1、Designation: D6245 12D6245 18Standard Guide forUsing Indoor Carbon Dioxide Concentrations to EvaluateIndoor Air Quality and Ventilation1This standard is issued under the fixed designation D6245; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide describes how measured values of indoor carbon dioxide (CO2) concentrations can be
3、used in evaluations ofindoor air quality and building ventilation.1.2 This guide describes the determination of CO2 generation rates from people as a function of body size and level of physicalactivity.1.3 This guide describes the experimentally-determined relationship between CO2 concentrations and
4、 the acceptability of aspace in terms of human body odor.1.4 This guide describes the following uses of indoor CO2 concentrations to evaluate building ventilationmass balance analysisto determine the percent outdoor air intake at an air handler, the tracer gas decay technique to estimate whole build
5、ing air changerates, 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 evaluatingbuilding ventilation and indoor air quality.1.6 T
6、his guide discusses some concentration measurement issues, but it does not include or recommend a method for measuringCO2 concentrations.1.7 This guide does not address the use of indoor CO2 to control outdoor air intake rates.1.8 UnitsThe values stated in SI units are to be regarded as standard. No
7、 other units of measurement are included in thisstandard.1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices a
8、nd determine theapplicability of regulatory limitations prior to use.1.10 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommen
9、dations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis of AtmospheresD3249 Practice for General Ambient Air Analyzer ProceduresE741 Test Method for Determining Air Change
10、 in a Single Zone by Means of a Tracer Gas Dilution2.2 Other Documents:ASHRAE Standard 62.1 Ventilation for Acceptable Indoor Air Quality31 This guide is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.05 on Indoor Air.Current edition
11、approved April 1, 2012June 1, 2018. Published May 2012June 2018. Originally approved in 1998. Last previous edition approved in 20072012 asD6245 07.D6245 12. DOI: 10.1520/D6245-12.10.1520/D6245-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at
12、 serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA 30329.30329,ht
13、tp:/www.ashrae.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that user
14、s consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions
15、For definitions and terms used in this guide, refer to Terminology D1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 air change rate, nthe total volume of air passing through a zone to and from the outdoors per unit time, divided by thevolume of the zone (s1, h1).43.2.2 bioeffluents, ng
16、ases emitted by people as a product of their metabolism that can result in unpleasant odors.3.2.3 single-zone, nan indoor space, or group of spaces, wherein the CO2 concentration is uniform and that only exchangesair with the outdoors.4. Summary of Guide4.1 When investigating indoor air quality and
17、building ventilation, a number of tools are available. One such tool is themeasurement and interpretation of indoor and outdoor CO2 concentrations. Using CO2 concentrations to evaluate building indoorair quality and ventilation requires the proper use of the procedures involved, as well as considera
18、tion of several factors relatedto building and ventilation system configuration, occupancy patterns, non-occupant CO2 sources, time and location of air sampling,and instrumentation for concentration measurement. This guide discusses ways in which CO2 concentrations can be used toevaluate building in
19、door air quality and ventilation.4.2 Section 6 discusses the rate at which people generate CO2 and the factors that affect this rate.4.3 Section 7 discusses the use of indoor concentrations of CO2 as an indicator of the acceptability of a space in terms ofperceptions of human body odor.4.4 Section 8
20、 describes the use of mass balance analysis to determine the percent outdoor air intake at an air handler based onthe measured CO2 concentrations in the supply, return, and outdoor air intake airstreams.4.5 Section 9 describes the use of the tracer gas decay technique to determine building air chang
21、e rates using occupant-generatedCO2 as a tracer gas. The tracer gas decay technique is described in detail in Test Method E741, and this section discusses theapplication of this test method to the special case of occupant-generated CO2 after the occupants have left the building.4.6 Section 10 descri
22、bes the use of the constant injection tracer gas technique with occupant-generated CO2 to estimate outdoorair ventilation rates. This technique is sometimes referred to as equilibrium analysis, and Section 10 discusses the use of thistechnique and the assumptions upon which it is based.4.7 Section 1
23、1 discusses the use of continuous monitoring of CO2 concentrations as a means of evaluating indoor air qualityand ventilation in buildings. In this discussion, continuous refers to real-time concentration measurement recorded with adatalogging device, generally over several days.4.8 Section 12 discu
24、sses CO2 concentration measurement issues, including measuring outdoor concentrations, sample locationsfor indoor concentration measurements, establishing the uncertainty of measured concentrations, and calibration.5. Significance and Use5.1 Indoor CO2 concentrations have been described and used by
25、some people as an indicator of indoor air quality. These useshave included both appropriate and inappropriate interpretations of indoor CO2 concentrations.Appropriate uses include estimatingexpected levels of occupant comfort in terms of human body odor, studying occupancy patterns, investigating th
26、e levels ofcontaminants that are related to occupant activity, and screening for the sufficiency of ventilation rates relative to occupancy.Inappropriate uses include the application of simple relationships to determine outdoor air ventilation rates per person from indoorCO2 concentrations without v
27、erifying the assumptions upon which these relationships are based, and the interpretation of indoorCO2 concentrations as a comprehensive indicator of indoor air quality.5.2 Outdoor air ventilation rates affect contaminant levels in buildings and building occupants perception of the acceptabilityof t
28、he indoor environment. Minimum rates of outdoor air ventilation are specified in building codes and indoor air qualitystandards, for example, ASHRAE Standard 62. The compliance of outdoor air ventilation rates with relevant codes and standardsare often assessed as part of indoor air quality investig
29、ations in buildings. The outdoor air ventilation rate of a building dependson the size and distribution of air leakage sites, pressure differences induced by wind and temperature, mechanical systemoperation, and occupant behavior. Given all of this information, ventilation rates are predictable; how
30、ever, many of theseparameters are difficult to determine in practice. Therefore, measurement is required to determine outdoor air change rates reliably.5.3 The measurement of CO2 concentrations has been promoted as a means of determining outdoor air ventilation rates perperson. This approach, referr
31、ed to in this guide as equilibrium analysis, is based on a steady-state, single-zone mass balance of CO2in the building and is sometimes presented with little or no discussion of its limitations and the assumptions on which it is based.As a result, in some cases, the technique has been misused and i
32、ndoor CO2 concentration measurements have been misinterpreted.4 A common way of expressing air change rate units is h-1 = air changes per hour.D6245 1825.4 When the assumptions upon which equilibrium analysis is based are valid, the technique can yield reliable measurementsof outdoor air ventilation
33、 rates. In addition, indoor CO2 concentrations can be used to determine other aspects of buildingventilation when used properly. By applying a mass balance at an air handler, the percent outdoor air intake in the supply airstreamcan be determined based on the CO2 concentrations in the supply, return
34、, and outdoor air. This percentage can be multiplied bythe supply airflow rate of the air handler to yield the outdoor air intake rate of the air handler. In addition, the decay of indoor CO2concentrations can be monitored in a building after the occupants have left to determine the outdoor air chan
35、ge rate of the building.5.5 Continuous monitoring of indoor and outdoor CO2 concentrations can be used to study some aspects of ventilation systemperformance, the quality of outdoor air, and building occupancy patterns.6. CO2 Generation Rates6.1 Human metabolism consumes oxygen and generates CO2 at
36、rates that depend on the level of physical activity, body size,and diet.6.2 The rate of oxygen consumption carbon dioxide generation of an individual VOCO22 in L/s of a person per person, at an airtemperature of 273 K and an air pressure of 101 kPa, is given by Eq 1:, the derivation of which is desc
37、ribed in detail in Ref (1):5VO25 0.00276 AD M0.23 RQ10.77! (1)VCO25RQ BMR M 0.000569 (1)where:AD = DuBois surface area m2,M = metabolic rate per unit of surface area, met (1 met = 58.2 W/m2), andRQ = respiratory quotient.RQ = respiratory quotient, dimensionless (defined in 6.3),BMR = basal metabolic
38、 rate, MJ/day, andM = metabolic rate per unit of surface area, met (dimensionless).The DuBois surface areaFor other values of equals about 1.8 mair temperature 2 for an average-sized adult and ranges from about0.8 to 1.4 m2 for elementary school aged children. Additional information on body surface
39、area is available in the EPA ExposureFactors Handbook (2). The respiratory quotient, RQ,T is theand pressure ratioP,VCO2 of the volumetricis given by Eq 2rate .VCO25RQ BMR M T P! 0.000211 (2)at which CO2 is produced to the rate at which oxygen is consumed. Therefore, the CO2 generation rate of an in
40、dividual isequal to VO2 multiplied by RQ.6.3 The respiratory quotient, RQ, is the ratio of the volumetric rate at which CO2 is produced by an individual to the rate atwhich oxygen is consumed. The value of RQ depends primarily on diet (2). Based on data on human nutrition in the United States,primar
41、ily the ratios of fat, protein, and carbohydrate intake, RQ equals about 0.85 (3).6.4 Chapter 9 of the ASHRAE Fundamentals Handbook, Thermal Comfort Values of BMR are (1), contains typical met levelsfor a variety of activities. Some of these values are reproduceda function of sex, age, and body mass
42、. Equations for the calculationof BMR are given in Table 1. (4).6.5 The value of the respiratory quotientvariable M (in dimensionless units of met) is used to describe the ratio of RQthedepends on diet, the level of physical activity and the physical condition of the person. human energy use associa
43、ted with aparticular physical activity to the BMR of an individual as discussed in detail in Ref RQ(1). equals 0.83 for an average adult5 The body surface area boldface numbersADin mparentheses2 can be estimated from the formularefer to a list of references at the endAofD = 0.203this standard.H0.725
44、W0.425 where H is the body height in m and W is the body mass in kg (1).TABLE 1 Equations for Calculating BMR (4)NOTE 1m is body mass in units of kg.Age (y) BMR: MJ/dayMales Females3 0.249 m 0.127 0.244 m 0.1303 to 10 0.095 m + 2.110 0.085 m + 2.03310 to 18 0.074 m + 2.754 0.056 m + 2.89818 to 30 0.
45、063 m + 2.896 0.062 m + 2.03630 to 60 0.048 m + 3.653 0.034 m + 3.538$60 0.049 m + 2.459 0.038 m + 2.755D6245 183engaged in light or sedentary activities. There are two primary references for obtaining met levels for different physical activitiesRQ(5, 6increases).Tables 2 and 3 to a value of about 1
46、 for heavy physical activity, about 5 met. Based on the expected variationin contain met levels for many common indoor activities drawn from those two references.RQ, it has only a secondary effect onCO2 generation rates.6.5 Fig. 1 shows the dependence of oxygen consumption and CO2 generation rates o
47、n physical activity in units of mets foraverage adults with a surface area of 1.8 m2. RQ is assumed to equal 0.83 in Fig. 1.6.6 Based on Eq 1 and Fig. 1, the CO2 generation rate corresponding to an average-sized adult (AD = 1.8 m2) engaged in officework (1.2 met) is about 0.0052 L/s. Based on Eq 1,
48、the CO2 generation rate for a child (AD = 1 m2) with a physical activity levelof 1.2 met is equal to 0.0029 L/s .6.6 Eq 1Table 4 can be used to estimate lists CO2 generation rates based on information on body surface area that is availablefor ranges of ages and met levels estimated using the body ma
49、ss data for males and females in the EPAExposure Factors Handbook(27), and other sources. However, these data do not generally apply to the elderly and sick and, therefore, the user must exercisecaution when considering buildings with such occupants.assuming RQ is equal to 0.85.6.7 To reflect the importance of variations in body size, that is, mass, in estimating CO2 generation rates, Fig. 1 and Fig. 2 showthe variation in VCO2 with age and body mass for females and males, respectively. Each plot displays VCO2 for 13 age ranges from 1 y to 80 y and for six
