Ashrae Journal - December 2008 - (Page 24) Table 1: Computed and Recommended CO2 Concentrations for Outdoor Airflow Monitoring or DCV Upper Control Limit (Cont.) Monitoring DCV Upper Actual Default Values LEED-EB IEQ Assumed CO2 Program Control Limit Steady-State Combined Outdoor Credit 1 Activity Level Generation Concentration Concentration Concentration Air Rate Per Person Concentration (Alarm Level) (Caution Level) Occupancy Category Retail Sales (Except Below) Mall Common Areas Barbershop Beauty and Nail Salons Pet Shops (Animal Areas) Supermarket Coin-operated Laundries Sports and Entertainment Spectator Areas Disco/Dance Floors Health Clubs/Aerobics Room Health Clubs/Weight Room Bowling Alley (Seating) Gambling Casinos Game Arcades Stages, Studios *From ‡Steady-state cfm L/s (met)* (cfm per person) (ppm)† (ppm)† (ppm)†,‡ (ppm)†,§ 16 9 10 25 26 15 11 7.8 4.6 5 12.4 12.8 7.6 5.3 1.5 1.5 1.2 1.2 1.2 1.5 1.4 0.013 0.013 0.010 0.010 0.010 0.013 0.012 1,188 1,800 1,408 803 788 1,240 1,469 1,300 1,900 1,600 900 900 1,400 1,600 1,069 1,620 1,267 723 709 1,116 1,322 1,366 2,070 1,619 924 906 1,426 1,689 8 21 22 26 13 9 17 11 4 10.3 10.8 13 6.5 4.6 8.3 5.4 1.5 3 4 3 1.5 1.2 1.2 1.5 0.013 0.025 0.034 0.025 0.013 0.010 0.010 0.013 1,975 1,600 1,927 1,369 1,369 1,520 993 1,545 2,100 1,700 2,100 1,500 1,500 1,700 1,100 1,700 1,778 1,440 1,735 1,232 1,232 1,368 894 1,391 2,271 1,840 2,216 1,575 1,575 1,748 1,142 1,777 62.1 2007 User’s Manual or taken directly or estimated from 2005 ASHRAE Handbook—Fundamentals, Chapter 8, Table 4. †Assumes 400 ppm ambient. concentration –10%. §Steady-state concentration +15%. ventilation air is provided can be determined by Equation 6. (6) and an activity level (m) of 1.5, the corresponding room CO2 concentration would be: (7) This is the equivalent to the Equation 13 in the article by Taylor.13 As an example, consider a typical museum gallery. Table 6-1 of Standard 62.1-2007 defines the default occupancy of 40 people per 1,000 ft² (100 m²), and a default combined outdoor air rate of 9 cfm/person (4.6 L/s per person) delivered to the breathing zone. Assuming an ambient CO2 concentration of 400 ppm (see the sidebar “What is the Ambient CO2 Concentration?”), a zone air-distribution effectiveness of 1.0 24 ASHRAE Journal Starting with the expected steady-state concentration of CO2 for any given space, we can develop values that would be useful in a CO2 monitoring program. It may be desirable for a building or system operator to have two sets of CO2 concentrations. One value would be to use as a caution point, warning that the concentrations are approaching the generally expected maxiashrae.org December 2008 CO2 Concentration Difference Criteria for OA Monitoring http://www.ashrae.org
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