Analysis of Ventilation Data from the

U.S. Environmental Protection Agency

Building Assessment Survey and

Evaluation (BASE) Study

Andrew Persily

Josh Gorfain

NISTIR 7145-REVISED
NISTIR 7145-REVISED

November 2008

(replaces version published in December 2004)

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

National Institute of Standards and Technology

Patrick Gallagher, Acting Director

Analysis of Ventilation Data from the

U.S. Environmental Protection Agency

Building Assessment Survey and

Evaluation (BASE) Study

Andrew Persily

Building and Fire Research Laboratory

Josh Gorfain

Building and Fire Research Laboratory

Prepared for:

U.S. Environmental Protection Agency

Washington, DC
ii
iii

ABSTRACT

The U.S. Environmental Protection Agency (EPA) Building Assessment Survey and Evaluation 

(BASE) study included a range of measurements in 100 randomly selected U.S. office buildings 

for the purpose of characterizing the existing building stock with respect to determinants of 

indoor air quality and occupant perceptions of indoor environments. One aspect of the evaluation 

was the characterization of the ventilation systems serving the study spaces and selected 

measurements of ventilation performance. This report presents an analysis of these data with a 

focus on supply and outdoor airflows, including comparisons of the measured data with design 

values and the outdoor air requirements in ASHRAE Standard 62-2001. The results indicate that, 

as expected based on thermal load considerations, the average value of the design and measured 

supply airflow are both about 5 L/s•m

2

 (1 cfm/ft2). The measured outdoor air ventilation is 

higher than might be expected, with a mean value of 49 L/s (105 cfm) per person based on 

volumetric airflow measurements at the air handlers and measured occupant densities. These 

outdoor air ventilation values are high on average relative to the minimum outdoor air 

requirements in Standard 62 due to the high outdoor air fractions (relative to minimum) and the 

actual occupancy being on average 80 % of the design occupancy. Nevertheless, about 17 % of 

the ventilation measurements are still below the 10 L/s (20 cfm) per person requirement in 

Standard 62. Under conditions of minimum outdoor air intake and accounting for the lower 

occupancy levels, the mean ventilation rate is roughly 11 L/s (22 cfm) per person and about onehalf of the values are below the per person requirement in Standard 62. In addition, this report 

contains a number of suggested modifications to the protocol used in these assessments for 

consideration in future studies.

This report is a revision of the original report on these data published in 2004. This revision 

reflects some additional analyses of the data, which results in some changes to the numerical 

values reported, but not to the overall conclusions. The additional analyses are discussed in 

Appendix F of this report, which was published as a NIST Letter Report in October 2008. All 

values in this revised report that have changed relative to the original report are noted in bold

font. Those tables and figures have been updated are also noted in bold font in the lists of tables 

and figures page vii and viii respectively.

Keywords: carbon dioxide, design, measurement, mechanical ventilation, office buildings, 

ventilation
iv
v

TABLE OF CONTENTS

Abstract iii

List of Tables vi

List of Figures vii

1. INTRODUCTION AND BACKGROUND 1

1.1 EPA BASE Study 1

1.2 Objectives of Ventilation Analysis 3

2. METHODOLOGY 3

2.1 Buildings, Study Spaces and Air Handling Systems 3

2.2 Measured Data 4

2.3 Timing of Building Evaluations 6

3. RESULTS 8

3.1 Building and Study Space Information 8

3.2 Ventilation System Design Parameters 9

3.3 Exhaust System Design and Building Airflow Balance 16

3.4 Measured Occupant Density 17

3.5 Ventilation System Performance Measurements 18

3.5.1 Supply Airflow 18

3.5.2 Outdoor Air Fraction 20

3.5.3 Outdoor Air Ventilation 26

3.5.4 Outdoor Airflows from Peak Carbon Dioxide 29

3.5.5 Supply Diffuser Airflows 33

3.5.6 Exhaust Airflows 33

4. DISCUSSION 34

4.1 Summary of Conclusions 34

4.2 Comparison with European Audit Project 35

4.3 Recommendations for Ventilation Assessment Protocols 36

5. ACKNOWLEDGEMENTS 37

6. REFERENCES 38

Appendix A: BASE Variables Used in Analysis 40

Appendix B: System Design Information 42

Appendix C: Volumetric Airflow Data Issues 49

Appendix D: Measured Data for Air Handlers 51

Appendix E: Measured Data for Study Spaces 72

Appendix F: Reanalysis of BASE Ventilation Data 93
vi
vii

LIST OF TABLES

1. HVAC performance parameters 2

2. Building information 8

3. Study space information 9

4. Ventilation system types 10

5. Outdoor air intake control 10

6. System design values 11

7. System design outliers 12

8. Outdoor air requirements based on Standard 62 addendum n 13

9. Reported frequencies of selected system maintenance activities 14

10. Summary of exhaust system design values 16

11. Net design airflow analysis 17

12. Summary of measured occupant density 17

13. Summary of measured supply airflows 19

14. Summary of measured outdoor air fraction 21

15. Summary of measured outdoor air ventilation – volumetric 27

16. Summary of measured outdoor air ventilation – CO2 ratio 28

17. Outdoor air ventilation adjusted for occupancy and outdoor air fraction 29

18. Summary of measured outdoor air ventilation – Peak CO2 30

19. Outdoor air ventilation for naturally ventilated spaces 32

20. Summary of measured supply airflows at diffusers 33
viii

LIST OF FIGURES

1. Frequency distribution of measurement based on month 7

2. Frequency distribution of measurement based on outdoor temperature 7

3. Design supply airflow capacity versus year built 14

4. Design minimum outdoor air intake versus year built 15

5. Design occupant density versus year built 15

6. Ratio of measured to design supply airflow versus outdoor temperature 19

7. Measured study space supply airflow versus outdoor temperature 20

8. Volumetric outdoor air fraction versus outdoor temperature 22

9. Outdoor air fraction for an idealized economizer cycle 22

10. Measured air change rates versus outdoor air temperature (Persily et al. 1992) 23

11. Return minus outdoor air CO2 concentration versus time of day 24

12. Outdoor air fraction based on CO2 versus volumetric 25

13. Ratio of measured to design outdoor airflow versus outdoor temperature 26

14. Outdoor air ventilation, CO2 ratio versus volumetric 28

15. Outdoor air ventilation, CO2 peak versus volumetric 31
ix
1

1. INTRODUCTION AND BACKGROUND

Building ventilation is a primary determinant of indoor air quality (IAQ) in buildings as it 

impacts indoor contaminant concentrations and occupant comfort. However, relatively few 

measurements of office building ventilation performance have been conducted, and those data 

that exist generally have not employed consistent measurement methods and have not involved 

representative collections of buildings. As discussed below, the EPA Building Assessment 

Survey and Evaluation (BASE) study was conducted to assess IAQ, including ventilation, in a 

large number of randomly selected office buildings throughout the U.S. using a standardized 

protocol. Ventilation performance assessment was a key part of the survey, and this report 

presents an analysis of the ventilation data collected during the study. The building evaluations 

were conducted by EPA contractors, and the analysis presented in this report is based on the 

ventilation data collected by the contractors.

1.1 EPA BASE Study

The EPA BASE study was originally conceived to address the IAQ data gap in public and 

commercial office buildings. As described in the protocol for the study (EPA 2003), the primary

goal of the study was to define the status of the existing building stock with respect to 

determinants of IAQ and occupant perceptions. The study was also intended to provide data that 

would form the basis for future building studies, as well as provide guidance on building design, 

construction, operation, and maintenance. EPA assembled a steering committee to support the 

design, planning, and implementation of the effort in the following areas: study design; building 

and heating, ventilating, and air conditioning (HVAC) characteristics; human response and 

questionnaires; environmental measurements; diagnostics and mitigation; and program 

integration. A protocol was then developed that incorporated the three major study areas: 

comfort and environmental measurements; building and HVAC characterization; and an 

occupant questionnaire. While certain aspects of the entire building were characterized, one or 

more representative sampling spaces (referred to in this report as study spaces) in each building 

were more intensively characterized due to cost and time limitations. Ultimately the data from 

the study will reside in a publicly accessible database, and it is expected that the data will be 

used for a number of applications, such as: developing distributions of IAQ, building and HVAC 

characteristics; developing new hypotheses regarding, for example, the causes of occupant 

symptoms; establishing standardized protocols for IAQ studies; examining the relationship of 

symptoms to building characteristics; and, developing guidance on building design, construction, 

operation, and maintenance.

Buildings included in the sample were not intended to be IAQ complaint buildings, although 

some complaint buildings may have been included. However, buildings that had been highly

publicized by the media for their IAQ problems were excluded. The building sampling strategy

randomized the sample to the extent possible, limited by the success in gaining access to 

buildings. Over the five-year period from 1994 to 1998, 100 buildings were studied as part of the 

BASE program. Each building was studied for a one-week period, generally in either the summer 

or winter, during which the various measurements were conducted. On Wednesdays and 

Thursdays of that week, HVAC system performance measurements were made at the same time 

that environmental measurements were made in the occupied space. These HVAC performance 

measurements were generally made at approximately 9:30 a.m. and 2:30 p.m. on each day. The 

HVAC performance measurements are described briefly in Table 1, which also contains the 

number of the data form from the BASE protocol.
2

Parameter Monitoring approach

Form

Number*

Supply and recirculation

airflow

Duct traverse for each air handling unit (AHU) serving

study space using pitot tube or hot-wire anemometer.

E-1

Percent outdoor air intake Calculation from carbon dioxide (CO2) concentration

measured in outdoor air and the supply and return air of

each AHU serving the study space.

E-1

Outdoor air intake For each AHU serving the study space, duct traverse in

the outdoor air intake duct. If not possible, estimate from

difference between supply and recirculation airflow.

E-1

Supply air temperature and

relative humidity

Measurement in supply air duct for each AHU serving

study space.

E-1

Exhaust fan operation Observation by technician mornings and afternoons of

monitoring days

E-3

Exhaust fan airflow Measurement of airflow rates of all exhaust fans serving

the study space using flow capture hood or duct traverse;

measurement of individual exhaust grilles within the

study area; one time measurement.

E-4

Local ventilation

performance – supply

airflow

Measurement of airflow from all supply diffusers serving

the study space (preferred) using flow capture hood;

measure a minimum of 50 % of the supply diffusers

serving the study space.

E-2

Outdoor air ventilation rate

– continuous CO2

Estimation of ventilation from continuous CO2

concentration at three locations in study space; only

method used in naturally ventilated buildings

E-5

* Form number for data collection in BASE protocol.

Table 1 HVAC performance parameters

The study areas in each building were selected based on the following criteria (EPA 2003):

• Number of occupants: 25 occupants who work for 20 or more hours per week and are 

available to complete the questionnaire, but preferably 50 to 60 such occupants.

• Served by no more than two air-handling units, but preferably just one.

• A maximum of three floors, but preferably just one.

• Preferably floor area not to exceed 1900 m2 (20 000 ft2)

There have been previous analyses of the building and HVAC data, as well as some papers 

describing the BASE study in more general terms (Brightman et al. 1996, Womble et al. 1995 

and 1996). Ludwig et al. (2002) present an analysis of the ventilation data, including a 

comparison with the outdoor air requirements in ASHRAE Standard 62-1999 (ASHRAE 1999). 

They conclude that ventilation rates based on indoor CO2 levels have lower uncertainties than the 

rates based on the other methods considered and that most of the measured values are higher than 

the requirements in Standard 62. However, the uncertainties considered are based only on 

instrumentation specifications and do not consider other sources of error. In particular, the 

uncertainties of the ventilation estimates using indoor CO2 are based on only the concentration 

measurements and not on validity of the assumptions inherent in the mass balance methodology

used to make these estimates. Also, their analysis did not investigate ventilation system design 

values and did not address other ventilation performance parameters of interest, such as supply

airflows. Apte et al. (2000) and Erdman et al. (2002) examine associations between sick building 

syndrome symptoms and indoor-outdoor CO2 concentration differences as surrogates for per 

person ventilation rates.
3

1.2 Objectives of Ventilation Analysis

The purpose of the analysis presented in this report is to produce information on ventilation 

system design and performance for the 100 BASE office buildings. While there have been some 

studies of ventilation in office buildings (Persily 1989, Persily and Dols 1991, Persily at al. 

1992), none have been associated with such thorough characterizations of indoor environmental 

conditions and occupant symptoms nor have they been applied to a representative set of 

buildings. Therefore, the BASE data provide a unique opportunity to obtain important 

information about U.S. office buildings including ventilation system design values, measured 

ventilation performance, and the relationship of these measurement results to design values and 

to requirements in standards. While the following sections describe the specific parameters that 

are considered, the focus of this analysis is primarily on supply airflows and outdoor air 

ventilation. It is envisioned that the results of this analysis will be used to investigate 

relationships of ventilation to IAQ performance parameters and to occupant symptoms. In 

addition to providing design and measured ventilation data, this study was performed to evaluate 

the BASE protocol with respect to its ability to obtain reliable ventilation performance data and 

to recommend modifications to the protocol for use in future studies.

2. METHODOLOGY

The data analysis involved calculations of various parameters using the data obtained by the EPA 

contractor, most of which is described in the results section. The overall analysis approach is 

summarized in this section, along with a more detailed discussion of some specific parameters 

such as the outdoor air fraction of an air handler.

The analysis focused primarily on the study spaces and the ventilation systems serving these 

spaces in terms of both design and measured performance. As noted earlier, the study spaces 

were portions of buildings, or in some cases whole buildings, that were the subject of the BASE 

study test protocol. In this study, ventilation design and performance is assessed primarily in 

terms of supply airflow and outdoor air intake, along with exhaust airflows to a lesser degree. In 

addition, occupancy levels are examined. All of the analysis performed by NIST employs data 

that were provided by EPA, much of which had already been processed by their contractors. For 

example, the data from duct traverses had already been converted into volumetric airflows. NIST 

did not use the raw data from the field to verify the processing done by the contractor, as the 

protocol and data processing already had significant quality control checks. The BASE variables 

used in the NIST analysis, as well as those obtained from the contractor’s analysis, are identified 

in Appendix A.

The analysis results are presented in the form of the following summary statistics for the 

variables of interest: mean, standard deviation, median, the 10th, 25th, 75th and 90th percentile 

values, and the minimum and maximum values.

2.1 Buildings, Study Spaces and Air Handling Systems

The data analysis focused first on the buildings involved in the BASE study and the study spaces 

in the buildings. Basic information was analyzed to characterize the age and size of the buildings 

as well as the size and occupancy of the study spaces. The air handling systems serving the study

spaces were examined in terms of the types of system, means of outdoor air intake control, and 

system design specifications. The latter includes supply, return and minimum outdoor airflow 

capacity and design occupant density. The system design airflows were obtained as part of the 

BASE protocol, when available, from system specifications and other design documentation. The 

primary outcomes of these analyses are the supply airflow capacity per unit floor area, expressed 
4

as L/s•m2 (cfm/ft2), and the minimum outdoor air intake in L/s•person (cfm/person). These 

design parameters are then examined as a function of building age to determine if any trends 

over time are evident. In addition, the design capacities of the exhaust ventilation systems are 

examined, including their contribution to the net airflow balance of the building.

2.2 Measured Data

The analysis of the measured data focused on the following ventilation performance parameters: 

supply airflow, outdoor air fraction, outdoor air ventilation, and exhaust airflow. An uncertainty

analysis is performed for all the calculated parameters based on propagation of the uncertainty

estimates for each of the measured quantities, i.e., 30 % for the measured outdoor air intake and 

recirculation airflow, 10 % for the supply airflows, and 90 mg/m3 (50 ppm(v)) for the CO2

concentrations. The uncertainties of the airflows are estimates from an analysis by the EPA 

contractor who performed the tests (EHE 2001a). The actual uncertainties may very well be 

larger, or perhaps smaller, than these estimates; however, there is insufficient information 

available to develop better estimates of the measurement uncertainties. The value for the CO2

monitors is based on the instrumentation specifications in the study protocol. 

Occupant Density

As part of the BASE protocol, the number of occupants in each study space was counted twice a 

day for at least two days during the test week. These data are analyzed to determine the occupant 

density of each space in units of number per 100 m2 (1000 ft2). These values are compared with 

the design occupancy based on the number of workstations in each study space and with the 

occupant density values in ASHRAE Standard 62-2001 (ASHRAE 2001a) and in addendum n to 

that standard (ASHRAE 2003).

Supply Airflow

The measured supply airflows for the individual air handlers are first compared with the design 

values. The ratios of measured to design are then evaluated as a function of system type and 

outdoor air temperature. The supply airflows for the air handlers were combined to determine the 

total supply airflow to each study space. The supply airflow to each study space was based on the 

percentage of the air handler airflow serving the study space, which is a variable determined in 

the ventilation system evaluation. The survey protocol did not provide an uncertainty estimate 

for these percentages. For the purposes of this analysis, the uncertainty is assumed to equal 10 % 

of the value except in cases where 100 % of the air is delivered to the study space. In those cases 

the uncertainty is assumed to be zero. The study space supply airflows are normalized by floor 

area served and examined as a function of outdoor air temperature.

Outdoor Air Fraction

A key ventilation performance parameter assessed in the study is the outdoor air fraction Fo, i.e., 

the ratio of the outdoor air intake to the supply airflow. It is of interest as a performance 

parameter itself and as a means of determining the outdoor air intake through multiplication by

the supply airflow. The outdoor air fraction was determined in two ways, dividing the measured 

outdoor airflow by the measured supply airflow and through the measurement of CO2

concentrations in the outdoor, supply and recirculation airstreams. The former determination is 

referred to as a volumetric value, while the latter is referred to as the CO2 ratio value.

The volumetric outdoor air fraction was determined for each air handler measurement based on 

whichever of the expressions in Equations (1a), (1b) and (1c) apply. In Equation (1a), Fovolumetric is determined by the measured outdoor air intake divided by the supply airflow. In 
5

cases where the outdoor air intake was not measured directly but the supply and recirculation 

flows were measured, Fo-volumetric was determined using Equation (1b). Finally, in cases where 

the supply airflow was not measured, Fo-volumetric was determined using Equation (1c) based 

on the sum of the outdoor and recirculation airflows. Mathematically, these three means of 

determining the volumetric intake fraction are expressed as follows:

Fo = QO/QS (1a)

Fo = (QS – QR)/QS (1b)

Fo = QO/(QO + QR) (1c)

where Fo is the outdoor air fraction and QO, QS and QR are the outdoor, supply and recirculation 

airflows respectively. The value of Fo with the minimum uncertainty was identified and is 

referred to as the best volumetric value of Fo. For some air handlers, the value of Fo could be 

determined using more than one of these expressions. For a small number of cases in which only

Equation (1b) could be used, the value of QS was less than QR, resulting in a negative value. In 

those cases, the outdoor air fraction and QO were both set to zero, but the large uncertainty

values were carried through the analysis.

Values of Fo were also determined based on measured CO2 concentrations in the outdoor, supply

and recirculation airstreams using Equation (2), 

Fo = (CR – CS) / (CR – CO) (2)

where CR, CS and CO are the CO2 concentrations in the supply, recirculation and outdoor 

airstreams respectively.

Outdoor Air Ventilation

Outdoor air intake is determined for individual air handlers using whichever of the following 

approaches was possible:

• Direct measurements of the volumetric airflow in the outdoor air intake duct using standard 

air speed traverse approaches.

• The difference between direct measurements of the supply and recirculation volumetric 

airflows.

• The outdoor air fraction based on CO2 (see Equation (2)) multiplied by the supply airflow.

The measured outdoor airflows for the individual air handlers are compared with the design 

values for minimum outdoor air for the systems where such a design value exists. The ratios of 

the measured to design values are evaluated as a function of system type and outdoor air 

temperature. Based on the measurements at the individual air handlers, the outdoor air 

ventilation in each study space is calculated. These calculations employ the value of the 

percentage of the air from each handler that is provided to the study space. As noted above, the 

protocol does not provide an uncertainty estimate for these values, and the uncertainty is 

assumed to equal 10 % except when the value is 100 %.

The outdoor air ventilation in the study space is also estimated based on the CO2 concentrations 

measured with the fixed monitors used in the study. A number of such monitors were deployed 

in each study space, which recorded the CO2 concentration (and other variables) every 5 min 

over several days. The CO2 concentrations were averaged across the study space and the peak 

value identified. In some cases both a morning and an afternoon peak were identified, if the 

concentration pattern indicated two distinct peaks. In other cases, only a single peak was 

determined for the day. The peak concentration minus the corresponding outdoor concentration 
6

is then used to estimate the outdoor airflow per person assuming that the CO2 concentration is at 

equilibrium and assuming a CO2 generation rate per person of 0.0052 L/s (0.011 cfm). This 

method is based on a single-zone mass balance of CO2 in the study space and therefore is valid 

only when the concentration is indeed at steady-state, the concentration is uniform throughout 

the space, airflows from adjoining spaces can be ignored, and the outdoor concentration, 

ventilation rate and generation rate are all constant (Persily 1997). Since the validity of these 

assumptions was not investigated as part of this study (except that the outdoor concentration was 

monitored), the validity of the results obtained with this method are subject to question.

Supply Diffuser and Exhaust Airflows

The BASE protocol included one measurement of the supply airflow at the accessible supply air 

diffusers and the exhaust airflow at exhaust grilles located in the study space. In the case of the 

supply diffusers, the total supply airflow to the study space is compared with the value based on 

the measurements at the air handler(s). The measured exhaust airflows are compared with the 

corresponding design values.

2.3 Timing of Building Evaluations

As noted earlier, the goal in the BASE study was to conduct the measurements during the winter 

and summer when the systems were more likely to be operating at minimum outdoor air 

conditions and to increase the likelihood that the system operation would not vary over the test 

week. Figure 1 is a plot of the measurement dates by month of the year. Note the large number of 

measurements made during the month of March. However, the month does not necessarily

indicate the percentage of outdoor air intake; the outdoor air temperature is a better predictor. 

Figure 2 shows the distribution of the measurements based on the outdoor air temperature at 

which the ventilation measurements were made. If one assumes that minimum outdoor air intake 

occurs for air temperatures below 5 °C (41 °F) and above 20 °C (68 °F), then 339 of the 548 

measurement events (or 62 %), with the outdoor temperature recorded, would correspond to 

minimum outdoor air intake. Of course, the percent of outdoor air intake as a function of outdoor 

temperature depends on the individual system, and some systems were 100 % outdoor air 

systems. But based on temperature alone, about one-third of the tests might be expected to be at 

other than minimum outdoor air intake. The issue of percent outdoor air intake, including the 

temperature dependence, is discussed again when the outdoor air fraction and outdoor air 

ventilation measurements are presented.
7

Figure 1 Frequency distribution of measurements based on month

 Figure 2 Frequency distribution of measurements based on outdoor temperature

0

25

50

75

100

125

(5 to 14 °F)

-15 to -10 °C

(14 to 23 °F)

-10 to -5 °C

-5 to 0 °C

(23 to 32 °F)

0 to 5 °C

(32 to 41 °F)

5 to 10 °C

(41 to 50 °F)

(50 to 59 °F)

10 to 15 °C

(59 to 68 °F)

15 to 20 °C

(68 to 77 °F)

20 to 25 °C

(77 to 86 °F)

25 to 30 °C

(86 to 95 °F)

30 to 35 °C

(> 95 °F)

> 35 °C

Outdoor temperature range

Number of measurements

0

20

40

60

80

100

120

January

February

March

April

MayJune

July

August

September

October

November

December

Month

Number of Measuremments
8

3. RESULTS

This section presents the results of the ventilation analysis performed on the BASE building data. 

These results include information on the buildings and study spaces, system design parameters, 

and measured values of occupant density, supply airflow, outdoor air fraction, outdoor air 

ventilation and exhaust airflow.

3.1 Building and Study Space Information

As noted earlier, 100 buildings were involved in the BASE study. These buildings were 

randomly selected as described in Womble et al. (1995), and were located throughout the United 

States. Table 1 presents a summary of the characteristics of the buildings. The years of 

construction range from 1850 to 1996, with a mean of 1961, though most of them have been 

renovated at some point. The total number of stories, below and above grade, range from 1 to 61, 

with a mean of 10 stories. The gross floor area of the buildings range from about 1700 m2

(18 000 ft2) to 134 200 m2 (1 445 000 ft2), with a mean of 24 800 m2 (266 000 ft2). The occupied 

floor areas, which exclude atria, vacant office space, hallways, stair and elevator shafts, 

mechanical rooms and core areas, range from 600 m2 (6000 ft2) to 98 500 m2 (1 060 000 ft2), 

with a mean of 16 400 m2 (177 000 ft2). Of the 100 buildings, 97 have mechanical ventilation 

systems while three employ predominantly natural ventilation, i.e., buildings NYBS06, ORIS02 

and WAIA01. (These building codes are used in the BASE study to identify each building, with 

the first two letters indicating the state in which they are located.) Ninety-nine of the buildings 

are air-conditioned (building WAIA01 being the exception), and all are heated.

Year of

construction

Number of

stories

Gross floor area

m

2 (ft2

)

Occupied floor area

m

2 (ft2

)

Mean 1961 10 24 800 (266 000) 16 400 (177 000)

Std. Dev. 31 11 27 900 (300 000) 18 500 (199 000)

Minimum 1850 1 1700 (18 000) 600 (6000)

10thpercentile 1906 3 3700 (40 000) 2300 (25 000)

25thpercentile 1953 4 7400 (80 000) 5100 (55 000)

Median 1972 6 14 000 (151 000) 8500 (91 000)

75thpercentile 1983 12 27 900 (300 000) 21 300 (229 000)

90thpercentile 1988 22 65 100 (701 000) 35 900 (386 000)

Maximum 1996 61 134 200 (1 445 000) 98 500 (1 060 000)

Table 2 Building information

It is interesting to compare the BASE buildings to those included in the 1995 U.S. Department of 

Energy Commercial Building Energy Consumption Survey or CBECS (DOE 1998). CBECS is a 

national survey of commercial buildings that is conducted quadrennially with a target population 

of all commercial buildings in the United States with more than 100 m2 (1000 ft2) of floor area. 

The median age of the CBECS buildings corresponds to a year of construction of 1972, which is 

identical to the BASE value. The mean floor area of the 1995 CBECS office buildings is 

1400 m

2

 (14 900 ft2), which is much less than the BASE buildings. However, as noted earlier, 

the BASE buildings were selected such that the study space had at least 25 occupants and 

preferably 50 or 60 occupants. The mean number of workers in the CBECS office buildings is 

38.4 and 74 % of the office buildings have less than 20 occupants. Therefore the difference in the 

floor areas between CBECS and BASE is not surprising. Of the 705 000 CBECS office 

buildings, all but 1000 are heated and 98 % are cooled, consistent with the BASE buildings. A
9

previous analysis of the BASE buildings relative to the CBECS data notes that the BASE 

buildings are most representative of office buildings with more than 50 occupants, which 

constitute roughly 11 % of the office building stock but about 73 % of the U.S. office building 

occupants (EHE 2001b).

The 100 study spaces within the buildings were selected based on the criteria described above, 

and some of their characteristics are summarized in Table 3. The occupied floor areas range from 

430 m2 (4600 ft2) to 6440 m2 (69 300 ft2), with a mean of 1540 m2 (16 600 ft2). The mean 

number of workstations is 72, which corresponds to 5.3 workstations per 100 m2 of floor area 

(4.9 per 1000 ft2). The number of workstations in this table is the sum of the number of private, 

partitioned and open-space workstations that were counted as part of the study space 

characterization. The study space characterization also yielded a value for the design floor area 

per workstation (variable name B1DESWS). Computing the number of workstations per floor 

area based on B1DESWS yields similar values to those obtained based on the number of 

workstations as presented in the table, but not identical. The number of workstation density in 

the table is below the default value of 7 per 100 m2 (1000 ft

2

) in ASHRAE Standard 62-2001, but 

close to the default value of 5 per 100 m2 (1000 ft2) for office space in addendum n to the 

standard (ASHRAE 2003). For the 97 study spaces with mechanical ventilation, the mean 

number of supply air diffusers is 106 and the mean floor area per diffuser of 18.4 m2 (198 ft2).

Occupied floor

area, m2 (ft

2

)

Number of

workstations

Workstations

per 100 m2

(1000 ft

2

)

Number of

supply air

diffusers

Floor area per

diffuser m2 (ft

2

)

# of values 100 100 100 97 97

Mean 1540 (16 600) 72 5.3 (4.9) 106 18.4 (198)

Std. Dev. 740 (8 000) 19 2.0 (1.9) 53 16.1(174)

Minimum 430 (4600) 39 1.0 (0.9) 6 5.3 (57)

10thpercentile 880 (9 500) 50 3.0 (2.8) 47 8.4 (91)

25thpercentile 1130 (12 100) 58 4.0 (3.7) 73 10.9 (118)

Median 1430 (15 400) 68 4.8 (4.5) 98 15.1 (163)

75thpercentile 1780 (19 200) 88 6.3 (5.8) 132 19.8 (213)

90thpercentile 2250 (24 200) 100 7.6 (7.1) 168 26.9 (290)

Maximum 6440 (69 300) 118 12.5 (11.6) 281 140.0 (1507)

Table 3 Study space information

3.2 Ventilation System Design Parameters 

The study spaces in the 97 mechanically ventilated buildings are served by a total of 141 

mechanical ventilation systems. Of these systems, 50 are constant air volume (CV) and 91 are 

variable air volume (VAV). CV systems provide a constant amount of supply air, while varying 

the supply air temperature to meet the heating and cooling loads of the space. VAV systems 

maintain a constant supply air temperature and vary the supply airflow to meet the loads. The 

system types are summarized in Table 4 based on the system classification and letter codes in the 

BASE protocol.

In addition to the system types in Table 4, other design features related to outdoor air intake 

control were collected for the ventilation systems. Table 5 presents this information for the 

mechanically ventilated buildings, including the number with systems that employ temperature 

(dry-bulb) or enthalpy economizer cycles. Twenty-one buildings have dedicated outdoor air fans, 
10

with 11 of those also conditioning the air. Five buildings have 100 % outdoor air systems, and 88 

have fixed minimum outdoor air intake dampers. A small number have the outdoor air intake 

controlled using airflow monitoring, supply/return fan tracking or building pressure.

Constant volume (CV)

Number

of systems Variable air volume (VAV)

Number

of systems

A Single duct, single zone 13 D Single duct 37

B Single duct, multiple zone reheat 8 E Single duct, reheat 17

J Dual duct 2 F Single duct, induction 7

K Dual duct, reheat 7 G Single duct, fan powered,

constant fan

8

N Multizone 17 H Single duct, fan powered,

intermittent fan

18

O Blow-through bypass 3 L Dual duct, single fan 3

M Dual duct, dual fan 1

TOTAL CV 50 TOTAL VAV 91

Table 4 Ventilation System Types

Outdoor air intake control

Number of

buildings

Economizer cycle (temperature control) 50

Economizer cycle (enthalpy control) 21

Dedicated outdoor air fan, conditioned 11

Dedicated outdoor air fan, unconditioned 10

100 % outdoor air 5

Fixed minimum outdoor air damper 88

Outdoor air intake controlled via monitoring 2

Outdoor air intake controlled via supply/return fan tracking 5

Outdoor air intake controlled by building pressure 4

Table 5 Outdoor air intake control

The availability of design information varies among the systems, however the information that 

does exist was analyzed and the results are summarized in Table 6. (Detailed design information 

for all the systems is provided in Appendix B.) Table 6 presents the floor area served by the 

systems, the design supply airflow capacity normalized by floor area served (for all systems as 

well as for CV and VAV systems separately), the ratio of design supply to return airflows, the 

design minimum outdoor air intake per person and per unit floor area, the ratio of the design 

minimum outdoor air intake to the design supply air capacity, and the occupant density. The 

occupant density is based on the number of occupants served by the air handler, which was 

obtained during the surveys from a building walkthrough or from the building management. 

(During the study space surveys, the actual number of occupants was counted and those results 

are presented later in this report.) When calculating the supply airflow capacities, the minimum 

outdoor air intake, and the occupant densities, some values were not in the expected range. These 

values include supply airflows greater than 15 L/s•m2 (3 cfm/ft2), minimum outdoor air intake 

greater than 33 L/s (70 cfm) per person or 5 L/s•m

2

 (1 cfm/ft2), and occupant densities greater 

than 12 per 100 m2 (1000 ft2). Values outside these ranges are included in the statistics in Table 

6, and the outliers themselves are identified in Table 7.

As seen in Table 6, for the 134 air handling systems with design data, the mean value of the 

design supply airflow normalized by floor area served is 5.86 L/s•m2 (1.15 cfm/ft2), which is 
11

close to the expected value of 5 L/s•m2 (1 cfm/ ft2) based on typical cooling loads and supply air 

temperatures in office buildings. The median value is even closer to the expected supply airflow 

rate, and the mean is slightly higher for CV systems and lower for VAV systems. The ratio of the 

design supply airflow to the design return airflow could be determined for 41 of the systems, and 

the mean value is 1.14. This value is consistent with the common design intent to provide more 

supply than return air to a space to achieve positive pressurization and to ensure that toilet and 

other exhaust systems are able to function properly. 

Design supply airflow capacity

L/s•m

2 (cfm/ft2 Floor area served )

m

2 (ft2

) All systems CV VAV

Supply/

Return

# of values 141 134 47 87 41

Mean 3100 (33 300) 5.86 (1.15) 7.01 (1.38) 5.25 (1.03) 1.14

Std. Dev. 4230 (45 600) 3.57 (0.70) 5.33 (1.05) 1.85 (0.36) 0.22

Minimum 110 (1200) 1.13 (0.22) 1.13 (0.22) 1.67 (0.33) 0.20

10thpercentile 540 (5800) 2.90 (0.57) 2.74 (0.54) 3.26 (0.64) 1.00

25thpercentile 990 (10 700) 4.15 (0.82) 4.19 (0.83) 4.15 (0.82) 1.07

Median 1640 (17 600) 5.21 (1.03) 5.63 (1.11) 4.99 (0.98) 1.11

75thpercentile 3440 (37 000) 6.78 (1.33) 7.83 (1.54) 6.17 (1.22) 1.25

90thpercentile 7620 (82 100) 8.45 (1.66) 11.21 (2.21) 7.56 (1.49) 1.28

Maximum 33 780 (363 600) 30.18 (5.94) 30.18 (5.94) 12.47 (2.45) 1.85

Design minimum outdoor air intake

L/s (cfm) per person L/s•m

2 (cfm/ft2

)

Minimum OA/

Supply

Occupant density

#/100 m

2 (1000 ft2

)

# of values 74 76 76 137

Mean 18.4 (39.0) 0.94 (0.18) 0.19 5.3 (4.9)

Std. Dev. 13.7 (29.0) 1.06 (0.21) 0.22 6.5 (6.1)

Minimum 1.3 (2.9) 0.17 (0.03) 0.06 0.9 (0.8)

10thpercentile 7.5 (16.0) 0.31 (0.06) 0.08 2.2 (2.0)

25thpercentile 10.6 (22.4) 0.42 (0.08) 0.10 2.9 (2.7)

Median 15.2 (32.1) 0.60 (0.12) 0.12 3.9 (3.7)

75thpercentile 23.6 (50.0) 0.92 (0.18) 0.15 5.9 (5.4)

90thpercentile 29.7 (63.0) 1.82 (0.36) 0.31 8.0 (7.4)

Maximum 98.3 (208.2) 6.67 (1.31) 1.00 65.1 (60.5)

Table 6 System design values

The mean value of the design minimum outdoor air intake per person is 18.4 L/s (39.0 cfm), and 

the median is 15.2 L/s (32.1 cfm). These values are above the minimum outdoor air requirement 

for office space in ASHRAE Standard 62-2001 (ASHRAE 2001) of 10 L/s (20 cfm) per person. 

The design outdoor air intake in Table 6 is based on the number of workstations, since the 

number of occupants used in the design is not available. However, dividing the design minimum 

outdoor airflow by the number of occupants based on the occupant density in ASHRAE Standard 

62-2001 (7 people per 100 m2 (1000 ft2)) instead of the actual number of workstations yields a 

mean per person outdoor air intake of 13.1 L/s (25.8 cfm) and a median of 8.5 L/s (16.7 cfm), 

which are closer to the ASHRAE requirement. Note that design the minimum outdoor air intake 

is available for only 76 of the 141 systems. Also, these systems were designed at various times, 

and therefore it is not clear what standard or code requirements the systems were used in the 

design. The table also provides the design minimum outdoor air intake on a floor area basis. 
12

Finally, the mean ratio of the minimum outdoor air intake to supply airflow capacity is 0.18 and 

the median value is 0.12, consistent with expected values of 10 % to 20 %. 

The mean value of the design occupant density in Table 6 is 5.3 people per 100 m2 (4.9 per 

1000 ft2), while the median value is 3.9 per 100 m2 (3.7 per 1000 ft2). As noted earlier when 

discussing the study spaces, these values for the individual air handlers are below the default 

value of 7 per 100 m2 (1000 ft2) in ASHRAE Standard 62-2001, but close to the default value of 

5 per 100 m2 (1000 ft2) for office space in addendum n to the standard (ASHRAE 2003).

System * Issue Comments

AZHW10 (2 of 2) High supply capacity, 24 L/s•m

2

(4.7 cfm/ft

2

)

System (1) at 8 L/s•m

2 (1.5 cfm/ft2

)

LAGW05 (1 of 2) High supply capacity, 18 L/s•m

2

(3.6 cfm/ft

2

)

System (2) at 4 L/s•m

2 (0.7 cfm/ft2

);

occupant density 5 times that of system (2);

floor area could be low

MOCS01 (1 of 1) High supply capacity, 27 L/s•m

2

(5.3 cfm/ft

2

)

PABS04 (2 of 2) High supply capacity, 25 L/s•m

2

(5.9 cfm/ft

2

)

System (1) at 4 L/s•m

2 (0.8 cfm/ft2

)

CAEW09 (1 of 1) High minimum outdoor air 53 L/s

(113 cfm) per person,

Minimum outdoor air based on supply and

return capacities

CAJS21 (2 of 2) High minimum outdoor air, 98 L/s

(208 cfm) per person

100 % outdoor air system; System (1) at 29

L/s (61 cfm) per person

MDDS01 (1 of 1) High minimum outdoor air, 51 L/s

(109 cfm) per person

NCDW03 (2 of 5) High minimum outdoor air, 38 L/s

(80 cfm) per person

Other 4 systems from 9 L/s (20 cfm) per

person to 16 L/s (33 cfm) per person;

system (2) occupant density about 25 % of

other 4 systems.

NECW02 (1 of 1) High minimum outdoor air, 38 L/s

(80 cfm) per person

High occupant density, 16 occupants per

100 m

2 (1000 ft2

)

TNFS10 (1 of 1) High minimum outdoor air, 34 L/s

(72 cfm) per person

Low occupant density, 1.1 occupants per

100 m

2 (1000 ft2

)

CAJW25 (1 of 1) High occupant density, 61

occupants per 100 m

2 (1000 ft2

)

Supply airflow 24 L/s•m

2 (2.5 cfm/ft2

);

floor area could be low

MOCS01 (1 of 1) High occupant density, 24

occupants per 100 m

2 (1000 ft2

)

NECW02 (1 of 1) High occupant density, 16

occupants per 100 m

2 (1000 ft2

)

SDBW02 (1 of 1) High occupant density, 38

occupants per 100 m

2 (1000 ft2

)

Low minimum outdoor air 1 L/s (3 cfm) per

person, consistent with high occupant

density value

TNDS05 (1 of 2) High occupant density, just over

12 occupants per 100 m

2 (1000 ft2

)

System (2) lists no occupants

* Values in parentheses refers to air handler number relative to total number of air handlers, e.g. 

(2 of 2) means second of two air handlers serving the study space.

Table 7 System design outliers+

 +

 The text in the table noted with a strikethrough corresponds to two occurrences that are no 

longer outliers given the modifications to the data described earlier.
13

The ventilation requirements in ASHRAE Standard 62-2001 were recently revised by addendum 

n to the standard (ASHRAE 2003). In the new procedure, the number of occupants is multiplied 

by an outdoor air requirement in units of L/s (cfm) per person and the product is added to the 

floor area multiplied by a separate requirement in units of L/s•m

2

 (cfm/ft2). For office space 

these values are 2.5 L/s (5 cfm) per person and 0.3 L/s•m

2

 (0.06 cfm/ft2). This method was used 

to determine the per person ventilation requirements of the study spaces based on the number of 

workstations and the floor area. Table 8 presents the results. Note that the mean outdoor air 

requirement is slightly lower than the 10 L/s (20 cfm) per person requirement in Standard 62-

2001, but the variation about the mean highlights the intended impact of occupant density.

Study space outdoor air requirement

L/s (cfm) per person

Mean 9.0 (19.1)

Std. Dev. 3.3 (6.9)

Minimum 4.8 (10.2)

10thpercentile 6.5 (13.7)

25thpercentile 7.2 (15.3)

Median 8.7 (18.3)

75thpercentile 10.0 (21.1)

90thpercentile 12.1 (25.7)

Maximum 33.5 (71.0)

Table 8 Study space outdoor air requirements based on Standard 62 addendum n

The system design values were examined to determine if there was a dependence on the year that 

the building was built. Figures 3 through 5 show the design supply airflow capacity, the design 

minimum outdoor air intake, and the occupant density, respectively, as a function of the year 

built. No clear trends are evident for any of these parameters, though there is a suggestion of 

lower supply airflows and occupant densities in newer buildings. Figures 3 and 4 show that more 

of the recent buildings employ VAV than CV systems, and that these VAV systems tend to have 

lower supply capacities as seen in Table 6. The supply air capacity was also examined as a 

function of the climate in which the building is located, as expressed by the number of heating 

and cooling degree days, but no relationship was evident.

The BASE protocol also obtained information on the frequency of a number of system 

maintenance activities. Table 9 summarizes the frequency of some inspection and maintenance 

activities that might impact ventilation airflows. Note that these frequencies are listed as the 

number of buildings, not the number of air handlers. Some of the less common frequencies, such 

as bi-weekly, are not included in the table. Also, not all of the buildings reported the inspection 

and maintenance items listed in the table. The air handler inspections appear to occur fairly

often, but there is no information on the extent of these inspections. The other four activities are 

reported to occur much less often, particularly ductwork inspections and system testing, 

adjusting and balancing. The ratios of the measured airflows to design values were evaluated 

with respect to these frequencies, but no trends were evident.
14

Frequency

Air handler

inspection

Ductwork

inspection

Controls

inspection

Controls

recalibration

Testing,

adjusting &

balancing

Number of buildings

Daily 14 0 14 0 0

Weekly 5 0 2 0 0

Monthly 23 1 4 4 0

Quarterly 29 2 12 3 0

Semi-annually 6 1 11 7 0

Annually 3 4 14 10 3

As needed 4 32 28 58 52

None 0 59 12 15 43

Table 9 Reported frequencies of selected system maintenance activities

Figure 3 Design supply airflow capacity versus year built
15

Figure 4 Design minimum outdoor air intake versus year built

Figure 5 Design occupant density versus year built

0

10

20

30

40

50

60

70

80

1840 1860 1880 1900 1920 1940 1960 1980 2000

Year built

Minimum outdoor air, cfm/person

0

5

10

15

20

25

30

35

Minimum outdoor air, L/s•person

CV

VAV
16

3.3 Exhaust System Design and Building Airflow Balance 

In addition to the air handlers discussed in the last section, the 159 exhaust ventilation systems 

serving the study spaces were also considered in an attempt to examine the net design airflow 

into or out of the buildings. Table 10 presents a summary of the design information for the 

exhaust systems, which are predominantly toilet exhausts but also include kitchen exhaust, 

building relief and other fans. Design airflows are available for only 129 of the exhaust fans. 

Note that the individual airflows cover a wide range, with the maximum design airflow 500 

times the minimum. The third column presents the design airflow normalized by floor area for 

the 126 systems for which the floor area served is available. (For toilet exhausts, the floor area is 

that of the toilet room.) While the variation in this normalized value is still large, it is less than 

for the airflows. The last column presents the normalized design airflows for only the toilet 

exhausts, which exhibit a smaller standard deviation than for all the exhaust fans.

All exhaust systems Toilet exhausts only

L/s (cfm) L/s•m

2 (cfm/ft2

) L/s•m

2 (cfm/ft2

)

# of values 129 126 88

Mean 2310 (4880) 14.9 (2.94) 14.3 (2.81)

Standard deviation 3290 (6960) 21.8 (4.28) 13.2 (2.59)

Minimum 40 (90) 0.6 (0.13) 0.7 (0.14)

10thpercentile 180 (390) 4.2 (0.83) 6.2 (1.23)

25thpercentile 400 (850) 6.8 (1.34) 7.5 (1.47)

Median 950 (2020) 9.6 (1.89) 10.1 (1.99)

75thpercentile 2610 (5530) 15.0 (2.96) 16.0 (3.15)

90thpercentile 4990 (10 570) 23.0 (4.52) 22.9 (4.51)

Maximum 21 250 (45 030) 189.0 (37.19) 91.3 (17.98)

Table 10 Summary of exhaust system design values

In addition to the exhaust fan design values, the net design airflow into, or out of, the buildings 

was also considered. The issue of interest is whether and to what extent these buildings are 

designed for positive pressurization, which is the typical design intent motivated by infiltration 

control, moisture transport through building envelopes and proper functioning of building 

exhaust fans. While the mean ratio of the supply to return design airflows for the study space air 

handlers in Table 6 is greater than one, this ratio does not include exhaust airflows and therefore 

does not describe the design airflow balance. In the BASE protocol, design values were obtained 

for air handler supply, return and outdoor airflows and for the exhaust fans serving the study

spaces. These design values do not allow the determination of the net airflow for the building 

when there are other air handlers and exhaust fans. Therefore, a design airflow analysis for the 

whole building could only be performed for the six study spaces that correspond to an entire 

building. Table 11 presents the relevant design values for these buildings and the results of the 

net airflow analysis.

With only six buildings, and a lack of design data in some cases, the net building airflow can be 

calculated for only a small number of cases. The sixth column of Table 11 contains the design 

supply airflow minus the design return and exhaust airflows for the three buildings for which it 

could be calculated. This quantity describes the net airflow into the conditioned space of the 

building. For buildings CAEW09 and CAJS22, the values are positive and equal to 0.05 L/s•m

2

(0.23 cfm/ft2) and 0.17 L/s•m2 (0.85 cfm/ft2) respectively. In building SDBW01 the value is 
17

negative but very small, -0.01 L/s•m2 (-0.05 cfm/ft2), which is very close to a balance between 

the airstreams. The last column presents the balance between the air entering and leaving the 

building, i.e., the design minimum outdoor air intake minus the exhaust. Only four values can be 

determined, with three positive and one slightly negative. The three positive values, for buildings 

CAES09, CAJS22 and SDBW01 respectively, are 0.05 L/s•m

2

 (0.23 cfm/ft2), 0.01 L/s•m

2

(0.03 cfm/ft2) and 0.01 L/s•m

2

 (0.05 cfm/ft2). The negative value is so close to zero that it 

indicates a balance between the minimum intake and exhaust airflows.

Design airflows, L/s (cfm) Net design airflow, L/s (cfm)

Building Supply Return

Minimum

outdoor air Exhaust

Sup. – ret.

– exh.

MinOA – Exh.

AZHS04 11 150

(23 610) No value No value

8330

(17 640) -- --

CAEW09 38 730

(82 050)

30700

(65040)

8030 (17

010)

600

(1280)

7430

(15 730)

7430

(15 730)

CAJS22 8970

(19 010) No value

1040

(2200)

780

(1650)

8190 (17

360)

260

(550)

SDBW01 9920

(21 010)

9590

(20310)

1500

(3170)

920

(1950)

-590

(-1250)

580

(1220)

TNFS08 8640

(183 10) No value

590

(1250)

600

(1260) -- -10(-10)

TXFS02 17 000

(36 020) No value No value No value -- --

Table 11 Net design airflow analysis

3.4 Measured Occupant Density

The actual number of occupants was counted at least four times in each study space. Table 12 

summarizes these observations. These data show that on average the actual occupancy is about 

80 % of the design occupancy as defined by the number of work stations, corresponding to a 

mean occupant density of 4.0 people per 100 m2 (3.7 per 1000 ft2). The occupant density data 

were also analyzed for only those times when the ventilation parameters were measured, 

typically on Wednesday and Thursday of the test week. There were 388 such values, but the 

summary statistics are essentially identical to those seen in Table 11.

Measured occupant density,

#/100 m

2 (#/1000 ft2

)

Measured density/Number

of work stations

# of values 824 824

Mean 4.0 (3.7) 0.78

Standard deviation 1.7 (1.6) 0.24

Minimum 0.9 (0.9) 0.24

10thpercentile 2.3 (2.2) 0.57

25thpercentile 2.8 (2.6) 0.65

Median 3.6 (3.3) 0.76

75thpercentile 5.0 (4.6) 0.87

90thpercentile 6.3 (5.9) 0.98

Maximum 11.1 (10.3) 3.13

Table 12 Summary of measured occupant density
18

3.5 Ventilation System Performance Measurements

This section presents the ventilation system performance measurement results for the air handlers 

serving the study spaces and for the study spaces themselves. There were 562 ventilation 

measurement events, that is, the total number of times that some or all of the ventilation 

measurements were made on the study space air handlers. These measurements cover 97 of the 

100 BASE buildings, excluding the three naturally ventilated buildings. Appendix C lists a 

number of cases where measurement issues associated with the volumetric airflow measurements 

were identified, along with any adjustments that were made to account for these issues. The 

measurements are presented in Appendix D for the air handlers and Appendix E for the study

spaces. Each measured value in these appendices is presented with an uncertainty estimate 

associated with the value. The naturally ventilated buildings are discussed in conjunction with 

the outdoor air ventilation estimated using peak CO2 concentrations in section 3.5.4. 

3.5.1 Supply Airflow 

Of the 562 measurement events, 495 included measurements of the system supply airflow. In 

some cases, the supply airflow is estimated by adding the outdoor air intake and the recirculation 

airflow, resulting in a total of 536 measured supply airflow values. As noted earlier, the 

uncertainty associated with the supply airflow measurements was estimated to equal 10 %. When 

the supply airflow is based on the sum of the outdoor and recirculation airflows, the uncertainty

in the supply airflow is about 25 %, based on a 30 % uncertainty in the outdoor airflow and 10 % 

in the recirculation flow.

The measured supply airflows are compared with the design supply capacities in the 512 cases 

where a design value exists. The mean value of the ratio of the measured supply airflow to the 

design value is 0.83. The mean is 0.72 for the VAV systems and 1.07 for the CV systems. The 

VAV systems are expected to have a lower ratio of measured to design, since these systems 

modulate the supply airflow in response to internal loads. Figure 6 is a plot of the measured to 

design ratio against outdoor temperature. Note that for the VAV systems, the ratio decreases for 

outdoor temperatures below about 15 °C (59 °F), presumably due to the lower cooling loads at 

these temperatures. The CV data points exhibit little dependence on outdoor temperature. Four 

CV points have a ratio of about 4.5, which all correspond to the single air handler serving study

space CAJS03. This air handler has the lowest design value of supply airflow capacity per unit 

floor area, and it is possible that the design value is in error or out of date. The mean ratio of 

measured to design for CV systems is reduced from 1.07 to 0.98 without these four values.

The supply airflows for the air handlers were combined to determine the supply airflow to each 

study space. These supply airflows were then divided by the study space floor area (B1AREA), 

and the results are summarized in Table 13 and plotted versus outdoor air temperature in Figure 

7. Both the table and the figure distinguish between VAV and CV systems. The values of the 

study space supply airflow per unit floor area range from 0.88 L/s•m2 (0.17 cfm/ft2) to 

21.11 L/s•m

2

 (4.15 cfm/ft2). The mean value for all the systems is 5.12 L/s•m2 (1.01 cfm/ft2); the 

mean uncertainty is 16 % of the measured value, and the maximum is 31 %. As expected, the 

VAV systems have lower supply airflows than the CV systems, and the dependence on outdoor 

temperature is similar to that seen in Figure 6. Note that the high points in Figure 7 do not 

correspond to the high points in Figure 6. The eight points in Figure 7 greater than 15 L/s•m

2

(3 cfm/ft2) correspond to cases with high design supply airflows (CAES17 and LAGW05).
19

Figure 6 Ratio of measured to design supply airflow versus outdoor temperature

Supply airflow/Floor area

L/s•m

2 (cfm/ft2

)

All systems VAV CV

# of values 384 289 95

Mean 5.12 (1.01) 4.55 (0.90) 6.86 (1.35)

Std. Dev. 3.02 (0.59) 2.62 (0.52) 3.46 (0.68)

Minimum 0.88 (0.17) 0.88 (0.17) 1.80 (0.35)

10thpercentile 2.16 (0.43) 2.12 (0.42) 2.25 (0.44)

25thpercentile 2.99 (0.59) 2.89 (0.57) 4.82 (0.95)

Median 4.69 (0.92) 4.30 (0.85) 5.72 (1.13)

75thpercentile 6.25 (1.23) 5.69 (1.12) 9.04 (1.78)

90thpercentile 8.47 (1.67) 7.19 (1.41) 11.34 (2.23)

Maximum 21.11 (4.15) 21.11 (4.15) 16.24 (3.20)

Table 13 Summary of measured supply airflows

0

1

2

3

4

5

-20 -10 0 10 20 30 40

0 20 40 60 80 100

VAV

CV

Measured supply airflow/Design supply airflow

Outdoor temperature (°F)

Outdoor temperature (°C)
20

Figure 7 Measured study space supply airflow versus outdoor temperature

3.5.2 Outdoor Air Fraction

The outdoor air fraction (i.e., the outdoor air intake divided by the supply airflow) was 

determined in two ways, dividing the measured outdoor airflow by the measured supply airflow 

and second through the measurement of CO2 concentrations in the outdoor, supply and 

recirculation airstreams. The former determination is referred to as the volumetric value, while 

the latter is referred to as the CO2 ratio value. The volumetric outdoor air fraction was 

determined for each air handler test based on whichever of the expressions in Equations (1a), 

(1b) and (1c), described in section 2.2, apply. For some air handlers, the value of Fo could be 

determined using more than one of the expressions. Of the 562 air handler test events, there were 

350 values of Fo based on QO divided by QS (Equation 1a), 125 based on (QS minus QR) divided 

by QS (Equation 1b) and 57 based on QO divided by (QO plus QR) (Equation 1c). As noted 

earlier, in some cases when Equation (1b) was applied, the value of QR was greater than QS, but 

the difference was never significantly different from zero. In those cases, the outdoor airflow and 

outdoor air fraction are both set equal to zero. For each determination of the outdoor air fraction, 

the uncertainty is calculated based on the uncertainties in QO, QS and QR. When Fo can be 

determined using more than one of these expressions, the value of Fo with the lowest uncertainty

is identified and referred to as the best volumetric value of Fo. The outdoor air fraction was also 

determined using CO2 concentrations measured in the outdoor, supply and recirculation 

airstreams using Equation (2).

Table 14 summarizes the measured outdoor air fractions for both the volumetric and CO2

methods. Some of the volumetric values are greater than 100 %, which does not make physical 

sense. However, in all of these cases but one, the uncertainty around the value includes 100 % 

outdoor air. That single value is not included in Table 14 or the subsequent analysis, but it is 

included in Appendix D. The mean volumetric outdoor air fraction is 0.38, and the mean CO2
21

value is 0.31. The mean uncertainty in the volumetric outdoor air fraction is 0.16, while the 

maximum uncertainty is 0.44. The uncertainties in the CO2-based values tend to be larger, with a 

mean uncertainty of 0.60 (roughly twice the mean outdoor air fraction) and several values as 

high as 2 to 4 in units of outdoor air fraction.

Best volumetric Carbon dioxide

# of values 509 520

Mean 0.38 0.31

Standard deviation 0.35 0.27

Minimum 0.00 0.00

10thpercentile 0.04 0.03

25thpercentile 0.10 0.11

Median 0.22 0.23

75thpercentile 0.59 0.44

90thpercentile 1.00 0.75

Maximum 1.52 1.20

Table 14 Summary of measured outdoor air fraction

Figure 8 is a plot of the outdoor air fraction against outdoor air temperature, with systems having 

economizer cycles distinguished from those that do not. Note that most of the low outdoor air 

intake values, i.e., outdoor air fractions below about 0.25, correspond to temperatures greater 

than 20 °C (68 °F). As expected, systems with economizer cycles tend to have higher outdoor air 

fractions at milder temperatures than systems without economizers; the non-economizer systems 

also tend to operate more consistently at lower outdoor air fractions. However, there are some 

exceptions to this general dependence, which could be due to a variety of causes such as the 

temperature and humidity sensors used to control the economizers being out of calibration. The 

dependence of outdoor air fraction on outdoor temperature leads one to expect that minimum 

outdoor air intake conditions are more likely to exist at these warmer temperatures than under 

colder conditions, which has implications for planning field evaluations of ventilation system 

performance.

Figure 9 is a plot of the outdoor air fraction against outdoor temperature for an idealized 

economizer cycle. It shows that such a system operates at minimum outdoor air at cold and hot 

temperatures, less than 0 °C (32 °F) and greater than 20 °C (68 °F), though these particular 

values are only examples. In between these two temperatures, the system uses outdoor air to cool 

the building, with a lower outdoor air fraction as the temperature gets colder. Figure 10 is a plot 

of whole building air change rates measured with the tracer gas decay method plotted against 

outdoor air temperature from a previous study (Persily et al. 1992). These data clearly exhibit the 

pattern seen in Figure 9. While the data in Figure 8 suggest the same pattern and are consistent 

with expected variations due to economizer operation, note that the actual data include typically

four points for each building generally over a narrow temperature range and not all the buildings 

have economizer cycles. 
22

0.0

0.2

0.4

0.6

0.8

1.0

1.2

-20 -10 0 10 20 30 40

0 20 40 60 80 100

Outdoor air fraction

Outdoor temperature (°F)

Outdoor temperature (°C)

Figure 8 Volumetric outdoor air fraction versus outdoor temperature

Figure 9 Outdoor air fraction for an idealized economizer cycle

0.00

0.25

0.50

0.75

1.00

1.25

1.50

-20 -10 0 10 20 30 40

0 20 40 60 80 100

Economizer cycle

No economizer cycle

Outdoor temperature (°F)

Outdoor temperature (°C)

Outdoor air fraction - volumetric
23

 Figure 10 Measured air change rates versus outdoor air temperature (Persily et al. 1992)

As noted earlier, the uncertainties in the CO2-based outdoor air fractions tend to be larger than 

the uncertainties in the volumetric values. The CO2 uncertainties are based on the concentration 

measurement uncertainty of 90 mg/m3 (50 ppm(v)). The larger uncertainties in the CO2 values 

occur due to the magnitude of the concentration measurement uncertainty relative to the 

concentration differences in Equation 2. The difference between CR and CO, relative to the 

concentration measurement uncertainty, is the primary determinant of the uncertainty in Fo. 

Figure 11 is a plot of the CO2 concentration difference between the recirculation and outdoor 

airstream versus time of day at which the concentration measurements began. The average 

concentration difference is 391 mg/m3 (217 ppm(v)), with a mean difference for measurements 

before noon of 418 mg/m3 (232 ppm(v)) and an afternoon mean of 369 mg/m3 (205 ppm(v)). 

Given that the concentration measurement uncertainty of 90 mg/m3 (50 ppm(v)) is equal to 25 % 

of the mean concentration difference, it is not surprising that the values of Fo based on CO2 are 

so imprecise.

In making these measurements, the same CO2 monitor was used to measure the concentration in 

the three airstreams over a relatively short period of time. Therefore, it is reasonable to expect 

that the uncertainty is lower for the differential CO2 concentrations in Equation 2 than for the 

absolute concentrations. The uncertainties in the CO2 outdoor air fractions were recalculated 

using an uncertainty of 90 mg/m3 (50 ppm(v)) for the differential concentrations. The mean 

uncertainty was reduced from 0.60 to 0.42, and the median value of the uncertainty decreased 

from 0.43 to 0.31. It is not possible to estimate the actual uncertainty in the differential 

concentrations after the fact, though it is likely to be less than for the absolute concentrations. 

Nonetheless, the form of the equation used to determine Fo from CO2 concentrations makes it 

advantageous to perform the uncertainty calculations based on the uncertainty in the differential 

concentration and also implies that one can tolerate some zero drift in the CO2 monitor without a 

large degradation in accuracy.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

-20 -10 0 10 20 30 40

0 20 40 60 80 100

Air change rate (h-1)

Outdoor temperature (°F)

Outdoor temperature (°C)
24

 Figure 11 Return minus outdoor air CO2 concentration versus time of day

Figure 12 is a plot of Fo based on CO2 versus the volumetric value. This comparison shows that 

despite the high level of uncertainty in the CO2 values, they are generally consistent with those 

based on volumetric airflows. The line in the plot corresponds to perfect agreement between the 

two parameters and is not a curve fit to the data. A linear regression of the CO2 to the volumetric 

values yields a slope of 0.61 and an r-squared of 0.58.

0

100

200

300

400

500

600

700

800

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

Start Time of Measurement

CR - CO (ppm(v))

0

200

400

600

800

1000

1200

1400

CR - CO (mg/m3

)
25

 Figure 12 Outdoor air fraction based on CO2 versus volumetric

0.00

0.25

0.50

0.75

1.00

1.25

0.00 0.25 0.50 0.75 1.00 1.25

Outdoor air fraction - Volumetric

Outdoor air fraction - CO2 ratio
26

3.5.3 Outdoor Air Ventilation

Of the 562 measurement events, 510 included traverse measurements, or estimates based on the 

difference between the supply and recirculation airflow, of the system outdoor air intake. The 

measured outdoor airflows are compared with the design minimum outdoor air intakes for the 

274 cases where such a design value exists. Figure 13 is a plot of the ratio of the measured 

outdoor air intake to the design intake versus outdoor air temperature, with a distinction between 

systems with economizer cycles and those without. The mean ratio of the measured to design 

outdoor airflow is 1.93, including one case where the measured value is about 30 times larger 

than the design minimum. The mean is 2.28 for the economizer systems and 1.37 for noneconomizer systems. Economizer systems are expected to have a higher ratio of measured to 

design, since they increase the outdoor air intake for free cooling and the design value is a 

minimum. Note the existence of many points with a ratio of measured to design below 1.0, 

which would not exist if the systems were operating as intended.

Figure 13 Ratio of measured to design outdoor airflow versus outdoor temperature

As described in section 2.2, outdoor air ventilation rates in the study spaces were calculated 

based on the measurements for the individual air handlers and the percentage of air from each 

handler provided to the study space. Table 15 summarizes the measured outdoor air ventilation 

to the study spaces. The second column presents these values on a per person basis using the 

actual number of occupants during each measurement. The mean value is 49 L/s (105 cfm) per 

person, which is high relative to the 10 L/s (20 cfm) per person value specified in many current 

building codes (based on ASHRAE Standard 62-2001). The mean uncertainty in the per person 

rates is about 40 % of the mean value. Of these per person values, 17 % are below 10 L/s (20 

cfm) per person and 9 % are below 5 L/s (10 cfm). Per person rates below 10 L/s (20 cfm) were 

seen in 22 of the 97 mechanically ventilated buildings, while rates below 5 L/s (10 cfm) were 

seen in 13 of the buildings. The table also presents the outdoor air ventilation in L/s•m

2

 (cfm/ft2) 

0

2

4

6

8

10

-20 -10 0 10 20 30 40

0 20 40 60 80 100

Economizer cycle

No economizer cycle

Measured/design minimum outdoor air intake

Outdoor temperature (°F)

Outdoor temperature (°C)
27

of floor area and air changes per hour. There are two less cases of ventilation per person because 

of two events without measured values of occupancy.

Per person

L/s (cfm) per person

Per unit floor area

L/s•m

2 (cfm/ft2

)

Air changes per

hour, h-1

# of values 367 369 369

Mean 49 (105) 1.87 (0.37) 1.83

Std. Dev. 54 (114) 2.08 (0.41) 2.07

Minimum 0 (0) 0 (0) 0.00

10thpercentile 6 (13) 0.24 (0.05) 0.22

25thpercentile 13 (27) 0.50 (0.10) 0.47

Median 30 (63) 1.03 (0.20) 0.98

75thpercentile 66 (140) 2.30 (0.45) 2.46

90thpercentile 116 (245) 4.64 (0.91) 4.46

Maximum 310 (657) 12.31 (2.42) 13.23

Table 15 Summary of Measured Outdoor Air Ventilation – Volumetric

Given the noted prevalence of minimum outdoor air intake conditions at higher outdoor air 

temperatures, the per person ventilation values were separated into those with outdoor 

temperatures below and above 20 °C (68 °F). The mean value below 20 °C (68 °F) is 60 L/s 

(126 cfm) per person, and the mean for temperatures greater than or equal to that value is 38 L/s 

(81 cfm) per person.

The per person outdoor air rates were also analyzed to identify those for which the outdoor air 

fraction was below 20 %, presuming that those values correspond to operation under minimum 

outdoor air intake. Of the 367 values of outdoor air per person, 148 correspond to less than 20 % 

outdoor air. (These minimum conditions are seen in 42 of the 97 mechanically ventilated 

buildings.) The mean of these values is 13.7 L/s (28.9 cfm) per person based on the measured 

number of occupants, and the median is 11.7 L/s (24.7 cfm). Normalizing these minimum 

outdoor airflows by the number of workstations, rather than the measured number of occupants, 

yields a mean of 10.5 L/s (22.2 cfm) per person and a median of 9.4 L/s (20.0 cfm). Of these 148 

values corresponding to minimum outdoor air, 41 % are below the per person requirement in 

Standard 62-2001 based on the measured number of occupants and 50 % are below that 

requirement based on the number of workstations. In other words, under minimum outdoor air 

intake, about one-half of the measured outdoor air intake rates are below the requirements in 

ASHRAE Standard 62-2001 based on the expected occupancy levels in the space. Similarly, 

about 20 % of these minimum values are below 5 L/s (10 cfm) per measured occupant and about 

25 % are below 5 L/s (10 cfm) per workstation.

Outdoor air ventilation was also determined from the CO2-based outdoor air fraction multiplied 

by the measured supply airflow. The values for the air handlers are then combined to determine 

the outdoor airflow per person for the study spaces, and the results are summarized in Table 16. 

Due to the large uncertainties in the CO2 outdoor air fraction, the mean uncertainty in the study

space outdoor airflow is also quite large, 85 L/s (179 cfm) per person. Nevertheless, the mean 

values of the volumetric and CO2-ratio outdoor ventilation airflow per person are remarkably

similar, 49 L/s (105 cfm) and 44 L/s (94 cfm) respectively. Figure 14 is a plot of the CO2-ratio 

ventilation to the volumetric values. While there is significant scatter about the line of perfect 

agreement, and a tendency for the CO2-ratio values to be lower at the highest per person 
28

ventilation, the two determinations are consistent on average. A linear regression of CO2-ratio to 

the volumetric ventilation yields a slope of 0.80 and an r-squared of 0.64. 

Outdoor air per person,

L/s (cfm)

# of values 356

Mean 44 (94)

Std. Dev. 47 (101)

Minimum 0 (0)

10thpercentile 5 (11)

25thpercentile 12 (26)

Median 31 (65)

75thpercentile 59 (125)

90thpercentile 96 (203)

Maximum 339 (717)

Table 16 Summary of Measured Outdoor Air Ventilation – CO2 Ratio

Figure 14 Outdoor air ventilation, CO2-ratio versus volumetric

As noted, the measured per person outdoor air ventilation values are high relative to the outdoor 

air requirement in ASHRAE Standard 62-2001. These values are higher than might be expected 

for two primary reasons; the occupant density is below design and the outdoor air fraction is 

frequently not at minimum, generally due to economizer operation. As noted earlier, the mean 

measured occupant density is about 3.5 persons per 100 m2 (3.2 per 1000 ft2), corresponding to 

about 80 % of the number of workstations and about half of the default occupant density in 

Standard 62-2001. In addition, the mean outdoor air fraction is about 0.40. If each outdoor air 
29

measurement is adjusted to the design occupant density (number of workstations) and to 

minimum outdoor air intake, then the per person ventilation values are more consistent with 

expectations. Table 17 presents these adjustments, with the measured outdoor air ventilation per 

person from Table 15 in the second column. The next column presents the outdoor air ventilation 

normalized by the number of workstations in the space rather than the measured occupancy, 

which reduces the mean ventilation rate to 36 L/s (76 cfm) per person. In the last two columns, 

the values are adjusted to an outdoor air fraction of 0.15. This adjustment involves dividing the 

outdoor air ventilation rate by the actual outdoor air fraction and then multiplying the result by

0.15, unless the actual fraction is already 0.15 or less. In the latter cases, the ventilation rate is 

not adjusted. The 15 % value is used as a typical value of the minimum outdoor air fraction. 

(Note from Table 6 that the mean value of the design minimum outdoor air fraction was 19 %, 

and the median was 12 %.) The values in the fourth column are based on the number of 

workstations in the study space, while the values in the last column use the default occupant 

density for office space in Standard 62-2001, i.e., 7 people per 100 m2 (1000 ft2). As discussed 

earlier, the design value for occupant density is not available for the study spaces. However, if 

one uses the default value in Standard 62-2001 for office space, as in the last column of Table 

17, the mean per person ventilation rate are very close to the requirement in the standard.

Adjusted to 15 % outdoor air

Measured

(Table 15)

Adjusted to #

of workstations

# of workstations

Standard 62 default

occupant density

L/s (cfm) per person

Mean 49 (105) 36 (76) 12 (26) 8 (18)

Std. Dev. 54 (114) 37 (79) 8 (17) 6 (13)

Minimum 0 (0) 0 (0) 0 (0) 0 (0)

10thpercentile 6 (13) 5 (10) 4 (9) 3 (5)

25thpercentile 13 (27) 10 (22) 7 (14) 5 (10)

Median 30 (63) 21 (45) 11 (23) 7 (15)

75thpercentile 66 (140) 52 (110) 16 (34) 11 (23)

90thpercentile 116 (245) 87 (184) 21 (44) 16 (34)

Maximum 310 (657) 210 (444) 47 (100) 42 (89)

Table 17 Outdoor air ventilation adjusted for occupancy and outdoor air fraction

3.5.4 Outdoor Airflows from Peak Carbon Dioxide

Indoor carbon dioxide concentrations were also used to estimate outdoor air ventilation, using a 

steady-state, single-zone mass balance analysis to relate the indoor CO2 concentration to the per 

person outdoor air ventilation as discussed in Section 2.2. As noted, a critical assumption behind 

the approach is that the indoor CO2 concentration is indeed at steady state. It is also assumes 

constant outdoor concentration, ventilation and occupancy, as well as a uniform indoor CO2

concentration. Note that this approach provides the only means to estimate the outdoor air 

ventilation in the three naturally ventilated buildings.

As described earlier, peak CO2 concentrations were used to estimate outdoor ventilation per 

person for all 100 study spaces. These estimates are based on averaging the CO2 concentrations 

among the fixed monitors in each space on a 10 min basis, and then identifying the maximum 

value of this average for the morning and afternoon of each day. The per person ventilation rates 

based on these estimates are summarized in Table 18. The second column contains all the values 

of the per person outdoor airflow determined from the peak CO2 data. The third column contains 
30

only those values obtained on the “test days,” i.e., those days (typically Wednesday and 

Thursday of the study week) during which the other ventilation measurements were made. The 

last column reproduces the summary statistics for the volumetric measurements from Table 15. 

The mean uncertainty in the peak CO2 ventilation rates is 10 L/s (22 cfm) per person, which is 

about one-half the mean uncertainty for the volumetric rates. Also, note that the peak CO2 values 

are significantly lower than those obtained from the volumetric measurements. This trend is 

contrary to what one might expect, as the outdoor airflows determined using the peak CO2

method include both ventilation system outdoor air intake and outdoor air infiltration due to 

envelope leakage, while the volumetric results include only the former. Figure 15 is a plot of the 

per person outdoor air ventilation determined from the peak CO2 concentrations versus the 

corresponding volumetric values. The solid line corresponds to perfect agreement. Note that 

above roughly 25 L/s (50 cfm) per person, almost all of the CO2-based values are lower than the 

volumetric airflows.

Outdoor air ventilation, L/s (cfm) per person

All peak CO2 data

Peak CO2 data on

“test days”

Volumetric results

from Table 15

# of values 548 353 367

Mean 20 (43) 21 (45) 49 (105)

Std. Dev. 14 (31) 17 (35) 54 (114)

Minimum 6 (13) 6 (13) 0 (0)

10thpercentile 10 (20) 10 (21) 6 (13)

25thpercentile 12 (26) 13 (27) 13 (27)

Median 18 (37) 18 (38) 30 (63)

75thpercentile 24 (50) 25 (53) 66 (140)

90thpercentile 32 (68) 33 (71) 116 (245)

Maximum 213 (452) 213 (452) 310 (657)

Table 18 Summary of Measured Outdoor Air Ventilation – Peak CO2

The reason that the peak CO2 values tend to be lower than expected has been investigated, but no 

explanation has yet been verified. Considering the methodology behind the peak CO2 analysis, 

one might suspect the lack of steady-state CO2 concentrations could be impacting the agreement 

between the two values. However, steady state is more likely to occur at the higher ventilation 

rates due to the shorter system time constants, resulting in better agreement at higher rates, which 

is contrary to what is seen in Figure 15. Another potential explanation is the existence of 

significant CO2 concentration gradients within the study spaces, as well as between them and 

adjoining spaces, given that the single-zone analysis method assumes a uniform concentration 

within the zone and neglects interzone transfer of CO2. While it is certainly possible that the CO2

concentrations were different in adjoining zones, one would expect the impact to be positive in 

some cases and negative in others. However, the differences in the data tend to all be in one 

direction. The level of agreement was examined in those study spaces that corresponded to an 

entire building, for which concentration differences in adjoining spaces are not an issue, and the 

peak CO2 and volumetric ventilation rates were not observed to agree any better. Note that the 

fixed CO2 monitors in the study spaces were placed at a height of 1.1 m (43 in.) above the floor 

and at locations representative of workstation layout and work activities, i.e., locations in 

hallways and passageways were intentionally avoided (EPA 2003). Given these guidelines on 

location, it is possible that the measured CO2 concentrations are higher than the study-space 
31

average. If the measured CO2 concentration is indeed higher than the true space average, then the 

calculated ventilation rates would be low relative to their actual value. Also, it is reasonable to 

expect that the lack of uniformity would be more pronounced at higher outdoor air ventilation 

with less recirculation of return air, leading to the observed increase in errors. However, it is not 

possible to verify the magnitude of the concentration nonuniformity in these spaces based on the 

available data, and therefore it cannot be confirmed whether this is necessarily a valid 

explanation for the observed differences. The peak CO2 concentrations were examined with the 

issue of nonuniformity in mind, and it was determined that the actual average concentration in 

the study space would have to be 360 mg/m3 to 720 mg/m3 (200 ppm(v) to 400 ppm(v)) lower 

than that measured by the fixed monitors to explain the observed differences. 

Figure 15 Outdoor air ventilation, CO2 peak versus volumetric

The peak CO2 analysis provides the only means for estimating ventilation rates in the three 

naturally ventilated buildings. Table 19 presents the estimated outdoor air ventilation rates for 

each of the three study spaces for each time period it was estimated, generally once in the 

morning and once in the afternoon. These values are presented first as per person values, based 

only on the difference between the peak CO2 concentration and the outdoor concentration, along 

with an estimate of the uncertainty in each value. The last column presents these values in air 

changes per hour, based on the study space volume and the measured occupancy. The first study

space, NYBS06, has high per person ventilation rates, especially in units of air changes per hour, 

but also high uncertainties. Since high ventilation values correspond to low differences between 

the peak CO2 concentration and the outdoor concentration, higher uncertainties always exist at 

higher ventilation rates. It is not clear why the ventilation rates in this building are so high, but it 

does have operable windows, 50 % of which were reported to be open during the measurements. 

In addition, the building has toilet exhausts with design flow rates per floor area on the high end 

of the buildings. However, the measured exhaust flows during the test week were zero. The 
32

afternoon reading on the third day for NYBS06 has a much lower ventilation rate than the other 

times. There were no outdoor concentration readings available for building ORIS02, and a value 

of 670 mg/m3 (373 ppm(v)) was assumed. While peak CO2 analysis allows the estimation of 

ventilation in the naturally ventilated buildings, the comparison with the volumetric values in the 

mechanically ventilated buildings does raise questions regarding their validity.

Study

space Date Time of day

Outdoor air

ventilation

per person

Uncertainty

in outdoor air

per person

Outdoor air

ventilation

Uncertainty in

outdoor air

ventilation

AM or PM L/s (cfm) h-1

NYBS06 6/16/98 AM 40.3 (85.4) 17.8 (38.0) 33.4 16.3

6/16/98 PM 27.8 (58.9) 8.8 (18.6) 28.5 12.4

6/17/98 AM 42.6 (90.2) 20.0 (42.3) 40.2 20.9

6/17/98 PM 33.3 (70.6) 12.4 (26.3) 40.3 18.1

6/18/98 AM 44.2 (93.6) 21.5 (45.5) 46.1 22.9

6/18/98 PM 19.6 (41.5) 4.6 (9.7) 7.8 4.5

ORIS02 8/30/94 AM 26.1 (55.4) 8.0 (17.0) 0.5 0.2

8/30/94 PM 25.9 (54.9) 7.9 (16.7) 0.4 0.2

8/31/94 AM 29.5 (62.5) 10.1 (21.4) 0.5 0.2

8/31/94 PM 28.0 (59.3) 9.2 (19.4) 0.6 0.3

9/1/94 AM 45.2 (95.7) 23.1 (49.0) 1.0 0.5

9/1/94 PM 28.3 (60.0) 9.4 (19.8) 0.5 0.2

WAIW01 2/25/97 AM 8.4 (17.9) 1.2 (2.5) 0.5 0.1

2/25/97 PM 7.4 (15.7) 1.0 (2.0) 0.4 0.1

2/26/97 AM 12.6 (26.8) 2.2 (4.6) 0.4 0.1

2/26/97 PM 7.4 (15.6) 1.0 (2.0) 0.4 0.1

2/27/97 AM 8.8 (18.7) 1.2 (2.6) 0.5 0.1

Table 19 Outdoor air ventilation for naturally ventilated spaces
33

3.5.5 Supply Diffuser Airflows

The BASE protocol calls for airflow to be measured at the individual supply diffusers serving the 

study space one time during the test week. Diffuser measurements were made in 88 of the 97 

mechanically ventilated buildings, and Table 20 presents the results of those measurements. The 

second column contains the number of diffusers in these 88 study spaces, while the third column 

summarizes the fraction of those diffusers for which the supply airflow was measured. The total 

supply airflow, normalized by study space floor area, is presented in the fourth column. This 

value is adjusted to account for less than 100 % of the diffusers being measured by assuming the 

supply airflow per diffuser at the unmeasured diffusers is the same as at the mean of the 

measured value. The last column is the total (adjusted) supply airflow in the fourth column 

divided by the supply airflow determined at the air handlers, as discussed in section 3.3.1. On 

average, the total supply airflow at the diffusers is only 73 % of the value measured at the air 

handlers. This lack of agreement is a function of the large measurement uncertainties in both 

values, plus the possibility of supply duct leakage. However, the existence and magnitude of 

such leakage was not assessed as part of this study, and these data do not serve as a reliable 

measure of duct leakage.

# of

diffusers

Fraction of

diffusers

measured

Total diffuser

flow, adjusted

L/s•m

2 (cfm/ft2

)

Total diffuser flow/

Study space supply

airflow at air handlers

Mean 93 0.94 3.40 (0.67) 0.73

Std. Dev. 42 0.09 1.66 (0.33) 0.36

Minimum 13 0.57 0.30 (0.06) 0.16

10thpercentile 39 0.86 1.31 (0.26) 0.36

25thpercentile 71 0.91 2.28 (0.45) 0.48

Median 93 0.97 3.27 (0.64) 0.67

75thpercentile 107 1.00 4.23 (0.83) 0.83

90thpercentile 146 1.00 5.25 (1.03) 1.22

Maximum 258 1.00 9.66 (1.90) 1.96

Table 20 Summary of measured supply airflows at diffusers

3.5.6 Exhaust Airflows

Airflows for the exhaust fans serving each study space were measured one time during the test 

week. Measured airflows were obtained for 56 of the 159 exhaust fans serving the study spaces. 

Of these values, design airflows are only available for 41 of the fans. Neglecting the seven cases 

where the measured exhaust airflow is zero, the average ratio of the measured exhaust airflow to 

the design value is 0.57. The median value is 0.47 and the standard deviation is 0.34; the 10 and 

90 percentile values are 0.21 and 0.99 respectively.
34

4. DISCUSSION

4.1 Summary of Results 

The ventilation-related information collected as part of the BASE study provides a unique 

characterization of ventilation system design and performance in U.S. office buildings. No such 

database of randomly selected office buildings existed prior to this effort, making the results of 

the survey that much more significant. While the office buildings studied tend to be larger and 

with higher occupancy than the average U.S. office building, the results obtained are quite 

revealing. In terms of design, the data show the relative prevalence of different system types and 

different approaches to outdoor air control, as described in Tables 4 and 5. Of the 141 ventilation

systems considered, 50 are constant volume and the rest are VAV. In almost 75 % of the study

spaces the systems employ economizer control to provide “free cooling” when the outdoor 

weather is appropriate. Twenty-one of the spaces have dedicated outdoor air fans, and five have 

100 % outdoor air systems.

As expected based on thermal load considerations, but never previously verified, the average 

value of the supply air capacity is about 5 L/s•m2 (1 cfm/ft2). Other system design parameters of 

interest have the following mean values: ratio of supply airflow capacity to return airflow 

capacity, 1.14; design minimum outdoor air per person (workstation), 18 L/s (39 cfm); and, ratio 

of design minimum outdoor air intake to supply air capacity, 19 %. The per person design 

minimum outdoor air intake, based on the number of workstations, is significantly higher than 

the requirement in ASHRAE Standard 62-2001 of 10 L/s (20 cfm) per person. However, if the 

per person design value is instead calculated using the default occupant density in the ASHRAE 

standard, the mean value of the minimum outdoor air intake per person is 13 L/s (26 cfm) and 

the median is roughly 9 L/s (17 cfm). However, as noted, the design occupancy used to 

determine the design minimum outdoor air intake is not available for the systems studied.

The BASE study also provides valuable information on occupant density in office buildings. The 

mean number of workstations per 100 m2 (1000 ft2) is about 5, as compared with the default 

value in Standard 62-2001 of 7. However, the recent revision of that standard via addendum n 

(ASHRAE 2003) reduces the default value to 5, which appears to be a reasonable change given 

the results of this study. The measured occupant density in the spaces is lower still, with a mean 

value of 4.0 people/100 m2 (3.7 people /1000 ft2), corresponding to about 80 % of the 

workstations being occupied.

The ventilation measurements indicate how the systems operate relative to their design and also 

provide performance parameters that can be used to analyze other data collected in the BASE 

study, for example contaminant concentrations and prevalence of occupant symptoms. The mean 

measured supply airflow for the 97 mechanically ventilated study spaces is very close to the 

mean design value, i.e., 5 L/s•m

2

 (1 cfm/ft2). As might be expected, these supply values are 

relatively independent of outdoor air temperature for the constant volume systems but tend to 

increase for warmer temperatures in the VAV systems. The measured outdoor air fraction, i.e., 

the ratio of the outdoor air intake to the supply airflow, has a mean value of about 0.40. For 

buildings with economizer controls, the outdoor air fraction tends to be lowest for warmer 

temperatures and increases at milder temperatures. However, with only 4 measurements per 

system, generally under similar weather conditions, the noted dependence mixes the results for 

many buildings, and the temperature dependence cannot be examined in detail for any single 

building. Outdoor air ventilation rates tend to be higher than might be expected, with a mean 

value of 49 L/s (105 cfm) per person based on the number of occupants and 36 L/s (76 cfm) per 

person based on the number of workstations in the space. Still, seventeen percent of these 
35

measured values (per occupant) are below the 10 L/s (20 cfm) per person requirement in 

ASHRAE Standard 62-2001, and these lower rates occur in 22 of the 97 mechanically ventilated 

buildings. While these values are high on average relative to the minimum outdoor air 

requirements in Standard 62, the high outdoor air fractions and the low occupancy relative to the 

actual number of workstations (and to the default occupancy value in the standard) explains most 

of the higher values. Adjusting the measured outdoor air ventilation rates to minimum outdoor 

air conditions and to the occupant density in Standard 62 reduces the mean to 9 L/s (19 cfm) per 

person. Considering only those values that correspond to minimum outdoor air intake, the mean 

ventilation rate is 14 L/s (29 cfm) per person. Adjusting these minimum values for the number of 

workstations rather than the measured occupancy levels yields a mean of 11 L/s (22 cfm) per 

person, with one-half of these minimum values being below the requirement in ASHRAE 

Standard 62-2001. In other words, under minimum outdoor air intake, about one-half of the 

measured outdoor air intake rates are below the requirements in ASHRAE Standard 62-2001 

based on the expected occupant levels in the space, and about one-quarter of the rates are below 

5 L/s (10 cfm) per person, i.e., one-half of the ASHRAE requirement.

The outdoor air ventilation rates calculated from the CO2-based outdoor air fraction (determined 

from airstream CO2 concentrations) multiplied by the volumetric supply airflow rate are 

generally consistent with the outdoor air rates from volumetric airflow measurements in the air 

handlers. However, the CO2 ratio ventilation rates have much larger uncertainties due to the 

larger uncertainties in the CO2-based outdoor air fractions. Outdoor air ventilation rates 

determined from steady-state analysis of peak CO2 concentrations in the space are consistently

lower than the volumetric outdoor air rates. A number of explanations have been explored, but 

the reason for this discrepancy has not been identified. Therefore, questions exist as to the 

reliability of the peak- CO2 ventilation rates.

4.2 Comparison with European Audit Project 

During the time of the BASE study, a similar research effort was conducted in Europe. The 

European Audit Project involved measurements of building characteristics, environmental 

conditions and ventilation performance, as well as the administration of occupant questionnaires, 

in 56 buildings in eleven European countries (Bluyssen et al. 1995 and 1996). Ventilation 

performance was measured in nine of the countries using a range of different techniques, e.g., 

tracer gas decay in a single room, constant concentration tracer gas, and subtraction of exhaust 

from supply airflows determined using velocity traverses. The final report (Bluyssen et al., 1995) 

contains one value of supply airflow, infiltration and outdoor airflow per unit floor area for each 

building in which they were measured. The results are also presented in the form of cumulative 

frequency distributions for outdoor and supply airflow in units of L/s-m

2

 and air changes per 

hour. The median value of the supply airflow is roughly 2.2 L/s- m

2

 (0.43 cfm/ft2), which is 

about one-half of the median for the BASE buildings. The median outdoor airflow in the 

European Audit buildings is about 1.7 L/s- m

2

 (0.33 cfm/ft2), which is somewhat higher than the 

median for the BASE buildings of 1.1 L/s- m

2

 (0.22 cfm/ft2). In units of air changes per hour, the 

medians are roughly 2.1 h-1 and 1.0 h-1 for the European and BASE buildings respectively. Given 

the uniqueness of these two datasets, a more detailed comparison of the ventilation results would 

be worth pursuing. 
36

4.3 Recommendations for Ventilation Assessment 

In addition to analyzing the ventilation-related data collected as part of the BASE study, another 

objective of this effort was to examine the procedures used to collect these data and recommend 

changes to the protocol for potential consideration in future studies. In terms of the design 

information, it would have been helpful to collect sufficient design data to perform an airflow 

balance on each building and each study space. The existing protocol includes the collection of 

design specifications for only the supply, return and exhaust fans that serve the study space. 

These data only allow the calculation of the net design airflow into and out of the building when 

the study space is a whole building. It would have been desirable to collect design data for all 

fans serving the building, including supply and return fan capacities, minimum outdoor air 

values, and exhaust fan capacities. Given the interest in net airflow balances for whole buildings, 

particularly in the context of infiltration and moisture control, such data would be of great 

interest.

The determination of the outdoor air fraction from CO2 concentrations in the supply, return and 

outdoor airstreams was associated with large measurement uncertainties due to the uncertainty in 

the concentration measurement itself and the low concentration differentials that exist under 

some conditions. These large uncertainties limited the usefulness of multiplying these outdoor air 

fractions by system supply airflows as a means of determining outdoor air intake. Nevertheless, 

this approach still has value based on the relative simplicity of measuring CO2 concentrations 

and on the fact that some outdoor air intakes are configured such that a velocity traverse is 

impractical. The CO2 approach to determining outdoor air fraction could be improved by using a 

more accurate concentration monitor, employing the uncertainty in the differential concentration 

rather than absolute concentration (when a single monitor is used), and making the concentration 

measurements after the indoor concentration has increased to the maximum degree expected 

based on the occupancy schedule. Despite these large uncertainties, the outdoor air fractions 

determined from CO2 concentrations agree on average with the volumetric outdoor air fractions.

Outdoor air ventilation measurements are performed for a number of reasons, but often to 

determine the minimum outdoor airflow for a system. Based on the measurements in this study, 

it is evident that one is more likely to encounter conditions of minimum intake at warmer 

outdoor air temperatures, perhaps 25 °C (77 °F) and above. Minimum intake is less likely to be 

encountered at colder temperatures based on the data presented here. Since the dependence of 

outdoor air fraction on temperature is building specific, it is important to obtain a sense of this 

dependency when studying a building if one aims to determine outdoor airflow under conditions 

of minimum intake.

Outdoor air ventilation was also estimated based on peak CO2 concentrations, using a singlezone steady-state mass balance analysis of each study space. The values determined tended to be 

lower than those based on volumetric airflow measurements at the air handlers, and the reason 

for this difference is not evident. In fact, one would expect these values to be higher since they

include envelope infiltration in addition to outdoor air intake. One potential explanation is that 

the concentrations measured in the space were elevated due to the influence of high CO2 levels 

from occupant exhalations. The CO2 data collected in the BASE study should be examined 

further to understand this discrepancy and potentially determine ways to improve this approach 

to estimate building ventilation. In addition, the reliability of the estimates of the generation rates 

of CO2 from occupants and of the occupant activity or met levels used in making these estimates 

merits evaluation if this approach is going to be more widely used. Current guidance on 

estimating ventilation rates based on peak CO2 levels (ASTM 1998) may then need to be updated 

based on the results of this evaluation.
37

In addition to these potential modifications of the BASE protocol, there are other ventilation 

performance parameters of interest that could be added to such evaluations. One such addition is 

the determination of envelope airtightness using fan pressurization testing. The importance of 

building leakage on energy consumption and indoor air quality has been discussed elsewhere and 

the available airtightness data is quite limited (Persily 1998). In addition, building survey

protocols could also be extended to include tracer gas measurements of infiltration rates, both 

with the ventilation systems on and off. These rates are again of interest due to their influence on 

energy and indoor air quality, and the number of office buildings in which they have been 

measured is indeed small.

The challenges in making reliable measurements of outdoor air intake rates is evident from this 

study. Some of the problems include limited access to system components, ductwork 

configurations that do not provide appropriate traverse planes, and accuracy limitations inherent 

in duct traverses. Alternative approaches to determining outdoor air intake at air handlers are 

being investigated and ideally will be more reliable and convenient for field application. One 

challenge in this respect is the lack of a primary standard for use in evaluating the accuracy of 

these various approaches.

Finally, the BASE ventilation assessment has provided a unique dataset for U.S. office buildings, 

but the study was focused intentionally on larger buildings. As noted in the discussion of the 

CBECS data, most U.S. office buildings are much smaller than those included in the BASE 

study. Based on both indoor air quality and energy considerations, there is a need to conduct a 

similar study in smaller office buildings. In addition to the obvious difference of size, smaller 

buildings tend to different system types that larger buildings and different approaches to design 

and operation.

5. ACKNOWLEDGEMENTS

This effort was supported by the U.S. Environmental Protection Agency under Interagency

Agreement No. DW-13-93936601-0. The authors express their appreciation to Gregory Brunner, 

Laureen Burton, John Girman, Robert Thompson and Susan Womble at EPA and Steven 

Emmerich and Jonathan Kruft at NIST for their support and assistance in this work. The many

useful comments of Terry Brennan and William Fisk are also acknowledged.
38

6. REFERENCES

Apte, MG, WJ Fisk and JM Daisey. 2000. Associations Between Indoor CO2 Concentrations and 

Sick Building Syndrome Symptoms in US Office Buildings: An Analysis of the 1994-1996 

BASE Study Data. Indoor Air, 10 (4): 246-257.

ASHRAE. 1999. ANSI/ASHRAE Standard 62-1999, Ventilation for Acceptable Indoor Air 

Quality. American Society of Heating, Refrigerating and Air-Conditioning Engineers.

ASHRAE. 2001a. ANSI/ASHRAE Standard 62-2001, Ventilation for Acceptable Indoor Air 

Quality. American Society of Heating, Refrigerating and Air-Conditioning Engineers.

ASHRAE. 2001b. ASHRAE Handbook of Fundamentals. American Society of Heating, 

Refrigerating, and Air Conditioning Engineers.

ASHRAE. 2003. Addendum n to ASHRAE Standard 62-2001. www.ashrae.org.

ASTM. 1998. D6245-98, Standard Guide for Using Indoor Carbon Dioxide Concentrations to 

Evaluate Indoor Air Quality and Ventilation. American Society for Testing and Materials.

Bluyssen, PM, EO Fernandes, PO Fanger, L Groes, G Clausen, CA Roulet, CA Bernhard, O 

Valbjorn. 1995. European Audit Project to Optimize Indoor Air Quality and Energy

Consumption in Office Buildings, Final Report. The Commission of the European Communities.

Bluyssen, PM, EO Fernandes, L Groes, G Clausen, PO Fanger, O Valbjorn, CA Bernhard, CA 

Roulet. 1996. European Indoor Air Quality Audit Project in 56 Office Buildings. Indoor Air 6: 

221-238.

Brightman, HS, SE Womble, EL Ronca and JR Girman. 1996. Baseline Information on Indoor 

Air Quality in Large Buildings (BASE '95). Proceedings of 7th International Conference on 

Indoor Air Quality and Climate, Nagoya, 3:1033-1038.

DOE. 1998. A Look at Commercial Buildings in 1995: Characteristics, Energy Consumption, 

and Energy Expenditures. DOE/EIA-0625(95). U.S. Department of Energy, Energy Information 

Administration.

EHE. 2000. Building Assessment Survey and Evaluation (BASE) Study Database Description 

and Variable List, Environmental Health & Engineering, Inc. Report #11868 to U.S. 

Environmental Protection Agency.

EHE. 2001a. The Evaluation of Ventilation Performance Measurements Conducted During the 

Building Assessment Survey Evaluation Study, Environmental Health & Engineering, Inc. 

Report to U.S. Environmental Protection Agency.

EHE. 2001b. Summary and Analysis Report of the BASE Study Building Selection Process, 

Environmental Health & Engineering, Inc. Report to U.S. Environmental Protection Agency.

EPA. 2003. A Standardized EPA Protocol for Characterizing Indoor Air Quality in Large Office 

Buildings. U.S. Environmental Protection Agency.

Erdmann, CA, KC Steiner and MG Apte. 2002. Indoor Carbon Dioxide Concentrations and Sick 

Building Syndrome Symptoms in the BASE Study Revisited: Analyses of the 100 Building 

Dataset. 9th International Conference on Indoor Air Quality and Climate, Monterey, 3: 443-448.

Ludwig, JF, BJ Baker and JF McCarthy. 2002. Analysis of Ventilation Rates for the BASE 

Study: Assessment of Measurement Uncertainty and Comparison with ASHRAE 62-1999. 

Proceedings of Indoor Air 2002. Volume 5: 388-393.
39

Persily, AK. 1989. Ventilation Rates in Office Buildings. Proceedings of IAQ '89 The Human 

Equation: Health and Comfort, San Diego: 128-136.

Persily, AK and WS Dols. 1991. Field Measurements of Ventilation and Ventilation 

Effectiveness in an Office/Library Building. Indoor Air 3: 229-246.

Persily, AK, WS Dols and SJ Nabinger. 1992. Environmental Evaluation of the Federal Records 

Center in Overland Missouri. National Institute of Standards and Technology, NISTIR 4883.

Persily, AK. 1997. Evaluating Building IAQ and Ventilation with Indoor Carbon Dioxide. 

ASHRAE Transactions 103(2): 193-204.

Persily, A. 1998. Myths About Building Envelopes. ASHRAE Journal 41(3): 39-47.

Womble, SE, JR Girman, EL Ronca, R Axelrad, HS Brightman and JF McCarthy. 1995. 

Developing Baseline Information on Buildings and Indoor Air Quality (BASE '94): Part I -

Study Design, Building Selection, and Building Description. Proceedings of Healthy Buildings 

'95, Milan, 3: 1305-1310.

Womble, SE, EL Ronca, JR Girman and HS Brightman. 1996. Developing Baseline Information 

on Buildings and Indoor Air Quality (BASE '95). Proceedings of ASHRAE IAQ 96. Paths to 

Better Building Environments, Baltimore: 109-117.
40

Appendix A: BASE Variables Used in Analysis

This appendix lists the variables used in the analysis presented in this report. The variable names 

referenced in the BASE protocol are as listed in the BASE Study Database Description and 

Variable List (EHE 2000) and from the initial processing of the field data by the EPA contractor.

Building Variables

EVENT: Building identifier

A1YEAR: Year built

A1YEAR2: Year of last building addition

A1AREA: Building occupied floor area

A1AREA2: Building gross floor area

A1BELOW: Building stories below grade

A1ABOVE: Building stories above grade

A1VENTIL: Building has mechanical or natural ventilation?

A1COOLIN: Building has air conditioning system, yes or no?

A1HEATIN: Building has air heating system, yes or no?

System Variables

SYSTEM: System number

C1TYPE: Central air handling and distribution system type code, A through P as described in 

Appendix B

C1RETFAN: Return fan, yes or no?

C1TS#PCT: Percent of system capacity serving the study space, by air handler #.

C5CONPOS: Dedicated outdoor air intake fan, outdoor air conditioned

C5UNPOS: Dedicated outdoor air intake fan, outdoor air unconditioned

C5UNSUC1: Outdoor air drawn into system by supply fan suction through distinct intake duct

C5UNSUC2: Outdoor air drawn directly into air handler by supply fan suction with no duct

C5CONST1: 100% outdoor air system

C5CONST2: System has temperature-based economizer

C5CONST3: System has fixed minimum outdoor air intake

C5CONST4: System has enthalpy-based economizer

C5CONST5: System controls outdoor air intake based on building pressure

C5MINOU1: Minimum outdoor air intake controlled by fixed damper

C5MINOU2: Minimum outdoor air intake controlled by airflow monitoring

C5MINOU3: Minimum outdoor air intake controlled by fan tracking

C7ARAT1: Design supply air capacity of system

C7ARAT2: Design minimum outdoor air intake for system

C7AAREA: Floor area served by system

C7AOCCU: Number of occupants served by air handler

C7ARETFA: System has a return fan?

C7ARET1: Design return air capacity

C7ARET2: Floor area served by return

Study Space Variables

EVENT: Building identifier

TSDESC: Floors and spaces constituting study space

B1AREA: Study space occupied floor area

B1AREA2: Study space gross floor area
41

B1AH#PCT: Percentage of study space air supply by air handler number #

B1CEILIN: Study space ceiling height

B1PLENUM: Study space plenum height

B1PRIV: Number of private workstations in study space

B1PART: Number of workstations in study space located in partitioned areas

B1OPEN: Number of workstations in study space located in open office areas

B1DESWS: Floor area per workstation

B1SUPPLY: Number of supply vents in the study space

B1OCC_#A and B1OCC_#B: Measured test space occupancy, with # indicating measurement 

event (Monday is 1, Tuesday is 2, ...); A indicates morning measurement and B indicates 

afternoon

Supply diffuser measurements

D3ADATE: Date of measurement

D3ARAT#: Measured supply diffuser airflow, # indicated which diffuser

Exhaust measurements

C7BAREA: Floor area served by exhaust fan

C7BRATE: Design exhaust airflow rate

C7BLOCAT; Location of exhaust fan

D2DATE: Date of measurement

D2FLOW: Measured airflow rate of exhaust fan

Weather

DATE: Date of measurement

TIME: Time of measurement

TEMP: Outdoor air temperature

Continuous carbon dioxide measurements using fixed monitors

CO2: Measured carbon dioxide concentration.

DATE: Date of measurement

EVENT: Building identifier

SITEID: Sample site identifier

TIME: Time of measurement

Variables provided with data analysis by EPA contractor

These apply to ventilation system airflow and carbon dioxide concentration measurements. 

Several are directly from the BASE variable list, but others (primarily volumetric airflow rates) 

are derived from BASE variables.

Building/study space number

Date of measurement

Period of measurement, AM or PM

Supply airflow rate, for each date and period

Outdoor airflow rate, for each date and period

Recirculation airflow rate, for each date and period

Supply air carbon dioxide concentration, for each date and period

Outdoor air carbon dioxide concentration, for each date and period

Recirculation air carbon dioxide concentration, for each date and period
42

Appendix B: System Design Information

This appendix presents the following design information for the air handlers serving the study

spaces:

System ID

System type from list below:

A Single Duct, Constant Volume, Single Zone

B Single Duct, Constant Volume, Multiple Zone Reheat

C Single Duct, Constant Volume, Multiple Zone Bypass

D Single Duct, Variable Air Volume

E Single Duct, Variable Air Volume, Reheat

F Single Duct, Variable Air Volume, Induction

G Single Duct, Variable Air Volume, Fan Powered, Constant Fan

H Single Duct, Variable Air Volume, Fan Powered, Intermittent Fan

I Single Duct, Variable Air Volume, Dual Conduit

J Dual Duct, Constant Volume

K Dual Duct, Constant Volume, Reheat

L Dual Duct, Variable Air Volume, Single Fan

M Dual Duct, Variable Air Volume, Dual Fan

N Multizone, Constant Volume

O Constant Volume, Blow- Through Bypass

P Texas Multizone, or Three-Deck Multizone

Design supply airflow capacity

Floor area served by system

Design supply airflow capacity per unit floor area

Design minimum outdoor air intake

Design minimum outdoor air intake per unit floor area

Number of occupants served by air handler

Design minimum outdoor air intake per person

Ratio of design minimum outdoor air intake to design supply airflow capacity

Occupant density per unit floor area

Design return airflow capacity

Ratio of design supply airflow capacity to design return airflow

Changes in the table relative to the original 2004 report are highlighted in yellow.
43

L/s cfm m2 ft2 L/s-m2 cfm/ft2 L/s cfm

ARFW01(01) N 5195 11006 890 9584 5.83 1.15

ARFW01(02) N 5195 11006 890 9584 5.83 1.15

ARFW02(01) E 10638 22538 3642 39201 2.92 0.57 708 1501

ARFW02(02) E 9011 19091 1529 16457 5.89 1.16 590 1251

ARFW03(01) H 4865 10306 729 7846 6.67 1.31

ARFW03(02) H 4510 9555 502 5404 8.98 1.77

AZHS02(01) E 7835 16600 1085 11680 7.22 1.42

AZHS02(02) E 7084 15009 855 9206 8.28 1.63

AZHS04(01) E 9540 20212 1731 18630 5.51 1.08

AZHS04(02) A 1606 3402 189 2033 8.50 1.67

AZHW10(01) N 9446 20012 1227 13203 7.70 1.52

AZHW10(02) N 7557 16010 317 3408 23.86 4.70

AZHW11(01) N 19364 41024 2599 27972 7.45 1.47

AZHW12(01) G 7455 15795 3732 40169 2.00 0.39 1077 2281

AZHW12(02) G 7462 15809 3202 34462 2.33 0.46 1077 2281

CAES17(01) K 11713 24814 1458 15696 8.03 1.58 1757 3722

CAEW07(01) K 17475 37022 3289 35398 5.31 1.05

CAEW001) E 38727 82048 6438 69295 6.01 1.18 8029 17010

CAJS01(01) A 2090 22499

CAJS01(02) A 711 7650

CAJS01(03) A 711 7650

CAJS02(01) J 14169 30018 1260 13561 11.24 2.21 2834 6004

CAJS03(01) B 9295 19692 8242 88721 1.13 0.22 1394 2954

CAJS21(01) K 6718 14233 924 9950 7.27 1.43 1429 3027

CAJS21(02) K 4520 9576 831 8944 5.44 1.07 4520 9576

CAJS222(01) E 8973 19011 1901 20466 4.72 0.93 1039 2201

CAJS23(01) J 8312 17610 1044 11237 7.96 1.57 945 2001

CAJW18(01) D 8218 17410 1646 17719 4.99 0.98

CAJW18(02) L 572 6154

CAJW19(01) K 16199 34320 2650 28521 6.11 1.20

CAJW20(01) F 75566 160094 13889 149499 5.44 1.07 13224 28016

CAJW24(01) E 28337 60035 3790 40800 7.47 1.47

CAJW25(01) F 14742 31233 1183 12730 12.46 2.45

CAJW26(01) F 38539 81648 7153 77000 5.39 1.06

COAS02(01) D 19248 40779 3439 37018 5.60 1.10

COAS04(01) D 47229 100059 5086 54750 9.28 1.83 4723 10006

COAS06(01) F 9134 19352 1427 15363 6.40 1.26 850 1801

FLDW07(02) N 7745 16410 2076 22350 3.73 0.73 1495 3167

FLDW08(01) H 11160 23643 1636 17608 6.82 1.34 1086 2301

FLDW10(01) H 5904 12507 1556 16750 3.79 0.75 520 1101

FLGS01(01) E 10211 21633 1878 20220 5.43 1.07 1417 3002

FLGS04(01) N 6707 14208 989 10650 6.78 1.33 708 1501

FLGS04(02) N 6707 14208 989 10650 6.78 1.33 708 1501

FLGS11(01) H 5564 11787 1486 16000 3.74 0.74 331 700

FLGS11(02) H 5564 11787 1486 16000 3.74 0.74 331 700

FLGS12(01) N 11557 24484 1033 11119 11.19 2.20 1747 3702

GADS01(01) E 10296 21813 2392 25748 4.30 0.85 1015 2151

GADS02(01) E 6990 14809 1686 18145 4.15 0.82 945 2001

GADS02(02) E 6990 14809 1686 18145 4.15 0.82 945 2001

GADS03(01) A 9583 20303 2187 23538 4.38 0.86

Design supply airflow 

capacity

Design minimum 

outdoor air intake

Floor area served 

by system

Design supply capacity 

per unit floor area System 

System ID type
44

L/s cfm m2 ft2 L/s-m2 cfm/ft 2 L/s cfm

ILBS01(01) H 1190 12805

ILBS01(02) H 967 10407

ILBS02(01) L 8501 18011 1030 11086 8.25 1.62

ILBS03(01) N 13954 29562 2240 24111 6.23 1.23

LAGW04(01) O 9918 21012 1926 20736 5.15 1.01 945 2001

LAGW04(02) O 8973 19011 2093 22527 4.29 0.84 945 2001

LAGW05(01) N 6848 14508 372 4000 18.43 3.63 666 1411

LAGW05(02) N 4534 9606 1239 13337 3.66 0.72 453 960

LAGW06(01) D 6973 14773 2091 22511 3.33 0.66 589 1248

LAGW06(02) B 1417 3002 130 1394 10.94 2.15 119 253

MABW05(01) D 8995 19056 4151 44681 2.17 0.43

MABW05(02) D 9779 20717 3819 41112 2.56 0.50

MABW06(01) E 6612 14008 1259 13548 5.25 1.03 756 1601

MABW08(01) G 15637 33129 3736 40215 4.18 0.82 3903 8269

MABW08(02) B 12001 25425 4441 47807 2.70 0.53 11992 25406

MDDS01(01) B 24309 51500 4317 46464 5.63 1.11 12360 26185

MDDS03(01) A 2125 4502 868 9342 2.45 0.48 659 1396

MDDS03(02) A 1835 3887 692 7449 2.65 0.52

MDDS04(01) D 2942 6234 606 6526 4.85 0.96 283 600

MDDS04(02) D 3396 7194 629 6765 5.40 1.06 340 720

MIBW01(01) D 3627 7684 851 9159 4.26 0.84

MIBW01(02) D 3859 8175 808 8696 4.78 0.94

MIBW03(01) D 19364 41024 3902 42000 4.96 0.98 2834 6004

MIBW04(01) D 16530 35020 3409 36691 4.85 0.95 1577 3342

MIBW04(02) D 16530 35020 2454 26419 6.73 1.33 1360 2882

MNBW01(01) D 7080 15000 1514 16301 4.67 0.92 661 1400

MNBW02(01) D 6667 14125 1818 19572 3.67 0.72

MNBW02(02) D 6620 14025 1818 19572 3.64 0.72

MNBW04(01) D 3423 36843

MOCS01(01) D 30699 65038 9722 104650 3.16 0.62

MOCS05(01) D 70843 150088 14957 160999 4.74 0.93

NCDW02(01) D 26448 56033 5092 54812 5.19 1.02

NCDW02(02) D 26448 56033 5092 54812 5.19 1.02

NCDW03(01) A 595 1261 215 2315 2.77 0.54 76 160

NCDW03(02) A 595 1261 233 2511 2.55 0.50 76 160

NCDW03(03) A 595 1261 197 2117 3.02 0.60 76 160

NCDW03(04) A 520 1101 126 1360 4.11 0.81 61 130

NCDW03(05) D 520 1101 112 1200 4.66 0.92 61 130

NCDW06(01) G 14780 31313 2038 21933 7.25 1.43

NECW01(01) M 87373 185108 10116 108893 8.64 1.70

NECW02(01) L 70843 150088 8492 91410 8.34 1.64 56674 120070

NECW03(01) F 40617 86051 9748 104930 4.17 0.82

NMES01(01) H 2810 5953 803 8640 3.50 0.69

NMES01(02) H 5054 10706 1444 15540 3.50 0.69

NMES02(01) B 14594 30918 1229 13231 11.87 2.34

NMES03(01) D 7887 16710 1036 11150 7.61 1.50

NMES03(02) D 9304 19712 1289 13875 7.22 1.42

NVAW01(01) D 52702 111655 7623 82056 6.91 1.36

NVAW02(01) D 42817 90713 9711 104534 4.41 0.87 6140 13008

NVAW03(01) N 4605 9756 664 7152 6.93 1.36

NVAW03(02) N 1736 3677 338 3640 5.13 1.01

System ID

System 

type

Design supply airflow 

capacity

Floor area served by 

system

Design supply capacity 

per unit floor area

Design minimum 

outdoor air intake
45

L/s cfm m2 ft2 L/s-m2 cfm/ft 2 L/s cfm

NYBS01(01) E 35421 75044 7353 79150 4.82 0.95 11689 24765

NYBS01(02) E 18891 40023 3077 33119 6.14 1.21 5667 12007

NYBS02(01) N 2208 4678 517 5560 4.27 0.84

NYBS02(02) N 2310 4893 503 5416 4.59 0.90

NYBS04(01) D 9446 20012 1412 15199 6.69 1.32

NYBS04(02) D 9446 20012 1558 16766 6.06 1.19

NYBS05(01) F 6777 14358 2483 26726 2.73 0.54 678 1436

NYBS07(01) B 5667 12007 1084 11670 5.23 1.03

ORIS03(01) K 22670 48028 4329 46602 5.24 1.03 2598 5503

ORIS03(03) K 22670 48028 2428 26138 9.33 1.84 2598 5503

ORIS04(01) O 7337 15544 1445 15552 5.08 1.00

PABS03(01) D 22528 47728 5313 57185 4.24 0.83 2409 5103

PABS04(01) D 17985 38102 4323 46530 4.16 0.82 3306 7004

PABS04(02) A 7486 15859 248 2670 30.18 5.94

SCDW01(01) E 11099 23514 1380 14851 8.04 1.58 945 2001

SCDW02(01) F 18891 40023 11297 121600 1.67 0.33 2834 6004

SDBW01(01) E 9918 21012 2145 23088 4.62 0.91 1497 3172

SDBW02(01) G 9446 20012 1705 18350 5.54 1.09 945 2001

SDBW04(01) B 11335 24014 1480 15934 7.66 1.51

TNDS05(01) B 13130 27816 4451 47907 2.95 0.58 13130 27816

TNDS05(02) A 7745 16410 2684 28891 2.89 0.57 7745 16410

TNDS06(01) D 132127 279924 33783 363649 3.91 0.77 19246 40774

TNDS07(01) N 8501 18011 952 10242 8.93 1.76

TNFS08(01) G 5904 12507 785 8447 7.52 1.48 590 1251

TNFS08(02) D 2739 5804 542 5832 5.06 1.00 425 900

TNFS09(01) G 8921 18901 1505 16200 5.93 1.17 1181 2501

TNFS09(02) G 6962 14749 1092 11750 6.38 1.26 708 1501

TNFS10(01) H 15420 32669 7312 78706 2.11 0.42 2928 6204

TXFS01(01) D 56561 119830 9652 103897 5.86 1.15 3840 8135

TXFS02(01) D 7793 16510 1373 14783 5.67 1.12

TXFS02(02) D 9210 19511 1483 15968 6.21 1.22

TXFS07(01) H 51262 108604 10380 111734 4.94 0.97

TXFS08(01) H 7179 15209 1688 18165 4.25 0.84 548 1161

TXFS08(02) H 6976 14779 1718 18495 4.06 0.80 581 1231

TXFS09(01) D 4581 9706 1123 12086 4.08 0.80 583 1236

TXFS09(02) D 5904 12507 1379 14844 4.28 0.84 763 1616

TXFW05(01) H 111932 237139 18792 202282 5.96 1.17

TXFW06(01) H 86797 183888 16357 176069 5.31 1.04

WAIW03(01) H 6612 14008 1985 21366 3.33 0.66 1984 4202

WAIW04(01) H 8973 19011 1730 18623 5.19 1.02

# of values 134 134 141 141 134 134 76 76

Mean 16097 34103 3098 33349 5.86 1.15 3269 6926

StdDev 21224 44964 4234 45579 3.57 0.70 7236 15331

Minimum 520 1101 112 1200 1.13 0.22 61 130

10th percentile 2850 6037 542 5832 2.90 0.57 331 700

25th percentile 6612 14008 989 10650 4.15 0.82 642 1360

Median 8973 19011 1636 17608 5.21 1.03 1027 2176

75th percentile 16059 34022 3439 37018 6.78 1.33 2834 6004

90th percentile 38671 81928 7623 82056 8.45 1.66 7887 16710

Maximum 132127 279924 33783 363649 30.18 5.94 56674 120070

System ID

System 

type

Design supply airflow 

capacity

Floor area served by 

system

Design supply capacity 

per unit floor area

Design minimum 

outdoor air intake
46

L/s-m2 cfm/ft2 cfm L/s /1000 ft2 /100 m2 L/s cfm

ARFW01(01) 46 4.8 5.2

ARFW01(02) 46 4.8 5.2

ARFW02(01) 0.19 0.04 60 25.0 11.8 0.07 1.5 1.6

ARFW02(02) 0.39 0.08 50 25.0 11.8 0.07 3.0 3.3

ARFW03(01) 44 5.6 6.0

ARFW03(02) 32 5.9 6.4

AZHS02(01) 42 3.6 3.9

AZHS02(02) 33 3.6 3.9 6707 14208 1.06

AZHS04(01) 68 3.7 3.9

AZHS04(02) 12 5.9 6.4

AZHW10(01) 35 2.7 2.9

AZHW10(02) 19 5.6 6.0

AZHW11(01) 113 4.0 4.3

AZHW12(01) 0.29 0.06 94 24.3 11.5 0.14 2.3 2.5

AZHW12(02) 0.34 0.07 45 50.7 23.9 0.14 1.3 1.4

CAES17(01) 1.20 0.24 70 53.2 25.1 0.15 4.5 4.8

CAEW07(01) 95 2.7 2.9 12752 27016 1.37

CAEW001) 1.25 0.25 150 113.4 53.5 0.21 2.2 2.3 30699 65038 1.26

CAJS01(01) 52 2.3 2.5

CAJS01(02) 30 3.9 4.2

CAJS01(03) 12 1.6 1.7

CAJS02(01) 2.25 0.44 111 54.1 25.5 0.20 8.2 8.8

CAJS03(01) 0.17 0.03 155 19.1 9.0 0.15 1.7 1.9 47229 100059 0.20

CAJS21(01) 1.55 0.30 50 60.5 28.6 0.21 5.0 5.4 5290 11207 1.27

CAJS21(02) 1.07 46 208.2 98.2 1.00 5.1 5.5

CAJS222(01) 0.55 0.11 183 12.0 5.7 0.12 8.9 9.6

CAJS23(01) 0.90 0.18 73 27.4 12.9 0.11 6.5 7.0

CAJW18(01) 59 3.3 3.6

CAJW18(02)

CAJW19(01) 92 3.2 3.5 15349 32519 1.06

CAJW20(01) 0.95 0.19 741 37.8 17.8 0.17 5.0 5.3 68009 144084 1.11

CAJW24(01) 224 5.5 5.9 25504 54032 1.11

CAJW25(01) 770 60.5 12586 26666 1.17

CAJW26(01) 420 5.5 5.9 30472 64558 1.26

COAS02(01) 133 3.6 3.9

COAS04(01) 0.93 0.18 310 32.3 15.2 0.10 5.7 6.1 42506 90053 1.11

COAS06(01) 0.60 0.12 55 32.7 15.5 0.09 3.6 3.9

FLDW07(02) 0.72 0.14 50 63.3 29.9 0.19 2.2 2.4

FLDW08(01) 0.66 0.13 69 33.4 15.7 0.10 3.9 4.2

FLDW10(01) 0.33 0.07 108 10.2 4.8 0.09 6.4 6.9

FLGS01(01) 0.75 0.15 70 42.9 20.2 0.14 3.5 3.7

FLGS04(01) 0.72 0.14 50 30.0 14.2 0.11 4.7 5.1

FLGS04(02) 0.72 0.14 50 30.0 14.2 0.11 4.7 5.1

FLGS11(01) 0.22 0.04 44 15.9 7.5 0.06 2.8 3.0

FLGS11(02) 0.22 0.04 46 15.2 7.2 0.06 2.9 3.1

FLGS12(01) 1.69 0.33 60 61.7 29.1 0.15 5.4 5.8

GADS01(01) 0.42 0.08 67 32.1 15.2 0.10 2.6 2.8

GADS02(01) 0.56 0.11 40 50.0 23.6 0.14 2.2 2.4

GADS02(02) 0.56 0.11 40 50.0 23.6 0.14 2.2 2.4

GADS03(01) 124 5.3 5.7

Occupant density

Design return fan 

capacity

Ratio of 

design 

supply to 

return

Ratio of 

design 

minimum OA 

to supply

Number of 

occupants

Design minimum 

OA per person

System ID

Design minimum 

outdoor air intake 

per unit floor area
47

L/s-m2 cfm/ft 2 cfm L/s /1000 ft2 /100 m2 L/s cfm

ILBS01(01) 35 2.7 2.9

ILBS01(02) 51 4.9 5.3

ILBS02(01) 45 4.1 4.4 7793 16510 1.09

ILBS03(01) 63 2.6 2.8

LAGW04(01) 0.49 0.10 40 50.0 23.6 0.10 1.9 2.1

LAGW04(02) 0.45 0.09 33 60.6 28.6 0.11 1.5 1.6

LAGW05(01) 1.79 0.35 42 33.6 15.9 0.10 10.5 11.3

LAGW05(02) 0.37 0.07 30 32.0 15.1 0.10 2.2 2.4

LAGW06(01) 0.28 0.06 66 18.9 8.9 0.08 2.9 3.2

LAGW06(02) 0.92 0.18 0.08

MABW05(01) 120 2.7 2.9 8180 17330 1.10

MABW05(02) 120 2.9 3.1 8426 17851 1.16

MABW06(01) 0.60 0.12 50 32.0 15.1 0.11 3.7 4.0 4362 9240 1.52

MABW08(01) 1.04 0.21 420 19.7 9.3 0.25 10.4 11.2 16105 34120 0.97

MABW08(02) 2.70 0.53 408 62.3 29.4 1.00 8.5 9.2

MDDS01(01) 2.86 0.56 241 108.7 51.3 0.51 5.2 5.6

MDDS03(01) 0.76 0.15 51 27.4 12.9 0.31 5.5 5.9

MDDS03(02) 33 4.4 4.8

MDDS04(01) 0.47 0.09 44 13.6 6.4 0.10 6.7 7.3

MDDS04(02) 0.54 0.11 24 30.0 14.2 0.10 3.5 3.8

MIBW01(01) 45 4.9 5.3 3254 6894 1.11

MIBW01(02) 34 3.9 4.2 3171 6719 1.22

MIBW03(01) 0.73 0.14 373 16.1 7.6 0.15 8.9 9.6 17427 36922 1.11

MIBW04(01) 0.46 0.09 172 19.4 9.2 0.10 4.7 5.0 14953 31678 1.11

MIBW04(02) 0.55 0.11 172 16.8 7.9 0.08 6.5 7.0 15170 32139 1.09

MNBW01(01) 0.44 0.09 45 31.1 14.7 0.09 2.8 3.0

MNBW02(01) 37 1.9 2.0

MNBW02(02) 31 1.6 1.7

MNBW04(01) 87 2.4 2.5

MOCS01(01) 295 2.8 3.0 25976 55032 1.18

MOCS05(01) 374 2.3 2.5

NCDW02(01) 110 2.0 2.2

NCDW02(02) 113 2.1 2.2

NCDW03(01) 0.35 0.07 7 22.9 10.8 0.13 3.0 3.3

NCDW03(02) 0.32 0.06 2 80.0 37.8 0.13 0.8 0.9

NCDW03(03) 0.38 0.08 8 20.0 9.4 0.13 3.8 4.1

NCDW03(04) 0.49 0.10 4 32.5 15.3 0.12 2.9 3.2

NCDW03(05) 0.55 0.11 4 32.5 15.3 0.12 3.3 3.6

NCDW06(01) 60 2.7 2.9

NECW01(01) 893 8.2 8.8 47229 100059 1.85

NECW02(01) 6.67 1.31 1500 80.0 37.8 0.80 16.4 17.7 56674 120070 1.25

NECW03(01) 921 8.8 9.4 36366 77045 1.12

NMES01(01) 12 1.4 1.5 2782 5893 1.01

NMES01(02) 41 2.6 2.8 5001 10596 1.01

NMES02(01) 77 5.8 6.3

NMES03(01) 20 1.8 1.9

NMES03(02) 45 3.2 3.5

NVAW01(01) 359 4.4 4.7

NVAW02(01) 0.63 0.12 393 33.1 15.6 0.14 3.8 4.0 39700 84109 1.08

NVAW03(01) 36 5.0 5.4 3674 7784 1.25

NVAW03(02) 12 3.3 3.5 1193 2527 1.46

Design minimum 

outdoor air intake per

unit floor area

Ratio of 

design 

minimum OA

to supply

Design 

minimum OA

per person

System ID

Design return fan 

capacity

Number

of 

occupants

Occupant density

Ratio of 

design 

supply to 

return
48

L/s-m2 cfm/ft 2 cfm L/s /1000 ft2 /100 m2 L/s cfm

NYBS01(01) 1.59 0.31 618 40.1 18.9 0.33 7.8 8.4

NYBS01(02) 1.84 0.36 332 36.2 17.1 0.30 10.0 10.8

NYBS02(01) 40 7.2 7.7

NYBS02(02) 28 5.2 5.6

NYBS04(01) 50 3.3 3.5 8501 18011 1.11

NYBS04(02) 70 4.2 4.5 8501 18011 1.11

NYBS05(01) 0.27 0.05 160 9.0 4.2 0.10 6.0 6.4 5313 11257 1.28

NYBS07(01) 65 5.6 6.0

ORIS03(01) 0.60 0.12 171 32.2 15.2 0.11 3.7 3.9

ORIS03(03) 1.07 0.21 82 67.1 31.7 0.11 3.1 3.4

ORIS04(01) 67 4.3 4.6

PABS03(01) 0.45 0.09 350 14.6 6.9 0.11 6.1 6.6

PABS04(01) 0.76 0.15 195 35.9 17.0 0.18 4.2 4.5 14169 30018 1.27

PABS04(02) 6966 14759 1.07

SCDW01(01) 0.68 0.13 90 22.2 10.5 0.09 6.1 6.5 10154 21513 1.09

SCDW02(01) 0.25 0.05 160 37.5 17.7 0.15 1.3 1.4 16530 35020 1.14

SDBW01(01) 0.70 0.14 61 52.0 24.5 0.15 2.6 2.8 9587 20312 1.03

SDBW02(01) 0.55 0.11 700 2.9 1.3 0.10 38.1 41.1

SDBW04(01) 57 3.6 3.9 11335 24014 1.00

TNDS05(01) 2.95 0.58 575 48.4 22.8 1.00 12.0 12.9

TNDS05(02) 2.89 0.57 1.00

TNDS06(01) 0.57 0.11 1067 38.2 18.0 0.15 2.9 3.2

TNDS07(01) 55 5.4 5.8

TNFS08(01) 0.75 0.15 46 27.2 12.8 0.10 5.4 5.9

TNFS08(02) 0.78 0.15 29 31.0 14.7 0.16 5.0 5.4

TNFS09(01) 0.78 0.15 104 24.1 11.4 0.13 6.4 6.9

TNFS09(02) 0.65 0.13 68 22.1 10.4 0.10 5.8 6.2

TNFS10(01) 0.40 0.08 86 72.1 34.0 0.19 1.1 1.2

TXFS01(01) 0.40 0.08 348 23.4 11.0 0.07 3.3 3.6

TXFS02(01) 42 2.8 3.1

TXFS02(02) 49 3.1 3.3

TXFS07(01) 362 3.2 3.5

TXFS08(01) 0.32 0.06 59 19.7 9.3 0.08 3.2 3.5

TXFS08(02) 0.34 0.07 53 23.2 11.0 0.08 2.9 3.1

TXFS09(01) 0.52 0.10 60 20.6 9.7 0.13 5.0 5.3

TXFS09(02) 0.55 0.11 33 49.0 23.1 0.13 2.2 2.4

TXFW05(01) 515 2.5 2.7 111460 236138 1.00

TXFW06(01) 495 2.8 3.0 86797 183888 1.00

WAIW03(01) 1.00 0.20 77 54.6 25.8 0.30 3.6 3.9

WAIW04(01) 54 2.9 3.1

# of values 76 76 137 74 74 76 137 137 41 41 41

Mean 0.94 0.18 154 39.0 18.4 0.19 4.9 5.3 22045 46705 1.14

StdDev 1.06 0.21 229 29.0 13.7 0.22 6.1 6.5 24074 51003 0.22

Minimum 0.17 0.03 2 2.9 1.3 0.06 0.8 0.9 1193 2527 0.20

10th percentile 0.31 0.06 30 16.0 7.5 0.08 2.0 2.2 3674 7784 1.00

25th percentile 0.42 0.08 42 22.4 10.6 0.10 2.7 2.9 6966 14759 1.07

Median 0.60 0.12 60 32.1 15.2 0.12 3.7 3.9 12752 27016 1.11

75th percentile 0.92 0.18 150 50.0 23.6 0.15 5.4 5.9 30472 64558 1.25

90th percentile 1.82 0.36 339 63.0 29.7 0.31 7.4 8.0 47229 100059 1.28

Maximum 6.67 1.31 1500 208.2 98.3 1.00 60.5 65.1 111460 236138 1.85

Ratio of 

design 

supply to 

return

Ratio of 

design 

minimum OA

to supply

Occupant density

Design return fan 

capacity

Number

of 

occupants

Design 

minimum OA

per person

System ID

Design minimum 

outdoor air intake per

unit floor area
49

Appendix C: Volumetric Airflow Data Issues

This appendix describes measurement issues identified with the volumetric airflow data and any

adjustments that were made to account for these issues. 

Building Measurement Issue Data adjustment

ARFW02 Wednesday a.m. volumetric outdoor air value for

system #2 significantly below other measured values for

that system, while outdoor air fraction for this time

period based on CO2 consistent with other values.

Delete suspect value, no

study space volumetric

outdoor airflow for

Wednesday a.m.

AZHS04 System #1 measured recirculation airflow greater than

supply airflow for 3 of 4 readings, leading to negative

values for outdoor airflow; not significantly different

from zero based on uncertainty in recirculation and

supply airflows.

Set system #1 outdoor

airflow equal to zero in

those 3 cases.

AZHW10 No outdoor airflow measurement on System #2, but

System #1 outdoor airflow values very close to sum of

supply airflows for System #1 and #2; survey notes

indicate common outdoor air intake for both systems.

Calculate study space

outdoor airflow based on

System #1 values alone.

CAJS01 No outdoor airflow measurement on System #1 of three

systems; all systems are 100% outdoor air; note that

System #1 supply airflow is only about 10 % of supply

airflow of other two systems.

Assume System #1 outdoor

airflow equals supply

airflow.

CAJW18 Two systems listed under system design information,

but no design or measured data on System #2; survey

notes indicate that System #2 is heating only and wasn’t

operating during test week.

Results based on System

#1 measurements alone.

CAJW26 Volumetric outdoor air fraction greater than 100 % for 3

of 4 readings, but not significantly different from 100 %

based on uncertainty.

Use the 3 calculated values

greater than 100 %.

COAS04 Measured recirculation airflow greater than supply

airflow for one reading, leading to negative value for

outdoor airflow; not significantly different from zero

based on uncertainty in recirculation and supply

airflows.

Set value of outdoor

airflow equal to zero in that

case.

ILBS01 Volumetric measurements of supply airflow only for

both systems; survey notes indicate outdoor air intake

damper closed during test week; outdoor airflows can

only be determined by product of supply airflow and

outdoor air fraction from CO2.

No adjustments made to

data.

LAGW05 Volumetric supply airflow values measured for both

systems, outdoor airflow values for System #2 are

duplicates of System #1 values; survey notes indicate

common outdoor air intake serves both systems.

Use System #1 values

alone to determine outdoor

air fraction and study space

outdoor airflow.

LAGW06 No volumetric supply airflow values and only one

outdoor airflow value for System #2; survey notes

indicate that System #2 does not always operate and that

common outdoor air intake serves both systems; System

#2 design supply capacity and minimum outdoor air

only 20 % of System #1.

Add single System #2

outdoor airflow to

corresponding System #1

value when calculating

study space outdoor

airflow.

MABW05 One System #2 measured recirculation airflow value

greater than supply airflow, leading to negative value

Set value of outdoor

airflow equal to zero.
50

for outdoor airflow; not significantly different from zero

based on uncertainty in recirculation and supply

airflows.

MDDS01 Measured recirculation airflow greater than supply

airflow for two readings, leading to negative values for

outdoor airflow; not significantly different from zero

based on assumed uncertainty in recirculation and

supply airflows.

Set value of outdoor

airflow equal to zero for

these two events.

NCDW03 Five systems; survey notes indicate outdoor air not

operated during study week; 5 of 20 potential outdoor

airflow values listed, could be leakage into system.

No volumetric airflow rates

calculated for the study

space.

NMES02 All 4 volumetric outdoor airflows greater than

volumetric supply airflows; outdoor air fraction

significantly greater than 100 % based on measurement

uncertainty for only 1 of the 4 values.

Use all values as

calculated.

NVAW03 System #1 measured outdoor airflows greater than

supply airflow for all 4 readings, leading to volumetric

outdoor air fraction greater than 100 %, but not

significantly greater.

No adjustments made to

data.

NYBS04 Thursday a.m. volumetric outdoor airflow for system #1

much higher than other values for both systems #1 and

#2.

No adjustments made to

data.

ORIS03 No volumetric outdoor airflows for System #3; survey

notes indicate outdoor air intake serves both systems #1

and #3.

Supply airflow for system

#1 based on sum of system

#1 and #3 values; outdoor

airflow based on System #1

values.

ORIS04 No volumetric outdoor or recirculation airflow values;

survey notes indicate outdoor air damper location

prevented reliable traverse..

Outdoor airflow from CO2

ratio only.

PABS03 Measured recirculation airflow greater than supply

airflow for all four readings, leading to negative values

for outdoor airflow; not significantly different from zero

based on assumed uncertainty in recirculation and

supply airflows.

Set all 4 values of outdoor

airflow equal to zero.
51

Appendix D: Measured Data for Air Handlers

This appendix presents the following information for the measurements in the air handlers 

serving the study spaces:

System ID

Day and time of measurement

Supply, outdoor and recirculation airflows, and associated uncertainties (values in italics were 

not measured directly but were derived from other airflow rates, i.e., supply = outdoor air + 

recirculation; outdoor air = supply – recirculation)

Outdoor air fraction, based on volumetric and carbon dioxide ratio methods, and associated 

uncertainties
52

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

ARFW01(01) Wed AM 6919 14658 692 1466 385 815 115 245

Wed PM 6703 14200 670 1420 363 768 109 231

Thurs AM 6583 13946 658 1395 370 784 111 235

Thurs PM 6655 14099 665 1410 363 768 109 231

ARFW01(02) Wed AM 6328 13407 633 1341 348 737 104 221

Wed PM 6439 13641 644 1364 348 737 104 221

Thurs AM 6477 13722 648 1372 378 800 113 240

Thurs PM 6602 13987 660 1399 355 753 107 226

ARFW02(01) Wed AM 5155 10922 516 1092 4220 8941 1266 2682

Wed PM 4946 10478 495 1048 4159 8810 1248 2643

Thurs AM

Thurs PM 4946 10478 495 1048 4183 8862 1255 2659

ARFW02(02) Wed AM 6544 13865 654 1386

Wed PM 6300 13347 630 1335 5013 10620 1504 3186

Thurs AM

Thurs PM 6394 13546 639 1355 5221 11062 1566 3319

ARFW03(01) Wed AM 3753 7951 375 795 158 334 47 100

Wed PM 4073 8629 407 863 100 211 30 63

Thurs AM 3961 8392 396 839 108 229 32 69

Thurs PM 3945 8358 395 836 108 229 32 69

ARFW03(02) Wed AM 2317 4908 232 491 254 539 76 162

Wed PM 2515 5328 251 533 287 608 86 182

Thurs AM 2575 5455 257 545 328 695 98 209

Thurs PM 2503 5302 250 530 303 643 91 193

AZHS02(01) Wed AM 4579 9700 458 970 1670 3538 985 2088

Wed PM 5361 11359 536 1136 2600 5508 987 2091

Thurs AM 4233 8967 423 897 1243 2633 992 2101

Thurs PM 4397 9315 440 931 1628 3449 940 1991

AZHS02(02) Wed AM 2541 5383 254 538 1177 2494 482 1020

Wed PM 2511 5319 251 532 1240 2628 456 967

Thurs AM 2041 4323 204 432 545 1155 493 1044

Thurs PM 2481 5256 248 526 692 1466 591 1252

AZHS04(01) Wed AM 10463 22166 1046 2217 0 0 3309 7010

Wed PM 10385 22001 1038 2200 0 0 3424 7254

Thurs AM 10229 21671 1023 2167 1069 2265 2932 6212

Thurs PM 9831 20827 983 2083 0 0 3339 7073

AZHS04(02) Wed AM 698 1478 182 386 99 209 30 63

Wed PM 707 1498 182 386 109 231 33 69

Thurs AM 716 1516 193 408 78 166 23 50

Thurs PM 810 1716 210 446 119 252 36 76

AZHW10(01) Wed AM 8276 17533 828 1753 10637 22536 3191 6761

Wed PM 7891 16717 789 1672 12242 25936 3673 7781

Thurs AM 9031 19132 903 1913 13458 28512 4037 8554

Thurs PM 9179 19446 918 1945 13545 28696 4063 8609

AZHW10(02) Wed AM 4178 8852 418 885

Wed PM 4297 9104 430 910

Thurs AM 4440 9406 444 941

Thurs PM 4321 9154 432 915

AZHW11(01) Wed AM 14204 30093 1420 3009 2705 5732 3731 7904

Wed PM 16743 35472 1674 3547 4916 10415 3923 8312

Thurs AM 16537 35036 1654 3504 5531 11719 3693 7824

Thurs PM 18116 38380 1812 3838 6206 13148 4006 8487

AZHW12(01) Wed AM 3647 7727 365 773 752 1594 226 478

Wed PM 3575 7574 357 757 863 1828 259 548

Thurs AM 3250 6885 325 689 145 307 43 92

Thurs PM 3105 6579 311 658 110 234 33 70

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
53

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

AZHW12(02) Wed AM 5236 11093 524 1109 1595 3380 479 1014

Wed PM 5236 11093 524 1109 1595 3380 479 1014

Thurs AM 5236 11093 524 1109 1617 3427 485 1028

Thurs PM 5705 12087 571 1209 1738 3683 522 1105

CAES17(01) Wed AM 16286 34503 1629 3450 3040 6441 4294 9098

Wed PM 15564 32974 1556 3297 2210 4682 4298 9106

Thurs AM 17549 37179 1755 3718 9895 20963 2890 6123

Thurs PM 16737 35459 1674 3546 5120 10847 3866 8191

CAEW07(01) Wed AM 17522 37122 1752 3712 5371 11380 1611 3414

Wed PM 18569 39341 1857 3934 16134 34182 4840 10255

Thurs AM 17522 37122 1752 3712 13365 28315 4009 8494

Thurs PM 17236 36516 1724 3652 18092 38329 5427 11499

CAEW09(01) Wed AM 11693 24773 1169 2477 3704 7847 1111 2354

Wed PM 12026 25478 1203 2548 3221 6824 966 2047

Thurs AM 12317 26095 1232 2609 1772 3753 531 1126

Thurs PM 11360 24067 1136 2407 1691 3583 507 1075

CAJS01(01) Wed AM 200 423 20 42 200 423 60 127

Wed PM 200 423 20 42 200 423 60 127

Thurs AM 155 329 16 33 155 329 47 99

Thurs PM 200 423 20 42 200 423 60 127

CAJS01(02) Wed AM 1336 2830 134 283 1336 2830 401 849

Wed PM 1315 2786 131 279 1315 2786 394 836

Thurs AM 1416 3000 142 300 1416 3000 425 900

Thurs PM 1323 2804 132 280 1323 2804 397 841

CAJS01(03) Wed AM 1538 3258 154 326 1538 3258 461 977

Wed PM 1739 3685 174 368 1739 3685 522 1105

Thurs AM 1613 3418 161 342 1613 3418 484 1025

Thurs PM 1647 3489 165 349 1647 3489 494 1047

CAJS02(01) Wed AM 14671 31081 1467 3108 12430 26333 3729 7900

Wed PM 13720 29067 1372 2907 12601 26696 3780 8009

Thurs AM 14671 31081 1467 3108 14368 30440 4310 9132

Thurs PM 14331 30362 1433 3036 15508 32856 4653 9857

CAJS03(01) Wed AM 40277 85330 4028 8533 40277 85330 12083 25599

Wed PM 41447 87811 4145 8781 41447 87811 12434 26343

Thurs AM 42384 89795 4238 8979 42384 89795 12715 26938

Thurs PM 41631 88200 4163 8820 41447 87811 12434 26343

CAJS21(01) Wed AM 6088 12897 609 1290 1265 2679 379 804

Wed PM 4911 10405 491 1040 1196 2534 359 760

Thurs AM 4558 9657 456 966 1647 3489 494 1047

Thurs PM 5117 10841 512 1084 1470 3115 441 935

CAJS21(02) Wed AM 2582 5470 258 547 2582 5470 775 1641

Wed PM 2849 6035 285 604 2849 6035 855 1811

Thurs AM 2865 6069 286 607 2865 6069 859 1821

Thurs PM 2902 6149 290 615 2902 6149 871 1845

CAJS222(01) Wed AM 4651 9854 465 985 391 829 1360 2881

Wed PM 5604 11873 560 1187 806 1708 1545 3272

Thurs AM 4494 9521 449 952 929 1968 1160 2458

Thurs PM 5567 11793 557 1179 1172 2483 1431 3032

CAJS23(01) Wed AM 11349 24044 1135 2404 837 1773 251 532

Wed PM 10010 21206 1001 2121 1016 2153 305 646

Thurs AM 11238 23808 1124 2381 967 2048 290 614

Thurs PM 11535 24439 1154 2444 1098 2326 329 698

CAJW18(01) Wed AM 10464 22170 1046 2217 845 1791 254 537

Wed PM 10922 23140 1092 2314 832 1763 250 529

Thurs AM 10709 22687 1071 2269 938 1986 281 596

Thurs PM 12081 25596 1208 2560 938 1986 281 596

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
54

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

CAJW19(01) Wed AM 17769 37645 1777 3764 8828 18703 3217 6816

Wed PM 17430 36926 1743 3693 7045 14925 3570 7563

Thurs AM 17769 37645 1777 3764 8753 18543 3236 6856

Thurs PM 16887 35777 1689 3578 5530 11715 3803 8056

CAJW20(01) Wed AM 33151 70234 3315 7023 39935 84606 11980 25382

Wed PM 36439 77200 3644 7720 41671 88284 12501 26485

Thurs AM 32055 67913 3206 6791 36462 77249 10939 23175

Thurs PM 32877 69654 3288 6965 36936 78252 11081 23476

CAJW24(01) Tues AM 19105 40475 1910 4048 13205 27975 3961 8393

Tues PM 20500 43432 2050 4343 741 1570 222 471

Wed AM 19105 40475 1910 4048 13205 27975 3961 8393

Wed PM 21788 46160 2179 4616 729 1545 219 463

Thurs AM 23076 48889 2308 4889 16164 34245 4849 10274

Thurs PM 23183 49116 2318 4912 20547 43530 6164 13059

CAJW25(01) Wed AM 17130 36292 1713 3629 9230 19555 2769 5867

Wed PM 18047 38233 1805 3823 17256 36560 5177 10968

Thurs AM 15964 33822 1596 3382 11337 24019 3401 7206

Thurs PM 17738 37580 1774 3758 18159 38473 5448 11542

CAJW26(01) Wed AM 29773 63078 2977 6308 33826 71665 10148 21499

Wed PM 33495 70962 3349 7096 37230 78875 11169 23662

Thurs AM 31205 66110 3120 6611 33311 70572 9993 21172

Thurs PM 32779 69446 3278 6945 30939 65547 9282 19664

COAS02(01) Wed AM 11323 23988 3163 6701 810 1717 243 515

Wed PM 10049 21290 2710 5742 1080 2289 324 687

Thurs AM 11012 23330 3021 6401 990 2098 297 629

Thurs PM 12065 25562 3188 6754 1553 3290 466 987

COAS04(01) Wed AM 34210 72477 3421 7248 780 1652 10596 22450

Wed PM 34890 73918 3489 7392 2278 4827 10387 22006

Thurs AM 33529 71036 3353 7104 153 324 10559 22371

Thurs PM 34330 72731 3433 7273 0 0 11020 23348

COAS06(01) Wed AM 3837 8130 384 813 927 1963 278 589

Wed PM 4818 10206 482 1021 999 2116 300 635

Thurs AM 6446 13657 645 1366 1074 2275 322 683

Thurs PM 5066 10733 507 1073 887 1878 266 564

FLDW07(02) Wed AM 7499 15888 1979 4192 977 2069 293 621

Wed PM 6766 14334 1755 3719 1002 2122 300 637

Thurs AM 6340 13431 1634 3461 983 2083 295 625

Thurs PM 6911 14643 1789 3791 1039 2201 312 660

FLDW08(01) Wed AM 6982 14793 698 1479 1307 2769 392 831

Wed PM 7647 16200 765 1620 871 1846 261 554

Thurs AM 7090 15020 709 1502 871 1846 261 554

Thurs PM 7116 15075 712 1508 4773 10112 1432 3034

FLDW10(01) Wed AM 3702 7844 370 784 285 603 85 181

Wed PM 3721 7883 372 788 324 686 97 206

Thurs AM 3783 8015 378 801 356 755 107 226

Thurs PM 3417 7240 342 724 228 482 68 145

FLGS01(01) Thurs AM 4769 10103 477 1010 931 1973 279 592

Thurs PM 5276 11178 528 1118 978 2072 293 622

Fri AM 4615 9778 462 978 905 1917 272 575

Fri PM 5005 10603 500 1060 991 2099 297 630

FLGS04(01) Wed AM 7019 14870 702 1487 246 522 74 157

Wed PM 7372 15618 737 1562 273 579 82 174

Thurs AM 7215 15285 721 1529 242 513 73 154

Thurs PM 7215 15285 721 1529 220 466 66 140

FLGS04(02) Wed AM 9411 19937 941 1994 395 837 118 251

Wed PM 9469 20062 947 2006 381 807 114 242

Thurs AM 9607 20353 961 2035 398 843 119 253

Thurs PM 10058 21308 1006 2131 413 875 124 263

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
55

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

FLGS11(01) Wed AM 2684 5686 268 569 433 917 130 275

Wed PM 4318 9149 432 915 449 950 135 285

Thurs AM 2288 4848 229 485 433 917 130 275

Thurs PM 4542 9623 454 962 399 846 120 254

FLGS11(02) Wed AM 3699 7837 370 784 532 1127 160 338

Wed PM 4594 9732 459 973 508 1077 153 323

Thurs AM 2976 6306 298 631 482 1022 145 307

Thurs PM 4250 9003 425 900 472 1000 142 300

FLGS12(01) Wed AM 10029 21246 2564 5431 1643 3480 493 1044

Wed PM 9658 20462 2452 5194 1655 3507 497 1052

Thurs AM 8985 19036 2252 4772 1664 3525 499 1057

Thurs PM 8774 18589 2219 4702 1538 3258 461 977

GADS01(01) Wed AM 5469 11587 1185 2511 2165 4588 650 1376

Wed PM 5890 12480 1327 2811 1895 4014 568 1204

Thurs AM 5522 11700 1187 2514 2313 4900 694 1470

Thurs PM 5669 12010 1238 2622 2145 4544 643 1363

GADS02(01) Wed AM 5291 11210 529 1121 855 1811 256 543

Wed PM 6143 13014 614 1301 978 2072 293 622

Thurs AM 5017 10630 502 1063 1101 2333 330 700

Thurs PM 6105 12933 610 1293 989 2096 297 629

GADS02(02) Wed AM 5017 10630 502 1063 1269 2688 381 806

Wed PM 5717 12112 572 1211 1118 2368 335 711

Thurs AM 5253 11129 525 1113 1090 2310 327 693

Thurs PM 6409 13577 641 1358 1180 2499 354 750

GADS03(01) Wed AM 11988 25399 1199 2540 956 2026 287 608

Wed PM 11462 24283 1146 2428 973 2061 292 618

Thurs AM 11415 24183 1141 2418 973 2061 292 618

Thurs PM 11274 23885 1127 2388 978 2072 293 622

ILBS01(01) Wed AM 4889 10359 489 1036

Wed PM 4428 9381 443 938

Thurs AM 4161 8816 416 882

Thurs PM 4792 10152 479 1015

ILBS01(02) Wed AM 4460 9450 446 945

Wed PM 4889 10359 489 1036

Thurs AM 4688 9932 469 993

Thurs PM 4720 10001 472 1000

ILBS02(01) Wed AM 7212 15280 721 1528 598 1267 179 380

Wed PM 7488 15864 749 1586 549 1163 165 349

Thurs AM 7015 14862 702 1486 476 1008 143 302

Thurs PM 7173 15196 717 1520 543 1151 163 345

ILBS03(01) Thurs AM 16385 34712 1638 3471 7661 16231 3088 6541

Thurs PM 15682 33225 1568 3322 6606 13995 3142 6657

Wed AM 16229 34382 1623 3438 5875 12446 3505 7425

Wed PM 16931 35870 1693 3587 6027 12768 3683 7804

LAGW04(01) Wed AM 9213 19518 921 1952 570 1207 171 362

Wed PM 9735 20624 973 2062 439 929 132 279

Thurs AM 8967 18997 897 1900 549 1163 165 349

Thurs PM 9827 20819 983 2082 533 1129 160 339

LAGW04(02) Wed AM 10687 22641 1069 2264 776 1644 233 493

Wed PM 10594 22446 1059 2245 821 1739 246 522

Thurs AM 10287 21795 1029 2179 837 1773 251 532

Thurs PM 10533 22315 1053 2232 792 1678 238 504

LAGW05(01) Wed AM 9409 19934 941 1993 2726 5775 818 1732

Wed PM 9075 19226 907 1923 3054 6471 916 1941

Thurs AM 9203 19498 920 1950 2868 6077 860 1823

Thurs PM 8972 19008 897 1901 3023 6405 907 1922

LAGW05(02) Wed AM 4926 10437 493 1044

Wed PM 4876 10331 488 1033

Thurs AM 5026 10649 503 1065

Thurs PM 4939 10464 494 1046

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
56

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

LAGW06(01) Wed AM 9962 21106 996 2111 1259 2668 378 800

Wed PM 10012 21211 1001 2121 1220 2584 366 775

Thurs AM 9933 21043 993 2104 1216 2575 365 773

Thurs PM 9992 21169 999 2117 1232 2609 369 783

LAGW06(02) Wed AM 141 298 42 90

Wed PM

Thurs AM

Thurs PM

MABW05(01) Wed AM 4182 8860 418 886 415 880 1205 2553

Wed PM 6951 14727 695 1473 1938 4107 1657 3510

Thurs AM 6556 13889 656 1389 1288 2728 1711 3625

Thurs PM 6838 14488 684 1449 1740 3687 1675 3549

MABW05(02) Wed AM 6104 12931 610 1293 637 1350 1750 3707

Wed PM 5991 12692 599 1269 0 0 2028 4296

Thurs AM 6443 13650 644 1365 325 689 1945 4121

Thurs PM 6725 14248 673 1425 4 1 8 7 2115 4481

MABW06(01) Wed AM 2112 4474 211 447 1965 4163 589 1249

Wed PM 2085 4417 208 442 2013 4265 604 1279

Thurs AM 1783 3776 178 378 1723 3651 517 1095

Thurs PM 1728 3662 173 366 1675 3548 502 1065

MABW08(01) Wed AM 12910 27352 1291 2735 8083 17124 1940 4110

Wed PM 13508 28619 1351 2862 9097 19273 1891 4006

Thurs AM 12597 26687 1260 2669 6698 14191 2172 4602

Thurs PM 12910 27352 1291 2735 7557 16011 2061 4365

MABW08(02) Wed AM 12379 26225 3588 7602 11952 25322 3586 7597

Wed PM 11883 25176 3431 7269 11427 24210 3428 7263

Thurs AM 11537 24443 3330 7055 11091 23498 3327 7049

Thurs PM 11686 24758 3332 7059 11091 23498 3327 7049

MDDS01(01) Wed AM 21258 45037 2126 4504 2408 5101 6041 12799

Wed PM 22707 48108 2271 4811 1439 3048 6773 14349

Thurs AM 20292 42990 2029 4299 0 0 7794 16512

Thurs PM 19889 42137 1989 4214 0 0 6884 14585

MDDS03(01) Wed AM 1329 2815 133 282 209 442 63 133

Wed PM 1332 2823 133 282 176 372 53 112

Thurs AM 1340 2838 134 284 191 404 57 121

Thurs PM 1332 2823 133 282 181 383 54 115

MDDS03(02) Wed AM 2129 4511 213 451 68 145 21 43

Wed PM 1928 4084 193 408 31 65 9 19

Thurs AM 2047 4336 205 434 65 137 19 41

Thurs PM 1994 4224 199 422 64 135 19 41

MDDS04(01) Wed AM 2558 5420 256 542 293 620 726 1539

Wed PM 2531 5362 253 536 284 601 720 1525

Thurs AM 2545 5391 254 539 260 550 731 1549

Thurs PM 2434 5157 243 516 206 437 711 1507

MDDS04(02) Wed AM 2142 4538 214 454 572 1212 517 1096

Wed PM 1924 4077 192 408 456 966 481 1019

Thurs AM 1993 4223 199 422 446 945 505 1070

Thurs PM 1940 4111 194 411 505 1070 472 1000

MIBW01(01) Wed AM 2857 6053 286 605 1698 3598 450 953

Wed PM 2990 6336 299 634 1949 4128 433 916

Thurs AM 2857 6053 286 605 1599 3387 473 1003

Thurs PM 3009 6375 301 637 1531 3243 536 1135

MIBW01(02) Wed AM 2295 4861 229 486 202 428 668 1416

Wed PM 2765 5857 276 586 1052 2230 583 1236

Thurs AM 2313 4901 231 490

Thurs PM 2443 5175 244 518

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
57

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

MIBW03(01) Wed AM 16081 34070 1608 3407 4577 9696 3808 8067

Wed PM 15998 33894 1600 3389 3486 7385 4080 8645

Thurs AM 16367 34675 1637 3468 3999 8472 4055 8592

Thurs PM 13975 29606 1397 2961 4711 9981 3111 6590

MIBW04(01) Wed AM 4319 9151 432 915 1317 2790 999 2116

Wed PM 4307 9124 431 912 1606 3403 917 1944

Thurs AM 5031 10658 503 1066 1264 2677 1237 2621

Thurs PM 5107 10819 511 1082 1651 3499 1156 2448

MIBW04(02) Wed AM 5624 11915 562 1191 2169 4594 1179 2499

Wed PM 5423 11489 542 1149 1883 3989 1193 2527

Thurs AM 5122 10851 512 1085 1327 2810 1248 2645

Thurs PM 5875 12447 588 1245 2401 5087 1196 2535

MNBW01(01) Wed AM 4257 9019 426 902 1104 2340 331 702

Wed PM 4816 10203 482 1020 1113 2359 334 708

Thurs AM 4284 9076 428 908 1072 2272 322 682

Thurs PM 4710 9978 471 998 1165 2469 350 741

MNBW02(01) Wed AM 5487 11625 549 1162 1526 3232 458 970

Wed PM 5869 12434 587 1243 1730 3666 519 1100

Thurs AM 4342 9199 434 920 1805 3823 541 1147

Thurs PM 5344 11322 534 1132 2233 4730 670 1419

MNBW02(02) Wed AM 8190 17352 819 1735 2419 5124 726 1537

Wed PM 10586 22427 1059 2243 4502 9539 1351 2862

Thurs AM 6853 14519 685 1452 4279 9066 1284 2720

Thurs PM 7689 16289 769 1629 3516 7450 1055 2235

MNBW04(01) Wed AM 9340 19787 934 1979 6735 14269 2021 4281

Wed PM 8931 18920 893 1892 7330 15530 2199 4659

Thurs AM 10270 21758 1027 2176 7256 15373 2177 4612

Thurs PM 9042 19157 904 1916 7740 16398 2322 4919

MOCS01(01) Wed AM 24167 51200 2417 5120

Wed PM 28638 60672 2864 6067

Thurs AM 25979 55040 2598 5504

Thurs PM 28396 60160 2840 6016

MOCS05(01) Wed AM 45207 95775 4521 9578 14860 31482 4458 9445

Wed PM 50117 106178 5012 10618 17710 37519 5313 11256

Thurs AM 40690 86206 4069 8621 8957 18975 2687 5693

Thurs PM 39282 83222 3928 8322 1018 2156 305 647

NCDW02(01) Wed AM 10767 22811 1077 2281 10054 21300 3016 6390

Wed PM 11227 23786 1123 2379 10622 22504 3187 6751

Thurs AM 11043 23396 1104 2340 5595 11854 1679 3556

Thurs PM 11227 23786 1123 2379 9311 19726 2793 5918

NCDW02(02) Wed AM 11595 24566 1160 2457 10054 21300 3016 6390

Wed PM 12976 27490 1298 2749 10622 22504 3187 6751

Thurs AM 12055 25541 1206 2554 5595 11854 1679 3556

Thurs PM 12239 25931 1224 2593 9311 19726 2793 5918

NCDW03(01) Wed AM

Wed PM

Thurs AM

Thurs PM

NCDW03(02) Wed AM

Wed PM

Thurs AM

Thurs PM

NCDW03(03) Wed AM

Wed PM

Thurs AM

Thurs PM 49 104 12 25 37 79 11 24

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
58

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

NCDW03(04) Wed AM 85 181 22 47 74 156 22 47

Wed PM 83 175 22 46 71 150 21 45

Thurs AM 88 186 23 49 76 161 23 48

Thurs PM 61 128 15 32 49 103 15 31

NCDW03(05) Wed AM

Wed PM

Thurs AM

Thurs PM

NCDW06(01) Wed AM 6300 13348 630 1335 2419 5124 726 1537

Wed PM 7078 14996 708 1500 4016 8508 1205 2552

Thurs AM 5322 11276 532 1128 3814 8081 1144 2424

Thurs PM 6300 13348 630 1335 2326 4927 698 1478

NECW01(01) Wed AM 42102 89197 4210 8920 13910 29471 4173 8841

Wed PM 40713 86254 4071 8625 16197 34315 4859 10295

Thurs AM 43810 92816 4381 9282 15625 33104 4688 9931

Thurs PM 43304 91744 4330 9174 25281 53560 7584 16068

NECW02(01) Wed AM 67711 143453 6771 14345 53438 113213 16031 33964

Wed PM 52310 110824 5231 11082 29626 62766 8888 18830

Thurs AM 68229 144550 6823 14455 51499 109107 15450 32732

Thurs PM 66517 140922 6652 14092 48731 103241 14619 30972

NECW03(01) Wed AM 27504 58269 2750 5827 18860 39956 5658 11987

Wed PM 31117 65925 3112 6593 20824 44118 6247 13236

Thurs AM 32121 68052 3212 6805 14980 31736 4494 9521

Thurs PM 28307 59971 2831 5997 24950 52859 7485 15858

NMES01(01) Wed AM 3517 7451 746 1581 1799 3811 540 1143

Wed PM 3384 7168 742 1571 2132 4516 640 1355

Thurs AM 3190 6758 678 1437 1699 3599 510 1080

Thurs PM 3310 7013 714 1512 1954 4140 586 1242

NMES01(02) Wed AM 5609 11884 1408 2983 1030 2182 309 655

Wed PM 5878 12453 1490 3157 1016 2152 305 645

Thurs AM 4957 10502 1298 2749 687 1455 206 436

Thurs PM 5638 11944 1440 3050 930 1970 279 591

NMES02(01) Wed AM 6220 13177 622 1318 8612 18245 2584 5474

Wed PM 6897 14612 690 1461 8561 18136 2568 5441

Thurs AM 7405 15687 740 1569 8021 16993 2406 5098

Thurs PM 5966 12640 597 1264 9075 19226 2722 5768

NMES03(01) Wed AM 3423 7251 342 725 248 526 1012 2144

Wed PM 3498 7410 350 741 466 986 975 2065

Thurs AM 3122 6614 312 661 319 677 897 1900

Thurs PM 3046 6454 305 645 5 8 123 947 2006

NMES03(02) Wed AM 4992 10577 499 1058 548 1161 1424 3016

Wed PM 6468 13704 647 1370 959 2033 1775 3760

Thurs AM 5470 11589 547 1159 1054 2233 1433 3036

Thurs PM 5991 12692 599 1269 865 1833 1650 3496

NVAW01(01) Wed AM 46440 98387 4644 9839 46478 98468 13943 29540

Wed PM 48395 102530 4840 10253 32571 69005 9771 20702

Thurs AM 49699 105291 4970 10529 27074 57358 8122 17207

Thurs PM 50350 106672 5035 10667 13962 29580 4189 8874

NVAW02(01) Wed AM 24729 52391 2473 5239 23554 49902 7066 14971

Wed PM 27597 58466 2760 5847 26457 56051 7937 16815

Thurs AM 24045 50942 2405 5094 23145 49035 6943 14710

Thurs PM 27465 58187 2746 5819 25638 54317 7691 16295

NVAW03(01) Wed AM 5207 11033 521 1103 5679 12031 1704 3609

Wed PM 5074 10751 507 1075 5747 12176 1724 3653

Thurs AM 5188 10992 519 1099 5702 12079 1710 3624

Thurs PM 5207 11033 521 1103 5724 12128 1717 3638

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
59

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

NVAW03(02) Wed AM 3695 7829 370 783 1802 3818 541 1146

Wed PM 3582 7590 358 759 1802 3818 541 1146

Thurs AM 3441 7291 344 729 1764 3737 529 1121

Thurs PM 3653 7739 365 774 1818 3851 545 1155

NYBS01(01) Wed AM 31613 66976 3161 6698 4645 9841 8686 18402

Wed PM 32918 69739 3292 6974 3897 8256 9308 19720

Thurs AM 31951 67692 3195 6769 3478 7369 9120 19322

Thurs PM 32612 69091 3261 6909 4138 8768 9143 19371

NYBS01(02) Wed AM 16430 34808 1643 3481 2423 5134 727 1540

Wed PM 17456 36982 1746 3698 2594 5496 778 1649

Thurs AM 17564 37211 1756 3721 2509 5315 753 1594

Thurs PM 17411 36887 1741 3689 2680 5677 804 1703

NYBS02(01) Wed AM 2861 6061 286 606 286 605 86 182

Wed PM 2981 6315 298 632 286 605 86 182

Thurs AM 3201 6781 320 678 235 498 71 150

Thurs PM 2101 4450 210 445 286 605 86 182

NYBS02(02) Wed AM 3901 8265 390 826 353 748 106 224

Wed PM 3401 7205 340 721 429 908 129 272

Thurs AM 3221 6824 322 682 378 801 113 240

Thurs PM 2321 4917 232 492 378 801 113 240

NYBS04(01) Wed AM 6706 14208 671 1421 91 193 27 58

Wed PM 7003 14838 700 1484 91 193 27 58

Thurs AM 7460 15805 746 1580 5717 12112 1715 3633

Thurs PM 7334 15537 733 1554 84 177 25 53

NYBS04(02) Wed AM 8252 17483 825 1748 306 648 92 195

Wed PM 8005 16959 800 1696 281 594 84 178

Thurs AM 8290 17563 829 1756 7559 16014 2268 4804

Thurs PM 8402 17801 840 1780 298 630 89 189

NYBS05(01) Wed AM 5655 11981 566 1198 1441 3052 432 916

Wed PM 6101 12926 610 1293 1454 3080 436 924

Thurs AM 5890 12478 589 1248 1454 3080 436 924

Thurs PM 5936 12575 594 1258 1347 2854 404 856

NYBS07(01) Wed AM 5071 10743 1256 2660 1008 2137 303 641

Wed PM 5311 11252 1315 2785 1058 2242 317 673

Thurs AM 5230 11080 1288 2729 1072 2272 322 682

Thurs PM 5006 10606 1238 2624 1001 2122 300 636

ORIS03(01) Wed AM 26408 55948 3083 6533 11842 25089 3553 7527

Wed PM 30621 64874 3537 7494 12767 27048 3830 8115

Thurs AM 23088 48915 2682 5683 10415 22065 3124 6619

Thurs PM 26075 55243 3024 6407 12144 25728 3643 7718

ORIS03(03) Wed AM

Wed PM

Thurs AM

Thurs PM

ORIS04(01) Wed AM

Wed PM 6117 12959 612 1296

Thurs AM 8734 18504 873 1850

Thurs PM 8528 18068 853 1807

PABS03(01) Wed AM 15911 33709 1591 3371 0 0 5214 11046

Wed PM 14736 31220 1474 3122 0 0 5125 10857

Thurs AM 14997 31773 1500 3177 0 0 5598 11860

Thurs PM 16288 34508 1629 3451 0 0 5908 12516

PABS04(01) Wed AM 11128 23577 1113 2358 2195 4651 659 1395

Wed PM 10982 23267 1098 2327 2121 4494 636 1348

Thurs AM 10311 21844 1031 2184 2009 4257 603 1277

Thurs PM 10610 22478 1061 2248 2121 4494 636 1348

PABS04(02) Wed AM 8150 17267 815 1727 309 655 93 196

Wed PM 8070 17098 807 1710 309 655 93 196

Thurs AM 7682 16275 768 1628 268 568 80 170

Thurs PM 8130 17225 813 1722 288 611 87 183

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
60

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

SCDW01(01) Wed AM 6063 12844 606 1284 1463 3100 439 930

Wed PM 5127 10863 513 1086 1279 2709 384 813

Thurs AM 5634 11935 563 1194 1340 2839 402 852

Thurs PM 4830 10234 483 1023 1063 2252 319 676

SCDW02(01) Wed AM 24154 51173 2415 5117 4391 9302 1317 2791

Wed PM 26087 55267 2609 5527 4875 10327 1462 3098

Thurs AM 23560 49914 2356 4991 4502 9539 1351 2862

Thurs PM 24526 51961 2453 5196 3795 8041 1139 2412

SDBW01(01) Wed AM 6419 13600 642 1360 2930 6208 879 1862

Wed PM 6870 14555 687 1455 3551 7524 1065 2257

Thurs AM 6547 13870 655 1387 3425 7256 1028 2177

Thurs PM 6776 14357 678 1436 3697 7832 1109 2350

SDBW02(01) Wed AM 7185 15222 718 1522 3187 6752 956 2026

Wed PM 6560 13898 656 1390 1923 4073 577 1222

Thurs AM 7150 15148 715 1515 2026 4292 608 1288

Thurs PM 6630 14045 663 1405 1561 3308 468 992

SDBW04(01) Wed AM 11859 25125 1186 2512 2541 5383 3037 6433

Wed PM 10063 21320 1006 2132 2001 4239 2620 5550

Thurs AM 9689 20528 969 2053 1891 4007 2532 5365

Thurs PM 9615 20369 961 2037 2081 4408 2456 5204

TNDS05(01) Wed AM 9596 20329 960 2033 9596 20329 2879 6099

Wed PM 10762 22800 1076 2280 10762 22800 3229 6840

Thurs AM 10232 21677 1023 2168 10232 21677 3070 6503

Thurs PM 9649 20442 965 2044 9649 20442 2895 6133

TNDS05(02) Wed AM 4616 9780 462 978 4616 9780 1385 2934

Wed PM 4454 9436 445 944 4454 9436 1336 2831

Thurs AM 4259 9022 426 902 4259 9022 1278 2707

Thurs PM 4031 8540 403 854 4031 8540 1209 2562

TNDS06(01) Wed AM 86266 182763 8627 18276 18357 38892 22124 46871

Wed PM 73705 156152 7371 15615 6302 13352 21522 45597

Thurs AM 67711 143452 6771 14345 8809 18663 18923 40091

Thurs PM 69550 147348 6955 14735 1539 3262 21556 45668

TNDS07(01) Wed AM 4470 9470 447 947 107 226 32 68

Wed PM 4318 9148 432 915 128 271 38 81

Thurs AM 4470 9470 447 947 135 286 40 86

Thurs PM 4516 9567 452 957 717 1520 215 456

TNFS08(01) Wed AM 3023 6405 302 641 616 1305 185 391

Wed PM 3047 6456 305 646 745 1579 224 474

Thurs AM 3262 6910 326 691 745 1579 224 474

Thurs PM 3952 8373 395 837 713 1511 214 453

TNFS08(02) Wed AM 1336 2830 312 662 359 760 108 228

Wed PM 1352 2864 328 695 300 636 90 191

Thurs AM 1364 2889 330 699 308 653 92 196

Thurs PM 1316 2788 319 675 296 628 89 188

TNFS09(01) Wed AM 6846 14504 685 1450 2527 5354 1465 3105

Wed PM 6295 13336 629 1334 2035 4312 1424 3018

Thurs AM 5889 12476 589 1248 1600 3389 1415 2998

Thurs PM 5932 12568 593 1257 1762 3733 1385 2933

TNFS09(02) Wed AM 5493 11637 549 1164 420 890 126 267

Wed PM 5925 12552 592 1255 420 890 126 267

Thurs AM 4057 8595 406 860 216 458 65 137

Thurs PM 4830 10233 483 1023 276 585 83 175

TNFS10(01) Wed AM 10660 22585 1066 2258 7334 15537 1460 3094

Wed PM 12565 26621 1257 2662 6728 14254 2155 4566

Thurs AM 11859 25124 1186 2512 8341 17672 1587 3363

Thurs PM 10446 22131 1045 2213 7362 15597 1395 2956

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
61

System ID Day Period L/s cfm L/s cfm L/s cfm L/s cfm

TXFS01(01) Wed AM 34668 73447 3467 7345

Wed PM 42496 90032 4250 9003 1933 4094 580 1228

Thurs AM 41862 88689 4186 8869 1789 3791 537 1137

Thurs PM 43118 91349 4312 9135 1720 3645 516 1094

TXFS02(01) Wed AM 8906 18868 891 1887 416 881 125 264

Wed PM 8008 16966 801 1697 400 847 120 254

Thurs AM 10773 22824 1077 2282 386 818 116 245

Thurs PM 9480 20085 948 2008 462 978 139 294

TXFS02(02) Wed AM 9588 20313 959 2031 450 954 135 286

Wed PM 10019 21226 1002 2123 462 978 139 294

Thurs AM 10486 22215 1049 2222 448 950 134 285

Thurs PM 9229 19552 923 1955 407 862 122 259

TXFS07(01) Wed AM 31610 66968 3161 6697 4042 8562 1212 2569

Wed PM 31610 66968 3161 6697 4475 9480 1342 2844

Thurs AM 29436 62362 2944 6236 4193 8884 1258 2665

Thurs PM 27596 58464 2760 5846 4382 9284 1315 2785

TXFS08(01) Wed AM 8107 17175 811 1718 373 791 112 237

Wed PM 8891 18837 889 1884 436 923 131 277

Thurs AM 8293 17570 829 1757 479 1014 144 304

Thurs PM 8646 18318 865 1832 512 1085 154 326

TXFS08(02) Wed AM 6913 14646 691 1465 366 776 110 233

Wed PM 7593 16087 759 1609 360 763 108 229

Thurs AM 6985 14799 699 1480 366 776 110 233

Thurs PM 7696 16305 770 1631 378 801 113 240

TXFS09(01) Wed AM 5083 10770 508 1077 975 2065 292 619

Wed PM 5168 10949 517 1095 947 2006 284 602

Thurs AM 5245 11112 525 1111 989 2095 297 628

Thurs PM 5191 10998 519 1100 1003 2124 301 637

TXFS09(02) Wed AM 5156 10924 516 1092 975 2065 292 619

Wed PM 5270 11164 527 1116 947 2006 284 602

Thurs AM 5092 10788 509 1079 989 2095 297 628

Thurs PM 5149 10909 515 1091 1003 2124 301 637

TXFW05(01) Wed AM 35400 74999 3540 7500 9156 19398 8633 18289

Wed PM 34115 72277 3412 7228 8465 17934 8417 17833

Thurs AM 41709 88366 4171 8837 24435 51768 6652 14094

Thurs PM 41826 88613 4183 8861 26065 55220 6313 13375

TXFW06(01) Wed AM 47533 100703 4753 10070 47738 101137 14321 30341

Wed PM 39884 84498 3988 8450 39878 84486 11963 25346

Thurs AM 40703 86234 4070 8623 40752 86336 12225 25901

Thurs PM 45621 96652 4562 9665 45700 96820 13710 29046

WAIW03(01) Wed AM 2958 6266 296 627 2986 6327 896 1898

Wed PM 4093 8672 409 867 3627 7684 1088 2305

Thurs AM 3407 7217 341 722 3469 7350 1041 2205

Thurs PM 4040 8560 404 856 3718 7877 1115 2363

WAIW04(01) Wed AM 1570 3327 157 333 1528 3237 458 971

Wed PM 1570 3327 157 333 1555 3294 466 988

Thurs AM 1570 3327 157 333 1541 3266 462 980

Thurs PM 1537 3256 154 326 1541 3266 462 980

# of values 536 510

Mean 11676 24737 1243 2633 5033 10662 2102 4453

StdDev 12731 26972 1298 2750 9113 19307 3422 7250

Minimum 49 104 12 25 0 0 9 19

10th percentile 2462 5215 252 534 219 465 89 188

25th percentile 4450 9428 449 951 473 1002 251 532

Median 6861 14537 720 1525 1527 3235 590 1251

75th percentile 12259 25972 1514 3207 4606 9759 2580 5465

90th percentile 31161 66018 3200 6780 13374 28334 5921 12544

Maximum 86266 182763 8626 18276 53438 113213 22124 46871

Supply airflow

Uncertainty in

supply airflow Outdoor airflow

Uncertainty in outdoor 

airflow
62

System ID Day Period L/s cfm L/s cfm

ARFW01(01) Wed AM 0.056 0.018 0.029 0.202

Wed PM 0.054 0.017 0.000 0.203

Thurs AM 0.056 0.018 0.086 0.203

Thurs PM 0.055 0.017 0.125 0.178

ARFW01(02) Wed AM 0.055 0.017 0.000 0.182

Wed PM 0.054 0.017 0.051 0.182

Thurs AM 0.058 0.018 0.125 0.178

Thurs PM 0.054 0.017 0.063 0.177

ARFW02(01) Wed AM 0.819 0.259 0.667 2.833

Wed PM 0.841 0.266 0.611 0.921

Thurs AM

Thurs PM 0.846 0.267 0.750 1.473

ARFW02(02) Wed AM 0.833 0.767

Wed PM 0.796 0.252 0.235 0.741

Thurs AM

Thurs PM 0.817 0.258 0.850 0.928

ARFW03(01) Wed AM 0.042 0.013 0.120 0.251

Wed PM 0.024 0.008 0.014 0.249

Thurs AM 0.027 0.009 0.041 0.207

Thurs PM 0.027 0.009 0.055 0.279

ARFW03(02) Wed AM 0.110 0.035 0.031 0.217

Wed PM 0.114 0.036 0.032 0.228

Thurs AM 0.127 0.040 0.054 0.175

Thurs PM 0.121 0.038 0.233 0.202

AZHS02(01) Wed AM 2909 6162 873 1849 0.365 0.218 0.418 0.341

Wed PM 2761 5850 828 1755 0.485 0.190 0.320 0.594

Thurs AM 2990 6334 897 1900 0.294 0.236 0.169 0.806

Thurs PM 2769 5866 831 1760 0.370 0.217 0.400 1.015

AZHS02(02) Wed AM 1364 2889 409 867 0.463 0.195 0.353 0.401

Wed PM 1270 2691 381 807 0.494 0.188 0.547 0.630

Thurs AM 1495 3168 449 950 0.267 0.243 0.465 0.549

Thurs PM 1789 3789 537 1137 0.279 0.240 0.365 0.885

AZHS04(01) Wed AM 10463 22167 3139 6650 0.000 0.316 0.100 0.142

Wed PM 10875 23040 3262 6912 0.000 0.330 0.000 0.156

Thurs AM 9160 19405 2748 5822 0.105 0.287 0.746 0.774

Thurs PM 10635 22531 3190 6759 0.000 0.340 0.091 0.129

AZHS04(02) Wed AM 599 1269 180 381 0.141 0.056 0.297 0.144

Wed PM 598 1267 179 380 0.154 0.061 0.375 0.134

Thurs AM 637 1350 191 405 0.109 0.044 0.570 0.546

Thurs PM 691 1464 207 439 0.147 0.058 0.382 0.133

AZHW10(01) Wed AM 0.854 0.264 0.246 0.597

Wed PM 1.004 0.310 0.893 1.264

Thurs AM 0.999 0.309 0.946 1.739

Thurs PM 1.003 0.310 0.967 1.639

AZHW10(02) Wed AM 0.139 0.585

Wed PM 0.627 1.113

Thurs AM 0.446 1.383

Thurs PM 0.550 1.345

AZHW11(01) Wed AM 11499 24361 3450 7308 0.190 0.263 0.162 0.227

Wed PM 11827 25057 3548 7517 0.294 0.236 0.278 0.395

Thurs AM 11006 23317 3302 6995 0.334 0.226 0.196 0.300

Thurs PM 11909 25231 3573 7569 0.343 0.224 0.150 0.335

AZHW12(01) Wed AM 0.206 0.065

Wed PM 0.241 0.076

Thurs AM 0.045 0.014 0.041 0.323

Thurs PM 0.036 0.011 0.072 0.224

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow
63

System ID Day Period L/s cfm L/s cfm

AZHW12(02) Wed AM 0.305 0.096

Wed PM 0.305 0.096

Thurs AM 0.309 0.098 0.269 0.468

Thurs PM 0.305 0.096 0.295 0.358

CAES17(01) Wed AM 13246 28062 3974 8419 0.187 0.264 0.250 0.364

Wed PM 13354 28292 4006 8488 0.142 0.277 0.250 0.364

Thurs AM 7654 16216 2296 4865 0.564 0.174 0.167 0.478

Thurs PM 11617 24612 3485 7383 0.306 0.233 0.259 0.541

CAEW07(01) Wed AM 0.307 0.097 0.585 1.638

Wed PM 0.869 0.275 1.148 2.340

Thurs AM 0.763 0.241 0.222 0.805

Thurs PM 1.050 0.332 1.200 4.418

CAEW09(01) Wed AM 0.317 0.100 0.118 0.838

Wed PM 0.268 0.085 0.368 0.603

Thurs AM 0.144 0.045 0.500 1.976

Thurs PM 0.149 0.047 0.281 0.480

CAJS01(01) Wed AM 1.000 0.316 0.000 0.710

Wed PM 1.000 0.316 0.000 0.986

Thurs AM 1.000 0.316 0.000 0.710

Thurs PM 1.000 0.316 0.000 1.775

CAJS01(02) Wed AM 1.000 0.316 0.286 1.051

Wed PM 1.000 0.316 0.722 0.969

Thurs AM 1.000 0.316 0.537 0.743

Thurs PM 1.000 0.316 0.556 0.899

CAJS01(03) Wed AM 1.000 0.316

Wed PM 1.000 0.316

Thurs AM 1.000 0.316 0.200 0.577

Thurs PM 1.000 0.316 0.538 1.236

CAJS02(01) Wed AM 0.847 0.268 0.000 7.100

Wed PM 0.918 0.290 1.000 4.000

Thurs AM 0.979 0.310 0.400 1.523

Thurs PM 1.082 0.342 0.444 1.433

CAJS03(01) Wed AM 1.000 0.316 0.143 2.551

Wed PM 1.000 0.316 0.900 2.378

Thurs AM 1.000 0.316 0.488 1.919

Thurs PM 0.996 0.315 0.667 1.889

CAJS21(01) Wed AM 0.208 0.066 0.200 0.361

Wed PM 0.244 0.077 0.333 0.497

Thurs AM 0.361 0.114 0.278 0.815

Thurs PM 0.287 0.091 0.327 0.715

CAJS21(02) Wed AM 1.000 0.316

Wed PM 1.000 0.316

Thurs AM 1.000 0.316

Thurs PM 1.000 0.316

CAJS222(01) Wed AM 4260 9025 1278 2708 0.084 0.293 0.171 0.410

Wed PM 4798 10165 1439 3050 0.144 0.276 0.175 0.359

Thurs AM 3565 7553 1069 2266 0.207 0.259 0.133 0.476

Thurs PM 4395 9310 1318 2793 0.211 0.258 0.070 0.330

CAJS23(01) Wed AM 0.074 0.023 0.208 0.301

Wed PM 0.102 0.032 0.053 0.373

Thurs AM 0.086 0.027 0.000 0.394

Thurs PM 0.095 0.030 0.000 0.394

CAJW18(01) Wed AM 0.081 0.026 0.224 0.401

Wed PM 0.076 0.024 0.174 0.353

Thurs AM 0.088 0.028 0.170 0.597

Thurs PM 0.078 0.025 0.148 0.379

Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow
64

System ID Day Period L/s cfm L/s cfm

CAJW19(01) Wed AM 8940 18941 2682 5682 0.497 0.188 0.374 1.054

Wed PM 10385 22001 3115 6600 0.404 0.209 0.506 1.014

Thurs AM 9016 19101 2705 5730 0.493 0.189 0.419 0.776

Thurs PM 11357 24062 3407 7218 0.327 0.228 0.379 1.030

CAJW20(01) Wed AM 1.205 0.381 0.967 1.002

Wed PM 1.144 0.362 0.955 1.051

Thurs AM 1.137 0.360 1.061 0.609

Thurs PM 1.123 0.355 0.970 0.743

CAJW24(01) Tues AM 0.691 0.219 0.143 1.020

Tues PM 0.036 0.011 0.033 0.236

Wed AM 0.691 0.219 0.143 1.020

Wed PM 0.033 0.011 0.033 0.236

Thurs AM 0.700 0.222 0.750 1.105

Thurs PM 0.886 0.280 0.400 1.523

CAJW25(01) Wed AM 0.539 0.170 0.462 0.599

Wed PM 0.956 0.302 0.842 0.973

Thurs AM 0.710 0.225 0.333 0.828

Thurs PM 1.024 0.324 0.842 0.973

CAJW26(01) Wed AM 1.136 0.359 0.667 1.133

Wed PM 1.112 0.351 0.500 1.129

Thurs AM 1.067 0.338 1.000 1.250

Thurs PM 0.944 0.298 1.000 0.870

COAS02(01) Wed AM 10512 22272 3154 6681 0.072 0.029 0.000 0.568

Wed PM 8969 19001 2691 5700 0.108 0.043 0.000 0.473

Thurs AM 10022 21232 3007 6370 0.090 0.037 0.143 0.408

Thurs PM 10512 22272 3154 6681 0.129 0.051 0.143 0.408

COAS04(01) Wed AM 33430 70825 10029 21247 0.023 0.310 0.372 0.623

Wed PM 32611 69091 9783 20727 0.065 0.298 0.270 0.495

Thurs AM 33376 70711 10013 21213 0.005 0.315 0.114 0.407

Thurs PM 34907 73953 10472 22186 0.000 0.321 0.000 0.507

COAS06(01) Wed AM 0.241 0.076 0.216 0.289

Wed PM 0.207 0.066 0.333 0.191

Thurs AM 0.167 0.053 0.065 0.308

Thurs PM 0.175 0.055 0.055 0.216

FLDW07(02) Wed AM 6523 13819 1957 4146 0.130 0.052 0.000 0.309

Wed PM 5764 12212 1729 3664 0.148 0.059 0.000 0.284

Thurs AM 5357 11348 1607 3405 0.155 0.061 0.040 0.283

Thurs PM 5873 12442 1762 3733 0.150 0.060 0.032 0.228

FLDW08(01) Wed AM 0.187 0.059 0.255 0.265

Wed PM 0.114 0.036 0.200 0.240

Thurs AM 0.123 0.039 0.143 1.020

Thurs PM 0.671 0.212 1.000 2.500

FLDW10(01) Wed AM 0.077 0.024 0.250 0.729

Wed PM 0.087 0.028 0.150 0.715

Thurs AM 0.094 0.030 0.192 0.554

Thurs PM 0.067 0.021 0.077 0.546

FLGS01(01) Thurs AM 0.195 0.062 0.268 0.357

Thurs PM 0.185 0.059 0.500 0.395

Fri AM 0.196 0.062 0.237 0.382

Fri PM 0.198 0.063 0.200 0.412

FLGS04(01) Wed AM 0.035 0.011 0.084 0.157

Wed PM 0.037 0.012 0.041 0.125

Thurs AM 0.034 0.011 0.108 0.154

Thurs PM 0.030 0.010 0.016 0.124

FLGS04(02) Wed AM 0.042 0.013 0.053 0.156

Wed PM 0.040 0.013 0.028 0.140

Thurs AM 0.041 0.013 0.069 0.152

Thurs PM 0.041 0.013 0.039 0.138

OA fraction 

- CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
65

System ID Day Period L/s cfm L/s cfm

FLGS11(01) Wed AM 0.161 0.051 0.045 0.211

Wed PM 0.104 0.033 0.034 0.122

Thurs AM 0.189 0.060 0.138 0.246

Thurs PM 0.088 0.028 0.038 0.134

FLGS11(02) Wed AM 0.144 0.045 0.036 0.257

Wed PM 0.111 0.035 0.030 0.143

Thurs AM 0.162 0.051 0.074 0.263

Thurs PM 0.111 0.035 0.047 0.165

FLGS12(01) Wed AM 8386 17766 2516 5330 0.164 0.065

Wed PM 8003 16955 2401 5086 0.171 0.067 0.125 0.178

Thurs AM 7322 15512 2196 4653 0.185 0.072 0.085 0.241

Thurs PM 7237 15331 2171 4599 0.175 0.069 0.156 0.159

GADS01(01) Wed AM 3304 6999 991 2100 0.396 0.147 0.250 0.729

Wed PM 3996 8465 1199 2540 0.322 0.121 0.364 0.684

Thurs AM 3209 6799 963 2040 0.419 0.155 0.333 0.621

Thurs PM 3524 7466 1057 2240 0.378 0.140 0.500 0.791

GADS02(01) Wed AM 0.162 0.051 0.171 0.350

Wed PM 0.159 0.050 0.167 0.239

Thurs AM 0.220 0.069 0.083 0.394

Thurs PM 0.162 0.051 0.185 0.266

GADS02(02) Wed AM 0.253 0.080 0.125 0.356

Wed PM 0.196 0.062 0.175 0.252

Thurs AM 0.208 0.066 0.125 0.445

Thurs PM 0.184 0.058 0.188 0.300

GADS03(01) Wed AM 0.080 0.025 0.091 0.125

Wed PM 0.085 0.027 0.000 0.101

Thurs AM 0.085 0.027 0.049 0.137

Thurs PM 0.087 0.027 0.000 0.105

ILBS01(01) Wed AM 0.111 0.264

Wed PM 0.000 0.189

Thurs AM 0.222 0.402

Thurs PM 0.160 0.286

ILBS01(02) Wed AM 0.263 0.385

Wed PM 0.222 0.322

Thurs AM 0.000 0.458

Thurs PM 0.000 0.167

ILBS02(01) Wed AM 7636 16177 2291 4853 0.083 0.026 0.000 0.645

Wed PM 6207 13149 1862 3945 0.073 0.023 0.074 0.525

Thurs AM 6942 14706 2082 4412 0.068 0.021 0.125 0.891

Thurs PM 6737 14274 2021 4282 0.076 0.024 0.000 0.789

ILBS03(01) Wed AM 10354 21935 3106 6581 0.362 0.219 0.333 0.497

Wed PM 10904 23101 3271 6930 0.356 0.220 0.286 0.420

Thurs AM 8723 18481 2617 5544 0.468 0.194 0.333 0.497

Thurs PM 9076 19229 2723 5769 0.421 0.205 0.167 0.478

LAGW04(01) Wed AM 0.062 0.020 0.333 0.994

Wed PM 0.045 0.014 0.000 0.568

Thurs AM 0.061 0.019 0.286 0.420

Thurs PM 0.054 0.017 0.152 0.433

LAGW04(02) Wed AM 0.073 0.023 0.333 0.994

Wed PM 0.077 0.025 0.125 0.356

Thurs AM 0.081 0.026 0.125 0.356

Thurs PM 0.075 0.024 0.111 0.316

LAGW05(01) Wed AM 6913 14646 2074 4394 0.190 0.063

Wed PM 6780 14365 2034 4309 0.219 0.073

Thurs AM 6714 14224 2014 4267 0.202 0.067

Thurs PM 6758 14317 2027 4295 0.217 0.072

LAGW05(02) Wed AM

Wed PM 0.443 0.236

Thurs AM

Thurs PM

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
66

System ID Day Period L/s cfm L/s cfm

LAGW06(01) Wed AM 0.126 0.040

Wed PM 0.122 0.039

Thurs AM 0.122 0.039

Thurs PM 0.123 0.039

LAGW06(02) Wed AM

Wed PM

Thurs AM

Thurs PM

MABW05(01) Wed AM 3767 7980 1130 2394 0.099 0.288 0.178 0.206

Wed PM 5013 10621 1504 3186 0.279 0.240 0.292 0.192

Thurs AM 5268 11161 1580 3348 0.196 0.262 0.383 0.246

Thurs PM 5098 10801 1529 3240 0.254 0.246 0.250 0.190

MABW05(02) Wed AM 5466 11581 1640 3474 0.104 0.287 0.137 0.192

Wed PM 6458 13681 1937 4104 0.000 0.339 0.101 0.184

Thurs AM 6118 12961 1835 3888 0.050 0.302 0.059 0.244

Thurs PM 6684 14161 2005 4248 0.006 0.314 0.101 0.179

MABW06(01) Wed AM 0.930 0.294 0.857 0.665

Wed PM 0.966 0.305 0.926 0.714

Thurs AM 0.967 0.306 0.839 0.595

Thurs PM 0.969 0.306 0.778 0.398

MABW08(01) Wed AM 4828 10228 1448 3068 0.626 0.163 0.500 0.791

Wed PM 4411 9346 1323 2804 0.673 0.155 0.593 0.609

Thurs AM 5898 12496 1769 3749 0.532 0.180 0.500 0.791

Thurs PM 5353 11341 1606 3402 0.585 0.170 0.500 0.791

MABW08(02) Wed AM 426 903 128 271 0.966 0.403 0.900 0.951

Wed PM 456 966 137 290 0.962 0.400 0.963 0.727

Thurs AM 446 945 134 284 0.961 0.400 1.000 1.000

Thurs PM 595 1260 178 378 0.949 0.393 1.000 1.000

MDDS01(01) Wed AM 18850 39936 5655 11981 0.113 0.284 0.138 0.615

Wed PM 21269 45060 6381 13518 0.063 0.298 0.565 3.531

Thurs AM 25084 53142 7525 15943 0.000 0.385 0.083 0.651

Thurs PM 21969 46543 6591 13963 0.000 0.346 0.000 0.710

MDDS03(01) Wed AM 0.157 0.050 0.143 0.204

Wed PM 0.132 0.042 0.167 0.478

Thurs AM 0.142 0.045 0.125 0.356

Thurs PM 0.136 0.043 0.200 0.288

MDDS03(02) Wed AM 0.032 0.010 0.333 2.485

Wed PM 0.016 0.005 0.012 0.175

Thurs AM 0.032 0.010 0.000 0.284

Thurs PM 0.032 0.010 0.000 0.237

MDDS04(01) Wed AM 2266 4800 680 1440 0.114 0.284 0.023 0.202

Wed PM 2247 4760 674 1428 0.112 0.285 0.000 0.145

Thurs AM 2285 4840 685 1452 0.102 0.288 0.070 0.166

Thurs PM 2228 4720 668 1416 0.085 0.292 0.021 0.149

MDDS04(02) Wed AM 1570 3325 471 998 0.267 0.243 0.197 0.295

Wed PM 1469 3112 441 933 0.237 0.251 0.143 0.255

Thurs AM 1547 3278 464 983 0.224 0.254 0.141 0.264

Thurs PM 1435 3040 431 912 0.260 0.245 0.104 0.205

MIBW01(01) Wed AM 1159 2455 348 737 0.594 0.168 0.469 0.319

Wed PM 1042 2207 313 662 0.652 0.159 0.286 0.420

Thurs AM 1259 2666 378 800 0.560 0.175 0.269 0.563

Thurs PM 1478 3131 443 939 0.509 0.185 0.345 0.516

MIBW01(02) Wed AM 2093 4433 628 1330 0.088 0.291 0.250 0.607

Wed PM 1712 3627 514 1088 0.381 0.214 0.222 0.537

Thurs AM 0.105 0.748

Thurs PM 0.345 0.516

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
67

System ID Day Period L/s cfm L/s cfm

MIBW03(01) Wed AM 11505 24374 3451 7312 0.285 0.238 0.250 0.364

Wed PM 12512 26509 3754 7953 0.218 0.256 0.353 0.441

Thurs AM 12368 26203 3710 7861 0.244 0.249 0.313 0.463

Thurs PM 9264 19626 2779 5888 0.337 0.225 0.667 0.567

MIBW04(01) Wed AM 3002 6361 901 1908 0.305 0.233 0.454 0.424

Wed PM 2700 5720 810 1716 0.373 0.216 0.356 0.504

Thurs AM 3767 7980 1130 2394 0.251 0.247 0.326 0.418

Thurs PM 3455 7321 1037 2196 0.323 0.229 0.408 0.502

MIBW04(02) Wed AM 3455 7321 1037 2196 0.386 0.213 0.333 0.414

Wed PM 3540 7500 1062 2250 0.347 0.223 0.400 0.508

Thurs AM 3795 8041 1139 2412 0.259 0.245 0.217 0.524

Thurs PM 3474 7360 1042 2208 0.409 0.208 0.357 0.536

MNBW01(01) Wed AM 0.259 0.082 0.500 0.395

Wed PM 0.231 0.073 0.405 0.412

Thurs AM 0.250 0.079 0.333 0.497

Thurs PM 0.247 0.078 0.429 0.440

MNBW02(01) Wed AM 0.278 0.088 0.412 0.450

Wed PM 0.295 0.093 0.400 0.609

Thurs AM 0.416 0.131 0.400 0.609

Thurs PM 0.418 0.132 0.400 0.609

MNBW02(02) Wed AM 0.295 0.093 0.250 0.729

Wed PM 0.425 0.134 0.333 0.994

Thurs AM 0.624 0.197 0.333 0.994

Thurs PM 0.457 0.145 0.500 1.581

MNBW04(01) Wed AM 0.721 0.228 0.714 0.414

Wed PM 0.821 0.260 1.077 0.799

Thurs AM 0.707 0.223 0.769 0.686

Thurs PM 0.856 0.271 0.867 0.624

MOCS01(01) Wed AM 0.200 0.288

Wed PM 0.273 0.267

Thurs AM 0.211 0.380

Thurs PM 0.200 0.288

MOCS05(01) Wed AM 0.329 0.104 0.333 0.497

Wed PM 0.353 0.112 0.230 0.363

Thurs AM 0.220 0.070 0.250 0.364

Thurs PM 0.026 0.008 0.214 0.258

NCDW02(01) Wed AM 0.934 0.295 0.800 1.207

Wed PM 0.946 0.299 0.750 1.105

Thurs AM 0.507 0.160 0.375 0.944

Thurs PM 0.829 0.262 0.667 1.133

NCDW02(02) Wed AM 0.867 0.274 0.800 1.207

Wed PM 0.819 0.259 0.750 1.105

Thurs AM 0.464 0.147 0.438 0.965

Thurs PM 0.761 0.241 0.667 1.133

NCDW03(01) Wed AM 185 391 55 117 0.288 0.142

Wed PM 141 299 42 90 0.135 0.193

Thurs AM 177 376 53 113 0.213 0.154

Thurs PM 178 378 54 113 0.179 0.171

NCDW03(02) Wed AM 79 167 24 50 0.119 0.170

Wed PM 76 162 23 49 0.213 0.154

Thurs AM 78 166 23 50 0.152 0.144

Thurs PM 81 172 24 51 0.072 0.205

NCDW03(03) Wed AM 12 25 4 8 0.000 0.125

Wed PM 12 25 4 8 0.000 0.222

Thurs AM 12 25 4 8 0.000 0.143

Thurs PM 12 25 4 8 0.759 0.291 0.217 0.629

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
68

System ID Day Period L/s cfm L/s cfm

NCDW03(04) Wed AM 12 25 4 7 0.862 0.343 0.000 3.550

Wed PM 12 25 4 7 0.858 0.341

Thurs AM 12 25 4 7 0.866 0.345

Thurs PM 12 25 4 7 0.806 0.314

NCDW03(05) Wed AM 57 121 17 36

Wed PM 61 129 18 39

Thurs AM 63 134 19 40 0.160 0.152

Thurs PM 59 126 18 38 0.119 0.170

NCDW06(01) Wed AM 0.384 0.121 0.489 0.350

Wed PM 0.567 0.179 0.429 0.550

Thurs AM 0.717 0.227 0.529 0.471

Thurs PM 0.369 0.117 0.333 0.331

NECW01(01) Wed AM 0.330 0.104 0.454 0.359

Wed PM 0.398 0.126 0.601 0.598

Thurs AM 0.357 0.113 0.475 0.437

Thurs PM 0.584 0.185 0.625 0.651

NECW02(01) Wed AM 0.789 0.250 0.700 1.726

Wed PM 0.566 0.179 0.667 1.133

Thurs AM 0.755 0.239 0.700 1.726

Thurs PM 0.733 0.232 0.800 1.811

NECW03(01) Wed AM 0.686 0.217 0.331 0.426

Wed PM 0.669 0.212 0.328 0.555

Thurs AM 0.466 0.147 0.263 0.385

Thurs PM 0.881 0.279 0.600 0.550

NMES01(01) Wed AM 1718 3640 515 1092 0.511 0.188 0.536 0.573

Wed PM 1252 2652 376 796 0.630 0.234 0.541 0.434

Thurs AM 1491 3159 447 948 0.533 0.196 0.600 0.471

Thurs PM 1356 2873 407 862 0.590 0.218 0.533 0.534

NMES01(02) Wed AM 4579 9702 1374 2910 0.184 0.072 0.324 0.402

Wed PM 4862 10301 1459 3090 0.173 0.068 0.194 0.400

Thurs AM 4271 9048 1281 2714 0.139 0.055 0.225 0.362

Thurs PM 4708 9974 1412 2992 0.165 0.065 0.108 0.384

NMES02(01) Wed AM 1.385 0.438 0.500 0.791

Wed PM 1.241 0.393 0.968 0.635

Thurs AM 1.083 0.343 0.922 1.503

Thurs PM 1.521 0.481 0.810 1.152

NMES03(01) Wed AM 3174 6725 952 2018 0.073 0.296 0.231 0.279

Wed PM 3032 6424 910 1927 0.133 0.279 0.250 0.243

Thurs AM 2802 5937 841 1781 0.102 0.287 0.130 0.310

Thurs PM 2988 6331 897 1899 0.019 0.311 0.083 0.237

NMES03(02) Wed AM 4444 9416 1333 2825 0.110 0.285 0.120 0.285

Wed PM 5509 11671 1653 3501 0.148 0.275 0.222 0.322

Thurs AM 4416 9355 1325 2807 0.193 0.263 0.240 0.291

Thurs PM 5126 10860 1538 3258 0.144 0.276 0.273 0.267

NVAW01(01) Wed AM 1.001 0.316 0.910 1.427

Wed PM 0.673 0.213 0.882 1.387

Thurs AM 0.545 0.172 0.692 1.323

Thurs PM 0.277 0.088 0.500 0.791

NVAW02(01) Wed AM 1242 2632 373 790 0.950 0.139 0.655 0.768

Wed PM 1210 2563 363 769 0.956 0.139 1.000 1.000

Thurs AM 981 2078 294 623 0.959 0.139 1.000 4.000

Thurs PM 1912 4052 574 1216 0.930 0.138 0.333 0.994

NVAW03(01) Wed AM 1.091 0.345 0.444 1.720

Wed PM 1.133 0.358 0.500 1.581

Thurs AM 1.099 0.348 0.333 0.994

Thurs PM 1.099 0.348 1.000 2.000

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
69

System ID Day Period L/s cfm L/s cfm

NVAW03(02) Wed AM 0.488 0.154 0.444 1.720

Wed PM 0.503 0.159 0.700 1.726

Thurs AM 0.513 0.162 0.500 0.791

Thurs PM 0.498 0.157 0.000 2.840

NYBS01(01) Wed AM 26968 57134 8090 17140 0.147 0.275 0.167 0.597

Wed PM 29021 61484 8706 18445 0.118 0.283 0.214 0.517

Thurs AM 28473 60324 8542 18097 0.109 0.286 0.241 0.502

Thurs PM 28473 60324 8542 18097 0.127 0.281 0.080 0.567

NYBS01(02) Wed AM 0.147 0.047 0.308 0.569

Wed PM 0.149 0.047 0.133 0.476

Thurs AM 0.143 0.045 0.267 0.488

Thurs PM 0.154 0.049 0.429 0.440

NYBS02(01) Wed AM 0.100 0.032 0.115 0.583

Wed PM 0.096 0.030 0.513 0.668

Thurs AM 0.074 0.023 0.238 0.433

Thurs PM 0.136 0.043 0.368 0.331

NYBS02(02) Wed AM 0.090 0.029 0.714 1.241

Wed PM 0.126 0.040 0.615 0.639

Thurs AM 0.117 0.037 0.441 0.655

Thurs PM 0.163 0.052 0.494 0.512

NYBS04(01) Wed AM 0.014 0.004 0.000 0.473

Wed PM 0.013 0.004 0.077 0.273

Thurs AM 0.766 0.242 0.444 0.860

Thurs PM 0.011 0.004 0.154 0.550

NYBS04(02) Wed AM 0.037 0.012 0.000 0.473

Wed PM 0.035 0.011 0.040 0.283

Thurs AM 0.912 0.288 0.400 0.762

Thurs PM 0.035 0.011 0.086 0.406

NYBS05(01) Wed AM 0.255 0.081 0.326 0.216

Wed PM 0.238 0.075 0.208 0.234

Thurs AM 0.247 0.078 0.270 0.225

Thurs PM 0.227 0.072 0.328 0.188

NYBS07(01) Wed AM 4062 8606 1219 2582 0.199 0.077 0.400 0.762

Wed PM 4253 9010 1276 2703 0.199 0.077 0.432 0.416

Thurs AM 4157 8808 1247 2642 0.205 0.080 0.364 0.684

Thurs PM 4005 8485 1201 2545 0.200 0.078 0.063 0.443

ORIS03(01) Wed AM 0.448 0.144 0.364 0.684

Wed PM 0.417 0.134 0.174 0.624

Thurs AM 0.451 0.145 0.295 0.604

Thurs PM 0.466 0.150 0.286 0.525

ORIS03(03) Wed AM 0.364 0.684

Wed PM 0.240 0.582

Thurs AM 0.348 0.567

Thurs PM 0.214 0.517

ORIS04(01) Wed AM 0.833 1.534

Wed PM 0.667 1.416

Thurs AM 0.800 1.811

Thurs PM 0.167 1.195

PABS03(01) Wed AM 16550 35064 4965 10519 0.000 0.328 0.205 0.328

Wed PM 16360 34661 4908 10398 0.000 0.348 0.000 0.374

Thurs AM 17977 38087 5393 11426 0.000 0.374 0.091 0.323

Thurs PM 18929 40102 5679 12031 0.000 0.363 0.053 0.373

PABS04(01) Wed AM 0.197 0.062 0.125 0.165

Wed PM 0.193 0.061 0.215 0.159

Thurs AM 0.195 0.062 0.214 0.207

Thurs PM 0.200 0.063 0.188 0.180

PABS04(02) Wed AM 0.038 0.012 0.045 0.167

Wed PM 0.038 0.012 0.047 0.157

Thurs AM 0.035 0.011 0.096 0.208

Thurs PM 0.035 0.011 0.063 0.177

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
70

System ID Day Period L/s cfm L/s cfm

SCDW01(01) Wed AM 0.241 0.076 0.212 0.222

Wed PM 0.249 0.079

Thurs AM 0.238 0.075 0.203 0.144

Thurs PM 0.220 0.070 0.185 0.155

SCDW02(01) Wed AM 0.182 0.057 0.286 0.420

Wed PM 0.187 0.059 0.250 0.364

Thurs AM 0.191 0.060 0.286 0.420

Thurs PM 0.155 0.049 0.500 0.527

SDBW01(01) Wed AM 0.456 0.144 0.385 0.389

Wed PM 0.517 0.163 0.471 0.460

Thurs AM 0.523 0.165 0.325 0.372

Thurs PM 0.546 0.173 0.455 0.471

SDBW02(01) Wed AM 0.444 0.140 0.444 0.344

Wed PM 0.293 0.093 0.444 0.344

Thurs AM 0.283 0.090 0.333 0.497

Thurs PM 0.236 0.074 0.250 0.364

SDBW04(01) Wed AM 9318 19742 2795 5922 0.214 0.257 0.094 0.444

Wed PM 8062 17081 2419 5124 0.199 0.261 0.115 0.548

Thurs AM 7798 16521 2339 4956 0.195 0.262 0.140 0.499

Thurs PM 7534 15961 2260 4788 0.216 0.256 0.167 0.478

TNDS05(01) Wed AM 1.000 0.316

Wed PM 1.000 0.316

Thurs AM 1.000 0.316

Thurs PM 1.000 0.316

TNDS05(02) Wed AM 1.000 0.316

Wed PM 1.000 0.316

Thurs AM 1.000 0.316

Thurs PM 1.000 0.316

TNDS06(01) Wed AM 67909 143871 20373 43161 0.213 0.257 0.276 0.343

Wed PM 67403 142799 20221 42840 0.086 0.292 0.335 0.284

Thurs AM 58901 124788 17670 37437 0.130 0.280 0.208 0.301

Thurs PM 68010 144087 20403 43226 0.022 0.310 0.222 0.322

TNDS07(01) Wed AM 0.024 0.008 0.000 0.710

Wed PM 0.030 0.009 0.200 0.577

Thurs AM 0.030 0.010 0.000 0.568

Thurs PM 0.159 0.050 0.000 0.710

TNFS08(01) Wed AM 0.204 0.064 0.196 0.160

Wed PM 0.245 0.077 0.205 0.168

Thurs AM 0.229 0.072 0.200 0.176

Thurs PM 0.180 0.057 0.176 0.191

TNFS085(02) Wed AM 977 2070 293 621 0.269 0.102 0.412 0.197

Wed PM 1051 2227 315 668 0.222 0.086 0.231 0.186

Thurs AM 1056 2236 317 671 0.226 0.087 0.202 0.221

Thurs PM 1019 2160 306 648 0.225 0.087 0.211 0.206

TNFS09(01) Wed AM 4319 9150 1296 2745 0.369 0.217 0.200 0.288

Wed PM 4259 9024 1278 2707 0.323 0.229 0.185 0.266

Thurs AM 4289 9087 1287 2726 0.272 0.242 0.231 0.279

Thurs PM 4170 8835 1251 2650 0.297 0.235 0.200 0.180

TNFS09(02) Wed AM 0.076 0.024 0.165 0.181

Wed PM 0.071 0.022 0.000 0.151

Thurs AM 0.053 0.017 0.056 0.157

Thurs PM 0.057 0.018 0.050 0.142

TNFS10(01) Wed AM 3326 7047 998 2114 0.688 0.153 0.634 0.681

Wed PM 5837 12367 1751 3710 0.535 0.180 0.444 0.860

Thurs AM 3518 7452 1055 2236 0.703 0.151 0.603 0.565

Thurs PM 3084 6534 925 1960 0.705 0.151 0.529 0.941

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
71

System ID Day Period L/s cfm L/s cfm

TXFS01(01) Wed AM 0.061 0.173

Wed PM 0.045 0.014 0.058 0.131

Thurs AM 0.043 0.014 0.071 0.204

Thurs PM 0.040 0.013 0.059 0.139

TXFS02(01) Wed AM 0.047 0.015 0.050 0.177

Wed PM 0.050 0.016 0.000 0.167

Thurs AM 0.036 0.011 0.000 0.215

Thurs PM 0.049 0.015 0.000 0.151

TXFS02(02) Wed AM 0.047 0.015 0.040 0.189

Wed PM 0.046 0.015 0.000 0.189

Thurs AM 0.043 0.014 0.000 0.237

Thurs PM 0.044 0.014 0.021 0.150

TXFS07(01) Wed AM 0.128 0.040 0.119 0.327

Wed PM 0.142 0.045 0.240 0.291

Thurs AM 0.142 0.045 0.214 0.258

Thurs PM 0.159 0.050 0.182 0.327

TXFS08(01) Wed AM 0.046 0.015 0.053 0.149

Wed PM 0.049 0.015 0.053 0.149

Thurs AM 0.058 0.018 0.063 0.177

Thurs PM 0.059 0.019 0.080 0.113

TXFS08(02) Wed AM 0.053 0.017 0.100 0.142

Wed PM 0.047 0.015 0.091 0.129

Thurs AM 0.052 0.017 0.056 0.157

Thurs PM 0.049 0.016 0.091 0.129

TXFS09(01) Wed AM 0.192 0.061 0.143 0.204

Wed PM 0.183 0.058 0.200 0.096

Thurs AM 0.188 0.060 0.125 0.178

Thurs PM 0.193 0.061 0.167 0.119

TXFS09(02) Wed AM 0.189 0.060 0.143 0.204

Wed PM 0.180 0.057 0.192 0.111

Thurs AM 0.194 0.061 0.125 0.178

Thurs PM 0.195 0.062 0.083 0.118

TXFW05(01) Wed AM 26244 55602 7873 16680 0.259 0.245 0.516 0.652

Wed PM 25650 54343 7695 16303 0.248 0.248 0.400 0.609

Thurs AM 17274 36598 5182 10979 0.586 0.170 0.161 0.462

Thurs PM 15762 33393 4729 10018 0.623 0.163 0.333 0.497

TXFW06(01) Wed AM 1.004 0.318 0.667 1.133

Wed PM 1.000 0.316 1.000 1.333

Thurs AM 1.001 0.317 0.800 0.724

Thurs PM 1.002 0.317 0.800 0.724

WAIW03(01) Wed AM 1.010 0.319 0.789 0.474

Wed PM 0.886 0.280 0.938 0.606

Thurs AM 1.018 0.322 0.905 0.908

Thurs PM 0.920 0.291 0.929 0.689

WAIW04(01) Wed AM 0.973 0.308 0.600 0.660

Wed PM 0.990 0.313 0.833 0.614

Thurs AM 0.982 0.310 0.500 0.527

Thurs PM 1.003 0.317 0.571 0.465

# of values 186 509 520

Mean 7930 16800 2379 5040 0.377 0.158 0.311 0.601

StdDev 11304 23948 3391 7185 0.350 0.120 0.270 0.625

Minimum 12 25 4 7 0.000 0.004 0.000 0.096

10th percentile 181 384 54 115 0.043 0.017 0.030 0.159

25th percentile 1508 3196 453 959 0.104 0.047 0.110 0.237

Median 4357 9230 1307 2769 0.222 0.144 0.231 0.433

75th percentile 9139 19361 2742 5808 0.594 0.275 0.444 0.711

90th percentile 18414 39012 5524 11703 1.000 0.316 0.750 1.133

Maximum 68010 144087 20403 43226 1.521 0.481 1.200 7.100

OA fraction - 

CO2

Uncert. in 

CO2 OA 

fraction

Recirculation Airflow

Uncertainty in

recirc. airflow Outdoor air 

fraction - 

volumetric

Uncert. in 

vol. OA 

fraction
72

Appendix E: Measured Data for Study Spaces

This appendix presents the following information for the measurements in the study spaces:

Study space ID

Day and time of measurement

Supply airflow per unit floor area and associated uncertainty

Outdoor airflow per person, per unit floor area and in air changes per hour based on volumetric 

airflow measurements (VOL), and associated uncertainties

Outdoor airflow per person, per unit floor area and in air changes per hour based on volumetric 

supply airflow times CO2 -based outdoor air fraction (RATIO), and associated uncertainties

Outdoor airflow rate per person based on peak CO2 analysis (PEAK), and associated 

uncertainties

Changes in the table relative to the original 2004 report are highlighted in yellow.
73

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

ARFW01 Wed AM 8.36 1.65 1.02 0.20 10.3 21.9 0.46 0.09 0.44 2.4 5.1 0.11 0.02 0.13

Wed PM 8.29 1.63 1.02 0.20 14.8 31.4 0.45 0.09 0.42 3.5 7.4 0.11 0.02 0.12

Thur AM 8.24 1.62 1.01 0.20 12.1 25.5 0.47 0.09 0.45 2.8 6.0 0.11 0.02 0.13

Thur PM 8.37 1.65 1.02 0.20 12.6 26.7 0.45 0.09 0.43 3.0 6.3 0.11 0.02 0.12

ARFW02 Wed AM 2.41 0.47 0.34 0.07

Wed PM 2.32 0.46 0.33 0.06 112.7 238.7 1.88 0.37 1.51 27.6 58.5 0.46 0.09 0.45

Thur AM

Thur PM 2.33 0.46 0.33 0.06 81.2 172.1 1.94 0.38 1.54 19.9 42.2 0.48 0.09 0.46

ARFW03 Wed AM 5.04 0.99 0.62 0.12 7.6 16.2 0.34 0.07 0.27 1.8 3.9 0.08 0.02 0.08

Wed PM 5.46 1.08 0.68 0.13 8.1 17.1 0.32 0.06 0.25 2.1 4.4 0.08 0.02 0.08

Thur AM 5.42 1.07 0.67 0.13 7.1 15.1 0.36 0.07 0.29 1.8 3.9 0.09 0.02 0.09

Thur PM 5.35 1.05 0.66 0.13 7.9 16.8 0.34 0.07 0.27 2.0 4.3 0.09 0.02 0.08

AZHS02 Wed AM 6.18 1.22 0.77 0.15 45.9 97.3 2.47 0.49 2.43 18.3 38.7 0.98 0.19 1.05

Wed PM 6.83 1.34 0.85 0.17 128.0 271.2 3.33 0.66 3.28 38.4 81.4 1.00 0.20 1.14

Thur AM 5.44 1.07 0.68 0.13 24.8 52.6 1.55 0.31 1.53 15.6 33.0 0.97 0.19 0.99

Thur PM 5.97 1.17 0.74 0.15 33.6 71.2 2.01 0.40 1.98 16.4 34.8 0.98 0.19 1.03

AZHS04 Wed AM 6.25 1.23 0.86 0.17 0.8 1.6 0.06 0.01 0.06 25.6 54.3 2.54 0.50 1.91

Wed PM 6.21 1.22 0.86 0.17 1.8 3.9 0.06 0.01 0.06 58.0 122.9 2.64 0.52 1.97

Thur AM 6.13 1.21 0.85 0.17 1.9 4.0 0.04 0.01 0.05 71.5 151.5 2.29 0.45 1.69

Thur PM 5.96 1.17 0.82 0.16 2.3 4.9 0.07 0.01 0.07 65.5 138.7 2.59 0.51 1.92

AZHW10 Wed AM 5.72 1.13 0.86 0.17 199.5 422.7 5.72 1.13 6.15 30.1 63.8 0.86 0.17 1.41

Wed PM 5.56 1.09 0.83 0.16 247.3 523.8 5.56 1.09 5.97 37.1 78.5 0.83 0.16 1.37

Thur AM 6.21 1.22 0.94 0.18 228.7 484.6 6.21 1.22 6.67 34.6 73.3 0.94 0.18 1.53

Thur PM 6.25 1.23 0.95 0.19 230.2 487.7 6.25 1.23 6.71 34.9 74.0 0.95 0.19 1.55

AZHW11 Wed AM 5.26 1.03 0.91 0.18 25.1 53.1 1.00 0.20 0.98 34.7 73.6 1.39 0.27 1.37

Wed PM 6.20 1.22 1.07 0.21 57.2 121.1 1.82 0.36 1.78 46.3 98.2 1.47 0.29 1.47

Thur AM 6.12 1.20 1.06 0.21 60.1 127.4 2.05 0.40 2.00 41.0 86.9 1.40 0.27 1.41

Thur PM 6.70 1.32 1.16 0.23 75.7 160.3 2.30 0.45 2.25 50.0 106.0 1.52 0.30 1.53

AZHW12 Wed AM 1.40 0.28 0.20 0.04 10.7 22.7 0.38 0.08 0.37 2.9 6.1 0.10 0.02 0.12

Wed PM 1.39 0.27 0.20 0.04 12.6 26.7 0.40 0.08 0.39 3.3 7.1 0.11 0.02 0.12

Thur AM 1.35 0.27 0.20 0.04 9.6 20.3 0.31 0.06 0.30 3.0 6.4 0.10 0.02 0.11

Thur PM 1.42 0.28 0.21 0.04 11.1 23.6 0.33 0.06 0.32 3.6 7.5 0.11 0.02 0.12

CAES17 Wed AM 19.59 3.86 2.77 0.55 64.7 137.0 3.66 0.72 3.60 91.6 194.1 5.18 1.02 5.13

Wed PM 18.72 3.68 2.65 0.52 50.2 106.4 2.66 0.52 2.61 97.8 207.2 5.18 1.02 5.11

Thur AM 21.11 4.15 2.99 0.59 235.6 499.1 11.90 2.34 11.71 72.7 154.1 3.67 0.72 4.14

Thur PM 20.13 3.96 2.85 0.56 113.8 241.0 6.16 1.21 6.06 86.7 183.6 4.69 0.92 4.73

CAEW07 Wed AM 5.28 1.04 0.91 0.18 57.2 121.2 1.62 0.32 1.44 19.0 40.2 0.54 0.11 0.54

Wed PM 5.60 1.10 0.97 0.19 161.3 341.8 4.86 0.96 4.33 53.5 113.4 1.61 0.32 1.62

Thur AM 5.28 1.04 0.91 0.18 155.9 330.3 4.03 0.79 3.59 51.7 109.6 1.34 0.26 1.34

Thur PM 5.20 1.02 0.90 0.18 180.9 383.3 5.45 1.07 4.86 60.0 127.1 1.81 0.36 1.82

Study Space 

ID

Uncertainty in

supply airflow

Period

Volumetric supply 

airflow

SUPPLY AIRFLOW

Volumetric Uncertainty in volumetric OA

OUTDOOR AIRFLOW
74
75

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

CAJW24 Tues AM 6.26 1.23 1.08 0.21 63.2 133.8 4.33 0.85 4.12 20.9 44.4 1.44 0.28 1.54

Tues PM 6.72 1.32 1.16 0.23 3.3 7.0 0.24 0.05 0.23 1.1 2.3 0.08 0.02 0.09

Wed AM 6.26 1.23 1.08 0.21 64.1 135.8 4.33 0.85 4.12 21.3 45.0 1.44 0.28 1.54

Wed PM 7.14 1.41 1.24 0.24 3.8 8.0 0.24 0.05 0.23 1.2 2.6 0.08 0.02 0.09

Thur AM 7.56 1.49 1.31 0.26 77.3 163.8 5.30 1.04 5.04 25.6 54.3 1.76 0.35 1.89

Thur PM 7.60 1.50 1.32 0.26 113.0 239.4 6.73 1.33 6.41 37.5 79.4 2.23 0.44 2.40

CAJW25 Wed AM 4.96 0.98 0.86 0.17 47.6 100.9 2.67 0.53 2.56 15.8 33.5 0.89 0.17 0.96

Wed PM 5.23 1.03 0.91 0.18 85.0 180.0 5.00 0.98 4.79 28.2 59.7 1.66 0.33 1.79

Thur AM 4.62 0.91 0.80 0.16 61.5 130.3 3.28 0.65 3.14 20.4 43.2 1.09 0.21 1.18

Thur PM 5.14 1.01 0.89 0.18 78.5 166.4 5.26 1.04 5.04 26.0 55.2 1.74 0.34 1.88

CAJW26 Wed AM 5.26 1.04 0.91 0.18 133.7 283.3 5.98 1.18 5.73 44.4 94.0 1.98 0.39 2.14

Wed PM 5.92 1.17 1.03 0.20 115.1 243.8 6.58 1.30 6.30 38.2 80.9 2.18 0.43 2.36

Thur AM 5.52 1.09 0.96 0.19 88.5 187.5 5.89 1.16 5.64 29.3 62.2 1.95 0.38 2.11

Thur PM 5.80 1.14 1.00 0.20 87.7 185.7 5.47 1.08 5.24 29.1 61.6 1.81 0.36 1.96

COAS02 Wed AM 3.37 0.66 1.06 0.21 6.9 14.6 0.24 0.05 0.17 2.3 4.8 0.08 0.02 0.06

Wed PM 2.99 0.59 0.91 0.18 9.5 20.2 0.32 0.06 0.23 3.2 6.7 0.11 0.02 0.09

Thur AM 3.28 0.65 1.01 0.20 9.6 20.4 0.29 0.06 0.21 3.2 6.8 0.10 0.02 0.08

Thur PM 3.59 0.71 1.08 0.21 15.8 33.4 0.46 0.09 0.33 5.2 11.1 0.15 0.03 0.12

COAS04 Wed AM 5.83 1.15 1.01 0.20 4.4 9.4 0.13 0.03 0.10 60.0 127.1 1.81 0.36 1.30

Wed PM 5.94 1.17 1.03 0.20 12.7 26.8 0.39 0.08 0.28 57.7 122.3 1.77 0.35 1.28

Thur AM 5.71 1.12 0.99 0.19 1.0 2.1 0.03 0.01 0.02 67.4 142.8 1.80 0.35 1.30

Thur PM 5.85 1.15 1.01 0.20 0.0 0.0 0.00 0.00 0.00 60.1 127.3 1.9 0.37 1.35

COAS06 Wed AM 2.80 0.55 0.40 0.08 27.3 57.7 0.68 0.13 0.64 8.6 18.3 0.21 0.04 0.23

Wed PM 3.52 0.69 0.50 0.10 25.6 54.3 0.73 0.14 0.69 8.1 17.2 0.23 0.05 0.25

Thur AM 4.71 0.93 0.67 0.13 22.8 48.4 0.78 0.15 0.75 7.2 15.3 0.25 0.05 0.27

Thur PM 3.70 0.73 0.52 0.10 21.6 45.8 0.65 0.13 0.62 6.8 14.5 0.20 0.04 0.22

FLDW07 Wed AM 3.75 0.74 1.06 0.21 22.7 48.1 0.49 0.10 0.40 7.2 15.2 0.15 0.03 0.15

Wed PM 3.38 0.67 0.94 0.19 25.0 53.0 0.50 0.10 0.41 7.9 16.8 0.16 0.03 0.15

Thur AM 3.17 0.62 0.88 0.17 25.2 53.4 0.49 0.10 0.40 8.0 16.9 0.16 0.03 0.15

Thur PM 3.46 0.68 0.96 0.19 24.7 52.4 0.52 0.10 0.43 7.8 16.6 0.16 0.03 0.15

FLDW08 Wed AM 4.55 0.90 0.79 0.16 25.0 53.0 0.85 0.17 0.72 8.3 17.6 0.28 0.06 0.27

Wed PM 4.99 0.98 0.86 0.17 16.3 34.6 0.57 0.11 0.48 5.4 11.5 0.19 0.04 0.18

Thur AM 4.62 0.91 0.80 0.16 12.0 25.4 0.57 0.11 0.48 4.0 8.4 0.19 0.04 0.18

Thur PM 4.64 0.91 0.80 0.16 89.4 189.3 3.11 0.61 2.62 29.6 62.8 1.03 0.20 0.98

FLDW10 Wed AM 2.38 0.47 0.34 0.07 3.7 7.7 0.18 0.04 0.18 1.2 2.4 0.06 0.01 0.06

Wed PM 2.39 0.47 0.34 0.07 4.5 9.5 0.21 0.04 0.20 1.4 3.0 0.07 0.01 0.07

Thur AM 2.43 0.48 0.34 0.07 3.8 8.0 0.23 0.05 0.23 1.2 2.5 0.07 0.01 0.08

Thur PM 2.20 0.43 0.31 0.06 3.3 7.0 0.15 0.03 0.14 1.0 2.2 0.05 0.01 0.05

FLGS01 Thur AM 2.99 0.59 0.42 0.08 16.3 34.6 0.58 0.11 0.57 5.2 10.9 0.18 0.04 0.21

Thur PM 3.31 0.65 0.47 0.09 17.2 36.3 0.61 0.12 0.60 5.4 11.5 0.19 0.04 0.22

Fri AM 2.89 0.57 0.41 0.08 18.1 38.3 0.57 0.11 0.56 5.7 12.1 0.18 0.04 0.20

Fri PM 3.14 0.62 0.44 0.09 18.0 38.2 0.62 0.12 0.61 5.7 12.1 0.20 0.04 0.22

SUPPLY AIRFLOW OUTDOOR AIRFLOW

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric Uncertainty in volumetric OA Study Space 

ID Period
76

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

FLGS04 Wed AM 9.70 1.91 1.41 0.28 6.9 14.6 0.38 0.08 0.38 1.8 3.8 0.10 0.02 0.12

Wed PM 9.90 1.95 1.43 0.28 7.5 15.8 0.39 0.08 0.38 1.9 4.1 0.10 0.02 0.12

Thur AM 9.93 1.95 1.44 0.28 7.8 16.6 0.38 0.08 0.38 2.1 4.4 0.10 0.02 0.12

Thur PM 10.24 2.01 1.49 0.29 7.9 16.6 0.39 0.08 0.38 2.1 4.4 0.10 0.02 0.12

FLGS11 Wed AM 2.15 0.42 0.26 0.05 11.9 25.2 0.32 0.06 0.37 2.8 5.9 0.08 0.02 0.11

Wed PM 3.00 0.59 0.37 0.07 13.1 27.8 0.32 0.06 0.36 3.1 6.5 0.08 0.01 0.11

Thur AM 1.77 0.35 0.22 0.04 12.0 25.5 0.31 0.06 0.35 2.8 6.0 0.07 0.01 0.10

Thur PM 2.96 0.58 0.36 0.07 11.6 24.6 0.29 0.06 0.33 2.7 5.8 0.07 0.01 0.10

FLGS12 Wed AM 9.03 1.78 2.48 0.49 37.3 79.1 1.48 0.29 1.58 11.8 25.0 0.47 0.09 0.57

Wed PM 8.69 1.71 2.37 0.47 34.5 73.1 1.49 0.29 1.60 10.9 23.1 0.47 0.09 0.58

Thur AM 8.09 1.59 2.18 0.43 35.4 75.0 1.50 0.29 1.60 11.2 23.7 0.47 0.09 0.58

Thur PM 7.90 1.55 2.15 0.42 25.6 54.3 1.38 0.27 1.48 8.1 17.2 0.44 0.09 0.53

GADS01 Wed AM 2.42 0.48 0.58 0.11 32.8 69.5 0.96 0.19 0.91 10.4 22.0 0.30 0.06 0.33

Wed PM 2.61 0.51 0.64 0.13 35.7 75.7 0.84 0.17 0.79 11.3 24.0 0.27 0.05 0.29

Thur AM 2.44 0.48 0.58 0.11 41.3 87.5 1.02 0.20 0.97 13.1 27.7 0.32 0.06 0.35

Thur PM 2.51 0.49 0.60 0.12 39.0 82.6 0.95 0.19 0.90 12.3 26.1 0.30 0.06 0.32

GADS02 Wed AM 3.06 0.60 0.37 0.07 36.0 76.3 0.63 0.12 0.60 8.6 18.2 0.15 0.03 0.18

Wed PM 3.52 0.69 0.43 0.08 29.9 63.4 0.62 0.12 0.59 7.0 14.9 0.15 0.03 0.17

Thur AM 3.05 0.60 0.37 0.07 35.4 74.9 0.65 0.13 0.61 8.3 17.6 0.15 0.03 0.18

Thur PM 3.71 0.73 0.45 0.09 33.9 71.8 0.64 0.13 0.61 8.0 16.9 0.15 0.03 0.18

GADS03 Wed AM 5.79 1.14 0.82 0.16 11.7 24.7 0.46 0.09 0.46 3.7 7.8 0.15 0.03 0.17

Wed PM 5.53 1.09 0.78 0.15 9.9 21.0 0.47 0.09 0.47 3.1 6.6 0.15 0.03 0.17

Thur AM 5.51 1.08 0.78 0.15 10.8 22.9 0.47 0.09 0.47 3.4 7.2 0.15 0.03 0.17

Thur PM 5.44 1.07 0.77 0.15 11.6 24.7 0.47 0.09 0.47 3.7 7.8 0.15 0.03 0.17

ILBS01 Wed AM 5.55 1.09 0.72 0.14

Wed PM 5.61 1.10 0.73 0.14

Thur AM 5.34 1.05 0.69 0.14

Thur PM 5.68 1.12 0.74 0.15

ILBS02 Wed AM 7.32 1.44 1.04 0.20 18.1 38.4 0.61 0.12 0.68 5.7 12.1 0.19 0.04 0.25

Wed PM 7.60 1.50 1.08 0.21 18.9 40.1 0.56 0.11 0.63 6.0 12.7 0.18 0.03 0.23

Thur AM 7.12 1.40 1.01 0.20 21.6 45.8 0.48 0.10 0.55 6.8 14.5 0.15 0.03 0.20

Thur PM 7.28 1.43 1.03 0.20 23.6 50.0 0.55 0.11 0.62 7.5 15.8 0.17 0.03 0.22

ILBS03 Wed AM 10.25 2.02 1.45 0.29 139.9 296.3 3.71 0.73 3.82 84.6 179.2 2.24 0.44 2.40

Wed PM 10.70 2.11 1.51 0.30 113.7 240.9 3.81 0.75 3.92 70.4 149.2 2.36 0.46 2.52

Thur AM 10.35 2.04 1.46 0.29 218.9 463.7 4.84 0.95 4.98 90.9 192.6 2.01 0.40 2.24

Thur PM 9.91 1.95 1.40 0.28 132.1 279.9 4.17 0.82 4.29 64.2 136.1 2.03 0.40 2.21

LAGW04 Wed AM 5.49 1.08 0.78 0.15 14.9 31.5 0.36 0.07 0.37 3.7 7.7 0.09 0.02 0.11

Wed PM 5.65 1.11 0.81 0.16 12.4 26.4 0.33 0.06 0.34 3.1 6.5 0.08 0.02 0.10

Thur AM 5.32 1.05 0.76 0.15 15.6 33.0 0.37 0.07 0.38 3.8 8.1 0.09 0.02 0.11

Thur PM 5.67 1.12 0.81 0.16 15.2 32.2 0.35 0.07 0.36 3.7 7.9 0.09 0.02 0.11

SUPPLY AIRFLOW OUTDOOR AIRFLOW

Study Space 

ID Period

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric Uncertainty in volumetric OA
L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

LAGW05 Wed AM 16.24 3.20 2.02 0.40 56.8 120.3 3.09 0.61 3.05 18.0 38.0 0.98 0.19 1.10

Wed PM 15.81 3.11 1.97 0.39 95.4 202.2 3.46 0.68 3.41 30.2 63.9 1.09 0.22 1.23

Thur AM 16.12 3.17 2.00 0.39 34.1 72.3 3.25 0.64 3.21 10.8 22.9 1.03 0.20 1.16

Thur PM 15.76 3.10 1.96 0.39 63.0 133.4 3.43 0.67 3.38 19.9 42.2 1.08 0.21 1.22

LAGW06 Wed AM 5.11 1.00 0.72 0.14 14.8 31.4 0.65 0.13 0.64 4.7 9.9 0.20 0.04 0.23

Wed PM 5.14 1.01 0.73 0.14 23.0 48.7 0.63 0.12 0.62 7.3 15.4 0.20 0.04 0.22

Thur AM 5.12 1.01 0.72 0.14 19.9 42.2 0.62 0.12 0.62 6.3 13.4 0.20 0.04 0.22

Thur PM 5.15 1.01 0.73 0.14 17.8 37.8 0.63 0.12 0.62 5.6 12.0 0.20 0.04 0.23

MABW05 Wed AM 0.88 0.17 0.13 0.03 2.7 5.7 0.09 0.02 0.08 6.4 13.5 0.21 0.04 0.19

Wed PM 1.34 0.26 0.21 0.04 10.9 23.0 0.32 0.06 0.30 9.6 20.4 0.29 0.06 0.27

Thur AM 1.29 0.25 0.20 0.04 6.9 14.6 0.23 0.04 0.21 9.0 19.0 0.29 0.06 0.28

Thur PM 1.34 0.26 0.21 0.04 9.3 19.8 0.29 0.06 0.27 9.3 19.6 0.29 0.06 0.27

MABW06 Wed AM 2.23 0.44 0.31 0.06 39.3 83.3 2.07 0.41 2.08 12.4 26.3 0.65 0.13 0.75

Wed PM 2.20 0.43 0.31 0.06 41.1 87.0 2.12 0.42 2.13 13.0 27.5 0.67 0.13 0.77

Thur AM 1.88 0.37 0.27 0.05 41.0 86.9 1.82 0.36 1.82 13.0 27.5 0.57 0.11 0.66

Thur PM 1.82 0.36 0.26 0.05 32.2 68.2 1.77 0.35 1.77 10.2 21.6 0.56 0.11 0.64

MABW08 Wed AM 4.48 0.88 0.76 0.15 54.1 114.6 3.30 0.65 3.30 24.7 52.3 1.50 0.30 1.61

Wed PM 4.56 0.90 0.77 0.15 44.9 95.1 3.47 0.68 3.48 19.9 42.1 1.54 0.30 1.66

Thur AM 4.31 0.85 0.73 0.14 38.3 81.1 2.87 0.56 2.88 9.8 20.7 0.73 0.14 0.89

Thur PM 4.40 0.87 0.74 0.15 36.4 77.1 3.07 0.60 3.08 8.6 18.2 0.73 0.14 0.90

MDDS01 Wed AM 5.06 1.00 0.88 0.17 14.6 30.9 0.57 0.11 0.44 36.7 77.7 1.44 0.28 1.10

Wed PM 5.41 1.06 0.94 0.18 13.7 29.0 0.34 0.07 0.26 64.5 136.7 1.61 0.32 1.23

Thur AM 4.83 0.95 0.84 0.16 0.0 0.0 0.0 0.00 0.00 57.7 122.3 1.88 0.37 1.41

Thur PM 4.73 0.93 0.82 0.16 0.0 0.0 0.0 0.00 0.00 45.9 97.2 1.63 0.32 1.25

MDDS03 Wed AM 2.29 0.45 0.28 0.06 3.8 8.0 0.18 0.04 0.22 1.0 2.1 0.05 0.01 0.07

Wed PM 2.16 0.43 0.27 0.05 2.9 6.2 0.14 0.03 0.16 0.8 1.7 0.04 0.01 0.05

Thur AM 2.25 0.44 0.28 0.05 3.6 7.5 0.17 0.03 0.20 0.9 1.9 0.04 0.01 0.06

Thur PM 2.21 0.43 0.27 0.05 4.0 8.5 0.16 0.03 0.19 1.0 2.2 0.04 0.01 0.06

MDDS04 Wed AM 4.02 0.79 0.49 0.10 17.6 37.4 0.74 0.15 0.60 18.3 38.7 0.77 0.15 0.63

Wed PM 3.81 0.75 0.47 0.09 15.7 33.3 0.63 0.12 0.52 18.5 39.2 0.74 0.15 0.61

Thur AM 3.88 0.76 0.48 0.09 16.4 34.8 0.60 0.12 0.49 20.7 43.9 0.76 0.15 0.63

Thur PM 3.74 0.74 0.46 0.09 13.9 29.5 0.61 0.12 0.50 16.8 35.6 0.73 0.14 0.60

MIBW01 Wed AM 3.08 0.61 0.40 0.08 32.0 67.9 1.15 0.23 1.12 13.6 28.8 0.49 0.10 0.51

Wed PM 3.43 0.67 0.45 0.09 45.4 96.1 1.80 0.35 1.74 11.8 25.1 0.47 0.09 0.55

Thur AM 3.09 0.61 0.40 0.08

Thur PM 3.25 0.64 0.42 0.08

MIBW03 Wed AM 5.37 1.06 0.93 0.18 36.0 76.3 1.53 0.30 1.53 30.4 64.4 1.29 0.25 1.32

Wed PM 5.35 1.05 0.93 0.18 21.2 44.9 1.16 0.23 1.16 25.0 52.9 1.37 0.27 1.39

Thur AM 5.47 1.08 0.95 0.19 27.4 58.1 1.34 0.26 1.34 28.1 59.5 1.37 0.27 1.39

Thur PM 4.67 0.92 0.81 0.16 24.8 52.6 1.57 0.31 1.57 16.8 35.5 1.06 0.21 1.10

SUPPLY AIRFLOW OUTDOOR AIRFLOW

Study Space 

ID Period

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric Uncertainty in volumetric OA

77
78
79

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

NECW02 Wed AM 8.20 1.61 1.42 0.28 226.7 480.3 6.47 1.27 4.89 75.2 159.3 2.15 0.42 1.83

Wed PM 6.34 1.25 1.10 0.22 109.1 231.2 3.59 0.71 2.71 36.2 76.7 1.19 0.23 1.02

Thur AM 8.26 1.63 1.43 0.28 175.9 372.6 6.24 1.23 4.72 58.3 123.6 2.07 0.41 1.76

Thur PM 8.06 1.59 1.40 0.27 310.1 657.0 5.90 1.16 4.46 102.8 217.9 1.96 0.39 1.67

NECW03 Wed AM 6.28 1.24 1.09 0.21 65.8 139.4 4.31 0.85 4.32 21.8 46.2 1.43 0.28 1.62

Wed PM 7.11 1.40 1.23 0.24 78.1 165.4 4.76 0.94 4.77 25.9 54.9 1.58 0.31 1.79

Thur AM 7.34 1.44 1.27 0.25 51.7 109.4 3.42 0.67 3.43 17.1 36.3 1.14 0.22 1.28

Thur PM 6.47 1.27 1.12 0.22 87.0 184.4 5.70 1.12 5.72 28.9 61.2 1.89 0.37 2.14

NMES01 Wed AM 4.88 0.96 0.98 0.19 72.5 153.7 1.51 0.30 1.52 17.5 37.1 0.37 0.07 0.45

Wed PM 4.95 0.97 1.02 0.20 69.9 148.2 1.68 0.33 1.69 17.2 36.5 0.41 0.08 0.51

Thur AM 4.35 0.86 0.90 0.18 68.2 144.4 1.27 0.25 1.28 17.1 36.3 0.32 0.06 0.39

Thur PM 4.78 0.94 0.98 0.19 57.7 122.2 1.54 0.30 1.55 14.2 30.1 0.38 0.07 0.47

NMES02 Wed AM 5.30 1.04 0.75 0.15 183.2 388.2 7.34 1.44 6.85 57.9 122.8 2.32 0.46 2.47

Wed PM 5.88 1.16 0.83 0.16 203.8 431.8 7.30 1.44 6.81 64.5 136.6 2.31 0.45 2.45

Thur AM 6.31 1.24 0.89 0.18 186.5 395.2 6.84 1.35 6.38 59.0 125.0 2.16 0.43 2.30

Thur PM 5.09 1.00 0.72 0.14 201.7 427.2 7.74 1.52 7.21 63.8 135.1 2.45 0.48 2.60

NMES03 Wed AM 4.69 0.92 0.58 0.11 7.2 15.3 0.44 0.09 0.41 15.9 33.7 0.97 0.19 0.91

Wed PM 5.55 1.09 0.69 0.14 20.4 43.1 0.79 0.16 0.74 29.0 61.4 1.13 0.22 1.06

Thur AM 4.79 0.94 0.59 0.12 17.0 35.9 0.77 0.15 0.71 20.9 44.4 0.95 0.19 0.89

Thur PM 5.04 0.99 0.63 0.12 12.3 26.1 0.51 0.10 0.48 25.4 53.8 1.06 0.21 0.99

NVAW01 Wed AM 6.31 1.24 1.09 0.22 151.8 321.5 6.31 1.24 6.62 50.3 106.6 2.09 0.41 2.48

Wed PM 6.57 1.29 1.14 0.22 104.2 220.8 4.42 0.87 4.64 34.6 73.2 1.47 0.29 1.74

Thur AM 6.75 1.33 1.17 0.23 86.6 183.5 3.68 0.72 3.86 28.7 60.9 1.22 0.24 1.44

Thur PM 6.84 1.35 1.18 0.23 50.8 107.6 1.90 0.37 1.99 16.8 35.7 0.63 0.12 0.74

NVAW02 Wed AM 4.15 0.82 0.72 0.14 82.9 175.6 3.95 0.78 3.73 27.5 58.2 1.31 0.26 1.40

Wed PM 4.63 0.91 0.80 0.16 132.3 280.3 4.44 0.87 4.19 43.9 93.0 1.47 0.29 1.57

Thur AM 4.04 0.79 0.70 0.14 133.3 282.3 3.88 0.76 3.67 44.2 93.6 1.29 0.25 1.37

Thur PM 4.61 0.91 0.80 0.16 121.8 258.0 4.30 0.85 4.07 40.4 85.6 1.43 0.28 1.52

NVAW03 Wed AM 8.78 1.73 1.08 0.21 174.0 368.6 7.38 1.45 6.97 45.1 95.5 1.91 0.38 2.17

Wed PM 8.54 1.68 1.05 0.21 148.0 313.6 7.44 1.47 7.03 38.4 81.4 1.93 0.38 2.19

Thur AM 8.51 1.67 1.05 0.21 106.6 225.9 7.36 1.45 6.95 27.7 58.7 1.91 0.38 2.17

Thur PM 8.74 1.72 1.08 0.21 127.8 270.8 7.44 1.46 7.03 33.1 70.1 1.93 0.38 2.19

NYBS01 Wed AM 9.42 1.85 1.37 0.27 35.3 74.9 1.39 0.27 1.43 43.8 92.8 1.72 0.34 1.78

Wed PM 9.88 1.94 1.43 0.28 54.1 114.6 1.27 0.25 1.31 78.1 165.5 1.84 0.36 1.90

Thur AM 9.71 1.91 1.40 0.28 40.8 86.5 1.17 0.23 1.21 62.6 132.6 1.80 0.35 1.86

Thur PM 9.81 1.93 1.42 0.28 35.3 74.7 1.34 0.26 1.38 47.7 101.0 1.81 0.36 1.87

NYBS02 Wed AM 6.72 1.32 0.83 0.16 16.4 34.7 0.63 0.12 0.58 3.9 8.2 0.15 0.03 0.17

Wed PM 6.34 1.25 0.78 0.15 14.6 30.9 0.71 0.14 0.65 3.5 7.4 0.17 0.03 0.19

Thur AM 6.38 1.26 0.78 0.15 13.6 28.9 0.61 0.12 0.55 3.3 6.9 0.15 0.03 0.16

Thur PM 4.39 0.86 0.54 0.11 17.5 37.0 0.66 0.13 0.60 4.1 8.7 0.16 0.03 0.18

SUPPLY AIRFLOW

Period

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric

OUTDOOR AIRFLOW

Study Space 

ID

Uncertainty in volumetric OA
80

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

NYBS04 Wed AM 5.40 1.06 0.76 0.15 3.3 7.1 0.14 0.03 0.14 0.9 1.9 0.04 0.01 0.05

Wed PM 5.42 1.07 0.77 0.15 3.9 8.3 0.13 0.03 0.13 1.0 2.2 0.04 0.01 0.04

Thur AM 5.70 1.12 0.81 0.16 99.0 209.8 4.78 0.94 4.84 24.4 51.6 1.18 0.23 1.46

Thur PM 5.69 1.12 0.80 0.16 3.5 7.5 0.14 0.03 0.14 1.0 2.0 0.04 0.01 0.04

NYBS05 Wed AM 2.50 0.49 0.43 0.09 12.8 27.1 0.64 0.13 0.54 4.2 9.0 0.21 0.04 0.20

Wed PM 2.69 0.53 0.47 0.09 13.8 29.2 0.64 0.13 0.55 4.6 9.7 0.21 0.04 0.20

Thur AM 2.60 0.51 0.45 0.09 14.5 30.8 0.64 0.13 0.55 4.8 10.2 0.21 0.04 0.20

Thur PM 2.62 0.52 0.45 0.09 12.3 26.2 0.59 0.12 0.51 4.1 8.7 0.20 0.04 0.19

NYBS07 Wed AM 4.87 0.96 1.30 0.26 18.3 38.8 0.97 0.19 0.90 5.8 12.3 0.31 0.06 0.32

Wed PM 5.10 1.00 1.36 0.27 27.1 57.5 1.02 0.20 0.94 8.6 18.2 0.32 0.06 0.34

Thur AM 5.03 0.99 1.34 0.26 21.4 45.4 1.03 0.20 0.96 6.8 14.4 0.33 0.06 0.34

Thur PM 4.81 0.95 1.28 0.25 23.8 50.5 0.96 0.19 0.89 7.5 16.0 0.30 0.06 0.32

ORIS03 Wed AM 3.89 0.77 0.71 0.14 64.9 137.6 1.75 0.34 1.62 21.5 45.6 0.58 0.11 0.61

Wed PM 4.52 0.89 0.82 0.16 74.8 158.6 1.88 0.37 1.75 24.8 52.6 0.62 0.12 0.65

Thur AM 3.40 0.67 0.62 0.12 65.6 138.9 1.54 0.30 1.42 21.7 46.1 0.51 0.10 0.53

Thur PM 3.84 0.76 0.70 0.14 108.7 230.2 1.79 0.35 1.66 36.0 76.3 0.59 0.12 0.62

ORIS04 Wed AM

Wed PM 3.98 0.78 0.69 0.14

Thur AM 5.68 1.12 0.98 0.19

Thur PM 5.55 1.09 0.96 0.19

PABS03 Wed AM 3.37 0.66 0.58 0.11 0.0 0.0 0.00 0.00 0.00 34.7 73.6 1.12 0.22 1.09

Wed PM 3.12 0.61 0.54 0.11 0.0 0.0 0.00 0.00 0.00 38.7 81.9 1.07 0.21 1.07

Thur AM 3.18 0.63 0.55 0.11 0.0 0.0 0.00 0.00 0.00 43.9 93.0 1.17 0.23 1.17

Thur PM 3.45 0.68 0.60 0.12 0.0 0.0 0.00 0.00 0.00 42.2 89.4 1.27 0.25 1.23

PABS04 Wed AM 4.88 0.96 0.69 0.14 8.5 17.9 0.63 0.12 0.60 2.5 5.3 0.19 0.04 0.21

Wed PM 4.82 0.95 0.69 0.13 9.0 19.1 0.61 0.12 0.58 2.7 5.6 0.18 0.04 0.20

Thur AM 4.55 0.90 0.65 0.13 7.5 16.0 0.58 0.11 0.54 2.3 4.8 0.17 0.03 0.19

Thur PM 4.74 0.93 0.67 0.13 9.2 19.5 0.61 0.12 0.58 2.7 5.8 0.18 0.04 0.20

SCDW01 Wed AM 5.88 1.16 0.83 0.16 18.5 39.2 1.42 0.28 1.42 5.9 12.4 0.45 0.09 0.51

Wed PM 4.97 0.98 0.70 0.14 18.3 38.7 1.24 0.24 1.24 5.8 12.2 0.39 0.08 0.45

Thur AM 5.46 1.08 0.77 0.15 18.1 38.4 1.30 0.26 1.30 5.7 12.1 0.41 0.08 0.47

Thur PM 4.68 0.92 0.66 0.13 15.9 33.6 1.03 0.20 1.03 5.0 10.6 0.33 0.06 0.37

SCDW02 Wed AM 7.58 1.49 1.31 0.26 26.1 55.4 1.38 0.27 1.15 8.7 18.4 0.46 0.09 0.43

Wed PM 8.18 1.61 1.42 0.28 25.9 54.9 1.53 0.30 1.28 8.6 18.2 0.51 0.10 0.48

Thur AM 7.39 1.45 1.28 0.25 23.9 50.7 1.41 0.28 1.18 7.9 16.8 0.47 0.09 0.44

Thur PM 7.69 1.51 1.33 0.26 22.6 47.9 1.19 0.23 0.99 7.5 15.9 0.39 0.08 0.37

SDBW01 Wed AM 3.87 0.76 0.55 0.11 43.1 91.3 1.77 0.35 1.96 13.6 28.9 0.56 0.11 0.71

Wed PM 4.15 0.82 0.59 0.12 64.6 136.8 2.14 0.42 2.37 20.4 43.3 0.68 0.13 0.86

Thur AM 3.95 0.78 0.56 0.11 56.1 119.0 2.07 0.41 2.29 17.8 37.6 0.65 0.13 0.83

Thur PM 4.09 0.80 0.58 0.11 60.6 128.4 2.23 0.44 2.47 19.2 40.6 0.71 0.14 0.89

Study Space 

ID Period

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric Uncertainty in volumetric OA

SUPPLY AIRFLOW OUTDOOR AIRFLOW
81

L/s•m2 cfm/ft2 L/s•m2 cfm/ft2 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1 L/s•person cfm/person L/s•m2 cfm/ft2 h- 1

SDBW02 Wed AM 3.66 0.72 0.63 0.12 49.9 105.6 1.62 0.32 1.80 16.5 35.0 0.54 0.11 0.67

Wed PM 3.34 0.66 0.58 0.11 53.3 112.9 0.98 0.19 1.08 17.7 37.5 0.32 0.06 0.41

Thur AM 3.64 0.72 0.63 0.12 35.3 74.8 1.03 0.20 1.14 11.7 24.8 0.34 0.07 0.43

Thur PM 3.37 0.66 0.58 0.12 31.7 67.3 0.79 0.16 0.88 10.5 22.3 0.26 0.05 0.33

SDBW04 Wed AM 11.17 2.20 1.58 0.31 47.1 99.7 2.39 0.47 2.68 56.4 119.6 2.87 0.57 3.24

Wed PM 9.48 1.87 1.34 0.26 55.6 117.8 1.89 0.37 2.11 73.0 154.6 2.48 0.49 2.79

Thur AM 9.13 1.80 1.29 0.25 44.0 93.2 1.78 0.35 1.99 59.1 125.1 2.39 0.47 2.70

Thur PM 9.06 1.78 1.28 0.25 39.3 83.2 1.96 0.39 2.19 46.5 98.5 2.32 0.46 2.62

TNDS05 Wed AM 2.08 0.41 0.32 0.06 59.1 125.1 2.08 0.41 2.32 16.7 35.3 0.59 0.12 0.77

Wed PM 2.27 0.45 0.35 0.07 89.6 189.8 2.27 0.45 2.54 25.7 54.5 0.65 0.13 0.85

Thur AM 2.16 0.42 0.34 0.07 65.3 138.3 2.16 0.42 2.41 18.7 39.7 0.62 0.12 0.81

Thur PM 2.04 0.40 0.32 0.06 82.7 175.3 2.04 0.40 2.28 23.7 50.2 0.58 0.11 0.76

TNDS06 Wed AM 2.64 0.52 0.46 0.09 17.3 36.7 0.56 0.11 0.51 21.0 44.5 0.68 0.13 0.62

Wed PM 2.25 0.44 0.39 0.08 6.7 14.2 0.19 0.04 0.17 22.9 48.5 0.66 0.13 0.59

Thur AM 2.07 0.41 0.36 0.07 5.4 11.5 0.27 0.05 0.24 11.7 24.8 0.58 0.11 0.52

Thur PM 2.13 0.42 0.37 0.07 1.3 2.8 0.05 0.01 0.04 18.3 38.7 0.66 0.13 0.59

TNDS07 Wed AM 5.55 1.09 0.79 0.15 3.1 6.6 0.13 0.03 0.14 1.0 2.1 0.04 0.01 0.05

Wed PM 5.36 1.06 0.76 0.15 2.6 5.5 0.16 0.03 0.17 0.8 1.7 0.05 0.01 0.06

Thur AM 5.55 1.09 0.79 0.15 2.6 5.6 0.17 0.03 0.18 0.8 1.8 0.05 0.01 0.06

Thur PM 5.61 1.10 0.79 0.16 14.6 31.0 0.89 0.18 0.96 4.6 9.8 0.28 0.06 0.35

TNFS08 Wed AM 3.59 0.71 0.51 0.10 14.5 30.8 0.80 0.16 0.86 3.5 7.4 0.19 0.04 0.26

Wed PM 3.63 0.71 0.52 0.10 20.9 44.3 0.86 0.17 0.93 5.3 11.1 0.22 0.04 0.28

Thur AM 3.81 0.75 0.54 0.11 15.7 33.3 0.87 0.17 0.93 3.9 8.3 0.22 0.04 0.28

Thur PM 4.34 0.85 0.60 0.12 15.3 32.4 0.83 0.16 0.89 3.8 8.1 0.21 0.04 0.27

TNFS09 Wed AM 3.29 0.65 0.48 0.10 10.7 22.8 0.93 0.18 0.96 5.9 12.5 0.51 0.10 0.55

Wed PM 3.18 0.63 0.46 0.09 12.2 25.8 0.76 0.15 0.78 7.9 16.7 0.49 0.10 0.53

Thur AM 2.71 0.53 0.40 0.08 7.5 15.8 0.58 0.11 0.60 6.2 13.2 0.49 0.10 0.51

Thur PM 2.86 0.56 0.42 0.08 8.4 17.9 0.65 0.13 0.66 6.2 13.2 0.48 0.09 0.50

TNFS10 Wed AM 6.20 1.22 1.07 0.21 84.9 179.9 4.27 0.84 3.53 20.7 43.9 1.04 0.21 1.06

Wed PM 7.31 1.44 1.27 0.25 75.3 159.5 3.92 0.77 3.24 26.4 55.8 1.37 0.27 1.27

Thur AM 6.90 1.36 1.20 0.24 103.9 220.1 4.85 0.96 4.02 24.6 52.2 1.15 0.23 1.18

Thur PM 6.08 1.20 1.05 0.21 81.0 171.6 4.28 0.84 3.55 19.2 40.6 1.01 0.20 1.04

TXFS01 Wed AM 3.58 0.71 0.62 0.12

Wed PM 4.39 0.86 0.76 0.15 5.9 12.4 0.20 0.04 0.17 1.9 4.1 0.07 0.01 0.06

Thur AM 4.33 0.85 0.75 0.15 4.6 9.7 0.19 0.04 0.15 1.5 3.2 0.06 0.01 0.06

Thur PM 4.46 0.88 0.77 0.15 6.5 13.8 0.18 0.04 0.15 2.2 4.6 0.06 0.01 0.06

TXFS02 Wed AM 6.64 1.31 0.81 0.16 10.8 22.9 0.31 0.06 0.35 2.5 5.4 0.07 0.01 0.10

Wed PM 6.47 1.27 0.79 0.16 12.9 27.2 0.31 0.06 0.35 3.0 6.4 0.07 0.01 0.10

Thur AM 7.63 1.50 0.93 0.18 9.5 20.1 0.30 0.06 0.34 2.2 4.7 0.07 0.01 0.10

Thur PM 6.71 1.32 0.82 0.16 14.7 31.2 0.31 0.06 0.35 3.5 7.3 0.07 0.01 0.10

SUPPLY AIRFLOW OUTDOOR AIRFLOW

Study Space 

ID Period

Volumetric supply 

airflow

Uncertainty in

supply airflow Volumetric Uncertainty in volumetric OA
82
83
84
85
86
87
88
89
90
91
 

92
93

Appendix F: Reanalysis of BASE Ventilation Data

This appendix presents the letter report published in October 2008 discussing the BASE 

ventilation data reanalysis that led to the revision of the original (2004) NIST report.

Reanalysis of BASE Ventilation Data

Letter Report to U.S. Environmental Protection Agency

October 10, 2008

Andrew Persily

Building and Fire Research Laboratory

National Institute of Standards and Technology

ABSTRACT

In 2004, the National Institute of Standards and Technology (NIST) published an analysis of the 

ventilation data collected as part of the U.S. Environmental Protection Agency (EPA) Building 

Assessment Survey and Evaluation (BASE) study [1]. That analysis provided a unique dataset of 

office building ventilation rates, both design and measured, along with many insights into 

building ventilation. The analysis also raised questions regarding the use of the difference 

between peak indoor carbon dioxide (CO2) concentrations and the corresponding outdoor CO2

concentrations to estimate building ventilation rates, as there was a systematic difference 

between the ventilation rates based on this method and those based on duct traverse 

measurements. The current study examined the discrepancies between the peak indoor CO2-

based and traverse-based ventilation rates in more detail. In addition, the overall ventilation rate 

dataset was re-examined for consistency and, as a result, some errors were corrected.

SUMMARY OF ANALYSIS AND REPORT CONTENT

The BASE ventilation data reanalysis effort focused on two primary areas: 1) general corrections 

and adjustments to the original data; and 2) the disagreement between the outdoor air ventilation 

rates based on peak indoor CO2 concentrations and those based on traverse measurements at the 

air handlers (sometimes referred to as volumetric rates). The corrections involved a detailed 

review of the data files generated by National Institute of Standards and Technology (NIST) and 

provided to U.S. Environmental Protection Agency (EPA) for the BASE (Building Assessment 

Survey and Evaluation) CD distributed by EPA [2]. In addition, outliers (primarily those with 

high measured ventilation rates) were examined in more detail. Regarding the second issue, a 

number of potential explanations were examined for the differences between the ventilation rates 

estimated from peak indoor CO2 concentrations and the traverse-based or volumetric rates.

DATABASE CORRECTIONS

As part of the data review, the various files used in the ventilation data analysis were studied and 

compared with the files on the CD distributed by EPA [2]. As a result, a number of changes were 

made to the dataset, which are identified below. However, none of the changes modify the 

overall conclusions of the study, only some of the summary statistics. An updated version of the 

original NIST report on the dataset [1] will be published with these corrections.
94

This data review effort involved a detailed examination of the data analysis files generated by the 

original analysis, including the following design parameters: 

Supply capacity of each air handling unit (AHU)

AHU return capacity

Floor area served by each AHU

AHU design minimum outdoor air intake

Number of occupants served by each AHU

AHU supply capacity divided by floor area served

AHU design minimum outdoor air per person

AHU ratio of minimum outdoor air to supply capacity

Number of occupants per unit floor area (for each AHU)

Ratio of supply to return airflow (for each AHU)

In addition, the following measured parameters were also reviewed:

AHU supply airflow and associated uncertainty

AHU outdoor airflow and associated uncertainty

AHU recirculation airflow and associated uncertainty

AHU outdoor air intake fraction and associated uncertainty

Study space supply airflow per unit floor area and associated uncertainty

Study space outdoor airflow (per person, per unit floor area and per unit volume) and 

associated uncertainty

The changes made to the data files as a result of this effort are documented in Table 1.

Building Parameter Modification Comment

CAJS01 Peak CO2 value and

outdoor airflow

calculated from peak

All values deleted. All indoor CO2 concentrations are

very erratic; two locations are

consistently below outdoors at

night.

CAJW20 % of AHU capacity

serving test space

(C1TS1PCT*)

Changed from 100 % to

14 %, based on floor area

and number of occupants

served.

Field notes indicate AHU serves 7

floors, not 1 as indicated by

original value of C1TS1PCT.

Results in 86 % reduction in supply

and outdoor airflows, and

associated reduction in uncertainty.

CAJW24 Uncertainty in CO2

ratio outdoor airflow

per person.

Fixed small error in

uncertainty in L/s•person

and cfm/person

Roughly 10 % reduction in these

two uncertainty values; no impact

on airflow results.

MOCS01 Floor area served by

system (C7AAREA*)

Increased by roughly a

factor of 8 (# of building

floors) as listed value is

only for a single floor.

Reduces design value of supply

airflow per unit floor area and

occupant density by factor of 8.

NCDW02 % of AHU capacity

serving test space

(C1TS1PCT)

Change from 50 % to

20 % for AHU #1 and to

30 % for AHU #2, based

on floor area and number

of occupants served.

Results in roughly 50 % reduction

in reported supply and outdoor

airflows, and associated reduction

in uncertainties.

PABS04 Design # of occupants

(C7AOCCU)

Replaced value of 0 with

blank cell for AHU #2

AHU serves perimeter; occupants

accounted for by other systems.

TNDS05 Design # of occupants

(C7AOCCU)

Replaced value of 0 with

blank cell for AHU #2.

AHU serves corridor; occupants

accounted for by other systems.
95

TXFS02 Uncertainty in CO2

ratio outdoor airflow

per floor area.

Fixed error in

uncertainty in L/s•m

2

and

cfm/ft

2

.

Corrected uncertainty values ten

times uncorrected; no impact on

airflow results.

* Variable name from BASE data dictionary.

Table 1 Modifications to BASE ventilation data parameters

As a result of these modifications, some of the summary statistics in the original NIST report to 

EPA (NISTIR 7145) also change. The affected tables and figures are presented below, with the 

table and figure number from the original report in parentheses. In the tables, the revised values 

are highlighted in bold font.

Design supply airflow capacity

L/s•m

2 (cfm/ft2 Floor area served )

m

2 (ft2

) All systems CV VAV

Supply/

Return

# of values 141 134 47 87 41

Mean 3100 (33 300) 5.86 (1.15) 7.01 (1.38) 5.25 (1.03) 1.14

Std. Dev. 4230 (45 600) 3.57 (0.70) 5.33 (1.05) 1.85 (0.36) 0.22

Minimum 110 (1200) 1.13 (0.22) 1.13 (0.22) 1.67 (0.33) 0.20

10thpercentile 540 (5800) 2.90 (0.57) 2.74 (0.54) 3.26 (0.64) 1.00

25thpercentile 990 (10 700) 4.15 (0.82) 4.19 (0.83) 4.15 (0.82) 1.07

Median 1640 (17 600) 5.21 (1.03) 5.63 (1.11) 4.99 (0.98) 1.11

75thpercentile 3440 (37 000) 6.78 (1.33) 7.83 (1.54) 6.17 (1.22) 1.25

90thpercentile 7620 (82 100) 8.45 (1.66) 11.21 (2.21) 7.56 (1.49) 1.28

Maximum 33 780 (363 600) 30.18 (5.94) 30.18 (5.94) 12.47 (2.45) 1.85

Design minimum outdoor air intake

L/s (cfm) per person L/s•m

2 (cfm/ft2

)

Minimum OA/

Supply

Occupant density

#/100 m

2 (1000 ft2

)

# of values 74 76 76 137

Mean 18.4 (39.0) 0.94 (0.18) 0.19 5.3 (4.9)

Std. Dev. 13.7 (29.0) 1.06 (0.21) 0.22 6.5 (6.1)

Minimum 1.3 (2.9) 0.17 (0.03) 0.06 0.9 (0.8)

10thpercentile 7.5 (16.0) 0.31 (0.06) 0.08 2.2 (2.0)

25thpercentile 10.6 (22.4) 0.42 (0.08) 0.10 2.9 (2.7)

Median 15.2 (32.1) 0.60 (0.12) 0.12 3.9 (3.7)

75thpercentile 23.6 (50.0) 0.92 (0.18) 0.15 5.9 (5.4)

90thpercentile 29.7 (63.0) 1.82 (0.36) 0.31 8.0 (7.4)

Maximum 98.3 (208.2) 6.67 (1.31) 1.00 65.1 (60.5)

Table 2 System Design Values (Table 6 in NISTIR 7145)
96

System * Issue Comments

AZHW10 (2 of 2) High supply capacity, 24 L/s•m

2

(4.7 cfm/ft

2

)

System (1) at 8 L/s•m

2 (1.5 cfm/ft2

)

LAGW05 (1 of 2) High supply capacity, 18 L/s•m

2

(3.6 cfm/ft

2

)

System (2) at 4 L/s•m

2 (0.7 cfm/ft2

);

occupant density 5 times that of system

(2); floor area could be low

MOCS01 (1 of 1) High supply capacity, 27 L/s•m

2

(5.3 cfm/ft

2

)

PABS04 (2 of 2) High supply capacity, 25 L/s•m

2

(5.9 cfm/ft

2

)

System (1) at 4 L/s•m

2 (0.8 cfm/ft2

)

CAEW09 (1 of 1) High minimum outdoor air 53 L/s

(113 cfm) per person,

Minimum outdoor air based on supply and

return capacities

CAJS21 (2 of 2) High minimum outdoor air, 98 L/s

(208 cfm) per person

100 % outdoor air system; System (1) at

29 L/s (61 cfm) per person

MDDS01 (1 of 1) High minimum outdoor air, 51 L/s

(109 cfm) per person

NCDW03 (2 of 5) High minimum outdoor air, 38 L/s

(80 cfm) per person

Other 4 systems from 9 L/s (20 cfm) per

person to 16 L/s (33 cfm) per person;

system (2) occupant density about 25 % of

other 4 systems.

NECW02 (1 of 1) High minimum outdoor air, 38 L/s

(80 cfm) per person

High occupant density, 16 occupants per

100 m

2 (1000 ft2

)

TNFS10 (1 of 1) High minimum outdoor air, 34 L/s

(72 cfm) per person

Low occupant density, 1.1 occupants per

100 m

2 (1000 ft2

)

CAJW25 (1 of 1) High occupant density, 61

occupants per 100 m

2 (1000 ft2

)

Supply airflow 24 L/s•m

2 (2.5 cfm/ft2

);

floor area could be low

MOCS01 (1 of 1) High occupant density, 24

occupants per 100 m

2 (1000 ft2

)

NECW02 (1 of 1) High occupant density, 16

occupants per 100 m

2 (1000 ft2

)

SDBW02 (1 of 1) High occupant density, 38

occupants per 100 m

2 (1000 ft2

)

Low minimum outdoor air 1 L/s (3 cfm)

per person, consistent with high occupant

density value

TNDS05 (1 of 2) High occupant density, just over

12 occupants per 100 m

2 (1000 ft2

)

System (2) lists no occupants

* Values in parentheses refers to air handler number relative to total number of air handlers, e.g. (2 of 2)

means second of two air handlers serving the study space.

Table 3 System design outliers*

(Table 7 in NISTIR 7145)

 * The text in the table noted with a strikethrough corresponds to two occurrences that are no longer

outliers given the modifications to the data described earlier.
97

Study space outdoor air requirement

L/s (cfm) per person

Mean 9.0 (19.1)

Std. Dev. 3.3 (6.9)

Minimum 4.8 (10.2)

10thpercentile 6.5 (13.7)

25thpercentile 7.2 (15.3)

Median 8.7 (18.3)

75thpercentile 10.0 (21.1)

90thpercentile 12.1 (25.7)

Maximum 33.5 (71.0)

Table 4 Study space outdoor air requirements based on Standard 62 addendum n

(Table 8 in NISTIR 7145)

Figure 1 Design supply airflow capacity versus year built

(Figure 3 in NISTIR 7145)
98

Figure 2 Design occupant density versus year built (Figure 5 in NISTIR 7145)

Figure 3 Measured study space supply airflow vs. outdoor temperature

(Figure 7 in NISTIR 7145)

0

1

2

3

4

5

0

5

10

15

20

25

-20 -10 0 10 20 30 40

0 20 40 60 80 100

CV

VAV

Outdoor temperature (°F)

Outdoor temperature (°C)

Supply airflow to test space (L/s•m2

)

Supply airflow to test space (cfm/ft2

)
99

Supply airflow/Floor area

L/s•m

2 (cfm/ft2

)

All systems VAV CV

# of values 384 289 95

Mean 5.12 (1.01) 4.55 (0.90) 6.86 (1.35)

Std. Dev. 3.02 (0.59) 2.62 (0.52) 3.46 (0.68)

Minimum 0.88 (0.17) 0.88 (0.17) 1.80 (0.35)

10thpercentile 2.16 (0.43) 2.12 (0.42) 2.25 (0.44)

25thpercentile 2.99 (0.59) 2.89 (0.57) 4.82 (0.95)

Median 4.69 (0.92) 4.30 (0.85) 5.72 (1.13)

75thpercentile 6.25 (1.23) 5.69 (1.12) 9.04 (1.78)

90thpercentile 8.47 (1.67) 7.19 (1.41) 11.34 (2.23)

Maximum 21.11 (4.15) 21.11 (4.15) 16.24 (3.20)

Table 5 Summary of measured supply airflows (Table 13 in NISTIR 7145)

Best volumetric Carbon dioxide

# of values 509 520

Mean 0.38 0.31

Standard deviation 0.35 0.27

Minimum 0.00 0.00

10thpercentile 0.04 0.03

25thpercentile 0.10 0.11

Median 0.22 0.23

75thpercentile 0.59 0.44

90thpercentile 1.00 0.75

Maximum 1.52 1.20

Table 6 Summary of measured outdoor air fraction

(Table 14 in NISTIR 7145)
100

Per person

L/s (cfm) per person

Per unit floor area

L/s•m

2 (cfm/ft2

)

Air changes per

hour, h-1

# of values 367 369 369

Mean 49 (105) 1.87 (0.37) 1.83

Std. Dev. 54 (114) 2.08 (0.41) 2.07

Minimum 0 (0) 0 (0) 0.00

10thpercentile 6 (13) 0.24 (0.05) 0.22

25thpercentile 13 (27) 0.50 (0.10) 0.47

Median 30 (63) 1.03 (0.20) 0.98

75thpercentile 66 (140) 2.30 (0.45) 2.46

90thpercentile 116 (245) 4.64 (0.91) 4.46

Maximum 310 (657) 12.31 (2.42) 13.23

Table 7 Summary of Measured Outdoor Air Ventilation – Volumetric

(Table 15 in NISTIR 7145)

Outdoor air per person,

L/s (cfm)

# of values 356

Mean 44 (94)

Std. Dev. 47 (101)

Minimum 0 (0)

10thpercentile 5 (11)

25thpercentile 12 (26)

Median 31 (65)

75thpercentile 59 (125)

90thpercentile 96 (203)

Maximum 339 (717)

Table 8 Summary of Measured Outdoor Air Ventilation – CO2 Ratio

(Table 16 in NISTIR 7145)
101

Figure 4 Outdoor air ventilation, CO2-ratio vs. volumetric

(Figure 14 in NISTIR 7145)

Adjusted to 15 % outdoor air

Measured

(Table 15*)

Adjusted to #

of workstations

# of workstations

Standard 62 default

occupant density**

L/s (cfm) per person

Mean 49 (105) 36 (76) 12 (26) 8 (18)

Std. Dev. 54 (114) 37 (79) 8 (17) 6 (13)

Minimum 0 (0) 0 (0) 0 (0) 0 (0)

10thpercentile 6 (13) 5 (10) 4 (9) 3 (5)

25thpercentile 13 (27) 10 (22) 7 (14) 5 (10)

Median 30 (63) 21 (45) 11 (23) 7 (15)

75thpercentile 66 (140) 52 (110) 16 (34) 11 (23)

90thpercentile 116 (245) 87 (184) 21 (44) 16 (34)

Maximum 310 (657) 210 (444) 47 (100) 42 (89)

* Refers to Table 15 in the original report.

** Adjustment based on default occupant density in Standard 62.1 2001 (same as 1989) and not in 2004

and 2007 versions.

Table 9 Outdoor air ventilation adjusted for occupancy and outdoor air fraction

(Table 17 in NISTIR 7145)
102

Outdoor air ventilation, L/s (cfm) per person

All peak CO2 data

Peak CO2 data on

“test days”

Volumetric results from

Table 15*

# of values 548 353 367

Mean 20 (43) 21 (45) 49 (105)

Std. Dev. 14 (31) 17 (35) 54 (114)

Minimum 6 (13) 6 (13) 0 (0)

10thpercentile 10 (20) 10 (21) 6 (13)

25thpercentile 12 (26) 13 (27) 13 (27)

Median 18 (37) 18 (38) 30 (63)

75thpercentile 24 (50) 25 (53) 66 (140)

90thpercentile 32 (68) 33 (71) 116 (245)

Maximum 213 (452) 213 (452) 310 (657)

* Refers to Table 15 in the original report.

Table 10 Summary of Measured Outdoor Air Ventilation – Peak CO2

(Table 18 in NISTIR 7145)

Figure 5 Outdoor air ventilation, CO2 peak vs. volumetric

(Figure 15 in NISTIR 7145)
103

In reviewing the data, the issue of low values of traverse measurements of airflow was examined 

but no changes were made to the dataset as a result. For the airflow traverses, the concern is the 

accuracy of the anemometer or pitot tube measurements at lower air speeds. While a small 

number of traverse measurements of airflow are in the range of 50 L/s (100 cfm), it is actually

the air speed measured in the duct that is most relevant to its accuracy. For the supply duct 

traverses, the mean measured air speed is 5.3 m/s (1000 ft/min), which is within the range at 

which such measurements are expected to be accurate. A small number of the air speeds are low 

enough to be of potential concern, but less than 1 % are below 0.3 m/s (60 ft/min). The mean air 

speed for the outdoor air intake traverses is 3.1 m/s (600 ft/min), again in a reliable range, with 

only about 3 % below about 0.3 m/s (60 ft/min). No modifications were made to the dataset to 

eliminate the low readings, but given the small number of such values, their removal would not 

have a major effect on the overall conclusions of the study.

OUTDOOR AIRFLOW: COMPARISON OF PEAK INDOOR CO2-BASED AND DUCT 

TRAVERSE-BASED VALUES

A key finding of the original study, and a primary motivation for this reanalysis, is the consistent 

difference between the outdoor airflow rates based on the duct traverse measurements and the 

estimates based on peak CO2 concentrations in the study spaces. The latter estimates were based 

on indoor CO2 concentrations measured continuously during several days of the study period 

using 3 to 4 fixed monitors distributed randomly in the study space. The concentrations were 

then averaged and peak values of those averages were determined for each morning and 

afternoon. This approach to ventilation rate estimation has been used for a number of years 

though often without a complete understanding of the assumptions inherent in the method [3]. 

The peak indoor CO2 method for estimating outdoor air ventilation rates is essentially a singlezone, constant injection tracer gas technique. Therefore, it is based on the assumption that the 

indoor CO2 concentration is uniform throughout the study space and that the test space is isolated 

from the rest of the building or that the rest of the building is at the same CO2 concentration as 

the study space. In addition, the approach as typically applied assumes that the indoor CO2

concentration is at steady-state and that the following quantities are constant: outdoor 

concentration, ventilation airflow rate, and building occupancy. The validity of these 

assumptions was not assessed as part of the BASE study and most of them cannot be assessed 

based on the available data.

As seen in Figure 5 above (corrected Figure 15 from the original report), for volumetric 

(traverse-based) outdoor airflow rates above about 20 L/s•person (40 cfm/person), the values 

based on peak CO2 concentrations are consistently lower than the volumetric values. This issue 

was discussed in the original report as follows:

“The reason that the peak CO2 values tend to be lower than expected has been investigated, 

but no explanation has yet been verified. Considering the methodology behind the peak CO2

analysis, one might suspect the lack of steady-state CO2 concentrations could be impacting 

the agreement between the two values. However, steady state is more likely to occur at the 

higher ventilation rates due to the shorter system time constants, resulting in better agreement 

at higher rates, which is contrary to what is seen in Figure 15. Another potential explanation 

is the existence of significant CO2 concentration gradients within the study spaces, as well as 

between them and adjoining spaces, given that the single-zone analysis method assumes a 

uniform concentration within the zone and neglects interzone transfer of CO2. While it is 
104

certainly possible that the CO2 concentrations were different in adjoining zones, one would 

expect the impact to be positive in some cases and negative in others. However, the 

differences in the data tend to all be in one direction. The level of agreement was examined 

in those study spaces that corresponded to an entire building, for which concentration 

differences in adjoining spaces are not an issue, and the peak CO2 and volumetric ventilation 

rates were not observed to agree any better. Note that the fixed CO2 monitors in the study

spaces were placed at a height of 1.1 m (43 in.) above the floor and at locations 

representative of workstation layout and work activities, i.e., locations in hallways and 

passageways were intentionally avoided (EPA 2003)1. Given these guidelines on location, it 

is possible that the measured CO2 concentrations are higher than the study-space average. If 

the measured CO2 concentration is indeed higher than the true space average, then the 

calculated ventilation rates would be low relative to their actual value. Also, it is reasonable 

to expect that the lack of uniformity would be more pronounced at higher outdoor air 

ventilation with less recirculation of return air, leading to the observed increase in errors. 

However, it is not possible to verify the magnitude of the concentration nonuniformity in 

these spaces based on the available data, and therefore it cannot be confirmed whether this is 

necessarily a valid explanation for the observed differences. The peak CO2 concentrations 

were examined with the issue of nonuniformity in mind, and it was determined that the actual 

average concentration in the study space would have to be 360 mg/m3 to 720 mg/m3

(200 ppm(v) to 400 ppm(v)) lower than that measured by the fixed monitors to explain the 

observed differences.”

Figure 15 in the original report actually included only a subset of the values, i.e., those with 

volumetric outdoor air ventilation rates less than 200 L/s•person (400 cfm/person). The corrected 

version above in Figure 5 contains all the points in the corrected dataset. The corrected dataset 

includes many outdoor airflow values with high uncertainties. These uncertainties were 

calculated using standard approaches to the propagation of error in which the estimated 

uncertainties in the values used to calculate the airflows were propagated through the 

mathematical operations used to determine the airflow rates. Note that these uncertainty

estimates do not account for biases in the measurement methods or the impact of the assumptions 

behind the peak CO2 method not being valid. For the volumetric values, the mean value of the 

ratio of the uncertainty in the outdoor airflow per person to the corresponding measured value is 

close to 1.1; the median ratio is about 0.3. The mean ratio of the uncertainty to the measured 

value for the peak indoor CO2-based values is much smaller, about 0.3, and there are values over 

1.0. The relative uncertainties for the volumetric flows tend to be larger due in part to the 

existence of a small number of measurement events with very low outdoor airflow rates but very

high uncertainties. These high uncertainty cases occur when the outdoor airflow is determined by

subtracting the recirculation airflow from the supply.

Figure 6 is a plot of the same data shown in Figure 5, but with only those values for which the 

ratio of the uncertainty to the measured value is less than one. These data exhibit less scatter than 

that seen in Figure 5. Figure 7 restricts the data plotted even further to values for which the ratio 

is less than 0.5. This plot is particularly striking in the very flat distribution of the data in which 

the volumetric values range from 0 L/s-person to about 250 L/s-person (500 cfm/person) while 

the peak indoor CO2-based values cover a much more narrow range from about 7 L/s-person 

(15 cfm/person) to 35 L/s•person (74 cfm/person). The ratio of the standard deviation to the 

 1

 This is reference number 4 in the list of references for this report.
105

mean for the values in Figure 7 is 1.0 for the volumetric rates but only 0.4 for the peak CO2

values. The lack of variability in the peak CO2 values relative to the volumetric rates is notable 

and is discussed further below.

Figure 6 Updated - Outdoor air ventilation, CO2 peak vs. volumetric (relative uncertainty < 1)
106

Figure 7 Updated - Outdoor air ventilation, CO2 peak vs. volumetric (rel. uncertainty < 0.5)

Nonuniform CO2 concentrations

As noted in the original report, one potential explanation for the discrepancy between the 

traverse and peak CO2 rates is nonuniformity in the CO2 concentrations in the space. 

Specifically, the fact that the CO2 concentrations were sampled “at a height of 1.1 m (43 in.)

above the floor and at locations representative of workstation layout and work activities” raises 

the question of whether the readings were impacted by the occupants’ local exhalations. In 

addition, the BASE protocol requires that these monitoring locations be selected among 5 m by

5 m grids of which more than 50 % of the area is occupied full time [4]. CO2 concentrations in 

the exhaled breath from people are in the range of 72 000 mg/m3 (40 000 ppm(v)) [3], which is 

well above the concentrations measured in the study spaces. Therefore the proximity of 

occupants to the indoor monitoring locations does lead to the potential for the measured 

concentrations being elevated relative to the space average.

The issue of nonuniform concentration was evaluated in two ways, by comparing the space 

concentrations to those measured in the air handler returns and by examining the uniformity

among the various sample locations in each study space.

As part of the ventilation evaluations, CO2 concentrations were measured on four occasions 

during the test week (typically on Wednesday and Thursday of the study week in the morning 

and afternoon) in the air handler return, supply, and outdoor airstreams to calculate the outdoor 

air intake fraction based on a mass balance of CO2 in the air handler. These discrete 

measurements of CO2 in the return were compared with the average of the concentrations in the 

study space taken at the same time, which is generally not the same time as peak in the study
107

space concentration. Note that the return airstreams sometimes contained air drawn from other 

spaces in addition to the study space, therefore the comparisons were only made for study spaces 

served by a dedicated air handler, i.e., an air handler that doesn’t serve any other spaces. Figure 8 

is a plot of the space concentration versus the corresponding concentration in the air handler 

return (open squares) as well as the difference between the space and return concentrations again 

plotted against the return concentration (open circles). The space concentrations do tend to 

exceed the return concentrations, though there are a small number of cases for which the space 

concentration is lower. The average difference for the 183 cases where both values exist equals 

108 mg/m3 (60 ppm(v)). The differences tend be higher for lower return concentrations, which 

correspond to higher ventilation rates. These higher ventilation rates are associated with higher 

outdoor air intake fractions, which result in less mixing of the indoor air and are consistent with 

the greater differences between space and return concentrations. 

Figure 8 Space and space-minus-return CO2 concentrations vs. return concentration

The return versus space concentration differences were also examined for study spaces that 

correspond to an entire building. One might expect the concentration differences to be more 

clearly defined in such situations because there is no interzone airflow and CO2 transport to 

confound the return-versus-space relationship. However, those study spaces revealed no 

significant differences relative to other spaces.

Some of the buildings tested later in the BASE project were also subject to continuous 

measurements of CO2 in the air handler returns. Several of these datasets were examined for 

systematic differences between the study space and air handler return peak CO2 concentrations. 
108

The results were largely consistent with those seen between the space and spot measurements in 

the return.

While the observed differences between the return and space concentrations indicate that the 

space concentrations may be elevated due to the presence of occupants, the magnitude of the 

impact is not sufficient to explain the observed differences between the volumetric and peak CO2

based ventilation rates. Figure 9 is a plot of the peak CO2 rates adjusted using the average spacereturn difference of 108 mg/m3

 (60 ppm(v)), i.e., with the peak space concentration reduced by

that average difference. In this figure, the adjusted rates are superimposed on the unadjusted data 

from Figure 6.

Figure 9 CO2 peak vs. volumetric ventilation rate adjusted for space-return concentration

The second approach used to examine the issue of nonuniform CO2 concentrations in the study

spaces was to consider the concentration variations within the space. As noted earlier, the CO2

concentrations were measured at multiple locations in each study space, and the concentrations 

among these locations varied. In an attempt to examine the impact of those nonuniformities, the 

ventilation rates were recalculated using the CO2 sampling location that yielded the lowest peak 

value. Figure 10 is a plot of the measured CO2 concentrations for study space MIBW03, 

including the outdoor and three indoor locations. The difference between the indoor locations is 

evident in this plot. Note that ASTM D6245 [3] requires that CO2 concentrations within the 

study space not vary from the space average by more than 10 % when estimating ventilation 

rates based on peak CO2 concentrations. This requirement is not met for this study space and for 

many of the other BASE study spaces.
109

Figure 10 Variation in CO2 concentrations among indoor locations (study space MIBW03)

For each study space, the indoor location with the lowest peak CO2 value was used to estimate 

the outdoor air ventilation values. Figure 11 is a plot of the outdoor airflows estimated using the 

monitoring location with the minimum peak CO2 value against the volumetric rates, with the 

airflows based on the peak average CO2 concentration from Figure 6 included as well. Using the 

minimum peak CO2 concentrations does increase the outdoor airflow values, but not enough to 

result in good agreement with the volumetric values. The improvement is more pronounced than 

that seen for the adjustment based on the average return-space concentration difference seen in 

Figure 9.
110

Figure 11 CO2 peak vs. volumetric ventilation rate, using monitoring location with minimum 

peak concentration

While using the return concentrations and the minimum peak CO2 concentrations instead of the

study space concentrations is not sufficient to explain the difference between the peak CO2 and 

the volumetric values, these two explanations are consistent with the existence of nonuniform 

concentrations in the study spaces.

If CO2 concentration variations between the study space and the rest of the building is an issue, 

then study spaces that are a whole building or are served by dedicated air handlers might be 

expected to exhibit better agreement between the peak indoor CO2-based and volumetric airflow

values. The level of agreement between the two airflow rates was examined for test spaces 

corresponding to a whole building (only 6 cases) or which were served by dedicated air handlers 

(43 cases), but no obvious difference in the agreement was evident. Note that within-space 

nonuniformity may have been an issue in these spaces as well.

Association of peak-volumetric difference with various factors

In investigating the differences between the peak indoor CO2-based estimates and volumetric 

measurements of the outdoor airflows in the BASE buildings, a number of parameters were 

considered to see if they were associated with the magnitudes of the differences and therefore 

might offer some explanation. 

Given the hypothesis that nonuniform indoor CO2 concentrations might be important, the 

standard deviation of the peak concentrations for the various indoor locations was computed for 
111

each study space. This standard deviation was then divided by the mean peak to determine the 

coefficient of variation (COV). Figure 12 is a plot of the relative difference between the 

volumetric and peak indoor CO2-based airflows (volumetric minus peak indoor CO2-based, 

divided by peak value) against the COV. The data in this figure do not show a strong dependence 

of the flow discrepancy on the COV.

Figure 12 Relative difference between airflows vs. coefficient of variation 

Given that the indoor concentrations are expected to be more uniform with more mixing, i.e., 

lower outdoor air fractions (%OA), the differences between the peak indoor CO2-based and 

volumetric airflows were also examined relative to %OA for the study space. The results are 

plotted in Figure 13. The volumetric airflows are below the peak indoor CO2-based values at the 

lowest values of %OA and become increasingly larger than the peak values as the %OA 

increases. Note that the low %OA values are consistent with more air mixing in the building, 

while higher values correspond to less. The trend seen here does support poor mixing as a 

potential explanation of the observed discrepancy. 
112

Figure 13 Relative difference between airflows vs. study space outdoor air fraction 

However, low %OA values also correspond to low outdoor airflow rates, and as seen in Figures 

5 through 7, the discrepancy is largest as the volumetric outdoor airflow rate increases. Therefore 

the trend in Figure 13 may be simply a manifestation of the dependency already noted. 

The discrepancy between the volumetric and peak indoor CO2-based airflow values were also 

examined for any dependence on a number of other factors, including the measured occupant 

density in the study space (number of people per unit floor area) and the estimated uncertainty of 

the peak indoor CO2-based airflow rate, but no dependence was observed.

Accuracy of volumetric airflows

While questions have been raised above regarding the precision and bias of the peak indoor 

CO2-based airflow rates, it is also reasonable to consider the accuracy of the traverse 

measurements. Industry guidance generally cites a measurement uncertainty of about 10 % for 

duct traverses under good field conditions [5-7], but the basis for this estimate is not well 

defined. The key question in the current study is whether there is a reason to suspect that the 

traverse measurements are biased high, particularly for the higher values of outdoor airflow per 

person. These higher values are associated with higher duct velocities. In general, traverse errors 

are more of a concern for low velocities, and therefore there is no particular reason to suspect the 

higher airflow rates to be inaccurate. While duct leakage would cause the delivered outdoor 

airflow to the space to be lower than that measured at the air handler, the amount of leakage 

required to account for the observed differences would have to be extremely high, as much as 

90 % of the supply air leaking out of the ductwork. This is much larger than the commercial 
113

building duct leakage values that have been measured in the field to date, which are more in the 

10 % to 20 % range [8].

One indication of the reliability of the duct traverse measurements is the comparison of the 

outdoor air fraction determined from the measured supply and outdoor airflow rates with the 

outdoor air fraction estimated from the CO2 concentrations in the return, outdoor, and supply

airstreams. As discussed in the original report, these two independent measurements of the 

outdoor air fraction are on average consistent. These data are replotted in Figure 14, and while 

there is some scatter in the data, no strong bias is evident.

Figure 14 Outdoor air fraction based on CO2 ratio vs. based on volumetric flows

A similar comparison can be made by comparing the outdoor airflow intake of the air handlers 

calculated from the supply traverse value times the outdoor air fraction determined from the 

airstream CO2 concentrations with the outdoor airflow measured by the traverse measurements. 

These data are plotted in Figure 15, and while there is significant scatter in the plot the two 

methods of determining this quantity are on average consistent. The mean value of the former 

(Qsupply x %OA) is about 4800 L/s (10 200 cfm), while the mean of the latter is about 5600 L/s 

(11 900 cfm). Therefore, the traverse measurements of outdoor airflow are somewhat higher on 

average, but not enough to account for the differences noted related to the peak indoor CO2-

based airflows. 
114

Figure 15 Outdoor airflow from CO2 ratio times supply airflow vs. volumetric outdoor airflow

Another check on the internal consistency of traverses was performed by calculating the ratio of 

the measured supply airflow to the sum of the outdoor and recirculation airflows. Only twelve 

events exist in which all three airflows were measured by duct traverses. Four of them are in one 

building where the supply and recirculation airflows are very close to each other, i.e., the outdoor 

air intake rate is quite low. The mean value of this ratio for all twelve events is 1.3; without the 

first building the mean is 1.1. This comparison does not prove that the traverse measurements are 

accurate but it does demonstrate their internal consistency. However, if a large and consistent 

systematic error existed, it might have been evident in these ratios. 

Another confirmation of the validity of the traverses is the comparison of the supply airflow 

traverse measurements with the design values. While there is much variation expected in this 

comparison, the mean measured supply airflow rate is 5.12 L/s•m

2

 (1.01 cfm/ft2), while the mean 

of the corresponding design value is 4.98 L/s•m

2

 (0.98 cfm/ft2). This comparison does not prove 

that the traverse values are accurate, but if there were a large systematic error, it should be 

evident in comparing the mean measured to the mean design value.

Limited range of peak CO2 ventilation rates

As noted earlier, the ventilation rates based on the indoor peak CO2 concentrations do not exhibit 

the range of rates seen for the volumetric rates. Considering the data in Figure 7, the peak CO2

ventilation rates never exceed about 35 L/s (74 cfm) per person, which corresponds to an indooroutdoor concentration difference of about 270 mg/m3

 (150 ppm(v)). In other words, the peak 

indoor CO2 concentrations are seldom less than 270 mg/m3 (150 ppm(v)) above the outdoors. 
115

This lower limit on the peak values is a very curious result, for which no explanation has been 

identified.

Conclusion on Peak CO2 versus Traverse Issue

The final comparison worth noting is a “reality-check” on the air change rates calculated from 

the traverse measurements and from the peak CO2 estimates. The mean test space outdoor air 

change rate based on traverse measurements is 1.83 h-1, or 1.87 L/s•m

2

 (0.37 cfm/ft2). Dividing 

this value by the mean outdoor air fraction of 0.31 (based on CO2 concentrations in the supply, 

return, and outdoor airstreams) yields 5.9 h-1 or 6.03 L/s•m

2

 (1.19 cfm/ft2), which is a very

reasonable value for the supply airflow rate in an office building. The mean outdoor air change 

rate based on peak indoor CO2 levels equals 0.83 h-1, or 0.85 L/s•m

2

 (0.17 cfm/ft2), which when 

divided by the average outdoor air fraction is 2.7 h-1 or 2.74 L/s•m2 (0.55 cfm/ft2). These supply

airflow rates based on the peak CO2 values are well below, about half of, typical supply airflow 

rates for an office building.

In conclusion, the discrepancy between the peak indoor CO2-based and traverse-based outdoor 

airflow rates has not been fully explained. However, there is good reason to suspect that the peak 

indoor CO2-based values may not provide reliable estimates of the BASE study space outdoor air 

ventilation rates. In particular, the measured test space CO2 concentrations may be elevated 

relative to the actual space concentrations based on the observed differences between the space 

concentrations and return concentrations, the concentration variation among the test space 

locations, and the fact that the study space concentration is seldom less than 270 mg/m3

(150 ppm(v)) above the outdoor concentration.

CONCLUSIONS

This reanalysis of the BASE ventilation data has uncovered a small number of corrections, none 

of which impact the conclusions of the study. However, the updated dataset is now more reliable 

and should be used instead of the original version released in 2004 [1]. The attempt to explain 

the difference between the outdoor air ventilation rates determined by the duct traverses and 

those based on the peak CO2 concentrations in the study spaces revealed some potential 

explanations related to concentration nonuniformities but they were not able to fully explain the 

magnitude of the differences. It is unlikely that these differences will be explained through 

additional analyses of the BASE data. However, future efforts to understand these differences are 

warranted through experimental efforts specifically designed to investigate the problem. Other 

potential explanations could also be studied in the future, such as those related to assumed values 

for the CO2 generation rates by the occupants.

ACKNOWLEDGEMENTS

This effort was supported by the U.S. Environmental Protection Agency under Interagency

Agreement No. DW-13-93936601. The authors express their appreciation to Gregory Brunner 

and John Girman at EPA for their support and assistance in this work. 
116

REFERENCES

[1] Persily, A. and Gorfain, J. 2004. Analysis of Ventilation Data from the U.S. Environmental 

Protection Agency Building Assessment Survey and Evaluation (BASE) Study, NIST 7145, 

National Institute of Standards and Technology.

[2] EPA. 2006. Building Assessment Survey and Evaluation (BASE) Study Data on Indoor Air 

Quality in Public and Commercial Buildings, (402-C-06-002).

[3] ASTM. 2007. D6245, Standard Guide for Using Indoor Carbon Dioxide Concentrations to 

Evaluate Indoor Air Quality and Ventilation.

[4] EPA. 2003. A Standardized EPA Protocol for Characterizing Indoor Air Quality in Large 

Office Building.

[5] ASHRAE. 1988. Standard 111-1988, Practices for Measurement, Testing, Adjusting, and 

Balancing of Building Heating, Ventilation, Air-Conditioning, and Refrigeration Systems.

[6] NEBB. 1991. Procedural Standards for Testing Adjusting Balancing of Environmental 

Systems. Rockville, Maryland, National Environmental Balancing Bureau.

[7] AABC. 1989. National Standards for Testing and Balancing Heating, Ventilating, and Air 

Conditioning Systems. Washington, DC, Associated Air Balance Council.

[8] Fisk. W.J., Delp, W.W., Diamond, R.C., Dickerhoff, D.J., Levinson, R., Modera, M.P., 

Nematollahi, M., and Wang, D. 2000. Duct Systems in Large Commercial Buildings: Physical 

Characterization, Air Leakage, and Heat Conduction Gains. Lawrence Berkeley National 

Laboratory Report No. LBNL-42339.