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Roger Hedrick is principal engineer at Architectural Energy Corporation, a member of NORESCO Energy and Sustainability Services. He is chair of SSPC 62.1, Ventilation for Acceptable Indoor Air Quality.

BY ROGER HEDRICK, BEMP, MEMBER ASHRAE

Standard 62.1 Update & PlansASHRAEs principal ventilation standard, Standard 62.1-2013, Ventilation for Acceptable Indoor Air Quality, was recently republished with a number of updates. A number of years ago, Standard 62.1 went through some fairly significant changes. The transition from the advisory language of 62-1989 to todays mandatory, code-intended language, which includes much more extensive requirements was long, difficult and contentious.

Fortunately, or perhaps naturally, revisions to 62.1-

2007 and 62.1-2010 have been much more straightfor-

ward. In large part, this is because the major issues have

been resolved and the changes are focused on improving

the details of the standard. For example, changes to 62.1-

2010 that resulted in 62.1-2013 include:

Table 6.2.2.2, Zone Air Distribution Effectiveness, is modified to increase the effectiveness of underfloor

air-distribution systems that meet certain conditions.

The Zone Air Distribution Effectiveness (Ez) is a factor

used in calculating the amount of outdoor air needed at

the zone that accounts for how well the ventilation air

gets from the diffuser to the occupant breathing zone.

For underfloor air distribution systems that have vertical

throws of less than 50 fpm (0.25 m/s) at a height of 4.5 ft

(1.37 m) above the floor, the standard now allows an Ez of

1.2. These systems may then meet the standard with less

outdoor air than systems with lower Ez values, depending

on the Ez value in the critical zone.

The requirements for the quality of water used in humidification systems is modified and clarified. In

previous versions of the standard, the language regard-

ing water used in humidification systems was unclear,

Water shall originate directly from a potable source or

from a source with equal or better water quality. In par-

ticular, it was not clear to users what water treatment

chemicals might be allowed. The language was clarified

that no chemicals could be added other than those that

meet either of two other standards (NSF/ANSI 60-2012,

Drinking Water Treatment ChemicalsHealth Effects and 21

CFR 173.310, Secondary Direct Food Additives Permitted In Food

For Human Consumption). For chemicals meeting 21 CFR

173.310, automated dosing equipment is required to be

used to control the chemical concentrations in the water.

Building-level pressurization requirements were clarified, and a definition of exfiltration was added.

Standard 62.1-2010 required that total building outdoor

air intake exceed total building exhaust airflow when-

ever the mechanical air-conditioning systems are dehu-

midifying. The wording was revised for the 2013 version

such that the requirement applies except When outdoor

air dry-bulb temperature is below the indoor zone dew-

point design temperature.

A performance alternative to the prescriptive ex-haust rates is added. This approach is similar to the IAQP

in that it allows a performance approach. It differs, how-

ever, in that monitoring of the concentrations of con-

taminants of concern is required and provides the ba-

sis for control of exhaust flow rates. Standard 90.1-2010

includes a requirement that garage ventilation systems

must vary flow rates based on monitored contaminant

levels. Standard 62.1, on the other hand, provided a re-

quired exhaust rate for parking garages, but no allow-

ance for reducing this flow. Thus, Standards 90.1 and 62.1

contained conflicting requirements. 62.1-2013 was mod-

ified to include a performance approach for exhaust sys-

tems, to address the conflict. This approach requires that

contaminants of concern be identified based on sources

in the zone, that concentration limits be specified, and

Roger Hedrick

This article was published in ASHRAE Journal, August 2014. Copyright 2014 ASHRAE. Posted at www.ashrae.org. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit www.ashrae.org.

A U G U S T 2 0 1 4 a s h r a e . o r g A S H R A E J O U R N A L 8 7

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monitoring systems be installed to ensure that exhaust

rates are adequate to maintain concentrations below the

specified limits.

Some changes are made to the outdoor airflow rates and zone types in Table 6.2.2.1 (previously known as Ta-

ble 6-1). These include the addition of refrigerated ware-

houses and, for sports-related zones, change the ven-

tilation rate to include a per-occupant component that

allows the use of demand-controlled ventilation in these

zones. For refrigerated warehouses, the area component

of the ventilation rate is set to zero, so no ventilation is

required when there are no occupants in the zone.

The filter requirement on air entering wetted cooling coils has been modified to change the MERV rating from 6

to 8. This change reduces potential for particulate deposi-

tion on the coils that could lead to biological or other con-

tamination. The SSPC believes that MERV 8 filters are now

so common that this change does not impose any signifi-

cant cost increase on building owners or operators.

Toilet exhaust air that is cleaned to Class 1 may be re-circulated. This is a change that came from a continuous

maintenance proposal, and was accepted by the SSPC.

The requirements for this air cleaning are subjective, but

include inoffensive odor.

Addenda in progress continue the trend of improving

the standard. The major addenda are described here

as currently drafted, but are subject to revision in the

approval process.

Addendum 62.1j will revise the Indoor Air Quality Pro-cedure (IAQP, the performance-based path for determin-

ing ventilation rates) by adding procedures for addressing

mixtures of contaminants. Additivity, the effect of combi-

nations of contaminants each at low concentrations, has

long been an implicit part of the Ventilation Rate Proce-

dure. The IAQP, on the other hand, allowed determination

of ventilation rates on the basis of keeping concentrations

of each individual contaminant below specified limits and

ignoring additive effects. Addendum j will require that in

the presence of mixtures of contaminants (nearly always

the case in non-industrial indoor environments) that ven-

tilation rates are calculated to keep the concentration of

the mixture below specified levels.

There has been a fair amount of effort in various quar-

ters aimed at increasing the usability of the IAQP. These

efforts have not yet resulted in new addenda. However,

it is hoped that efforts to define adequate filtration

approaches or lists of contaminants and concentration

limits, possibly used in conjunction with each other,

may eventually result in methods of providing accept-

able indoor air quality with lower ventilation rates and

the associated reductions in energy consumption.

Addendum 62.1k will modify the classification of laboratory hood exhaust air. This change will explicitly

allow EH&S (Environmental Health and Safety) Profes-

sionals to determine the appropriate air class for labora-

tory hood exhaust airstreams. Those that are Class 3 or

better could then use heat wheel energy recovery.

Addendum 62.1p will allow ventilation air in some zones to be reduced to zero based on occupancy sensors.

Currently, ventilation air must be provided to all zones

during periods of expected occupancy, even when zones

are unoccupied. This addendum will allow occupancy sen-

sors to be used to determine if a zone is unoccupied and

then reduce ventilation air to zero. This reduction will only

be allowed for zones where occupants are the primary con-

taminant source, i.e., those with an area component of the

ventilation rate of 0.06 cfm/ft (0.305 L/sm2)

Addendum 62.1r will modify DCV (demand con-trolled ventilation) control requirements to improve

clarity. The changes also remove the assumption that the

Standard is intended for use only as calculations for code

review and not operation.

Addendum 62.1q will revise requirements restrict-ing the location of positively pressurized exhaust ducts.

Draft Addendum DA-53 aims to strengthen require-ments for equipment maintenance and sensor calibra-

tion. These requirements are particularly aimed are sen-

sors used for DCV control.

At the meeting of the Standing Standards Project

Committee in Denver in June 2013, the committee

brainstormed ideas for how the standard could be fur-

ther improved. A fairly extensive list of topics was gener-

ated. Many of these are concepts for possible addenda.

Some examples include:

Requirements for personal ventilation systems and corresponding revision of ventilation rates.

Additional requirements for building controls and provision of standard sequences of operation.

Revisions to area components of the ventilation rates in light of lower-emitting building materials.

Methods to account for emission rate decay as build-ings age.

Modifications appropriate for areas outside the U.S. and Europe.

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allow existing buildings to show compliance other than

by meeting all of the requirements intended for new

construction. This placed weatherization programs in the

difficult position of applying Standard 62.2 outside of its

scope or not applying an IAQ standard when weatherizing

multifamily dwelling in buildings taller than three stories.

Addendum 62.1a and a corresponding addendum to

Standard 62.2 will change the scopes of both standards

such that single family homes and dwelling units in mul-

tifamily buildings, regardless of height, will be covered

by Standard 62.2 while the common areas of multifamily

buildings will be covered by Standard 62.1. This will allow

weatherization programs to apply the existing building

appendix of 62.2 to any residential building. It also has the

benefit of providing uniform ventilation requirements

for all apartments, regardless of the height of the build-

ing in which they are located. It also will clarify coverage

of mixed use buildings of three stories or less. Currently,

it is unclear which standard covers a building with retail

on the first floor and apartments on the second and third

floor. The current scope language for both standards

defines coverage by building. The proposed scope change

will explicitly determine coverage at the zone level.

This change in scope is not expected to have major

impacts in other areas of the standard. It will, however,

have a significant impact on users. Nearly all multifam-

ily residential buildings will need to comply with both

Standards 62.1 and 62.2. It is unclear how future stan-

dards will fit with the model codes that are a primary

user of the standards. There will also be impacts on

LEED, where compliance with ventilation standards is

a prerequisite for certification. Finally, Standards 90.1

and 189.1 have similar scope as the current 62.1, and

the scope of 90.2 is similar to that of 62.2. The proposed

changes will impact this symmetry.

SSPC 62.1 is focused on improving the usability of

Standard 62.1, while providing flexibility to building

designers. The tension between providing acceptable

indoor air quality and reducing energy consumption is a

never ending issue. SSPC 62.1s primary goal is to assure

that building occupants are provided with acceptable

indoor air quality, but we are open to changes that allow

energy savings but dont compromise IAQ. The SSPC

welcomes change proposals from ASHRAE members and

the public. See How to Submit a Proposed Change to a

Standard at www.ashrae.org/standards-researchtech-

nology/standards-formsprocedures.

Inclusion of additional alternate compliance paths, particularly for use in existing buildings.

Addition of requirements for low humidity limits. Improvements to the natural ventilation procedure. Further improvements to DCV requirements.

One exception to the theme of improving the details

of the standard is Addendum 62.1a. This addendum will

change the scope of the standard. Currently Standard

62.1 covers all buildings except residential buildings three

stories high or less. Standard 62.2 covers single family

houses and multifamily buildings up to three stories. The

two standards result in significantly different require-

ments between multifamily buildings that are three (62.2)

or four (62.1) stories tall. More significantly, Standard

62.2 has an appendix that provides alternative compli-

ance methods for existing buildings. This appendix is

heavily used by residential weatherization programs.

When residences are weatherized under these programs,

compliance with Standard 62.2 is often required to

assure that measures do not compromise the IAQ in the

homes. Standard 62.1 has no corresponding method to

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