ASTM D6245-98(2002)
(Guide)Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation
Standard Guide for Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation
SCOPE
1.1 This guide describes how measured values of indoor carbon dioxide (CO2) concentrations can be used in evaluations of indoor air quality and building ventilation.
1.2 This guide describes the determination of CO 2 generation rates from people as a function of body size and level of physical activity.
1.3 This guide describes the experimentally-determined relationship between CO2 concentrations and the acceptability of a space in terms of human body odor.
1.4 This guide describes the following uses of indoor CO2 concentrations to evaluate building ventilation-mass balance analysis to determine the percent outdoor air intake at an air handler, the tracer gas decay technique to estimate whole building air change rates, and the constant injection tracer gas technique at equilibrium to estimate whole building air change rates.
1.5 This guide discusses the use of continuous monitoring of indoor and outdoor CO2 concentrations as a means of evaluating building ventilation and indoor air quality.
1.6 This guide discusses some concentration measurement issues, but it does not include or recommend a method for measuring CO 2 concentrations.
1.7 This guide does not address the use of indoor CO 2 to control outdoor air intake rates.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 6245 – 98 (Reapproved 2002)
Standard Guide for
Using Indoor Carbon Dioxide Concentrations to Evaluate
Indoor Air Quality and Ventilation
This standard is issued under the fixed designation D 6245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3249 Practice for General Ambient Air Analyzer Proce-
dures
1.1 This guide describes how measured values of indoor
E 741 Test Method for DeterminingAir Change in a Single
carbon dioxide (CO ) concentrations can be used in evalua-
Zone by Means of Tracer Gas Dilution
tions of indoor air quality and building ventilation.
2.2 Other Documents
1.2 This guide describes the determination of CO genera-
ASHRAE Standard 62 Ventilation for Acceptable Indoor
tion rates from people as a function of body size and level of
Air Quality
physical activity.
1.3 This guide describes the experimentally-determined re-
3. Terminology
lationship between CO concentrations and the acceptability of
3.1 Definitions—For definitions and terms used in this
a space in terms of human body odor.
guide, refer to Terminology D 1356.
1.4 This guide describes the following uses of indoor CO
3.2 Definitions of Terms Specific to This Standard:
concentrations to evaluate building ventilation–mass balance
3.2.1 air change rate, n—the total volume of air passing
analysis to determine the percent outdoor air intake at an air
through a zone to and from the outdoors per unit time, divided
handler, the tracer gas decay technique to estimate whole
–1 –1 4
by the volume of the zone (s ,h ).
building air change rates, and the constant injection tracer gas
3.2.2 bioeffluents, n—gases emitted by people as a product
technique at equilibrium to estimate whole building air change
of their metabolism that can result in unpleasant odors.
rates.
3.2.3 single-zone, n—an indoor space, or group of spaces,
1.5 This guide discusses the use of continuous monitoring
wherein the CO concentration is uniform and that only
of indoor and outdoor CO concentrations as a means of
exchanges air with the outdoors.
evaluating building ventilation and indoor air quality.
1.6 This guide discusses some concentration measurement
4. Summary of Guide
issues, but it does not include or recommend a method for
4.1 When investigating indoor air quality and building
measuring CO concentrations.
ventilation, a number of tools are available to understand the
1.7 This guide does not address the use of indoor CO to
building being studied. One such tool is the measurement and
control outdoor air intake rates.
interpretationofindoorandoutdoorCO concentrations.Using
1.8 This standard does not purport to address all of the
CO concentrations to evaluate building indoor air quality and
safety concerns, if any, associated with its use. It is the
ventilation requires the proper use of the procedures involved,
responsibility of the user of this standard to establish appro-
as well as consideration of several factors related to building
priate safety and health practices and determine the applica-
and ventilation system configuration, occupancy patterns, non-
bility of regulatory limitations prior to use.
occupant CO sources, time and location of air sampling, and
2. Referenced Documents instrumentation for concentration measurement. This guide
2 discusses ways in which CO concentrations can be used to
2.1 ASTM Standards:
evaluate building indoor air quality and ventilation.
D 1356 Terminology Relating to Sampling and Analysis of
4.2 Section 6 discusses the rate at which people generate
Atmospheres
CO and the factors that affect this rate.
4.3 Section 7 discusses the use of indoor concentrations of
CO as an indicator of the acceptability of a space in terms of
This guide is under the jurisdiction ofASTM Committee D22 on Sampling and 2
Analysis of Atmospheres and is the direct responsibility of Subcommittee D22.05 perceptions of human body odor.
on Indoor Air.
Current edition approved March 10, 1998. Published May 1998.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from American Society of Heating, Refrigerating, and Air-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Conditioning Engineers, Inc., 1791 Tullie Circle, NE, Atlanta, GA 30329.
Standards volume information, refer to the standard’s Document Summary page on A common way of expressing air change rate units is ach = air changes per
the ASTM website. hour.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6245 – 98 (2002)
4.4 Section 8 describes the use of mass balance analysis to rates per person. This approach, referred to in this guide as
determine the percent outdoor air intake at an air handler based equilibrium analysis, is based on a steady-state, single-zone
on the measured CO concentrations in the supply, return, and mass balance of CO in the building and is sometimes
2 2
outdoor air intake airstreams. presented with little or no discussion of its limitations and the
4.5 Section 9 describes the use of the tracer gas decay assumptions on which it is based. As a result, in some cases,
technique to determine building air change rates using the technique has been misused and indoor CO concentration
occupant-generated CO as a tracer gas. The tracer gas decay measurements have been misinterpreted.
technique is described in detail in Test Method E 741, and this 5.4 When the assumptions upon which equilibrium analysis
section discusses the application of this test method to the
is based are valid, the technique can yield reliable measure-
special case of occupant-generated CO after the occupants ments of outdoor air ventilation rates. In addition, indoor CO
2 2
have left the building.
concentrations can be used to determine other aspects of
4.6 Section 10 describes the use of the constant injection building ventilation when used properly. By applying a mass
tracer gas technique with occupant-generated CO to estimate
balance at an air handler, the percent outdoor air intake in the
outdoor air ventilation rates. This technique is sometimes supply airstream can be determined based on the CO concen-
referred to as equilibrium analysis, and Section 10 discusses trations in the supply, return, and outdoor air. This percentage
the use of this technique and the assumptions upon which it is
can be multiplied by the supply airflow rate of the air handler
based. to yield the outdoor air intake rate of the air handler. In
4.7 Section 11discussestheuseofcontinuousmonitoringof
addition, the decay of indoor CO concentrations can be
CO concentrations as a means of evaluating indoor air quality monitored in a building after the occupants have left to
and ventilation in buildings. In this discussion, continuous
determine the outdoor air change rate of the building.
refers to real-time concentration measurement recorded with a
5.5 Continuous monitoring of indoor and outdoor CO
datalogging device over several days.
concentrations can be used to study some aspects of ventilation
4.8 Section 12 discusses CO concentration measurement
system performance, the quality of outdoor air, and building
issues, including measuring outdoor concentrations, sample
occupancy patterns.
locations for indoor concentration measurements, establishing
the uncertainty of measured concentrations, and calibration.
6. CO Generation Rates
6.1 Human metabolism consumes oxygen and generates
5. Significance and Use
CO at rates that depend on the level of physical activity, body
5.1 Indoor CO concentrations have been described and
size, and diet.
usedbysomepeopleasanindicatorofindoorairquality.These
6.2 The rate of oxygen consumption V in L/s of a person
O
uses have included both appropriate and inappropriate inter-
is given by Eq 1:
pretations of indoor CO concentrations. Appropriate uses
0.00276 A M
include estimating expected levels of occupant comfort in D
V 5 (1)
O
~0.23 RQ 1 0.77!
terms of human body odor, studying occupancy patterns,
investigating the levels of contaminants that are related to
where:
occupant activity, and screening for the sufficiency of ventila-
A = DuBois surface area m ,
D
tion rates relative to occupancy. Inappropriate uses include the
M = metabolic rate per unit of surface area, met (1 met =
application of simple relationships to determine outdoor air 2
58.2 W/m ), and
ventilation rates per person from indoor CO concentrations
RQ = respiratory quotient.
without verifying the assumptions upon which these relation- 2
The DuBois surface area equals about 1.8 m for an
ships are based, and the interpretation of indoor CO concen- 2
average-sized adult and ranges from about 0.8 to 1.4 m for
trations as a comprehensive indicator of indoor air quality.
elementary school aged children. Additional information on
5.2 Outdoor air ventilation rates affect contaminant levels in
body surface area is available in the EPA Exposure Factors
buildings and building occupants’ perception of the acceptabil-
Handbook (2). The respiratory quotient, RQ, is the ratio of the
ity of the indoor environment. Minimum rates of outdoor air
volumetric rate at which CO is produced to the rate at which
ventilation are specified in building codes and indoor air
oxygen is consumed. Therefore, the CO generation rate of an
quality standards, for example, ASHRAE Standard 62. The
individual is equal to V multiplied by RQ.
O
compliance of outdoor air ventilation rates with relevant codes
6.3 Chapter 8 of the ASHRAE Fundamentals Handbook,
and standards are often assessed as part of indoor air quality
Thermal Comfort (1), contains typical met levels for a variety
investigations in buildings. The outdoor air ventilation rate of
of activities. Some of these values are reproduced in Table 1.
a building depends on the size and distribution of air leakage
6.4 The value of the respiratory quotient RQ depends on
sites, pressure differences induced by wind and temperature,
diet, the level of physical activity and the physical condition of
mechanicalsystemoperation,andoccupantbehavior.Givenall
the person. It is equal to 0.83 for an average adult engaged in
of this information, ventilation rates are predictable; however,
light or sedentary activities. RQ increases to a value of about 1
many of these parameters are difficult to determine in practice.
Therefore, measurement is required to determine outdoor air
change rates reliably.
5 2
5.3 The measurement of CO concentrations has been
2 The body surface area A in m can be estimated from the formula A =
D D
0.725 0.425
promoted as a means of determining outdoor air ventilation 0.203H W where HisthebodyheightinmandWisthebodymassinkg(1).
D 6245 – 98 (2002)
TABLE 1 Typical Met Levels for Various Activities
experimentalstudiesinbothchambersandrealbuildingsandis
Activity met the most well-established link between indoor CO concentra-
tions and indoor air quality.
Seated, quiet 1.0
Reading and writing, seated 1.0
7.2 At the same time people are generating CO they are
Typing 1.1
also producing odor-causing bioeffluents. Similar to CO
Filing, seated 1.2
generation, the rate of bioeffluent generation depends on the
Filing, standing 1.4
Walking, at 0.89 m/s 2.0
level of physical activity. Bioeffluent generation also depends
House cleaning 2.0-3.4
on personal hygiene such as the frequency of baths or showers.
Exercise 3.0-4.0
Because both CO and bioeffluent generation rates depend on
physical activity, the concentrations of CO and the odor
intensity from human bioeffluents in a space exhibit a similar
for heavy physical activity, about 5 met. Based on the expected
dependence on the number of occupants and the outdoor air
variation in RQ, it has only a secondary effect on CO
ventilation rate.
generation rates.
7.3 Experimental studies have been conducted in chambers
6.5 Fig. 1 shows the dependence of oxygen consumption
and in occupied buildings in which people evaluated the
and CO generation rates on physical activity in units of mets
acceptability of the air in terms of body odor (3-7). These
foraverageadultswithasurfaceareaof1.8m . RQisassumed
experiments studied the relationship between outdoor air
to equal 0.83 in Fig. 1.
ventilation rates and odor acceptability, and the results of these
6.6 Based on Eq 1 and Fig. 1, the CO generation rate
studies were considered in the development of most ventilation
correspondingtoanaverage-sizedadult(A =1.8m )engaged
D
standards and guidelines (including ASHRAE Standard 62).
inofficework(1.2met)isabout0.0052L/s.BasedonEq1,the
This entire section is based on the results of these studies.
CO generation rate for a child (A =1m ) with a physical
2 D
7.3.1 These studies concluded that about 7.5 L/s of outdoor
activity level of 1.2 met is equal to 0.0029 L/s .
air ventilation per person will control human body odor such
6.7 Eq 1 can be used to estimate CO generation rates based
that roughly 80 % of unadapted persons (visitors) will find the
on information on body surface area that is available in the
odor at an acceptable level. These studies also showed that the
EPA Exposure Factors Handbook (2) and other sources.
same level of body odor acceptability was found to occur at a
However, these data do not generally apply to the elderly and
CO concentration that is about 650 ppm(v) above the outdoor
sick and, therefore, the user must exercise caution when
concentration.
dealing with buildings with such occupants.
7.3.2 Fig. 2 shows the percent of unadapted persons (visi-
tors) who are dissatisfied with the level of body odor in a space
7. CO as an Indicator of Body Odor Acceptability
asafunctionoftheCO concentrationaboveoutdoors(8).This
7.1 This section describes the use of CO to evaluate indoor
figure accounts only for the perception of body odor and does
air quality in terms of human body odor acceptability and
not account for other environmental factors that may influence
therefore, the adequacy of the ventilation rate to control body
the dissatisfaction of visitors to the space, such as the concen-
odor. The material in this section is based on a number of
trations of other pollutants and thermal parameters. Based on
the relationship in Fig. 2, the difference between indoor and
outdoor CO concentrations can be used as an indicator of the
acceptability of the air in a space in terms of body odor and,
therefore,asanindicatoroftheadequacyof
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 6245 – 98 (Reapproved 2002)
Standard Guide for
Using Indoor Carbon Dioxide Concentrations to Evaluate
Indoor Air Quality and Ventilation
This standard is issued under the fixed designation D 6245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3249 Practice for General Ambient Air Analyzer Proce-
dures
1.1 This guide describes how measured values of indoor
E 741 Test Method for DeterminingAir Change in a Single
carbon dioxide (CO ) concentrations can be used in evalua-
Zone by Means of Tracer Gas Dilution
tions of indoor air quality and building ventilation.
2.2 Other Documents
1.2 This guide describes the determination of CO genera-
ASHRAE Standard 62 Ventilation for Acceptable Indoor
tion rates from people as a function of body size and level of
Air Quality
physical activity.
1.3 This guide describes the experimentally-determined re-
3. Terminology
lationship between CO concentrations and the acceptability of
3.1 Definitions—For definitions and terms used in this
a space in terms of human body odor.
guide, refer to Terminology D 1356.
1.4 This guide describes the following uses of indoor CO
3.2 Definitions of Terms Specific to This Standard:
concentrations to evaluate building ventilation–mass balance
3.2.1 air change rate, n—the total volume of air passing
analysis to determine the percent outdoor air intake at an air
through a zone to and from the outdoors per unit time, divided
handler, the tracer gas decay technique to estimate whole
–1 –1 4
by the volume of the zone (s ,h ).
building air change rates, and the constant injection tracer gas
3.2.2 bioeffluents, n—gases emitted by people as a product
technique at equilibrium to estimate whole building air change
of their metabolism that can result in unpleasant odors.
rates.
3.2.3 single-zone, n—an indoor space, or group of spaces,
1.5 This guide discusses the use of continuous monitoring
wherein the CO concentration is uniform and that only
of indoor and outdoor CO concentrations as a means of
exchanges air with the outdoors.
evaluating building ventilation and indoor air quality.
1.6 This guide discusses some concentration measurement
4. Summary of Guide
issues, but it does not include or recommend a method for
4.1 When investigating indoor air quality and building
measuring CO concentrations.
ventilation, a number of tools are available to understand the
1.7 This guide does not address the use of indoor CO to
building being studied. One such tool is the measurement and
control outdoor air intake rates.
interpretationofindoorandoutdoorCO concentrations.Using
1.8 This standard does not purport to address all of the
CO concentrations to evaluate building indoor air quality and
safety concerns, if any, associated with its use. It is the
ventilation requires the proper use of the procedures involved,
responsibility of the user of this standard to establish appro-
as well as consideration of several factors related to building
priate safety and health practices and determine the applica-
and ventilation system configuration, occupancy patterns, non-
bility of regulatory limitations prior to use.
occupant CO sources, time and location of air sampling, and
2. Referenced Documents instrumentation for concentration measurement. This guide
2 discusses ways in which CO concentrations can be used to
2.1 ASTM Standards:
evaluate building indoor air quality and ventilation.
D 1356 Terminology Relating to Sampling and Analysis of
4.2 Section 6 discusses the rate at which people generate
Atmospheres
CO and the factors that affect this rate.
4.3 Section 7 discusses the use of indoor concentrations of
CO as an indicator of the acceptability of a space in terms of
This guide is under the jurisdiction ofASTM Committee D22 on Sampling and 2
Analysis of Atmospheres and is the direct responsibility of Subcommittee D22.05 perceptions of human body odor.
on Indoor Air.
Current edition approved March 10, 1998. Published May 1998.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from American Society of Heating, Refrigerating, and Air-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Conditioning Engineers, Inc., 1791 Tullie Circle, NE, Atlanta, GA 30329.
Standards volume information, refer to the standard’s Document Summary page on A common way of expressing air change rate units is ach = air changes per
the ASTM website. hour.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6245 – 98 (2002)
4.4 Section 8 describes the use of mass balance analysis to rates per person. This approach, referred to in this guide as
determine the percent outdoor air intake at an air handler based equilibrium analysis, is based on a steady-state, single-zone
on the measured CO concentrations in the supply, return, and mass balance of CO in the building and is sometimes
2 2
outdoor air intake airstreams. presented with little or no discussion of its limitations and the
4.5 Section 9 describes the use of the tracer gas decay assumptions on which it is based. As a result, in some cases,
technique to determine building air change rates using the technique has been misused and indoor CO concentration
occupant-generated CO as a tracer gas. The tracer gas decay measurements have been misinterpreted.
technique is described in detail in Test Method E 741, and this 5.4 When the assumptions upon which equilibrium analysis
section discusses the application of this test method to the
is based are valid, the technique can yield reliable measure-
special case of occupant-generated CO after the occupants ments of outdoor air ventilation rates. In addition, indoor CO
2 2
have left the building.
concentrations can be used to determine other aspects of
4.6 Section 10 describes the use of the constant injection building ventilation when used properly. By applying a mass
tracer gas technique with occupant-generated CO to estimate
balance at an air handler, the percent outdoor air intake in the
outdoor air ventilation rates. This technique is sometimes supply airstream can be determined based on the CO concen-
referred to as equilibrium analysis, and Section 10 discusses trations in the supply, return, and outdoor air. This percentage
the use of this technique and the assumptions upon which it is
can be multiplied by the supply airflow rate of the air handler
based. to yield the outdoor air intake rate of the air handler. In
4.7 Section 11discussestheuseofcontinuousmonitoringof
addition, the decay of indoor CO concentrations can be
CO concentrations as a means of evaluating indoor air quality monitored in a building after the occupants have left to
and ventilation in buildings. In this discussion, continuous
determine the outdoor air change rate of the building.
refers to real-time concentration measurement recorded with a
5.5 Continuous monitoring of indoor and outdoor CO
datalogging device over several days.
concentrations can be used to study some aspects of ventilation
4.8 Section 12 discusses CO concentration measurement
system performance, the quality of outdoor air, and building
issues, including measuring outdoor concentrations, sample
occupancy patterns.
locations for indoor concentration measurements, establishing
the uncertainty of measured concentrations, and calibration.
6. CO Generation Rates
6.1 Human metabolism consumes oxygen and generates
5. Significance and Use
CO at rates that depend on the level of physical activity, body
5.1 Indoor CO concentrations have been described and
size, and diet.
usedbysomepeopleasanindicatorofindoorairquality.These
6.2 The rate of oxygen consumption V in L/s of a person
O
uses have included both appropriate and inappropriate inter-
is given by Eq 1:
pretations of indoor CO concentrations. Appropriate uses
0.00276 A M
include estimating expected levels of occupant comfort in D
V 5 (1)
O
~0.23 RQ 1 0.77!
terms of human body odor, studying occupancy patterns,
investigating the levels of contaminants that are related to
where:
occupant activity, and screening for the sufficiency of ventila-
A = DuBois surface area m ,
D
tion rates relative to occupancy. Inappropriate uses include the
M = metabolic rate per unit of surface area, met (1 met =
application of simple relationships to determine outdoor air 2
58.2 W/m ), and
ventilation rates per person from indoor CO concentrations
RQ = respiratory quotient.
without verifying the assumptions upon which these relation- 2
The DuBois surface area equals about 1.8 m for an
ships are based, and the interpretation of indoor CO concen- 2
average-sized adult and ranges from about 0.8 to 1.4 m for
trations as a comprehensive indicator of indoor air quality.
elementary school aged children. Additional information on
5.2 Outdoor air ventilation rates affect contaminant levels in
body surface area is available in the EPA Exposure Factors
buildings and building occupants’ perception of the acceptabil-
Handbook (2). The respiratory quotient, RQ, is the ratio of the
ity of the indoor environment. Minimum rates of outdoor air
volumetric rate at which CO is produced to the rate at which
ventilation are specified in building codes and indoor air
oxygen is consumed. Therefore, the CO generation rate of an
quality standards, for example, ASHRAE Standard 62. The
individual is equal to V multiplied by RQ.
O
compliance of outdoor air ventilation rates with relevant codes
6.3 Chapter 8 of the ASHRAE Fundamentals Handbook,
and standards are often assessed as part of indoor air quality
Thermal Comfort (1), contains typical met levels for a variety
investigations in buildings. The outdoor air ventilation rate of
of activities. Some of these values are reproduced in Table 1.
a building depends on the size and distribution of air leakage
6.4 The value of the respiratory quotient RQ depends on
sites, pressure differences induced by wind and temperature,
diet, the level of physical activity and the physical condition of
mechanicalsystemoperation,andoccupantbehavior.Givenall
the person. It is equal to 0.83 for an average adult engaged in
of this information, ventilation rates are predictable; however,
light or sedentary activities. RQ increases to a value of about 1
many of these parameters are difficult to determine in practice.
Therefore, measurement is required to determine outdoor air
change rates reliably.
5 2
5.3 The measurement of CO concentrations has been
2 The body surface area A in m can be estimated from the formula A =
D D
0.725 0.425
promoted as a means of determining outdoor air ventilation 0.203H W where HisthebodyheightinmandWisthebodymassinkg(1).
D 6245 – 98 (2002)
TABLE 1 Typical Met Levels for Various Activities
experimentalstudiesinbothchambersandrealbuildingsandis
Activity met the most well-established link between indoor CO concentra-
tions and indoor air quality.
Seated, quiet 1.0
Reading and writing, seated 1.0
7.2 At the same time people are generating CO they are
Typing 1.1
also producing odor-causing bioeffluents. Similar to CO
Filing, seated 1.2
generation, the rate of bioeffluent generation depends on the
Filing, standing 1.4
Walking, at 0.89 m/s 2.0
level of physical activity. Bioeffluent generation also depends
House cleaning 2.0-3.4
on personal hygiene such as the frequency of baths or showers.
Exercise 3.0-4.0
Because both CO and bioeffluent generation rates depend on
physical activity, the concentrations of CO and the odor
intensity from human bioeffluents in a space exhibit a similar
for heavy physical activity, about 5 met. Based on the expected
dependence on the number of occupants and the outdoor air
variation in RQ, it has only a secondary effect on CO
ventilation rate.
generation rates.
7.3 Experimental studies have been conducted in chambers
6.5 Fig. 1 shows the dependence of oxygen consumption
and in occupied buildings in which people evaluated the
and CO generation rates on physical activity in units of mets
acceptability of the air in terms of body odor (3-7). These
foraverageadultswithasurfaceareaof1.8m . RQisassumed
experiments studied the relationship between outdoor air
to equal 0.83 in Fig. 1.
ventilation rates and odor acceptability, and the results of these
6.6 Based on Eq 1 and Fig. 1, the CO generation rate
studies were considered in the development of most ventilation
correspondingtoanaverage-sizedadult(A =1.8m )engaged
D
standards and guidelines (including ASHRAE Standard 62).
inofficework(1.2met)isabout0.0052L/s.BasedonEq1,the
This entire section is based on the results of these studies.
CO generation rate for a child (A =1m ) with a physical
2 D
7.3.1 These studies concluded that about 7.5 L/s of outdoor
activity level of 1.2 met is equal to 0.0029 L/s .
air ventilation per person will control human body odor such
6.7 Eq 1 can be used to estimate CO generation rates based
that roughly 80 % of unadapted persons (visitors) will find the
on information on body surface area that is available in the
odor at an acceptable level. These studies also showed that the
EPA Exposure Factors Handbook (2) and other sources.
same level of body odor acceptability was found to occur at a
However, these data do not generally apply to the elderly and
CO concentration that is about 650 ppm(v) above the outdoor
sick and, therefore, the user must exercise caution when
concentration.
dealing with buildings with such occupants.
7.3.2 Fig. 2 shows the percent of unadapted persons (visi-
tors) who are dissatisfied with the level of body odor in a space
7. CO as an Indicator of Body Odor Acceptability
asafunctionoftheCO concentrationaboveoutdoors(8).This
7.1 This section describes the use of CO to evaluate indoor
figure accounts only for the perception of body odor and does
air quality in terms of human body odor acceptability and
not account for other environmental factors that may influence
therefore, the adequacy of the ventilation rate to control body
the dissatisfaction of visitors to the space, such as the concen-
odor. The material in this section is based on a number of
trations of other pollutants and thermal parameters. Based on
the relationship in Fig. 2, the difference between indoor and
outdoor CO concentrations can be used as an indicator of the
acceptability of the air in a space in terms of body odor and,
therefore,asanindicatoroftheadequacyof
...
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