, and HVAC manufacturing.
• • Compliance nature: Voluntary and recommended for best practice.
• • Enforcement: Typically checked by building owners, facility managers, and consultants during IAQ investigations or building performance audits.

Key Requirements Overview

The standard requires professionals to understand the relationship between occupant CO2 generation and indoor concentrations. Key provisions include:

• • Calculating CO2 generation rates based on occupancy and activity levels.
• • Employing mass balance analysis at air handling units to quantify the percentage of outdoor air in the supply stream.
• • Utilizing CO2 as a tracer gas for estimating air change rates through techniques like decay or constant injection methods.
• • Recognizing CO2 levels as an indicator of occupant comfort related to bioeffluents, rather than a sole determinant of overall IAQ.
• • Considering measurement issues, sampling locations, and potential uncertainties when interpreting CO2 data.

Related Standards & References

ASTM D6245-18 works in conjunction with other essential standards. It references ASTM D1356 for terminology related to air sampling and analysis, and ASTM E741 for tracer gas dilution methods, providing a more robust framework for ventilation assessments. Furthermore, it aligns with ASHRAE Standard 62.1, "Ventilation for Acceptable Indoor Air Quality," which sets ventilation rate requirements that CO2 monitoring can help verify.