NAT’L INST. OF STAND & TECH {

111 III 1 III

! MBS

A11107 3103b7 PUBLICATIONS

NBSIR 83-2770

Air Exchange Rate Measurements

in the National Archives Building

August 1 983

Prepated for and sponsored by:

Public Buildings Service

General Services Administration

7th and D Streets, SW

1 Washington, DC 20407

and

National Archives and Records Service

National Archives Building

Washington, DC 20408

ti atiomal r.rr~.\i

STAMO/.SOS IXURAPY SEP 3 0 1983

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NBSIR 83-2770 G-<^ ' ^

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AIR EXCHANGE RATE MEASUREMENTS V<

IN THE NATIONAL ARCHIVES BUILDING

Samuel Silberstein

Richard A. Grot

Douglas 0. Pruitt Philip Engers

Patrick J. Lane

Steven E. Schweinfurth

August 1 983

Prepared for and sponsored by:

Public Buildings Service

General Services Administration

7th and D Streets, SW

Washington, DC 20407

and

National Archives and Records Service

National Archives Building

Washington, DC 20408

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Abstract

Air exchange measurements were carried out at the National

Archives Building under various combinations of temperature and

wind speed. The average air exchange rate under normal operation

of the heating, ventilating, and air-conditioning system (HVAC)

was 0.9 h

_1 for an average temperature difference of 11.3°C and

an average wind speed of 2.7 m/s. This rate is approximately

twice those for n ew General Services Administration (GSA) office

buildings. No clear dependence of air exchange rate on

temperature differences up to 17°C or wind speeds up to 5 m/s was

found.

With outdoor air dampers closed and fans operating, the

average air exchange rate was 1.2 h“"* for an average temperature

difference of 8.2°C and an average wind speed of 1.7 m/s.

A test of interzone air movement showed that air migrates

rapidly from non-stack to stack areas with fans operating

normally

.

The building could not be pressurized beyond an indooroutdoor pressure difference of Pa. At this pressure

difference, the air exchange rate was 1.5 h~1. As in the case of

normal operation of the HVAC system, this rate is also

approximately twice those for new GSA office buildings.

AIR EXCHANGE RATE MEASUREMENTS IN THE NATIONAL ARCHIVES BUILDING

INTRODUCTION

The National Bureau of Standards (NBS) was asked by the

General Services Administration (GSA) and the National Archives

and Records Service (NARS) to measure air exchange rates of the

National Archives Building under various conditions, including

pressurization. This was done to aid in evaluating whether use

of the current heating, ventilating, and ai r-condi t ionining

(HVAC) system is consistent with preservation of archival

records. The tests performed by NBS are as follows: 1) The air

exchange rate of the building was measured under normal operation

of the HVAC system. 2) The air exchange rate was measured with

outdoor air dampers closed in order to determine how much air

leakage was through dampers. 3) The air exchange rate was

measured with dampers closed and fans off in order to determine

how much the HVAC system contributes to air leakage. 4) Air

leakage from the office and public areas to the stack areas was

measured. 5) Fan pressurization measurements were performed in

order to measure the intrinsic weather-independent envelope

tightness of the building.

METHODS

The National Archives Building

The National Archives Building, located between Pennsylvania

and Constitution Avenues, and between 7th and 9th Streets, in

downtown Washington, is pictured in Fig. 1. Its volume is

306,253.5 m3, according to GSA. A schematic diagram of the

building is shown in Fig. 2. The northern side of the building,

bordering on Pennsylvania Avenue, is composed of ten stories of

offices. Each of these stories is subdivided in the center of

the building into from one to three floors of stacks, where

records are stored. In addition, there are offices located on

several of the stack floors. Nine air handling systems serve the

building (other than the garage). Each system except for systems

2 and 4 is composed of two supply fans and a return fan; systems

2 and 4 are composed of one supply and return fan each. All fans

in each system operate simultaneously. Fig. 2 shows the areas

served by each system.

Installation of automated tracer gas equipment

One set of tubes and wires was connected from each airhandling system to a computer and electron-capture gas

chromatography detector located in the basement. Each set of

tubes and wires consists of 1/16-inch inner diameter (id) plastic

tubing for injecting tracer gas into the supply fans, 1/4-inch id

plastic tubing for sampling return air, wiring connected to a thermistor to measure return air temperature, and wiring

connected to relays to determine whether fans were operating. In

addition, a thermistor was placed outside the air intake of fan 1

1
to measure outdoor temperature, and a weather station was

installed on the roof to measure wind speed and direction. All

temperature and wind measurements were taken once a minute and

the results averaged each hour. In all tests other than those

for which fans were manually shut off, all fans operated

continuously. Outdoor air dampers were automatically modulated

by the building HVAC system and no record was kept of their

status

.

Automated tracer gas equipment used for all tests

The automated tracer gas system developed at NBS and

described elsewhere [1] was used to measure sulfur hexafluoride

concentration and calculate hourly air exchange rates for each of

the nine zones. The instrument was calibrated against samples

containing known concentrations of sulfur hexafluoride. At 50

minutes past the hour, the system injected sulfur hexafluoride

tracer gas for up to ten minutes. The maximal flow rate per zone

was 80 L/s. Concentrations at each location were measured by a gas chromatograph, electron capture detector at 10-minute

intervals thereafter and the results recorded on a floppy disk.

The last four concentrations were fit by regression analysis to

an equation of the form:

C = C 0 e - r t (1)

where

I = air exchange rate, h" 1 t = time after injection, h

C = concentration, ppb

C 0

= initial concentration, ppb

A weighted average of the nine air exchange rates was

calculted and called the air exchange rate of the building. The

weighting factors were closely related to the flow rates of the

air handling systems. It would have been preferable to weight

air exchange rates by relative zone volumes but these data were

unavailable. Table 1 shows these flow rates and the weighting

factors. Average indoor temperature was calculated from the nine

return air temperatures. Because these temperatures were always

very close to each other, they were not weighted. Regression

analysis of air exchange rate vs. indoor-outdoor temperature

difference (always positive in these tests) was done essentially

as described elsewhere [2], Standard errors were also calculated

as described in reference 2.

In the earlier tests conducted from March 24, 1983 through

April 2, tracer gas was injected into each of the nine zones each

hour and its concentration permitted to decay. It was found that

gas was not always completely mixed within the first half hour.

It was also found that tracer gas often migrated into zones 1-5.

Therefore, for the later tests conducted from April 14 through

21, the system was programmed to inject gas once every three

hours for the full 10-minute injection period into zones 6-9

2
only. During the later tests, the tendency for gas to accumulate

in zones 1-5 was no longer noted. Tracer gas was permitted to

thoroughly mix during the first hour. During the third hour,

concentrations were low. Consequently only data collected during

the second hour were used. Fig. 3 shows that there is little

difference between earlier and later data.

Test 1. Normal operation of the HVAC system

No modifications of the HVAC system were required for tests

conducted under normal HVAC operation.

Test 2. Outdoor air dampers closed

To determine how much air leakage was through dampers, air

exchange rates were measured between March 25 and 28 after the

Archives maintenance staff shut all outdoor air dampers.

Test 3. Dampers closed and fans off

To determine how much the HVAC system contributes to air

leakage, air exchange rates were measured during the evening of

April 18 after the maintenance staff shut off the fans. Shutting

off the fans automatically closed the outdoor-air dampers.

Test 4. Air leakage from the office and public areas to the

stack areas

To determine whether air leaks into areas where archives are

stored (stacks) from other areas (non-stack areas), gas was

injected only into zones 1-5. Unlike during the earlier tests,

it mixed evenly throughout the building. (These data were also

used as normal fan-operation data.)

Test 5. Fan pressurization measurements

To measure the intrinsic weather-independent envelope

tightness of the building, a fan pressurization test was

conducted the evening of April 22. Sampling tubes leading from

systems 8 and 9 were rerouted to sample air in stack areas 7W-1

and 14W-1, both served by air-handling system 6, as seen in Fig.

1. Just prior to pressurizing the building, it was determined

that tracer-gas concentrations in these two stack areas were

nearly equal to that in return fan 6, suggesting that tracer gas

was uniformly distributed in that zone.

The maintenance staff shut off all the return air fans,

closed the exhaust air dampers, and fully opened the supply air

dampers (including dampers and fans serving the garage) prior to

tracer gas injection. Tracer gas was manually injected for 30

minutes at a flow rate of 0.25 L/s in order to maintain a high

enough concentration for the high air exchange rates anticipated

during the test. Differential pressure gauges were installed

across the entrance doorways on Pennsylvania and Constitution

Avenues. Since the concentrations in the two stack areas (and in

fact in the remaining 7 air-handling systems) were all nearly

3
constant during tracer gas injection at about 200 ppb, the air

exchange rate was calculated by the equation:

I = F/C-V (2)

where

F = tracer gas flow rate, m3/h

V = bu il d i n g v ol urn e , m

^

Pressurization was maintained for three hours after

injection was terminated. After injection was terminated, the

air exchange rate was also calculated by the computer in the

usual manner.

RESULTS

Test 1. Normal operation of the HVAC system

The results of air exchange rate measurements under normal

HVAC-system operation are shown in Table 2. Fig. 3 shows air

exchange rate measurements plotted against temperature difference

with wind speeds indicated next to the points. Curves

representing one standard error unit about the line are also

shown. The average air exchange rate was 0.9*0. 3 h“^,

corresponding to an average temperature difference (AT) of 11.3°C

and an average wind speed of 2.7 m/s. During normal operation of

the HVAC system, the average indoor temperature of the Archives

Building remained nearly constant at 2 2.8±0.5°C (standard

deviation or sd). The best-fit regression line is given by the

eq uat i on :

I = 0.5 + 0.4 (AT) (3)

where

AT

T

Tin

out

T in - T 0 y t > ° c average indoor temperature, °C

outdoor temperature, °C

The correlation coefficient, R2, is 0.23, reflecting the large

amount of data scatter. The uncertainty of the first

coefficient, as measured by the standard error, is 97 % ; the

uncertainty of the second coefficient is 21%. It can be seen in

Fig. 3 that a linear relationship between I and AT going through

the origin cannot be excluded. Neither can the possibility that

I is independent of AT for AT below 17°C be excluded.

At constant AT (this can be visualized, for example, by

going up any corridor 1°C wide in Fig. 3), air exchange rate does

not incrase with increasing wind speed; if anything, it

decreases. In fact, there is no apparent relationship between

air exchange rate and wind speeds of 0.6-5 m/s encountered during

the study.

4
Test 2. Outdoor air dampers closed

In order to determine how much air leakage was through

outdoor air dampers, a tracer-gas study was performed

with outdoor dampers closed. The results of air exchange rate

measurements with dampers closed are shown in Table 3. Fig. 3

shows the results of this experiment compared with the results of

the previous study. The average air exchange rate was 1.2 h-1 at

an average temperature difference of 8.2°C and an average wind

speed of 1.7 m/s. Two distinct temperature difference regimes

make up this study: 1) small AT (4 data points below 2°C), and 2)

large AT (6 data points between 11 and 17°C). There are no data

directly comparable to the first regime in the study under normal

fan operation, but there are 20 points in the large AT region.

The two large AT results are nearly identical: an air exchange

rate of 1. 1*0.2 h-1 at a temperature difference of 13. 4oc and

wind speed of 1.6 m/s with dampers closed, compared with an air

exchange rate of 1.0*0. 3 h“1 at a temperature difference of

13.5°C and wind speed of 2.8 m/s.

As in the case of normal HVAC-system operation, the large

data scatter make it difficult to assign a definite relationship

between AT and I. In the present instance, neither a direct nor

inverse dependence, nor independence of AT and I can be excluded.

The standard error bands are not drawn, but are so wide that they

encompass the origin and most of the normal HVAC-system operation

data. The combined normal HVAC-system operation and damperclosed data are about as well fit by I = 1 h“1 as by any other

rel ationshi p.

Test 3. Fans off and dampers closed

In order to determine how much the HVAC system contributes

to air leakage, a tracer-gas test was done in which fans were

turned on only at the beginning and end in order to mix the air,

but left off in the middle of the test for about two hours.

During this time, outdoor air dampers were also closed. An air

exchange rate could not be calculated from the data obtained by

this test because nearly all the gas ended up in zone 8

immediately after injection.

Test 4. Air leakage from the office and public areas to the

stack areas

It was determined from information supplied by GSA that airhandling systems 6-9 serve mainly the stacks, while systems 1-5

serve mainly the remainder of the building (Fig. 2). Therefore,

tracer gas was injected only into zones 1 to 5 in order to test

whether there was significant air leakage into the stack areas

from the rest of the building. It was found that there was

immediate, thorough mixing between the stack and non-stack areas.

The tracer gas concentrations in the nine zones were so uniform

during the test, in fact, that it was possible to calculate an

air exchange rate for the building (see Fig. 3 and Table 2,

5
4/19/83, hour 13).

Test 5. Fan pressurization measurements

Fan pressurization measurements were performed in order to

measure the intrinsic weather-independent envelope tightness of

the building. The building was pressurized by closing off all

exhaust air dampers and return fans, including those serving the

garage, and opening all supply air dampers and fans.

Concentration measurements were made in two stack areas on the

7th and 14th stack floors. (There are 21 stack floors.) The

building could be pressurized to maximum pressure differences of

only 14 Pa, measured at the Constitution Avenue entrance on the

ground floor (corresponding to the fifth stack floor) and 10 Pa

at the Pennsylvania Avenue entrance on the main floor

(corresponding to the third stack floor). It was noticed during

the test that there were strong drafts from the garage through

two doorways into the main body of the building. The average

temperature difference during the test was 5.9°C and the average

wind speed was 1.5 m/s.

The air exchange rate calculated by the constant

concentration method (equation 2) was 1.5 h-1. Air exchange

rates were also calculated by the concentration-decay method

(equation 1) for two hours. As shown in Table 4, these air

exchange rates were 0.0 h

- *' for the 14th floor for both hours and

0.1 and 0.4 h

- 1 for the 7th floor. The rates calculated by the

concentration decay method may even be lower than expected in the

absence of pressurization (Fig. 3).

CONCLUSIONS AND RECOMMENDATIONS

Air exchange measurements were taken under various

combinations of temperature and wind speed. The average air

exchange rate was 0.9 h”1 for an average temperature difference

of 11.3°C and an average wind speed of 2.7 m/s. The indoor

temperature was very nearly constant at around 23°C and the

outdoor temperature was always lower than the indoor temperature.

No clear dependence of air exchange rate on temperature

differences up to 17°C or wind speeds up to 5 m/s was found. If a more complete assessment of the National Archives Building is

desired, then further air exchange rate measurements would need to

be taken at different times of the year, and at higher wind

speeds than those encountered during the tests.

The test done with air dampers closed and fans operating

showed that at a temperature difference between 11 and 17°C, the

air exchange rate was the same as that when dampers were

operating automatically. This may be because under normal

operation of the HVAC system, dampers would be closed at these

outdoor temperatures. It would be useful to conduct this type of

test under different weather conditions and record damper opening

and closing.

The test with dampers closed and fans off resulted in tracer

gas ending up in one zone (8), so no useful results could be

obtained.

6
A test of interzone air movement showed that air migrates

rapidly from non-stack to stack areas with fans operating

normally

.

The building could not be pressurized beyond an indooroutdoor pressure difference of 14 Pa. There was some doubt about

the resulting air exchange rate obtained at this pressure

difference since a rate of 1.5 h-1 was obtained by the constant

concentration method and rates under 0.5 h-1 were obtained by the

tracer-gas decay method. The first air exchange rate seems more

likely because it is at least higher than air exchange rates in

the absence of pressurization.

There are uncertainties as to the exact areas served by the

various air-handling systems (Fig. 2) and this tubing and wiring

could prove invaluable in accurately charting the building. For

this reason, and to conduct further tests described below, it is

recommended that the tubing and wiring be left in place.

A similar study of eight new GSA buildings in various parts

of the United States (unpublished data) shows that the Archives

Building is about twice as leaky as new office buildings, both

under normal operation of the HVAC system and under

pressurization. Their air exchange rates under normal operation

of the HVAC systems vary from 0.2 to 0.6 h~' for outdoor

temperatures of 4-10°C and wind speeds under 1.3 m/s. Their air

exchange rates at a pressure difference of 14 Pa were 0.5 to 0.9

h-1

.

ACKNOWLEDGMENT

We wish to

Poyner, and Joe

in carrying out

thank Ron Diggs, Lewis Johnson, Louis Olsen, Dan

Schaefer of GSA for their invaluable assistance

the tests.

REFERENCES

1. R. A. Grot, C. M. Hunt and D. Harrje, "Tracer gas automated

equipment for complex building studies," pp. 103-128 in "First

Air Infiltration Center (AIC) Conference: Air infiltration and

measuring techniques, Proceedings," AIC, Bracknell, UK, 1980.

2. S. Silberstein, "Air leakage measurements of an unpartitioned

mobile home," National Bureau of Standards Interagency Report 80-

2105, Washington, 1980.

7
TABLE 1. Air Handling System Flow Rates and Air Exchange Rate

Weighting Factors.

Sy stem FI ow

103 cfm

rate

, m3/s

Air exchange rate

weighting factor

1 69 33 1 2 5.9 2. 8 0.09

3 62 29 1 4 5.9 2.8 0.09

5 40 19 0.6

6 70 33 1 7 65 31 1 8 66 31 1 9 66 31 1
TABLE 2. Air Exchange Rates under Normal HVAC-System Operation

LEGEND

W SPEED = wind speed, m/s

W DIR = wind direction, degrees clockwise from north

T-OUT = outdoor temperature, oc

T-IN = average indoor temperature, °C

T-DIFF = T-IN - T-OUT, oC

AER = average air exchange rate, h"

(weighting factors in Table 1)

RET = return air fan

DATE HOUR W SPEED W DIR

3/24/83 1 8 2.2 45.0

T-OUT T-IN T-DIFF

7.7 22.4 14.7

RET 1 Z 1.44

RET 2 z 1.14

RET 3 z 1.63

RET 4 z 1.52

RET 5 z .83

RET 6 z .88

RET 7 z 1.20

RET 8 z 1.20

RET 9 z 1.22

DATE HOUR w SPEED

3/24/83 22 2.2

RET 1 = 1.04

RET 2 z 1.39

RET 3 z 1.36

RET 4 z 1.36

RET 5 z .91

RET 6

- .60

RET 7 z .66

RET 8 z .58

RET 9 = 1.37

DATE HOUR w SPEED

3/24/83 23 2.6

RET 1 = 1.41

RET 2 z 1.40

RET 3 z 1.33

RET 4 z 1.15

RET 5 z .77

RET 6 z .70

RET 7 z .51

RET 8 z .62

RET 9 z . 66

W DIR T-OUT T-IN

45.0 7.3 22.3

W DIR T-OUT T-IN

45.0 7.2 22.2

T-DIFF

15.0

T-DIFF

15.0

AER

1.23

AER

.94

AER

.87

9
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

3/25/83 1 3.0 45.0 6.9 22. 1 15.2

RET 1 - 1.34

RET 2 z 1.17

RET 3 z 1.64

RET 4 z 1.38

RET 5 z .77

RET 6 z 1.56

RET 7 z 2.13

RET 8 z 2.19

RET 9 = 1.90

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/25/83 8 2.7 67.5 5.1 21.9 16.8

RET 1 = 1 . 16

RET 2 z 1.05

RET 3 z 1.01

RET 4 z 1.03

RET 5 z .67

RET 6 z .59

RET 7 z .85

RET 8 z .81

RET 9 = .73

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/25/83 9 2.8 67.5 5.4 22.1 16.7

RET 1 = 1.48

RET 2 z 1.72

RET 3 z 1.75

RET 4 z 1.53

RET 5 z .74

RET 6 z 1.32

RET 7 z 1.64

RET 8 z 1.50

RET 9 = 1.24

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/25/83 14 2.7 112.5 8.4 22.4 14.0

RET 1 - 1.38

RET 2 z 1.26

RET 3 z 1.73

RET 4 z 1.49

RET 5 z .71

RET 6 z .90

RET 7 z 1.48

RET 8 z 1.58

RET 9 z 1.00

AER

1.69

AER

.85

AER

1.43

AER

1.29

10
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

/ 25/ 83 15 2.9 90.0 8.9 22.4 13.5

RET 1 - 1.98

RET 2 Z 1.54

RET 3 z 1.97

RET 4 z 1.45

RET 5 z .52

RET 6 z .97

RET 7 z 1.39

RET 8 z 1.48

RET 9 = . 58

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/ 1/83 18 1.5 180.0 14.8 23.4 8.6

RET 1 1.70

RET 2 z 1.92

RET 3 z 2.72

RET 4 z 1.33

RET 5 z .36

RET 6 z 0.00

RET 7 z .22

RET 8 z .44

RET 9 =• 1.81

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/ 2/83 2 .6 67.5 10.9 23.2 12.3

RET 1 = 1.36

RET 2 z 2.30

RET 3 z 1.30

RET 4 z .32

RET 5 z .39

RET 6 z .16

RET 7 z .60

RET 8 z .49

RET 9 = 1.13

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

[/I 4/ 83 13 2.6 157.5 18.5 23.0 4.5

RET 1 .91

RET 2 z .43

RET 3 z 0.00

RET 4 z .26

RET 5 z 0.00

RET 6 z .66

RET 7 z .45

RET 8 z .61

RET 9 z .57

1

1

AER

1.32

AER

1.09

AER

.81

AER

.48
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

1/14/83 16 4.2 135.0 17.8 22.8 5.0

RET 1 - .73

RET 2 z .38

RET 3 z .78

RET 4 z .32

RET 5 z .63

RET 6 z .38

RET 7 z .43

RET 8 z .74

RET 9 = .26

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/ 14/83 19 3.3 135.0 16.4 23.0 6.6

RET 1 = 1.98

RET 2 z .55

RET 3 z . 80

RET 4 z .51

RET 5 z .54

RET 6 z .47

RET 7 z .58

RET 8 z 1.37

RET 9 = .70

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/I 4/ 83 22 2. 1 135.0 16.1 23.0 6.9

RET 1 - 1.92

RET 2 z .49

RET 3 z .57

RET 4 z .70

RET 5 z .74

RET 6 z .60

RET 7 = .56

RET 8 z 1.58

RET 9 = .34

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/I 5/ 83 1 1.9 157.5 15.8 23.1 7.3

RET 1 = 2.20

RET 2 z .76

RET 3 z 1.18

RET 4 z .31

RET 5 z .30

RET 6 z .31

RET 7 z .76

RET 8 z .68

RET 9 z .82

AER

.55

AER

.93

AER

.89

AER

.92

12
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

/ 1 5/ 83 4 1.9 157.5 16.6 23.1 6.5

RET 1 = 1.37

RET 2 .32

RET 3 Z 1.06

RET 4 z .49

RET 5 z. .53

RET 6 z .89

RET 7 z .41

RET 8 z 1.20

RET 9 z .84

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/ 1 5/ 83 7 2.6 157.5 17.7 23.2 5.5

RET 1 = 1.26

RET 2 z .70

RET 3 z .42

RET 4 z .63

RET 5 z .47

RET 6 z .46

RET 7 z .47

RET 8 z .29

RET 9 z .34

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

/I 5/ 83 10 2.3 180.0 18.6 23.7 5.1

RET 1 = 1.48

RET 2 z .71

RET 3 z .35

RET 4 z .48

RET 5 z .82

RET 6 z .65

RET 7 z .53

RET 8 z .58

RET 9 = .64

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

718/83 4 2.5 292.5 9.7 22.2 12.5

RET 1 = 1.48

RET 2 z 0.00

RET 3 z 1.70

RET 4 z .14

RET 5 z .93

RET 6 z .95

RET 7

— .88

RET 8 z .38

RET 9 z .98

AER

.91

AER

.54

AER

.71

AER

1.02

13
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

4/18/83 7 2.3 292.5 10. 8 22.3 11.5

RET 1 = .71

RET 2 Z .90

RET 3 Z .91

RET 4 Z 1.46

RET 5 z .71

RET 6 z .49

RET 7 z 1.44

RET 8 = 2.55

RET 9 = 1.69

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

4/1 8/83 10 2.0 270.0 10.0 22.8 12.8

RET 1 = .84

RET 2 z .71

RET 3 z 1.12

RET 4 z .35

RET 5 z .38

RET 6 z .79

RET 7 Z . 80

RET 8 z .58

RET 9 = .53

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

4/18/83 13 1.8 270.0 11.9 23.0 11.1

RET 1 = 1.46

RET 2 z 1 . 56

RET 3 z 1.00

RET 4 z .48

RET 5 z 0.00

RET 6 z .62

RET 7 z .31

RET 8 z 1.19

RET 9 = 1.10

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

4/18/83 22 2. 1 67.5 11.1 22.9 11.8

RET 1 = .47

RET 2 z .32

RET 3 z 1.01

RET 4 z .74

RET 5 z .72

RET 6 z .13

RET 7 z .56

RET 8 z .56

RET 9 z .92

AER

1.24

AER

.74

AER

.86

AER

.62

14
TABLE 2 (continued)

DATE

4/19/83

DATE

4/19/83

DATE

4/19/83

DATE

4/19/83

HOUR W SPEED

1 2.6

RET 1 = 1.52

RET 2 Z .15

RET 3 z .23

RET 4 z .68

RET 5 z .75

RET 6 z .62

RET 7 z .64

RET 8 z .53

RET 9 = 2.43

HOUR w SPEED

7 3.6

RET 1 - .94

RET 2 z 0.00

RET 3

• z 1.76

RET 4 z .55

RET 5 z .34

RET 6 z .62

RET 7 z .75

RET 8 z .57

RET 9 = 1.62

HOUR w SPEED

13 4.5

RET 1 = 1.25

RET 2 z 1.41

RET 3 z 1.31

RET 4 z 1.02

RET 5 z .08

RET 6 z .77

RET 7 z .23

RET 8 z .61

RET 9 = .64

HOUR w SPEED

16 4.3

RET 1 = 1.29

RET 2 z .71

RET 3 z .57

RET 4 z .47

RET 5 z .41

RET 6 z .90

RET 7 z .23

RET 8 z .75

RET 9 z .29

W DIR

112.5

W DIR

225.0

W DIR

270.0

W DIR

202.5

T-OUT

10.3

T-OUT

10.2

T-OUT

10.9

T-OUT

12.2

T- IN T-DIFF AER

22.8 12.5 .96

T-IN T-DIFF AER

22.7 12.5 .96

T-IN T-DIFF AER

23.7 12.8 .75

T-IN T-DIFF AER

23.7 11.5 .65

15
TABLE 2 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF AER

1/19/83 19 5.0 292.5 9.6 23.4 13.8 .68

RET 1 - 1.10

RET 2 z .01

RET 3 z .49

RET 4 z .62

RET 5 z .33

RET 6 z .40

RET 7 z .48

RET 8 z .55

RET 9 z 1.35

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF AER

1/19/83 22 4.1 292.5 8.6 23.2 14.6 .59

RET 1 = 1.02

RET 2 z 1.13

RET 3 z .73

RET 4 z .73

RET 5 z .61

RET 6 z .75

RET 7 z .35

RET 8 z .59

RET 9 z .06

16
TABLE 3. Air Exchange Rates with Fans Off and Outdoor Dampers Closed

LEGE ND

W SPEED = wind speed, m/s

W DIR = wind direction, degrees clockwise from north

T-OUT = outdoor temperature, oc

T-IN = average indoor temperature, °C

T-DIFF = T-IN - T-OUT, oc

AER = average air exchange rate, h” 1 (weighting factors in Table 1)

RET = return air fan

DATE

3/2 5/83

DATE

3/25/83

DATE

3/25/83

HOUR

18

W SPEED

2.1

RET 1 = 2.01

RET 2 Z 1.05

RET 3 z 1.13

RET 4 z .99

RET 5 z .46

RET 6 z .26

RET 7 z .81

RET 8 z .50

RET 9 = .64

HOUR

21

w SPEED

1.5

RET 1 1.97

RET 2 z 1.05

RET 3 z .97

RET 4 z 1.09

RET 5 z .76

RET 6 = .77

RET 7 z .68

RET 8 z 1.03

RET 9 = 1.86

HOUR

22

w SPEED

1.6

RET 1 = 1.03

RET 2 z 1.48

RET 3 z 1.03

RET 4 z 1.29

RET 5 z .46

RET 6 z .46

RET 7 z .49

RET 8 z .62

RET 9 z 1.48

W DIR

45.0

W DIR

22.5

W DIR

45.0

T-OUT

9.6

T-OUT

9.7

T-OUT

8.7

T-IN T-DIFF

22.5 12.9

T-IN T-DIFF

22.2 12.5

T-IN T-DIFF

22.2 13.5

AER

.86

AER

1 . 17

AER

.83

17
TABLE 3 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

3/25/83 23 1.6 45.0 8.5 22. 1 13.6

RET 1 = 1 . 80

RET 2 z 1.43

RET 3 z 1.31

RET 4 z 1.11

RET 5 z . 84

RET 6 .68

RET 7 z .87

RET 8 z .73

RET 9 = 1.64

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/26/83 0 1.4 45.0 9.2 22.0 12. 8

RET 1 = 2.50

RET 2 a 1.79

RET 3 z 1.26

RET 4 z 1.08

RET 5 z .90

RET 6 z .73

RET 7 z .93

RET 8 z 1.03

RET 9 = 2.24

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/26/83 2 1 .

90.0 6.4 21.4 15.0

RET 1 - 2.10

RET 2 z 2. 16

RET 3 z .78

RET 4 z 1 .10

RET 5 z .43

RET 6 z .49

RET 7 z .54

RET 8 z .98

RET 9 z 1.14

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/27/83 12 3.1 112.5 18.8 19.9 1.1

RET 1 = 1.79

RET 2 z 1.79

RET 3 z 2.07

RET 4 z 1.63

RET 5 z .46

RET 6 z .81

RET 7 z .54

RET 8 z 1.95

RET 9 z .92

AER

1.14

AER

1.40

AER

.97

AER

1.28

18
TABLE 3 (continued)

DATE HOUR W SPEED W DIR T-OUT T-IN T-DIFF

3/27/83 18 1.1 27 0.0 19.6 19.9 .3

RET 1 = 1.67

RET 2 z 2.19

RET 3 z 3.24

RET 4 z 1 . 82

RET 5 z 1.52

RET 6 z 1.24

RET 7 z 1.57

RET 8 z 1.75

RET 9 = 2.57

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/27/83 22 2.0 270.0 19.8 19.9 . 1 RET 1 - 1.91

RET 2 z 2.08

RET 3 z 2.16

RET 4 z .68

RET 5 z 0.00

RET 6 z .90

RET 7 z 0.00

RET 8 z .91

RET 9 - 1.25

DATE HOUR w SPEED W DIR T-OUT T-IN T-DIFF

3/2 8/83 2 1.4 292.5 19.5 19.7 .2

RET 1 = 2.44

RET 2 z 2.24

RET 3 z 1.75

RET 4 z 2.04

RET 5 = .92

RET 6 z .69

RET 7 z .63

RET 8 z 1.03

RET 9 z 3.01

AER

1.96

AER

1.09

AER

1.55

19
TABLE 4. Air Exchange Rates with Building Pressurized to 8-14 Pa

L EGEND

W SPEED = wind speed, m/s

W DIR = wind direction, degrees clockwise from

T-OUT = outdoor temperature, °C

T-IN = average indoor temperature, °C

T-DIFF = T-IN - T-OUT, °C

RET = return air fan

7W-1 and 14W-1 = stack areas

DATE HOUR W SPEED

4/21/83 19 1.4

RET 1 — .09

RET 2 z .12

RET 3 z .39

RET 4 z .01

RET 5 z . 1 8

RET 6 z .56

RET 7 z .26

14W-1 z .02

7W-•1 = .14

DATE HOUR w SPEED

4/21/83 20 .9

RET 1 - .39

RET 2 = .27

RET 3 z .20

RET 4 z .14

RET 5 z .15

RET 6 z .12

RET 7 z .14

14W-1 z 0.00

7W-1 z .43

W DIR T-OUT T-IN

292.5 17.9 23.8

W DIR T-OUT T-IN

315.0 17.8 24.0

north

T-DIFF

5.9

T-DIFF

6.2

20
Figure 1. The National Archives Building, located between

Pennsylvania and Constitution Avenues, and between 7th and 9th

Streets, in downtown Washington.

21
r j <

U. 09 u

II. 3 0C O a <

?

?

8 A, 9 A

3B

1A.3B

1 A,

3 A,5B

1 A,3 A,

3B,4,5B

1 A, 3 A

Figure 2. Schematic side view of National Archives Building,

showing areas served by air-handling systems, from information

supplied by GSA. Each of the nine air-handling systems of the

building except 2 and 4 has two supply air fans labelled "A" and

"B", and one return air fan; systems 2 and 4 have one supply and

return fan each. All fans in each system operate simultaneously.

The numbers in the figure above refer to supply fans.

22
2.0

Figure 3. Relationship of air exchange rate to indoor-outdoor

temperature difference and wind speed under normal fan operation

and with outdoor air dampers closed. Wind speeds (m/s) are

shown to the right of data points. Solid line is best-fit

regression line for normal HVAC-system operation. Curves

represent 1 standard error unit on each side of regression line.

Dotted line is best fit regression line for outdoor air dampers

closed. O , normal operation, early tests (see Methods); ,

normal operation, late tests (see Methods); , normal operation

(late test), test of air mixing between stack areas and other

areas; A, outdoor air dampers closed; • , normal operation

average; , outdoor air dampers closed average; overall

average.

23
NBS-1 14A (REV. 2-8CI U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

REPORT NO.

SHEET (See instructions) NBSIR 83-2770 (GSA) September 1933

4. TITLE AND SUBTITLE

Air Exchange Rate Measurements in the National Archives Building

5. author(S) Samuel Silberstein, Richard A. Grot, Douglas 0. Pruitt, Philip Engers,

Patrick Lane and Steven E. Schweinfurth

6. PERFORMING ORGANIZATION (If joint or other than N BS. see in struction s) 7. Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report 8< Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City. State. ZIP)

Public Building Service of the General Services Administration

7th and D Streets, SW Washington, DC 20407 AND

National Archives and Record Service, National Archives Building,

Washington, DC 20408

10. SUPPLEMENTARY NOTES

~~

1 Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here) Air exchange measurements were carried out at the National Archives Building under

various combinations of temperature and wind speed. The average air exchange rate

under normal operation of the heating, ventilating, and air-conditioning system

(HVAC) was 0.9 h~l for an average temperature difference of 11.3 C and an average

wind speed of 2.7 m/s. This rate is approximately twice those for new General

Services Administration (GSA) office buildings. No clear dependence of air

exchange rate on temperature differences up to 17 C or wind speeds up to 5 m/s was found.

With outdoor air dampers closed and fans operating, the average air exchange rate was 1.2 h for an average temperature difference of 8.2°C and an average wind

speed of 2.8 m/s.

A test of interzone air movement showed that air migrates rapidly from non-stack

to stack areas with fans operating normally.

The building could not be pressurized beyond an indoor-outdoor pressure_cjlif ference

of 14 Pa. At this pressure difference, the air exchange rate was 1.5 h . As in

the case of normal operation of the HVAC system, this rate is also

twice those for new GSA office buildings.

approximately

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Air exchange rate; archives; building envelopel infiltration; pressurization;

records storage; ventilation.

13. AVAILABILITY

Uni imited

| | For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

14. NO. OF

PRINTED PAGES

26

15. Price

£k] Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $8.50

USCOMM-DC 6043-P80