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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In reality, most systems require permanent airflow measurement devices to assure compliance with the standard. For systems that provide a constant volume of supply air to the conditioned space, outside airflow rates will vary as a result of a.
Understanding and assessing the potential risk as well as the asrae to provide a functional solution is the duty of the design professional. 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 intended to minimize the potential for adverse health effects.
Ventilation code enforcement has proven to be difficult because it is often misunderstood by the code enforcement agency in the local jurisdiction. Whether or not it explicitly requires airflow measuring devices or not is irrelevant. All of these variations can be compensated for by using an airflow measuring station at the intake to the air-handling unit with automatic controls. Outside airflow rates may require reset on variable volume systems based on calculations of the multi-space asyrae defined under 6.
Interpretations for Standard
Ventilation effectiveness is discussed in 6. 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.
62-2001 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. According to this section, “Under the ventilation rate procedure, for other than intermittent variable occupancy as defined in 6.
Standard 62 has been incorporated into many building codes. Especially in facilities with variable occupancy and activity levels. Designers should exercise caution when implementing strategies that rely on ERV units for outside air and result in building pressures that are close to net neutral by design. The statement below merely indicates that 622-001 body odor will most likely be acceptable if the conditions above are true.
The system shall be designed to maintain the supply airflow and minimum outdoor airflow as required by section 6 under any load condition. Variable occupancy can either be detected by a. Net neutral control requires more precise instrumentation and the margin of error is much smaller. Recirculation with air-cleaning systems is also an effective means for controlling contaminants when using the Indoor Air Quality Procedure.
Anything that changes the pressurization flow will result in fluctuations in building pressure.
The statement, “in the absence of wind and stack effect” is of concern since external factors can significantly influence infiltration and exfiltration across the building envelope. However, it neglects ashra significant influence of external pressure variations on all systems that result from changes in wind and stack pressures, which 622-001 exceeds 0. Consideration should be given for a limited night setback mode with provision for humidity and pressurization control.
Conversely, “When contaminants are generated in the space or conditioning system independent of occupants or their activities, supply of outdoor air should lead occupancy so that acceptable conditions will exist at the start of occupancy. A base ventilation rate will always be required, regardless of occupancy, to dilute such contaminants.
Interpretations for Standard 62-2001
If cleaned [filtered], recirculated air is used to reduce the outdoor air flow rate below the values shown in Table 2, the [Indoor] Air Quality Procedure, 6.
This can be accomplished by determining the critical zone fraction, Z, to calculate the corrected fraction of outdoor air, Y. Designers claiming this procedure must be able to substantiate that rates are maintained during all load conditions. Airflow sensors provided with VAV boxes should not be used for this calculation.
Also, caution should be exercised when reducing outside ashraw rates since outside air is required to maintain proper building pressure. In such cases, twice the amount of outside air as indicated in Table 2 would be stanxard for acceptable indoor air quality.
Using the steady-state model described in Appendix C of the Standard, 15 CFM per person would be the resulting quantity of outside air introduced into a space if a.
The critical space is that space with the greatest required fraction of outdoor air in the stanadrd to this space.
The concept of providing “a direct solution” is desirable in principle. 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”.
ASHRAE Standard 62-2001
The calculation requires that the total supply airflow rate measured, QSA, usually with an airflow measuring station in 62-2001 total supply air circuit and the airflow rate of the critical zones is measured with an airflow measuring station capable of accurate measurement. The principal comment regarding 6. Typically, the pressurization airflow, QP, is maintained at a fixed differential, regardless of the supply airflow rate required for temperature control.
This will be a standar improvement since a large portion of the dilution air required for acceptable IAQ is needed to dilute contaminants generated independently of the occupants and their activities.
Requiring only a “snap-shot” of airflow rates is analogous to providing a one-time setup for temperature control, which obviously would not be very effective. In addition, stzndard airflow rates will vary as a result of changes in mixed air plenum pressure.
As a result of the requirements set forth in the standard for compliance “under any load condition”, section 5 should require airflow measurement with automatic controls at the intake of all air-handling units that function to provide a building or space with outside air, regardless of the size or the axhrae of system.
Designers must choose and claim compliance under one procedure, not a combination of both. Designers should provide an acceptable indoor environment to maintain occupant productivity and health.
Unfortunately, almost every facility has contaminants generated from within the space i. ASHRAE Standard 62 standar a short, but often misinterpreted, document outlining ventilation requirements for acceptable indoor air quality.
Moisture is a prerequisite for mold and fungal growth and the condition should be avoided.