In each occupiable space, the ventilation system shall be designed to deliver the required rate of outdoor airflow to the breathing zone.
Ventilation systems shall be designed to have the capacity to supply the minimum outdoor airflow rate, determined in accordance with this section. Murphy (9) described ventilation reset control (VRC), an approach that adjusts intake airflow based on current system ventilation efficiency (), accounting for changes in zone airflow.403.3.1.1 Outdoor airflow rate. Warden (10) advocated sensing and maintaining the C concentration in the supply air by adjusting intake airflow in a trim-and-respond fashion, but this approach focused on Standard 62-1989 rates and equations and it did not account for changes in population or airflow in each zone.
#To calculate people outdoor airflow rate in breathing zone manual
The User's Manual for Standard 62.12004 included one possible approach to DCV in multiple-zone systems, which responded to increased zone-level CO2 by first opening the local VAV damper, then the outdoor air damper but since it was largely unproven, it was removed in the 2007 User's Manual. But published information related to dynamic reset for multiple-zone systems, wherein one central air handler supplies a mixture of outdoor air and recirculated air for two or more zones, is limited. Zone-level DCV in 100% outdoor air systems, wherein one central air handler supplies only outdoor air to more than one zone without any recirculation between zones, follows directly from the single-zone approaches, provided each zone includes the necessary controls (airflow sensor, modulating damper and so on). Resetting intake airflow downward as population decreases and/ or as efficiency increases saves energy while maintaining the proper dilution ventilation in the system.ĭynamic reset approaches based on changes in population (demand controlled ventilation ) have been described (7,8,9) for single-zone systems, wherein one air handler supplies a mixture of outdoor air and recirculated air for one ventilation zone. Designers may specify optional controls that allow the system to operate with less-than-design intake airflow while still providing no less than the currently required outdoor airflow values. The minimum outdoor airflow rates and most of the multiple-zone system equations used for design, along with appropriate non-design parameters, can be used to find the outdoor airflow values needed at any operating condition. Standard 62.1 recognizes this fact and allows systems to be designed using optional dynamic reset controls to change either zone-level or system-level outdoor airflow, or both, in response to changes in zone population and system ventilation efficiency. To comply with Standard 62.1, the model building codes, (5,6) and LEED-NC, ventilation systems must be designed using the Standard 62.1 rates and equations.Īs conditions change during operation, however, the intake airflow required also changes. Designers need these minimum worstcase values to establish the mechanical system capacity for both heating and cooling. ASHRAE Standard 62.1-2007 (1) prescribes minimum breathing-zone outdoor airflow rates and the equations needed to determine zone-level and system-level (intake) outdoor airflow requirements for three major ventilation configurations: single-zone, 100% outdoor air, and multiple-zone systems.Īs described previously, (2,3,4) designers must use Standard 62.1 rates and equations along with appropriate design parameters, such as zone population and floor area, to calculate the minimum breathing-zone outdoor airflow () required for each zone (in any system), and the minimum system outdoor air intake flow (), which depends upon the ventilation system configuration.
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