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Details of Addenda to ASHRAE Standard 62-1999 and Comparison with Previous Versions Addenda

62-1999

Review of Addenda

Foreword

Details of New Version

Changes in Previous Version

Remarks/Comments

62j

This replaces the current performance requirement for natural ventilation systems with a prescriptive requirement that is similar to many model-building codes. The existing section is difficult for designers to understand and to use and it is difficult to enforce.

Section 5.1 is deleted and replaced as follows:

5.1 Natural Ventilation. Use of natural ventilation systems designed in accordance with this section shall be permitted in lieu of or in conjunction with mechanical ventilation systems.

Exception: An engineered natural ventilation system when approved by the authority having jurisdiction need not meet the requirements of 5.1.1 and 5.1.2.

[Comment: This exception is added to allow specially engineered systems such as those that use wind power, stack effect, and other natural forces to move air through conduits other than windows. It also may be used to show compliance for

The following section 5.1 is deleted. 5.1 Ventilation system may be mechanical or natural. When mechanical ventilation is used, provision for air flow measurement should be included.

When natural ventilation and infiltration are relied upon, sufficient ventilation shall be demonstrable. When infiltration and natural ventilation are insufficient to meet ventilation air requirements, mechanical ventilation shall be provided. The use of energy recovery ventilation systems should be considered for energy

This revised section gives prescriptive requirements for natural ventilation systems for designers to follow. The design parameters such as location and size of openings in 5.1.1 should be followed, whereas the control and accessibility stated in 5.1.2 are obvious practical requirements.

Liaison with Project Architect is necessary for designing the location and size of openings.

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a room that exceeds 8m (25ft) in depth but which can be shown to be sufficiently ventilated by perimeter windows.]

5.1.1 Location and Size of Openings. Naturally ventilated spaces shall be permanently open to and within 8m (25ft) of operable wall or roof openings to the outdoors, the openable area of which is a minimum of 4% of the net occupiable floor area. Where openings are covered with louvers or otherwise obstructed, openable area shall be based on the free unobstructed area through the openings. Where interior spaces without direct openings to the outdoors are ventilated through adjoining rooms, the opening between rooms shall be permanently unobstructed and have a free area not less than 8% of the area of the interior room nor less than 2.3m2 (24ft2).

5.1.2 Control and Accessibility. The means to open required operable openings shall be readily accessible to building occupants whenever the space is occupied.

Add to top of section 6 (or to section 6.1 if addendum 62I is approved)

conservation purposes in meeting ventilation requirements.

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This section is not required for natural ventilation systems; natural ventilation systems shall be designed in accordance with Section 5.1.

62l

This is a created new section on construction and ventilation system start-up, recognizing that acceptable indoor air quality is impacted by more than just the design of HVAC system. Requirements include such measures as ventilation system balancing.

The section is added immediately before 62-99 Section 7 References

7 CONSTRUCTION AND SYSTEM

START-UP 7.1 CONSTRUCTION PHASE 7.1.1 Application. 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.

7.1.2 Filters. Systems designed with particle filters shall not be operated without filters in place.

7.1.3 Protection of Materials. 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. Non-porous materials with visible microbial growth shall be decontaminated.

This new section states some of the conditions of the site before system start-up is carried out, such as those for filters in 7.1.2, protection of materials in 7.1.3 and protection of occupied areas in 7.1.4. This section for start-up is also applicable to start-up of all HVAC systems, and not just ventilation system mentioned here. The separation of the construction site from the nearby existing occupied areas is emphasized, highlighting some obvious protective measures. Protection of construction materials is also mentioned and should be followed by all

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7.1.4 Protection of Occupied Areas

7.1.4.1 Application. The requirements of Section 7.1.4 apply when construction requires a building permit and entails sanding, cutting, grinding or other activities that generate significant amounts of airborne particles or procedures that generate significant amounts of gaseous contaminants. 7.1.4.2 Protective Measures. Measures shall be employed to reduce the migration of construction materials; measures include, but are not limited to, sealing the construction area using temporary walls or plastic sheathing, exhausting the construction areas, and/or pressurizing contiguous occupied areas.

7.2 SYSTEM START-UP 7.2.1Application. The requirements of this section apply to the following ventilation systems. a) Newly installed air handling systems; b) Existing air handling systems

undergoing supply air or outdoor air flow reduction. Only the requirements of Section 7.2.2 shall

contractors. Ventilation system start-up should include the following steps: a. checking of filters b. air balancing c. testing of drain pans d. air distribution systems

clear of dirt and debris e. testing of damper

controls The documentation listed in 7.2.6 is usually provided by the contractor before completion and handover of the installation as a requirement of the contract. Nevertheless, for some specific systems and installations, O & M manuals, test records, record drawings and other documents may have to be submitted earlier for adequate information and

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apply to these altered systems; or c) Existing air handling distribution

systems undergoing alterations affecting more than 25% of the floor area served by the systems. Only the requirements of Section 7.2.2 shall apply to these altered systems.

7.2.2 Air Balancing. Ventilation systems shall be balanced in accordance with ASHRAE Standard 111, SMACNA “HVAC Systems – Testing, Adjusting and Balancing,” 2nd edition, or equivalent at least to the extent necessary to verify conformance with the total outdoor air flow and space supply air flow requirements of this standard.

7.2.3 Testing of Drain Pans. To minimize conditions of water stagnation that may result in microbial growth, drain pans shall be field- tested under normal operating conditions to ensure proper drainage. Exception: Field testing of drain pans is not required if units with factory installed drain pans have been certified (attested in writing ) by the manufacturer for proper drainage when installed as recommended.

reference by users and operators where necessary, especially for some complicated systems and installations for which sufficient prior training for O & M personnel is required.

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7.2.4 Ventilation System Start-up. Ventilation air distribution systems shall be clean of dirt and debris.

7.2.5 Testing Damper Controls. Prior to occupancy, each ventilation system shall be tested to ensure that outdoor air dampers operate in accordance with the system design.

7.2.6 Documentation The following Ventilation System Documentation shall be provided to the building owner or its designee, retained within the building, and made available to the building operating personnel: a) An Operation and Maintenance

Manual describing basic data relating to the operation and maintenance of ventilation systems and equipment as installed.

b) HAVC controls information consisting of diagrams, schematics, control sequence narratives and maintenance and/or calibration information.

c) An air balance report documenting the work performed for Section 7.2.2.

d) Construction drawings of record, control drawings, and final drawings.

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e) Design criteria and assumptions.

62m

This is a newly created section on operating and maintenance procedures, recognizing the importance of these procedures to acceptable indoor air quality. Requirements include such measures as frequency of system inspection.

8 OPERATION AND

MAINTENANCE 8.1 GENERAL

8.1.1 Application. The requirements of this section apply to buildings and their ventilation systems and their components constructed or renovated after the adoption date of this section.

8.1.2 Operation and Maintenance. The ventilation system shall be operated and maintained at a minimum in accordance with the provisions of this standard.

8.1.3 Building Alterations or Change-of-use. Ventilation system design, operation and maintenance shall be re-evaluated when changes in building use or occupancy category, significant building alterations, significant changes in occupant density, or other changes inconsistent with system design assumptions are made.

Although this is a new section, the requirements and procedures detailed herein are, in fact, common practices which need to be followed for effective and efficient operation and maintenance of HVAC systems and components to ensure indoor air quality of the premises with supply of air conditioning. Cleaning, inspection and rectification of defects and defective installations are spelt out for easy reference. The components and equipment of ventilation systems listed in this section requiring cleaning, inspection or other maintenance requirements include filters in 8.4.1.1, dampers in 8.4.1.2,

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8.2 OPERATION AND MAINTENANCE MANUAL

An operation and maintenance manual either written or electronic shall be developed, and maintained on site or in a centrally accessible location for the working life of the applicable ventilation system equipment or components. This manual shall be updated as necessary. The manual shall include, at a minimum the operation and maintenance procedures, final design drawings, operation and maintenance schedules, and any changes made thereto and the maintenance requirements and frequencies detailed in section 8.4.

8.3 VENTILATION SYSTEM

OPERATION Mechanical and natural ventilation systems shall be operated in a manner consistent with the Operations and Maintenance Manual.

8.4 VENTILATION SYSTEM

MAINTENANCE 8.4.1 Ventilation system components.

humidifiers in 8.4.1.3, dehumidification coils in 8.4.1.4, drain pans in 8.4.1.5, air intake louvers in 8.4.1.6 and sensors in 8.4.1.7. This section 8 also emphasized the importance of close adherence to O & M Manuals for carrying out procedures, precautions, review, methods and steps of actual operation and maintenance including calibration of instruments and sensors.

Re-evaluation of system design is required after building alterations or change of use. This is highly recommended to ensure satisfactory operation and output of the HVAC systems to meet the demand.

Sections 8.4.1.8, 8.4.1.9,

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The building ventilation system components shall be maintained in accordance with the Operations and Maintenance Manual or as required by this section and summarized in Table 8-1

. 8.4.1.1 Filters and Air Cleaning Devices. All filters and air cleaning devices shall be replaced or maintained as specified by the Operating and Maintenance Manual.

8.4.1.2 Outdoor Air Dampers. At a minimum of once every three months or as specified in the Operations and Maintenance Manual, the outdoor air dampers and actuators shall be visually inspected or remotely to verify that they are functioning in accordance with the Operation and Maintenance Manual.

8.4.1.3 Humidifiers. Humidifiers shall be cleaned and maintained to limit fouling and microbial growth. These systems shall be inspected at a minimum of once every three months of operation and/or treated as specified in the Operations and Maintenance Manual.

8.4.1.4 Dehumidification Coils. All

8.4.1.10, 8.4.2 and 8.4.3 describe methods and requirements to enhance the indoor air quality and to minimize microbial growth or contamination.

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dehumidifying cooling coils shall be visually inspected for cleanliness and microbial growth regularly when it is likely that dehumidification occurs but no less than once per year or as specified in the Operations and Maintenance Manual and shall be cleaned when fouling or microbial growth is observed.

8.4.1.5 Drain pans. Drain pans shall be visually inspected for cleanliness and microbial growth at minimum of once per year during the cooling season or as specified in the Operations and Maintenance Manual and shall be cleaned if needed. Areas adjacent to drain pans that were subjected to wetting shall be investigated, cleaned if necessary, and the cause of unintended wetting rectified.

8.4.1.6 Outdoor Air Intake Louvers. Outdoor air intake louvers, bird screens, mist eliminators and adjacent areas shall be visually inspected for cleanliness and integrity at a minimum of once every six months or as specified in the Operations and Maintenance Manual and cleaned as needed. When visible debris or visible biological material is observed it shall be removed. Physical damage to louvers,

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screens or mist eliminators shall be repaired if such damage impairs their function in preventing contaminant entry.

8.4.1.7 Sensors. Sensors whose primary function is dynamic minimum outdoor air control, such as flow stations at an air handler and those used for demand control ventilation, shall have their accuracy verified as specified in the Operation and Maintenance Manual. This activity shall occur at a minimum of once every six months or periodically per the Operation and Maintenance Manual. A sensor failing to meet the accuracy specified in the Operation and Maintenance Manual shall be recalibrated or replaced.

8.4.1.8 Outdoor Airflow Verification. The total quantity of outdoor air to air handlers except for units under 1000 LPS (2000 CFM) of supply air shall be measured in minimum outdoor air mode once every five years. If measured minimum airflow rates are less than the design minimum rate (+/- 10% balancing tolerance) documented in the Operations and Maintenance Manual, they shall be adjusted or modified to bring them to the

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minimum design rate or evaluated to determine if the measured rates are in compliance with this standard.

8.4.1.9 Cooling Towers. Cooling tower water systems shall be treated to limit the growth of microbiological contaminants including legionella sp. per the Operations and Maintenance Manual or the water treatment program.

8.4.1.10 Equipment/Component Accessibility. The space provided for routine maintenance and inspection around ventilation equipment shall be kept clear.

8.4.2 Visible Microbial Contamination. Visible microbial contamination shall be investigated and rectified. 8.4.3 Water Intrusion. Water intrusion or accumulation in ventilation system components such as ducts, plenums and air handlers shall be investigated and rectified.

62p

Combustion processes consume oxygen from combustion air and produce

(The following new Section 5.7 focused only on combustion air for fuel-burning appliances)

The following section 5.7 is deleted.

This new section draws the attention of designers and operators to the

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water vapor, carbon dioxide and other contaminants. Many building codes already adequately and appropriately address the proper indoor use of fuel burning appliances, in terms of both combustion air and venting of combustion products. However, this standard must independently address combustion processes, since all designers may not be subject to building codes and building code content can change independently from minimum mandatory requirements.

5.7 Combustion Air. Fuel-burning appliances, both vented and unvented, shall be provided with sufficient air for combustion and adequate removal of combustion products, in accordance with manufacturer instructions. Products of combustion from vented appliances shall be vented directly outdoors.

5.7 Fuel burning appliances, including fireplaces located indoors, shall be provided with sufficient air for combustion and adequate removal of combustion products. When infiltration supplies all or part of the combustion sir, the supply rate of air shall be demonstrable (Appendix B shows on method of demonstrating adequate combustion air). The operating of clothes dryers and exhaust fans may require introduction of additional makeup air to avoid interference with fuel burning appliances. Combustion system, kitchen bathroom, and clothes dryer vents shall not be exhausted into attics, crawl spaces, or basements.

provision of sufficient air for combustion and adequate removal of combustion products to ensure proper use of fuel burning appliances. The concept is obvious and manufacturer instructions should be followed to ensure this.

62q

This addendum modifies several definitions for clarity. In addition, several definitions that are adequately defined for the purpose of the Standard in standard dictionaries are deleted for brevity, as are

The following definitions are modified or added to section 3: Air, exhaust: air removed from a space and discharged to outside the building by means of mechanical or natural ventilation systems.

The following definitions in section 3 are deleted: Absorption Adsorption Chemisorb

Definitions of some common terms have been deleted as their meaning can be easily found in dictionaries and textbooks or because they are not used in the Standard.

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others that are not used in the body of the Standard.

Air, makeup: any combination of outdoor and transfer air intended to replace exhaust air and exfiltration. Air, outdoor: ambient air that enters a building through a ventilation system, through intentional openings for natural ventilation, or by infiltration. Air, recirculated: air removed from a space and reused as supply air. Air, supply: air delivered by mechanical or natural ventilation to a space, comprising any combination of outdoor air, recirculated air or transfer air. Air, transfer: air moved from one indoor space to another. Mechanical ventilation: ventilation provided by mechanically powered equipment such as motor-driven fans and blowers, but not by devices such as wind-driven turbine ventilators and mechanically operated windows. Natural ventilation: ventilation provided by thermal, wind or diffusion effects through doors, windows, or other

Dust Fumes Gas Oxidation Particulate matter Plug flow Smoke Total suspended particulate matter Respirable particles Vapour

On the other hand, the added definitions provide clear and concise meaning to HVAC terms to avoid confusion and ambiguity. In particular, the definitions for ventilation, natural ventilation and mechanical ventilation can distinctly differentiate the installations and the kind of provisions included. There is also a clear definition for each of occupiable space and net occupiable space. The definitions in this section can be taken as reference for specifying systems, installations and equipment as well as for adoption in drawings and O & M documentation.

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intentional openings in the building. Net occupiable space: the floor area of an occupiable space defined by the inside surfaces of its walls but excluding shafts, column enclosures, and other permanently enclosed, inaccessible, and unoccupiable areas. Obstructions in the space such as furnishings, display or storage racks, and other obstructions, whether temporary or permanent, may not be deducted from the space area. Occupiable space: an enclosed space intended for human activities, excluding those spaces intended primarily for other purposes, such as storage rooms and equipment rooms, that are only occupied occasionally and for short periods of time. Ventilation: the process of supplying air to or removing air from a space for the purpose of controlling air contaminant levels, humidity, or temperature within the space. Volume, space: the total volume of an occupiable space enclosed by the building envelope, plus that of any spaces

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permanently open to the occupiable space, such as a ceiling attic used as a ceiling return plenum.

62s

This addendum clarifies and updates requirements for equipment-related particle filtration. These requirements are intended to lower the level of particulate matter in the ventilation system where wet surfaces are present, thereby reducing the rate of dirt accumulation on ventilation system components, including ductwork. Dirt accumulation on wet surface provides a substrate that may lead to microbial growth which may in turn cause the ventilation system to become a source of contaminants. In addition to reducing the rate of accumulation of particulate matter, filtration also reduces the level of

5.8 Particulate Matter Removal. Particulate matter filters of air cleaners having a minimum efficiency reporting value (MERV) of not less than 6 when rated in accordance with ASHRAE Standard 52.2-199933, shall be provided upstream of all cooling coils or other devices with wetted surfaces through which air is supplied to an occupiable space.

The following Section 5.8 is deleted.

5.8 Airborne particulate contaminants vary in size, as shown in Fig.2. Microorganisms, dusts, fumes, smoke, and other particulate matter may be captured by air filters. Many bacteria (99% exceed 1 micrometer in size) are attached to larger particles. Lung damaging particles that may enter the lungs are 0.2 to 5 micrometers in size (see Fig.2). When it is necessary to remove particulate contaminants, air filters or dust collectors should be used. Dust collectors, not air filters, should be used where the dust loading equals or exceed 10 mg/m3 (4 grains/100 ft3). Air filters and dust collectors shall be selected for the particle size and loading encountered. Filters shall be

This section deals with particulate filters which are specific to individual projects. Project engineers should specify the particular requirements to suit the specific application and use by the clients.

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airborne particles that may be harmful to humans, such as airborne microorganisms and respirable particles. However, the removal of these potentially harmful particles is not the primary purpose of the requirements in this addendum.

tested in accordance with ASHRAE Standard 52 76 (Ref 8) or MIL Std 282 (Ref 9). Dust collectors may be wet, dry, or electrostatic as required by particle size and loading (see Table 1, Chapter 11, ASHRAE Handbook 1983 Equipment Volume (Ref 10).

62w

This addendum defines performance criteria for air stream surface materials in ventilation system equipment and ducts. Conformance with these criteria is intended to minimize the potential for microbial growth and dissemination through the air distribution system. Installation provisions are intended to minimize internal insulation material from becoming loose, damaged, or collecting dirt at joints and seams. Other addenda will address the introduction of dirt and debris into the ventilation

5.5 Air Stream Surfaces: All stream surfaces in equipment, and ducts in the heating, ventilation and air conditioning system shall be designed and constructed in accordance with the following requirements: 5.5.1 Resistance to Mold Growth: Material surfaces shall be determined to be resistant to mold growth in accordance with a standardized test method, such as Underwriters Laboratories, Inc. (UL) 181 “Mold growth and Humidity Test”, ASTM C 1338 “Standard Test Method for Determining Fungi Resistance of Insulation Material and Facings”, or other comparable test methods. Exception: sheet metal surfaces and metal fasteners NOTE: Even with this resistance, any air stream surface that is continuously wetted

The following section 5.5 is deleted.

5.5 Ventilation ducts and plenums shall be constructed and maintained to minimize the opportunity for growth and dissemination of microorganisms through the ventilation system. Construction also shall comply with applicable standards such as UL 181, NFPA 90A, NFPA 90B, and SMACNA (Refs 2-6).

This section indicates the standards for determining or identifying the resistance to mould growth and resistance to erosion of air stream surfaces. However, in our practice, sheet metal surfaces are used and no interior linings as insulation are permitted. So, there is no difficulty in complying with this section.

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system (filtration) and condensate control (coils, drain pans, etc.), which are also associated with microbial growth and dissemination.

is still subject to microbial growth. 5.5.2 Resistance to Erosion: Air stream surface materials shall be evaluated in accordance with the Underwriters Laboratories, Inc. (UL) 181 “Erosion Test” and shall not break away, crack, peel, flake off, or show evidence of delamination or continued erosion under test conditions. Exception: sheet metal surfaces and metal fasteners.

Annex II

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Details of Addenda to ASHRAE Standard 62-2001 and Comparison with Previous Versions Addenda

62-2001

Review of Addenda

Foreword

Details of New Version

Changes in Previous Version

Remarks/Comments

62i

This addendum replaces material in Sections 4 and 6 regarding the use of the IAQ Procedure. It describes situations in which the IAQ Procedure can be used, and it does so in mandatory and enforceable language. It does not tell one how to use this procedure; Addendum 62 h addresses this issue.

A new section 6.1 is added and current sections 6.1, 6.2 and 6.3 as 6.2, 6.3 and 6.4 are renumbered respectively. 6.1 General. Either the Ventilation Rate Procedure or the IAQ Procedure shall be used to design each ventilation system in a building, subject to the following considerations and restrictions. 6.1.1 Ventilation Rate Procedure. This is a prescriptive procedure in which outdoor air intake rates are determined based on space type/application, occupancy level, and floor area. Note: The Ventilation Rate Procedure minimum rates are based on contaminants sources and source strengths that are typical for the listed space types.

The following first four paragraphs of section 6 are deleted: Indoor air quality is a function of many parameters including outdoor air quality, the design of enclosed spaces, the design of the ventilation system, the way this system is operated and maintained, and the presence of sources of contaminants and the strength of such sources. This Standard deals with the design of a ventilation system as it is affected by all these factors, so that an acceptable level of indoor air quality can be provided. Design documentation shall clearly

The new version of section 6.1 replaces the old version with Ventilation Rate Procedure in section 6.1.1 and IAQ Procedure in section 6.1.2. It is recommended to follow either of these procedures for designing the outdoor air intake rate and the choice will depend on the nature of the occupancy or the sources of contaminants as mentioned in each of these sections.

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6.1.2 IAQ Procedure. This is a design procedure in which outdoor air intake rates and other system design parameters are based on an analysis of contaminant sources, contaminant concentration targets and perceived acceptability targets. The IAQ Procedure allows credit to be taken for controls that remove contaminants (for example, air cleaning device) or for other design techniques (for example, selection of materials with lower source strengths) that can be reliably demonstrated to result in door contaminant concentrations equal to or lower than those achieved using the Ventilated Rate Procedure. The IAQ procedure may also be used where the design is intended to attain specific target contaminant concentrations or levels of acceptability of perceived indoor air quality. Delete Exception 1 in Section 6.1.3.

state which assumptions were used in the design so that the limits of the system in removing contaminants can be evaluated by others before the system is operated in a different mode before new sources are introduced into the space. Indoor air should not contain contaminants that exceed concentrations known to impair health or cause discomfort to occupants. Such contaminants include various gases, vapors, microorganism, smoke, and other particulate matter. These may be present in makeup air or to be introduced from indoor activities, furnishings, building materials, surface coatings, and air treatment components. Deleterious factors include toxicity, radioactivity, potential to induce infection or allergies, irritants, extreme thermal conditions, and objectionable odors. The Ventilation Rate Procedure

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(6.1) provides one way to achieve acceptable air quality. This procedure prescribes the rate at which ventilation air must be delivered to a space and various means to condition that air. The ventilation rates in Table 2 are derived from physiological considerations, subjective evaluations, and professional judgments. The Indoor Air Quality Procedure (6.2) provides an alternative performance method for achieving acceptable air quality. This procedure uses one or more guidelines for the specification of acceptable concentrations of certain contaminants in indoor air but does not prescribe ventilation rates or air treatment methods.

62k

This addendum deletes the current Section 4 (Classification) and adds a new informative appendix addressing application of

Delete the current Section 4 (Classification) of ASHRAE Standard 62-2001 and add the following new appendix to the standard. Appendix K:

Section 4 (Classification) is deleted.

The new addendum mainly deals with application and compliance of the standard 62-2001 for new and existing buildings.

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the standard in new and existing buildings. The current Section 4 discusses the two procedures for determining design ventilation rates, but it contains no requirements and is therefore inconsistent with a standard in code-intended language. The new appendix attempts to address the issue of application of the standard in new and existing buildings. The appendix contains informative guidance on when the standard applies in new and existing buildings. It also contains a code-language version of these requirements that could be adopted, with or without modification, by jurisdictions that do not have a building code. Earlier versions of this addendum attempted to make this material part of the standard (in Section 4),

This appendix contains application and compliance suggestions that are intended to assist users and enforcement agencies in applying this standard. For the most part, ASHRAE Standard 62-2001 is specifically written for new buildings because some of its requirements assume that other requirements within the standard have been met. In the case of existing buildings, retroactive application and compliance with all the requirements of this standard may not be practical. However, the principles established in this standard may be applied to most existing commercial and institutional buildings. Some existing buildings may achieve acceptable indoor air quality despite not meeting the requirements of ASHRAE Standard 62-2001 due to, for example, good maintenance and capital improvement procedures, building materials that, by virtue of their age, have very low contaminant emission rates, and many other factors. (Appendix K also stipulates the details for application and compliance for new

For new buildings, it is straightforward. All sections and appendices are applicable to new buildings falling within the scope of this standard. For existing buildings, the addendum requires that the standard should be applied in the following circumstances. Additions: All additions to existing buildings should meet the requirements except for existing ventilation system extended to serve the additions. Repairs: It is not required for repaired existing equipment or building components to retroactively comply with this standard. Replacement: Any component of a building that is removed and replaced should meet the applicable

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but it was pointed out that this could create conflicts with building codes that contain their own compliance and enforcement sections.

buildings and existing buildings.) requirements of Section 5. Substantial Alterations: If a building is substantially altered, the requirements of this standard should be met. Substantial Alteration means any alteration with cost exceeding 50% of the building’s fair market value. Change in Use: If there is a change in nature of use, such as from office to retail, the minimum ventilation rates required by Section 6 should be met.

62t

This addendum replaces Section 5.11. In so doing, it clarifies and codifies requirements for drain pan design, carryover from cooling coils, access for inspection and cleaning, and requirements related to the proper application of humidifiers and water spray devices within the air

5.11 Drain Pans. Drain pans, including their outlets and seals, shall be designed and constructed in accordance with this section. 5.11.1 Drain Pan Slope. Pans intended to collect and drain liquid water shall be sloped at least 10 mm per meter from the horizontal toward the drain outlet or shall be otherwise designed to

The following section is deleted: 5.11 Microbial contamination in buildings is often a function of moisture incursion from sources such as stagnant water in HVAC air distribution systems and cooling towers. Air handling unit condensate pans shall be designed for

The revised section describes clearly the requirements of condensate management including drain pan slope, drain outlet size, drain seal and drain pan size in sub-sections 5.11.1 to 5.11.4. Preventive measures against microbial growth are stipulated.

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distribution systems. Recognizing that liquid water within air distribution systems increases the likehood of microbial growth, the requirement in this addendum seek to prevent standing water in drain pans, limit water droplet carryover, and minimize stagnant water in humidifier and water spray sumps. Finned-tube coils collect dirt and thereby promote microbial growth. Coil surfaces can be cleaned, but proper cleaning depends upon coil depth, fin spacing, and fin geometry. Since coil depth, fin spacing, and fin geometry combine to determine coil pressure drop, this coil pressure drop can be used as a measure of the relative difficulty of coil cleaning. To ensure cleanibility, this addendum limits coil

ensure that water drains freely from the pan whether fan is on or off. 5.11.2 Drain Outlet. The drain pan outlet shall be located at the lowest point(s) of the drain pan and shall be of sufficient diameter to preclude drain pan overflow under any normally expected operating condition. 5.11.3 Drain Seal. For configuration 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 allowing complete drainage of the drain pan under any normally expected operating condition, whether the fan is on or off. 5.11.4 Pan Size. The drain pan shall be located under the water-producing device. Drain pan width shall be sufficient 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

self-drainage to preclude the buildup of microbial slime. Provision shall be made for periodic in-situ cleaning of cooling coils and condensate pans. Air-handling and fan coil units shall be easily accessible for inspection and preventive maintenance. Steam is preferred as a moisture source for humidifiers, but care should be exercised to avoid contamination from boiler water or steam supply additives. If cold water humidifiers are specified, the water shall originate from a potable source, and, if re-circulated, the system will require frequent maintenance and blow-down. Care should be exercised to avoid particulate contamination due to evaporation of spray water. Standing water used in conjunction with water sprays in HVAC air distribution systems should be treated to avoid microbial buildup. If the relative humidity in

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pressure drop rather than the depth of finned-tube coils. Condensate not collected or collected but improperly drained leads to downstream surface wetting and increased potential for microbial growth, so this addendum clarifies requirements for condensate management, including drain pan size and drain outlet size. Sufficient access facilitates periodic inspection, routine maintenance, and periodic or as-required cleaning. Inspection and cleaning are necessary to avoid the buildup of dirt and debris and, in some situations, microbial growth within air distribution systems.

assembly and extended downstream from the leaving face or edge to a distance of one half of the installed vertical dimension of the water-producing device or assembly.

occupied spaces and low velocity ducts and plenums exceeds 70%, fungal contamination can occur. Special care should be taken to avoid entrainment of moisture drift from cooling towers into the make up air and building vents.

5.12 Finned-Tube Coils and Heat Exchangers.

Under this section for finned-tube coils and heat exchangers, it is

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5.12.1 Drain Pans. A drain pan in accordance with Section 5.11 shall be provided beneath all dehumidifying cooling coil assemblies and all condensate-producing heat exchangers. 5.12.2 Finned-Tube Coil Selection for Cleaning. Individual finned-tube coils or multiple finned-tube coils in series without adequate intervening access spaces(s) of at least 457mm shall be selected to result in no more than 187 Pa combined pressure drop when dry coil face velocity is 2.54 m/s. Exception: When clear and complete instruction for access and cleaning of both upstream and downstream coil surfaces are provided.

recommended that design and site installation should take into account the respective requirements listed in all sub-sections of this addendum (for drain pan slope, drain outlet, drain seal and pan size ) except section 5.12.2 for which the designer should make his own evaluation for specific requirements of performance for coil selection to suit the particular application.

5.13 Humidifies and Water-Spray Systems. 5.13.1 Water Quality. Water shall originate directly from a potable source or from a source with equal or better water quality. 5.13.2 Obstructions. Air cleaners or

A new Section 5.13 is added to specify requirements for humidifiers and water spray devices in the air distribution system.

It is advisable to follow section 5.13.1 to ensure quality of water used in humidifiers and water-spray systems. However, to avoid ambiguity, the absorption distance mentioned in section 5.13.2 has to be clarified by the manufacturers for this

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ductwork obstructions, such as turning vanes, volume dampers, and ducts 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 distance recommended by the humidifier or water spray system manufacturer. Exception: Equipment such as eliminators, coils, or evaporative media may be located within the absorption distance recommended by the manufacturer, provided a drain pan complying with the requirements of 5.11 is used to capture and remove any water that may drop out of the airstream due to impingement on these obstructions.

requirement to be complied with.

5.14 Access for Inspection, Cleaning, and Maintenance 5.14.1 Equipment Clearance. Ventilation equipment shall be installed with sufficient working space for inspection and routine maintenance (e.g., filter replacement and fan belt adjustment and replacement)

A new Section 5.14 is added to specify access requirements and intended to accommodate periodic inspection, cleaning, and routine maintenance.

Section 5.14 explicitly states the requirements for sufficient working space for inspection and routine maintenance as well as unobstructed access for system components and equipment, which require routine inspection, cleaning, maintenance and calibration.

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5.14.2 Ventilation Equipment Access. Access doors, panels, or other means shall be provided and sized to allow convenient and unobstructed access sufficient to inspect, maintain, and calibrate all ventilation system components for which routine inspection, maintenance, or calibration is necessary. Ventilation system components comprise, for example, air-handling units, fan-coil units, water-source heat pumps, other terminal units, controllers, and sensors. 5.14.3 Air Distribution System. Access doors, panels, or other means shall be provided in ventilation equipment, duct-work, 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 having a total of more than four rows and air washers, evaporative coolers, heat wheels, and other heat

This is obviously a requirement that must be observed and followed.

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exchangers (d) Both upstream and down stream

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

62u

This addendum adds requirements related to the control of ventilation systems. An improperly controlled system is unlikely to deliver ventilation air at design minimum levels. This addendum does not cover optional demand-controlled ventilation requirements. It specifically addresses VAV system controls for outdoor air intake airflow. The intake control requirements recognize that at low supply volumes sufficient outdoor

A new Section 5.3 is added as follows: 0.3 Ventilation System Controls. Mechanical ventilation systems shall include controls, manual or automatic that enable the fan system to operate whenever spaces served are occupied. The system shall be designed to maintain the minimum outdoor air flow as required by Section 6 under any load condition. Note: VAV systems with fixed outdoor air damper positions must comply with this requirement at minimum supply air flow.

A proper control system is required for mechanical ventilation systems and a minimum outdoor airflow rate must be achieved. This is certainly a good practice to follow. The designer should state the requirements clearly in the specification and the contractor is required to carry out the installation and testing and commissioning to ensure the design intent is met.

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airflow may not be maintained if a fixed outdoor air intake damper position is used. In many cases, an active outdoor air control system must be provided to ensure minimum intake rates are maintained.

62v

This addendum adds requirements to ensure that the air distribution system is capable of delivering outdoor air to the occupied spaces. In systems with AC units, heat pumps, or fan-coil units mounted in the ceiling or floor plenum, ventilation air is often supplied to the plenum to mix with recirculated air. Where outdoor air is poorly distributed in such systems, units that are far from the outdoor air supply to the plenum may not receive the intended levels of outdoor air. In any air distribution

Revise Section 5.2 as follows: 5.2 Ventilation Air Distribution. Ventilation systems shall be designed in accordance with the following: Add new subsections to Section 5.2 as follows: 5.2.1 Designing for Air Balancing. The Ventilation air distribution system 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. 5.2.2 Plenum Systems. When the ceiling or floor plenum is used both to recirculate return air and to distribute

Section 5.2 is revised with an aim to ensure that adequate outdoor air is distributed to all parts of the ventilation systems and provision for system balancing should be included. Designers are recommended to comply with the requirements stipulated including documentation of design assumptions and reference standards. Designers and contractors should take note of this good practice to avoid leakage of exhaust air (possibly with contaminants in some cases)

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system, required airflow can only be assured by measuring actual airflow and adjusting dampers and orifices to account for the effect of as-installed duct pressure drops, i.e., the system must be balanced. Designers must consider and make provision for system balancing. Note that balancing is addressed in terms of designing the system so that it can be balanced; this addendum does not require balancing at any particular time, as that issue is covered in other addenda. Also, note that balancing is not a one-time event but must be re-evaluated over time as indicated in other sections of the standard.

ventilation air to ceiling-mounted or floor-mounted terminal units, the system shall be engineered such that each space is provided with its required minimum ventilation air flow. Note: Direct connection of ventilation air ducts to ventilating terminal units is an alternate method of satisfying the intent of this requirement. 5.2.3 Documentation. The design documents shall specify minimum requirements for air balancing testing or reference applicable national standards for measurement and balancing air flow. The design documentation shall state assumptions that were made in the design with respect to ventilation rates and air distribution.

5.3 Exhaust Duct Location. Exhaust ducts that convey potentially harmful contaminants shall be negatively pressurized relative to spaces through which they pass, so that exhaust air cannot leak into occupied spaces; supply, return, or outdoor air ducts; or plenums. Exception: Exhaust ducts that are sealed in accordance with SMACNA Seal Class A.

to occupied spaces where the exhaust ducts run through before going to the outdoor.

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62ab

This addendum clarifies the requirements for control of contaminants from stationary, non-combustion local sources with integrated capture systems (e.g., a device with an exhaust port intended to be connected to an exhaust duct on installation, such as a large photocopying machine and some photographic equipment.) In general, strong sources of contaminants can be treated most effectively by capturing the contaminants locally and exhausting them to the outdoors, rather than ventilating at a rate sufficient to dilute the contaminants to reasonable concentration levels. Equipment that is designed to be discharged indoors as recommended by the manufacturer is exempted from this requirement.

5.6 Local Capture of Contaminants. The discharge from non-combustion equipment that captures the contaminants generated by the equipment shall be ducted directly to the outdoors. Exception: Equipment specifically designed for discharge indoors in accordance with the manufacturer’s recommendations.

The following Section 5.6 is deleted. 5.6 Contaminants from stationary local sources within space shall be controlled by collection and removal as close to the source as practicable.

The new version suggests local capturing of exhaust or contaminants such as those generated from photocopying machines by direct connection of exhaust ducts to the concerned equipment or machine. Designers are recommended to follow the requirements if there is no problem of spacing or location, which often can be allowed for in the early stage of design and liaison with the architect.