Continuous monitoring of temperature, relative humidity, and carbon dioxide is conducted to evaluate thermal conditions and outside air mix into occupied spaces during normal work hours. Data is logged and stored for evaluation of ventilation effectiveness for thermal comfort.

Heating, Ventilation, and Air-Conditioning (HVAC) layouts are inspected to determine the location of supply air, return air, and outside supply air duct locations. Where indicated, volumetric airflow measurements determine the local deliveries and balance of the HVAC system.

Carbon dioxide (CO2) monitoring gives an indication of the effectiveness of the air-handling system to supply and distribute fresh air throughout the work areas. CO2 is a normal by-product of human respiration; elevated levels can cause a "stale air" sensation, though no acute effects or health hazards exist.

Low humidity can cause eye, nose and throat irritation (particularly in the winter). High humidity encourages the growth of biological contaminants.

Criteria for evaluating indoor environments are provided by the following American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) standards:

• ASHRAE 62-2004, Ventilation for Acceptable Indoor Air Quality
• ASHRAE 55-2004, Thermal Environmental Conditions for Human Occupancy

Measured levels of temperature, humidity, carbon dioxide, ventilation rates, and occupant density are compared to these ASHRAE standards.

It should be noted that not more than 80% of a given human population can be adequately accommodated for thermal comfort within acceptable ranges.