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Study of Ventilation and Carbon Dioxide in an Office Building.


pdf icon Study of Ventilation and Carbon Dioxide in an Office Building. (779 K)
Nabinger, S. J.; Persily, A. K.; Dols, W. S.

ASHRAE Transactions, Vol. 100, No. 2, 1994.

Keywords:

office buildings; ventilation; carbon dioxide; indoor air quality; monitoring; tracer gas; ventilation rates

Abstract:

Ventilation rates and indoor carbon dioxide levels were monitored for two years in a new office building near St. Louis, Missouri. These measurements were made to assess the operation and performance of the ventilation system in this building and to investigate the relationship between indoor carbon dioxide levels and air change rates. Ventilation rates were measured with the tracer gas decay technique using an automated measuring system. Indoor carbon dioxide concentrations were also measured with an automated system. The ventilation rates exhibited a dependence on outdoor temperature that was expected based on the heating, ventilating, and air-conditioning (HVAC) system's controls. The air change rates under conditions of minimum outdoor air intake were about 0.5 air changes per hour (ach), which is lower than both the air change rate corresponding to the building design value for minimum outdoor air intake and the rate that corresponds to the recommended minimum outdoor airflow per person in ASHRAE Standard 62-1989. The indoor carbon dioxide concentrations were generally lower than the 1,000-ppm guideline in Standard 62. The relationship between the indoor carbon dioxide levels and the building air change rates was similar to that seen in other office buildings. These results are presented as part of a discussion on the use of equilibrium analysis of carbon dioxide concentrations to determine building air change rates. This discussion points out limitations in the use of equilibrium analysis of carbon dioxide concentrations in office buildings.