Referenced in the IMC. Major Scope Changes and More in Standard Other changes to the edition include the following: A revised definition of "environmental tobacco smoke" ETS to include emissions from electronic smoking devices and the smoking of cannabis Revised operations and maintenance requirements to better align Standard More Information. Commentaries Commentaries Commentaries Commentary Commentaries Commentaries.
District of Columbia District of Columbia Codes. Florida Florida Codes 6th ed. Arizona Phoenix. California California References. Illinois Illinois - Chicago. Pennsylvania Pennsylvania - Philadelphia. Washington Washington - Bellevue.
Energy Energy References Inspection. In , the standard reduced minimum outdoor airflow rates and introduced an alternative performance-based approach, the IAQ Procedure, which allowed for the calculation of the amount of outdoor air necessary to maintain the levels of indoor air contaminants below recommended limits.
In —the last time the standard was revised in its entirety—the IAQ Procedure was modified to improve enforceability, but more significantly the Ventilation Rate Procedure was modified, changing both the minimum outdoor airflow rates and the procedures for calculating both zone-level and system-level outdoor airflow rates.
For more specific information on these and other changes made to the standard, refer to Informative Appendix O. Standard Change proposals can be submitted online at www.
The project committee for Standard SCOPE 2. Spaces that contain smoking or that do not meet the requirements in the standard for sepa- ration from spaces that contain smoking b.
Patient care areas not listed in this standard c. Laboratories with hazardous materials 3. ETS is commonly referred to as secondhand smoke. This definition includes smoke produced from the combustion of cannabis and con- trolled substances and the emissions produced by electronic smoking devices. The free area of the wall is the ratio of area of the open- ings through the wall, such as openings between louver blades and undercuts, divided by the gross area length times height of the wall.
ETS-free area: an area where no smoking occurs and that is separated from ETS areas accord- ing to the requirements of this standard. Hazardous chemicals are any chemicals that are classified as a health hazard or simple asphyxiant, in accordance with the Hazard Communication Standard 29 CFR Obstructions in the space, such as furnishings, display or storage racks, and other obstructions, whether temporary or permanent, are considered to be part of the net occupiable area. Such care includes monitoring, evaluation, and treatment services.
Such rooms and spaces that are also part of a dwelling unit are not sleeping units. Informative Note: A ventilation zone is not necessarily an independent thermal control zone; however, spaces that can be combined for load calcula- tion purposes can often be combined into a single zone for ventilation calculations purposes. The results of this investigation shall be documented in accordance with Section 4. The status of compliance with national ambient air quality stan- dards shall be determined for the geographic area of the building site.
In the United States, areas with no U. Informative Notes: 1. Air quality data collected at outdoor monitors across the U. Internet links to detailed information on the NAAQS and contaminant levels for other select counties and regions can be found in Informative Appendix D.
An observational survey of the building site and its immediate sur- roundings shall be conducted during hours the building is expected to be normally occupied to identify local contaminants from surrounding facilities that will be of concern if allowed to enter the building. Regional air quality compliance status b. Local survey information 1. Date of observations 2. Time of observations 3. Site description 4. Description of facilities on site and on adjoining properties 5.
Observation of odors or irritants 6. Observation of visible plumes or visible air contaminants 7. Description of sources of vehicle exhaust on site and on adjoining properties 8. Identification of potential contaminant sources on the site and from adjoining proper- ties, including any that operate only seasonally c. Conclusion regarding the acceptability of outdoor air quality and the information support- ing the conclusion 5.
Ventilating systems shall be designed in accordance with the requirements of the following subsections. Ventilation air distribution systems shall be provided that allow field verification of outdoor air intake flow Vot during operation. The ventilation air dis- tribution system for variable air volume VAV and multispeed constant air volume CAV appli- cations shall be provided with means to adjust the system to achieve at least the minimum ventilation airflow as required by Section 6 under any load condition or dynamic reset condition.
When the ceiling or floor plenum is used both to recirculate return air and to distribute ventilation air to ceiling-mounted or floor-mounted terminal units, the sys- tem shall be engineered such that each space is provided with its required minimum ventilation airflow. Informative Note: Systems with direct connection of ventilation air ducts to terminal units, for example, comply with this requirement.
The design documents shall specify minimum requirements for air balance testing or reference applicable national standards for measuring and balancing airflow. The design documentation shall state assumptions that were made in the design with respect to ventilation rates and air distribution.
Exception to 5. Mechanical ventilation systems shall include controls in accordance with the following subsections. All airstream surfaces in equipment and ducts in the HVAC system shall be designed and constructed in accordance with the requirements of the following sub- sections. Informative Note: Even with this resistance, any airstream surface that is continuously wet- ted is still subject to microbial growth.
Airstream surface materials shall be evaluated in accordance with the erosion test in UL and shall not break away, crack, peel, flake off, or show evi- dence of delamination or continued erosion under test conditions. Ventilation system outdoor air intakes shall be designed in accor- dance with the following subsections.
Outdoor air intakes including openings that are required as part of a natural ventilation system shall be located such that the shortest distance from the intake to any spe- cific potential outdoor contaminant source listed in Table shall be equal to or greater than a.
Where snow accumulation is expected, the surface of the snow at the expected average snow depth shall be considered to be a surface directly below an intake. Outdoor air intakes that are part of the mechanical ventilation sys- tem shall be designed to manage rain entrainment in accordance with one or more of the fol- lowing: a.
Limit water penetration through the intake to 0. Select louvers that limit water penetration to a maximum of 0. This water penetration rate shall be determined for a minimum 15 minute test duration when subjected to a water flow rate of 0. Manage the water that penetrates the louver by providing a drainage area or moisture removal devices.
Select louvers that restrict wind-driven rain penetration to less than 2. Use rain hoods sized for no more than fpm 2. Manage the water that penetrates the intake opening by providing a drainage area or mois- ture removal devices.
Air-handling and distribution equipment mounted outdoors shall be designed to prevent rain intrusion into the airstream when tested at design airflow and with no airflow, using the rain test apparatus described in UL , Section Where climate dictates, outdoor air intakes that are part of the mechanical ventilation system shall be designed as follows to manage water from snow that is blown or drawn into the system: a.
Access doors to permit cleaning of wetted surfaces shall be provided. Outdoor air ductwork or plenums shall pitch to drains designed in accordance with the requirements of Section 5. Outdoor air intakes shall include a screening device designed to prevent penetration by a 0. The screening device material shall be corro- sion resistant.
The screening device shall be located, or other measures shall be taken, to pre- vent bird nesting within the outdoor air intake. Informative Note: Any horizontal surface may be subject to bird nesting. The discharge from noncombustion equipment that captures the contaminants generated by the equipment shall be ducted directly to the outdoors. The use of ozone generating devices shall comply with the following sections. Motors and relays are examples of electronic devices that would be exempt.
Air-cleaning devices shall be listed and labeled in accordance with UL Informative Note: The use of devices not intended for air cleaning with the potential to gen- erate ozone should be avoided. Ultraviolet generating devices in supply air or spaces shall not transmit nm wavelengths.
Informative Note: Ultraviolet devices used in treatment of closed water systems may pro- duce nm wavelengths, which may generate ozone. Fuel-burning appliances, both vented and unvented, shall be provided with air for combustion and removal of combustion products in accordance with manufacturer instructions.
Products of combustion from vented appliances shall be vented directly outdoors. Particulate matter filters or air cleaners having either a. The dew-point limit shall not be exceeded when system perfor- mance is analyzed with outdoor air at the dehumidification design condition that is, design dew point and mean coincident dry-bulb temperatures and with the space interior loads both sensible and latent at cooling design values and space solar loads at zero.
Exceptions to 5. Buildings or spaces that are neither equipped with nor served by mechanical cooling equipment. Buildings or spaces equipped with materials, assemblies, coatings, and furnishings that resist microbial growth and that are not damaged by continuously high indoor air dew points.
Examples of spaces are shower rooms, swimming pool enclosures, kitchens, spa rooms, or semicooled warehouse spaces that contain stored contents that are not damaged by continuously high indoor air dew points or microbial growth. This requirement reduces the risk of microbial growth in buildings and their intersti- tial spaces because it limits the mass of indoor water vapor that can condense or be absorbed into mechanically cooled surfaces. Ventilation systems for a building equipped with or served by mechanical cooling equipment shall be designed such that the total building outdoor air intake equals or exceeds the total building exhaust under all load and dynamic reset conditions.
Where an imbalance is required by process considerations and approved by the authority having jurisdiction AHJ , such as in certain industrial facilities. When outdoor air dry-bulb temperature is below the indoor space dew-point design temperature. Informative Note: Although individual zones within a building may be neutral or negative with respect to outdoors or to other zones, net positive mechanical intake airflow for the build- ing as a whole reduces infiltration of untreated outdoor air.
Drain pans, including their outlets and seals, shall be designed and con- structed in accordance with this section. Pans intended to collect and drain liquid water shall be sloped at least 0. The drain pan outlet shall be located at the lowest point s of the drain pan and shall be sized to preclude drain pan overflow under any normally expected operating condition.
For configurations that result in negative static pressure at the drain pan relative to the drain outlet such as a draw-through unit , the drain line shall include a P-trap or other sealing device designed to maintain a seal against ingestion of ambient air, while allow- ing complete drainage of the drain pan under any normally expected operating condition, whether the fan is ON or OFF. The drain pan shall be located under the water producing device. Drain pan width shall be sized to collect water droplets across the entire width of the water producing device or assembly.
For horizontal airflow configurations, the drain pan length shall begin at the leading face or edge of the water producing device or assembly and extend downstream from the leaving face or edge to a distance of either a. A drain pan, in accordance with Section 5.
Individual finned-tube coils or multiple finned-tube coils in series without intervening access spaces of at least 18 in. Steam and direct-evaporative humidifiers, air washers, direct-evaporative coolers, and other water spray systems shall be designed in accor- dance with this section. Water purity shall meet or exceed potable water standards at the point where it enters the ventilation system, space, or water vapor generator.
Water vapor generated shall contain no chemical additives other than those chemicals in a potable water system. Boiler water additives that meet the requirements of 21 CFR Air cleaners or ductwork obstructions, such as turning vanes, volume dampers, and duct offsets greater than 15 degrees, that are installed downstream of humidifiers or water spray systems shall be located a distance equal to or greater than the absorption dis- tance recommended by the humidifier or water spray system manufacturer.
Exception 5. Ventilation equipment shall be installed with working space that will allow for inspection and routine maintenance, including filter replacement and fan belt adjustment and replacement. Access doors, panels, or other means shall be pro- vided and sized to allow unobstructed access for inspection, maintenance, and calibration of all ventilation system components for which routine inspection, maintenance, or calibration is necessary.
Ventilation system components include air-handling units, fan-coil units, water- source heat pumps, other terminal units, controllers, and sensors.
Access doors, panels, or other means shall be provided in ventilation equipment, ductwork, and plenums, located and sized to allow convenient and unobstructed access for inspection, cleaning, and routine maintenance of the following: a. Outdoor air intake areaways or plenums b. Mixed-air plenums c. Upstream surface of each heating, cooling, and heat-recovery coil or coil assembly having a total of four rows or fewer d.
Both upstream and downstream surface of each heating, cooling, and heat-recovery coil having a total of more than four rows, and air washers, evaporative coolers, heat wheels, and other heat exchangers e. Air cleaners f. Drain pans and drain seals g.
Fans h. Humidifiers 5. The building envelope and interior surfaces within the building envelope shall be designed in accordance with the following subsections. The building envelope, including roofs, walls, fenestration sys- tems, and foundations, shall comply with the following: a. A weather barrier or other means shall be provided to prevent liquid-water penetration into the envelope. An appropriately placed vapor retarder or other means shall be provided to limit water vapor diffusion to prevent condensation on cold surfaces within the envelope.
Exterior joints, seams, or penetrations in the building envelope that are pathways for air leakage shall be caulked, gasketed, weather stripped, provided with a continuous air bar- rier, or otherwise sealed to limit infiltration through the envelope to reduce uncontrolled entry of outdoor air moisture and pollutants.
Informative Note: In localities where soils contain high concentrations of radon or other soil- gas contaminants, the AHJ might impose additional measures such as subslab depressurization. Pipes, ducts, and other surfaces within the build- ing whose surface temperatures are expected to fall below the surrounding dew-point tempera- ture shall be insulated.
The insulation system thermal resistance and material characteristics shall prevent condensate from forming on the exposed surface and within the insulating material. A management plan must be submitted along with the design specifying design assumptions and limits of the plan. The plan must be provided to the owner. In order to limit the entry of vehicular exhaust into occupiable spaces, buildings with attached parking garages shall be designed to a. Air shall be classified, and its recirculation shall be limited in accordance with the following subsections.
Air return, transfer, or exhaust air leaving each space or location shall be designated at an expected air-quality classification not less than that shown in Table , , or or as approved by the AHJ. Air leaving spaces or locations that are not listed in Table , , or shall be designated with the same classification as air from the most similar space or location listed in terms of occupant activities and building construction. Classification of air from spaces where ETS is present is not addressed.
Spaces that are expected to include ETS do not have a classification listed in Table Informative Note: Classifications in Tables , , and are based on relative contami- nant concentration using the following subjective criteria: 1.
Class 1: Air with low contaminant concentration, low sensory-irritation intensity, and inoffensive odor. Class 2: Air with moderate contaminant concentration, mild sensory-irritation inten- sity, or mildly offensive odors.
Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes.
Class 3: Air with significant contaminant concentration, significant sensory-irritation intensity, or offensive odor. Class 4: Air with highly objectionable fumes or gases or with potentially dangerous particles, bioaerosols, or gases, at concentrations high enough to be considered as harmful.
If air leaving a space or location passes through an air-cleaning system, redesignation of the cleaned air to a cleaner classification shall be permitted per the following requirements: a. Class 2 air where based on the subjective criteria in the informative note for Section 5. Class 3 and Class 4 air when all requirements of Sections 6. A mixture of air that has been transferred through or returned from spaces or locations with different air classes shall be redesignated with the highest classifica- tion among the air classes mixed.
Informative Note: For example, mixed return air to a common system serving both a Class 1 space and a Class 2 space is designated as Class 2 air. Redesignation of Class 1 air to Class 2 air shall be permitted for Class 1 spaces that are ancillary to Class 2 spaces. Informative Note: For example, an office within a restaurant might be designated as a space ancillary to a Class 2 space, thus enabling the office to receive Class 2 air.
When the Ventilation Rate Procedure of Section 6 is used to determine ventilation airflow values, recirculation of air shall be limited in accordance with the requirements of this section. Recirculation or transfer of Class 1 air to any space shall be permitted.
Class 4 air shall not be recirculated or transferred to any space or recirculated within the space of origin. Design documentation shall indicate the justification for classification of air from any occupancy category, airstream, or location not listed in Table , , or Such buildings shall be constructed and operated in accordance with Sections 5.
Dwelling units, including hotel and motel guestrooms, and adjacent properties under different ownership with separation walls that are structurally independent and that contain no openings. This exception shall apply only when a. Adjacent spaces otherwise required to be held at negative pressure and posted with signs due to the presence of hazardous or flammable materials or vapors. Informative Note: Examples of methods for demonstrating relative pressure include engi- neering analysis, pressure differential measurement, and airflow measurement.
Solid walls, floors, ceilings, and doors equipped with automatic closing mechanisms shall separate ETS areas from ETS-free areas. Informative Note: Examples of methods for demonstrating air motion are engineering anal- ysis and the use of a directional airflow indicator at representative locations in the opening, such as on 1 ft 0.
Acceptable means of doing so include fixed openings in doors, walls, or floors, transfer grilles, transfer ducts, or unducted air plenums with air pressure differentials in compliance with Section 5.
Air-handling and natural ventilation systems shall not recirculate or transfer air from an ETS area to an ETS-free area. Exhaust or relief air from an ETS area shall be discharged such that none of the air is recirculated back into any ETS-free area.
A sign shall be posted outside each entrance to each ETS area. An area that was previously an ETS area but now meets the require- ments of an ETS-free area shall be permitted to be classified as such where smoke exposure has stopped and odor and irritation from residual ETS contaminants are not apparent. In addi- tion, the requirements for exhaust ventilation in Section 6. Informative Note: Although the intake airflow determined using each of these approaches may differ significantly because of assumptions about the design, any of these approaches is a valid basis for design.
The prescriptive design procedure presented in Section 6. The performance-based design procedure pre- sented in Section 6. The prescriptive or engineered system design proce- dure presented in Section 6. Each ventilation system that provides outdoor air shall com- ply with Sections 6.
Exception to 6. Informative Note: Occupied spaces ventilated with outdoor air that is judged to be unac- ceptable are subject to reduced air quality when outdoor air is not cleaned prior to introduction to the occupied spaces. In buildings located in an area where the national standard or guideline for PM10 is exceeded, particle filters or air- cleaning devices shall be provided to clean the outdoor air at any location prior to its introduc- tion to occupied spaces.
Particulate matter filters or air cleaners shall have either a. In buildings located in an area where the national standard or guideline for PM2. Air-cleaning devices for ozone shall be provided when the most recent three-year average annual fourth-highest daily maximum eight-hour average ozone concentra- tion exceeds 0. Such devices shall be operated where the outdoor ozone levels are expected to exceed 0. Exceptions to 6. Informative Note: In the U. In buildings located in an area where the national standard for one or more contaminants not addressed in Section 6.
The outdoor air intake flow Vot for a ventilation system shall be determined in accordance with Section 6. Informative Note: Additional explanation of terms used below is contained in Normative Appendix A, along with a ventilation system schematic Figure A Ventilation zone parameters shall be determined in accordance with Sections 6.
The outdoor airflow required in the breathing zone Vbz of the occupiable space or spaces in a ventilation zone shall be not less than the value determined in accordance with Equation Equation accounts for people-related sources and area-related sources inde- pendently in the determination of the outdoor air rate required at the breathing zone.
The use of Equation in the context of this standard does not necessarily imply that simple addition of outdoor airflow rates for different sources can be applied to any other aspect of IAQ. The rates in Table are based on all other applicable requirements of this standard being met. If other requirements of the standard are not met, then the rates do not apply. Where the occupancy category for a proposed space or zone is not listed, the requirements for the listed occupancy category that is most similar in terms of occupant density, activities, and building construction shall be used.
Outpatient facilities to which the rates apply are freestanding birth centers, urgent care centers, neighborhood clinics and physicians offices, Class 1 imaging facilities, outpatient psychiatric facilities, outpatient rehabilitation facilities, and outpatient dental facilities. The requirements of this table provide for acceptable IAQ. The requirements of this table do not address the airborne transmission of airborne viruses, bacteria, and other infectious contagions.
Informative Note: These rates are intended only for outpatient dental clinics where the amount of nitrous oxide is limited. They are not intended for dental operatories in institutional buildings where nitrous oxide is piped. B Where combustion equipment is intended to be used on the playing surface, additional dilution ventilation, source control, or both shall be provided.
D Rate is per water closet, urinal, or both. Provide the higher rate where periods of heavy use are expected to occur. The lower rate shall be permitted to be used otherwise. E Rate is for a toilet room intended to be occupied by one person at a time. For continuous system operation during hours of use, the lower rate shall be permitted to be used. Other- wise the higher rate shall be used. F See other applicable standards for exhaust rate.
G For continuous system operation, the lower rate shall be permitted to be used. Otherwise the higher rate shall be used. H Exhaust air that has been cleaned to meet Class 1 criteria from Section 5. I Rate is per showerhead. The Ventilation Rate Procedure minimum rates are based on contaminant sources and source strengths that are typical for the listed occupancy categories.
Where unusual sources are expected, the additional ventilation or air cleaning required shall be calculated using Section 6. Zones where emissions are expected from stored hazardous materials are not typical for any listed occupancy category. Dry ice, theatrical smoke, and smoke-producing activities are not typical for any listed occupancy categories. Volumetric airflow rates are based on dry-air density of 0.
Rates shall be permitted to be adjusted for actual density. Air from one residential dwelling shall not be recirculated or transferred to any other space outside of that dwelling. Design zone population Pz shall equal the largest peak number of people expected to occupy the ventilation zone during typical use. Where the number of people expected to occupy the ventilation zone fluctuates, zone population equal to the average number of people shall be permitted, pro- vided such average is determined in accordance with Section 6.
Where the largest or average number of people expected to occupy the ventilation zone cannot be established for a specific design, an estimated value for zone pop- ulation shall be permitted, provided such value is the product of the net occupiable area of the ventilation zone and the default occupant density listed in Table Default occupancy for dwelling units shall be two persons for studio and one-bedroom units, with one additional person for each additional bedroom.
The zone air distribution effectiveness Ez shall be determined in accordance with Table or Normative Appendix C. For some configurations, the default value depends on space and supply air tem- perature. Calculation of Ez using the procedures in Normative Appendix C may result in val- ues greater than those listed in Table for systems with the same description.
A stratified air distribution system shall be designed in accordance with the following subsections, or the zone air distribution effective- ness Ez shall be determined in accordance with Normative Appendix C. The return air openings or pathways shall be located more than 9 ft 2. The zone shall not contain any devices that mechanically mix the air, and shall be protected from impinging airstreams from adjacent ventilation zones.
Informative Note: Ceiling fans, blowers, air curtains, aspirating diffusers without adequate draft separation, or other devices that disrupt the stratification cause the zone air distribution effectiveness to be similar to a well-mixed system. A personalized ventilation system shall be designed in accordance with the following subsections, or the zone air distribution effectiveness Ez shall be determined in accordance with Normative Appendix C.
Informative Note: A personalized ventilation system is primarily for exposure control and dilution of contaminants in the breathing zone and may provide some spot cooling. Personal- ized ventilation is used when the occupant spends most of their time in one occupied space. It is used in conjunction with another air distribution system that handles the area ventilation requirements and thermal loads in the space.
The personalized air shall be distributed in the breathing zone and designed such that the velocity is equal to or less than 50 fpm 0.
The zone outdoor airflow Voz provided to the ventilation zone by the supply air distribution system shall be determined in accordance with Equation For ventilation systems wherein one or more air handler sup- plies a mixture of outdoor air and recirculated air to only one ventilation zone, the outdoor air intake flow Vot shall be determined in accordance with Equation For ventilation systems wherein one or more air handler supplies only outdoor air to one or more ventilation zones, the outdoor air intake flow Vot shall be determined in accordance with Equation For ventilation systems wherein one or more air handler supplies a mixture of outdoor air and recirculated air to more than one ven- tilation zone, the outdoor air intake flow Vot shall be determined in accordance with Sec- tions 6.
The uncorrected outdoor air intake Vou flow shall be determined in accordance with Equation The occupant diversity ratio D shall be determined in accordance with Equation to account for variations in population within the ventilation zones served by the system. Design system population Ps shall equal the larg- est peak number of people expected to occupy all ventilation zones served by the ventilation system during use.
Informative Note: Design system population is always equal to or less than the sum of design zone population for all zones in the area served by the system because all zones may not be simultaneously occupied at design population. The system ventilation efficiency Ev shall be determined in accordance with Section 6. Informative Note: These procedures also establish zone minimum primary airflow rates for VAV systems.
System ventilation efficiency Ev shall be determined in accordance with Equation or For each zone, the minimum primary air- flow Vpz-min shall be determined in accordance with Equation The design outdoor air intake flow Vot shall be determined in accordance with Equation Ventilation systems shall be designed to be capable of providing not less than the minimum ventilation rates required in the breathing zone where the zones served by the system are occupied, including all full- and part-load conditions.
Informative Note: The minimum outdoor air intake flow may be less than the design value at part-load conditions. Where it is known that peak occupancy will be of short duration, ventilation will be varied or interrupted for a short period of time, or both, the design shall be permitted to be based on the average conditions over a time period T determined by Equation a I-P or b SI.
Zones with fluctuating occupancy: The zone population Pz shall be permitted to be aver- aged over time T. Zones with intermittent interruption of supply air: The average outdoor airflow supplied to the breathing zone over time T shall be not less than the breathing zone outdoor airflow Vbz calculated using Equation Systems with intermittent closure of the outdoor air intake: The average outdoor air intake over time T shall be not less than the minimum outdoor air intake Vot calculated using Equation , , or as appropriate.
The system shall be permitted to be designed to reset the outdoor air intake flow Vot , the space or ventilation zone airflow Voz as operating conditions change, or both. DCV shall be permitted as an optional means of dynamic reset. Current population estimates used in DCV control calculations shall not result in ventilation rates that are less than those required by the actual population during any one-hour time period.
Sensors shall be factory calibrated and certified by the manufacturer to require calibration not more frequently than once every five years. Upon detec- tion of sensor failure, the system shall provide a signal that resets the ventilation system to sup- ply the required minimum quantity of outdoor air Vbz to the breathing zone for the design zone population Pz.
A written description of the equipment, methods, control sequences, set points, and the intended operational functions shall be provided. A table shall be provided that shows the minimum and maximum outdoor intake airflow for each system.
Variations in the efficiency with which outdoor air is dis- tributed to the occupants under different ventilation system airflows and temperatures shall be permitted as an optional basis of dynamic reset. A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooling or exhaust air makeup shall be permitted as an optional basis of dynamic reset.
Breathing zone outdoor airflow Vbz shall be determined in accordance with Sections 6. Each contaminant of concern, for purposes of the design, shall be identified. For each contaminant of concern, indoor sources and outdoor sources shall be identified, and the emission rate for each contaminant of concern from each source shall be determined.
Where two or more contaminants of concern target the same organ system, these contaminants shall be considered to be a contaminant mixture. For each contaminant of concern, a concentration limit and its corresponding exposure period and an appropriate reference to a cognizant authority shall be specified.
For each contaminant mixture of concern, the ratio of the concentration of each contaminant to its concentration limit shall be determined, and the sum of these ratios shall be not greater than one. Informative Note: Odors are addressed in Section 6. The design level of indoor air acceptability shall be specified in terms of the percentage of building occupants, visitors, or both expressing satis- faction with perceived IAQ. Zone and system outdoor airflow rates shall be the larger of those determined in accordance with Section 6.
Using a steady-state or dynamic mass-balance analysis, the minimum outdoor airflow rates required to achieve the concentration limits specified in Sec- tion 6. Informative Appendix E includes steady-state mass-balance equations that describe the impact of air cleaning on outdoor air and recirculation rates for ventilation sys- tems serving a single zone.
In the completed building, measurement of the concentration of contaminants or contaminant mixtures of concern may be useful as a means of checking the accu- racy of the design mass-balance analysis, but such measurement is not required for compliance. Using a subjective occupant evaluation conducted in the completed building, the minimum outdoor airflow rates required to achieve the level of accept- ability specified in Section 6.
The minimum outdoor airflow rates shall be not less than those found in accordance with Section 6. In this case, the Ventilation Rate Procedure shall be used to determine the required zone minimum outdoor airflow, and the IAQ Procedure shall be used to determine the addi- tional outdoor air or air cleaning necessary to achieve the concentration limits of the contami- nants and contaminant mixtures of concern. Informative Note: The improvement of IAQ through the use of air cleaning or provision of additional outdoor air in conjunction with minimum ventilation rates may be quantified using the IAQ Procedure.
Where the IAQ Procedure is used, the following information shall be included in the design documentation: the contaminants and contaminant mixtures of concern considered in the design process, the sources and emission rates of the contaminants of con- cern, the concentration limits and exposure periods and the references for these limits, and the analytical approach used to determine ventilation rates and air-cleaning requirements.
The con- taminant monitoring and occupant or visitor evaluation plans shall also be included in the doc- umentation. Natural ventilation systems shall comply with the requirements of either Section 6. Designers shall provide interior air barriers, insu- lation, or other means that separate naturally ventilated spaces from mechanically cooled spaces to prevent high-dew-point outdoor air from coming into contact with mechanically cooled surfaces. Any zone designed for natural ventilation shall include a mechanical ventilation system designed in accordance with Section 6.
Zones in buildings that have all of the following: a. Natural ventilation openings that comply with the requirements of Section 6. Controls that prevent the natural ventilation openings from being closed during peri- ods of expected occupancy, or natural ventilation openings that are permanently open.
Zones that are not served by heating or cooling equipment. For ceilings that are parallel to the floor, the ceiling height H to be used in Sections 6. For zones wherein ceiling height increases as distance from the ventilation increases, the ceiling height shall be the average height of the ceiling determined over a distance not greater than 6 m 20 ft from the openings.
The naturally ventilated area in zones or portions of zones shall extend from the openings to a distance determined by Sections 6. Openings shall meet the requirements of Section 6. For zones where ceilings are not parallel to the floor, the ceiling height shall be determined in accordance with Section 6. For zones with openings on only one side of the zone, the naturally ventilated area shall extend to a distance not greater that two times the height of the ceiling from the openings.
For zones with openings on two opposite sides of the zone, the naturally ventilated area shall extend between the openings separated by a distance not greater than five times the height of the ceiling. Floor area outside that line shall comply with Section 6.
Informative Note: Floor area outside that line refers to the remaining area of the zone that is not bounded by the walls that have the openings and the line drawn between the openings.
Zones or portions of zones to be naturally venti- lated shall have a permanently open airflow path to openings directly connected to the outdoors. The minimum flow rate to the zone shall be determined in accordance with Section 6. This flow rate shall be used to determine the required openable area of openings, accounting only for buoyancy-driven flow.
Wind-driven flow shall be used only where it can be demon- strated that the minimum flow rate is provided during all occupied hours. Openings shall be sized in accordance with Section 6.
Informative Note: Permanently open airflow path refers to pathways that would allow air- flow unimpeded by partitions, walls, furnishings, etc. Where the zone is ventilated using a single open- ing or multiple single openings located at the same elevation, the openable area as a percent of the net occupiable floor area shall be greater than or equal to the value indicated in Table Where the zone is ventilated using two openings located at different elevations or multiple pairs of such openings, the openable area as a percent of the net occupiable floor area shall be greater than or equal to the value indicated in Table Where openings are obstructed by louvers or screens, the openable area shall be based on the net free area of the opening.
Where interior zones, or portions of zones, without direct openings to the outdoors are ventilated through adjoining zones, the opening between zones shall be permanently unobstructed and have a free area of not less than twice the percent of occupiable floor area used to determine the opening size of adjacent exterior zones, or 25 ft2 2.
Informative Note: Tables and are based solely on buoyancy-driven flow and have not been created to address thermal comfort. For an engineered natural ventilation system, the designer shall a. The means to open required openings shall be readily accessible to building occupants whenever the space is occupied.
Controls shall be designed to coordinate operation of the natural and mechanical ventilation systems. Where the Natural Ventilation Procedure is used, the designer shall document the values and calculations that demonstrate conformance with the compliance path and the controls systems and sequences required for operation of the natural ventilation system, including coordination with mechanical ventilation systems.
Where the Prescriptive Compli- ance Path is used for buildings located in an area where the national standard for one or more contaminants is exceeded, any design assumptions and calculations related to the impact on IAQ shall be included in the design documents.
The Prescriptive Compliance Path or the Performance Compliance Path shall be used to meet the requirements of this section. Exhaust makeup air shall be permit- ted to be any combination of outdoor air, recirculated air, or transfer air. The design exhaust airflow shall be determined in accordance with the requirements in Tables and While the required exhaust systems are operating, the exhaust airflow of zones listed in Table shall be larger than their respective supply airflow.
Exhaust systems are required for any occupancy category listed in Table Where intermittent operation is allowed in Table , exhaust equipment is intended to be operated when the space is in use. The exhaust airflow shall be determined in accor- dance with the following subsections. Contaminants or mixtures of concern for purposes of the design shall be identified. For each contaminant or mixture of concern, indoor sources occu- pants, materials, activities, and processes and outdoor sources shall be identified, and the emission rate for each contaminant of concern from each source shall be determined.
For each contaminant of concern, a concentration limit and its corresponding exposure period and an appropriate reference to a cognizant author- ity shall be specified. Design criteria and assumptions shall be docu- mented and made available for operation of the system after installation.
See Sections 4. The requirements of this section apply to ventilation systems and the spaces they serve in new buildings and additions to or alterations in existing buildings. Systems designed with particle filters shall not be operated without filters in place.
When recommended by the manufacturer, building materials shall be protected from rain and other sources of moisture by appropriate in-transit and on-site procedures.
Porous materials with visible microbial growth shall not be installed. Nonporous materials with visible microbial growth shall be decontaminated. The requirements of Section 7. Measures shall be employed to reduce the migration of con- struction-generated contaminants to occupied areas. Informative Note: Examples of acceptable measures include, but are not limited to, sealing the construction area using temporary walls or plastic sheathing, exhausting the construction area, or pressurizing contiguous occupied areas.
Air duct systems shall be constructed in accordance with the following standards, as applicable: a. The requirements of this section apply to the following ventilation sys- tems: a.
Newly installed air-handling systems b. Existing air-handling systems undergoing supply air or outdoor airflow reduction Only the requirements of Section 7. Ventilation systems shall be balanced in accordance with ASHRAE Standard or another applicable national standards so as to verify conformance with the total outdoor airflow requirements of this stan- dard Vot.
To minimize conditions of water stagnation that may result in microbial growth, drain pans shall be field tested under operating conditions that are the most restrictive to condensate flow to demonstrate proper drainage. Exception to 7. Informative Note: Above conditions usually occur at full fan airflow for draw-through fans and minimum fan airflow for blow-through fans. Ventilation air distribution systems shall be clean of dirt and debris.
Prior to occupancy, each ventilation system shall be tested to demonstrate that outdoor air dampers operate in accordance with the system design. Please first log in with a verified email before subscribing to alerts. Please first verify your email before subscribing to alerts. Already Subscribed to this document. You can download and open this file to your own computer but DRM prevents opening this file on another computer, including a networked server. PDF Price. Not a Member?
0コメント