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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Section 5 specifies the systems and equipment recommended under Standard 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.
The scope of Asurae 62 “applies to all indoor or enclosed spaces that people may occupy, except where other applicable standards and requirements dictate larger amounts of ventilation than this standard. Consideration should be given for a limited night setback mode with provision for humidity and pressurization control. In the absence standarf objective means to assess the acceptability of such contaminants, the judgment of acceptability must necessarily derive from subjective evaluations of impartial observers.
Using CO2 as an indicator of bioeffluents does not eliminate the need for consideration of other contaminants. It does not state the “indoor air quality shall be considered acceptable. However, contaminants that are not appreciably reduced 6-2001 the air-cleaning system may be the controlling factor in design and prohibit the reduction of air below shandard set by the Ventilation Rate Procedure. Although these devices may be adequate for modulating a box for thermal comfort, the combination of low quality airflow pickups and low cost atandard sensors in the DDC controller will not result in the measurement accuracy necessary for proper calculation of equation Once again, permanent airflow measuring stations would provide continuous outdoor airflow verification and provide necessary control inputs for an acceptable indoor environment.
The system shall be designed to maintain the supply airflow and minimum outdoor airflow as required by section 6 under any load condition.
It should be clear to the design professional that the dynamic nature of mechanical ventilation requires dynamic control. In the Ventilation Rate Procedure, 4. In addition, outside airflow rates will vary as a result of changes in mixed air plenum pressure. Increasing the critical zone supply flow by providing reheat can reduce total outside airflow rates.
Designers must choose and claim compliance under one procedure, not a combination of both. Since airflow rates are typically reduced in the Indoor Air Quality Procedure, its measurement and control is even more critical, especially on systems where the thermal load changes independent of the occupants and their activities. The system outdoor air quantity shall then be determined using Equation see References 23 and However, the uncertainty of indirect techniques introduces a significant level of risk.
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.
ASHRAE Standard 62-2001
The principal comment regarding 6. It must also include individual sensor and transmitter uncertainties. The pressurization airflow relationship is as follows: CO2 is an indicator of human activities and hence “bioeffluents” and not a measure of indoor air quality.
The International Mechanical Code has ashrrae 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 stadard conditions.
They should also evaluate the IAQ risk of their design.
It is also not practical to measure all potential contaminants and 622-2001 some cases, such as with fungus or mold, measurement may not be possible. The proposed addendum, only addresses positive pressure during periods of dehumidification. 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.
ASHRAE Standard | Midwest Air Filter
Maintaining a building at net neutral pressure under these conditions would be more appropriate. Although outside airflow rates into many buildings have increased with the use of the technology, there is potential for an increase in building pressurization problems, which could lead to increased mold and fungal growth.
Unlike thermal comfort, the effect of indoor air quality is difficult to measure. The calculation requires that the total supply airflow rate measured, QSA, usually with an airflow measuring station in the total supply air circuit and the airflow rate of the critical zones is measured with an airflow measuring station capable of accurate measurement.
The designer, occupants, and facility owners should carefully consider the method employed prior to implementation. 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.
Once more the Standard attempts to clear up the misunderstandings about CO2. The statement, “in the absence of wind and stack effect” is of concern since qshrae factors can significantly influence infiltration and exfiltration across the building envelope. However, there are numerous risks associated with both the quantitative and subjective evaluations provided within the procedure that every designer should be aware of.
A key distinction over the existing procedure will be the requirement for ventilation rates to be determined based on both occupant and space ventilation requirements. Outside airflow rates can also be reduced if the critical zones have variable occupancy. The actual occupant dissatisfaction is exponentially greater in practice.
Interpretations for Standard
Present motivation to design to the standard has been driven mostly by liability asurae risk management concerns and in shandard cases the desire of the design professionals to meet their obligation by designing to national, professional standards. Recirculation criteria are defined in 6. Also, caution should be exercised when reducing outside airflow rates since outside air is required to maintain proper building pressure.
Unfortunately, almost every facility has contaminants generated from within the space i. In addition, the HVAC system must be able to maintain occupied spaces at positive pressure with respect to the construction areas. Providing permanently mounted airflow measuring stations would also support the requirements set forth in 7. In such cases, twice the amount of outside air as indicated in Table 2 would be required for acceptable indoor air quality.
Its value as an indicator of actual ventilation rates is questionable. Standard 62 has been incorporated into many building codes. 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.