ANSI/ASHRAE Standard (Including ANSI/ASHRAE Addenda listed in Appendix H). Ventilation for Acceptable. Indoor Air Quality. Ventilation standards and mechanical codes have evolved to address ASHRAE Standard (2). Ventilation for .. ASHRAE Standard The Ventilation Rate Procedure found in ASHRAE Standard Addendum N was applied to Monmouth University’s Multipurpose Athletic.

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The Ventilation Rate Procedure “prescribes the rate at which ventilation air must be delivered to a space and various means to condition that air.

As with section 5. Designers should provide an acceptable indoor environment standarc maintain occupant productivity and health.

The widespread use of energy recovery ventilators ERV in some geographic areas has decreased the amount of outside air used to pressurize a building. Advanced VAV control strategies can satisfy the requirements of 6.

ASHRAE Standard 62-2001

According to this section, “Under the ventilation rate procedure, for other than intermittent variable occupancy as defined in 6.

However, contaminants that are not appreciably reduced by the air-cleaning system may be the controlling factor in design and prohibit the reduction of air below that set by the Ventilation Rate Procedure. The lack of specific guidelines to effectively overcome the effect of changing system dynamics on ventilation rates and distribution for today’s HVAC systems is partially to blame for design deficiencies.

Once again, permanent airflow measuring stations would provide continuous outdoor airflow verification and provide necessary control inputs for an acceptable indoor environment. The critical space is that space with the greatest required fraction of outdoor air stanxard the supply asyrae this space.

This is a significant advantage over differential pressure airflow measuring technologies various pitot tube arrays and airflow measuring dampers and CO2 sensors, whose transmitters are often subject to drift. Other potential contaminants for which definite limits have not been set 6-22001 discussed in Appendix B. It should be clear to the design professional that the dynamic nature of mechanical ventilation requires dynamic control.

In addition, increased humidity combined with wind and stack driven infiltration during periods when the ventilation system is not operating may be a significant factor influencing mold and fungal growth. This addendum addresses azhrae control and building pressurization. The International Mechanical Code has adopted a rigid interpretation of the Ventilation Rate Procedure of the parent document and requires devices and controls to maintain per person ventilation requirements at all load conditions.


However, the uncertainty of indirect techniques introduces a significant level of risk.

ASHRAE Standard | Midwest Air Filter

The system outdoor air quantity shall then be determined using Equation see References 23 and Net neutral control requires more precise instrumentation and the margin of error is much smaller. The following excerpts stress the potential risk of “claiming” the Indoor Air Quality Procedure.

Maintaining a building at net neutral pressure under these conditions would be more appropriate. The designer, occupants, and facility owners should carefully consider the method employed prior to implementation. Although this may sound impractical to some designers, the productivity and health benefits is far greater than the cost to satisfy the requirements for acceptable indoor air quality.

In the absence of objective means to assess the acceptability of such contaminants, the judgment of acceptability must necessarily derive from subjective evaluations of impartial observers. Therefore, systems that meet the minimum requirements of Table 2 and the outside air requirements set forth in 6. According to the Indoor Air Quality Procedure, providing dilution ventilation as prescribed by the Ventilation Rate Procedure will provide acceptable indoor air quality “ipso facto”.

All systems constructed or renovated after the adoption date of the parent document are required to be operated and maintained in accordance to the provisions set forth in this section of the standard. Studies have indicated that a ventilation rate of 15 CFM per person is adequate to dilute body odor.

In reality, this latter scenario describes most facilities and suggests that outside airflow rates are directly set by the HVAC system based on design parameters, prior to occupancy. The proposed addendum, only addresses positive pressure during periods of dehumidification. According to this procedure, 6.

Whenever the temperature of a building envelope is lower than the dew point of air migrating across it, there will be condensation.

There is the potential for condensation to occur under a positive pressure environment during periods of humidification in cold climates since the dew point of the air within the building could potentially be greater than the temperature of the building envelope.

Such systems shall be designed to maintain the building at net positive pressure with respect to outdoors, in the absence of wind and stack effect, during all hours of dehumidification. Anything that changes the pressurization flow will result in fluctuations in building pressure.


An area that only recently has received attention is the owner-occupant’s motivation to increase productivity and reduce the adverse impact a poor indoor environment can have on human health and well-being.

Interpretations for Standard 62-2001

Outside airflow rates can also be reduced if the critical zones have variable occupancy. Ventilation effectiveness is discussed in 62-2001. Mechanical ventilation systems shall include either manual or automatic controls that enable the fan system to operate whenever the spaces served are occupied.

Section 3 addresses definitions used within the standard. When applied in accordance to manufacturer’s recommendations, airflow measuring devices such as those manufactured by EBTRON, only require the verification of operation by test and balance professionals. The purpose of ASHRAE Standard 62, as defined in Section 1, is to “specify minimum ventilation rates and indoor air quality that will be acceptable to human occupants and are standarr to minimize the potential for adverse health effects.

Understanding and assessing the potential risk as well as ashrrae ability to provide a functional solution is the duty of the design professional. The pressurization airflow relationship is as follows: Being a rate based standard, continuous airflow measurement should be a central component of any effective control strategy ashrqe assure acceptable indoor air quality.

Designers must choose and claim compliance under one procedure, not a combination of both.

A revised procedure, addendum 62n, was under its third public review when this document was created. The system shall be designed to maintain the supply airflow and minimum outdoor airflow as required by section 6 under any load condition. Although these devices may be adequate for modulating a box for thermal comfort, the combination of low quality airflow pickups and low cost pressure sensors in the DDC controller will not result in the measurement accuracy necessary for proper calculation of equation The actual occupant dissatisfaction is exponentially greater in practice.

The allowable contaminant concentration in the occupied zone can be used with various system models standqrd Appendix [D] to compute the required outdoor air flow rate. Airflow sensors provided with VAV boxes should not be used for this calculation. Unfortunately, almost every facility has contaminants generated from within stanxard space i. The start-up phase, covered in section 7.