Overall and component airtightness values of a five-story apartment building

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Overall and component airtightness values of a five-story apartment

building

Shaw, C. Y.; Magee, R. J.; Rousseau, J.

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Overall and component

airtightness values of a five-story

apartment building

Shaw, C.Y.; Magee, R.J.; Rousseau, J.

NRCC-34049

A version of this document is published in :ASHRAE Transactions, 97(2), pp. 347-353, 91

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OVERALL AND COMPONENT AIRTIGHTNESS

VALUES OF A FIVE-STORY APARTMENT

BUILDING

C.Y. Shaw, Ph.D., P.E.

Member ASHRAE

ABSTRACT

R.J. Magee

Fan pressurization and balanced fan pressurization tests were conducted on afive-story apartment building to deter-mine its air leakage characteristics. The overall airtightness of the building envelope and the airtightness values of the exterior walls of three individual stories were obtained, as well as the airtightness values of interior partitions, stair-wells, and floor/ceiling separations. The methods used to measure the airtightness values are described, and the test results are reported.

INTRODUCTION

The envelopes and interior partitwns of apartment buildings are not airtight. The cracks and openings in them permit some air leakage into and out of a building. They also allow the indoor air to flow from one area to another inside the building. These airflows contribute to the build-ing's heating and cooling load and also to the transport of pollutants inside. With a renewed demand for energy conservation and a growing concern for indoor air quality, there is an increased need to understand and control such airflows.

Several airflow models have been developed for predic-ting such air movement (Kurabuchl et al. 1990; Said 1990). One of the major problems in applying these models is the lack of air leakage characteristics for various types of buildings, particularly for the interior partitions of high-rise apartment buildings. This paper describes a project carried out to measure the airtightness values (air leakage rates measured by the fan depressurization method) of the exterior walls and interior partitions of a five-story

apart-ment building. The methods used and the results obtained

are presented.

TEST BUILDING

The five-story masonry building was constructed in 1981 (Figure 1 and Table 1). The building has a basement, a ground floor, and four typical stories. The basement houses a party room, a laundry room, storage areas, a transformer vault, and a mechanical room. Approximately half the ground floor is occupied by commercial tenants and is separated from the rest of the building. The garbage room is also located on the ground floor. Each typical story

(second through fifth floors) has 12 apartment units-six on

each side of a corridor (Figure 2) . The elevator shaft, enclosed garbage chute, and electrical/service room are located at the center of the corridor. There are two

stair-J. Rousseau ·

Figure 1 Test building showing test setup for measuring airtightness of the building envelope

wells, one on each end of the building. The south stairwell has a hatchway to the outside.

The building has a central heating and ventil ating system that supplies air to the corridor of each story through two supply air registers. There are no return air grilles in the corridor. Return air is drawn into the heating and ventilating system through a dampered opening in the outdoor air supply duct inside the basement mechanical room.

TABLE 1

Description of Test Building

Year Constructed: 1981

Year Tested: 1989 Hei ght (stories): 5

Wall Construction

Exterior Wall: 80 mm (3 in) Face brick 25 mm (1 in) Air space 200 mm (8 in) Co ncrete block 38 mm (1.5 in) Rigid glass fiber

insulation

Metal Studs

38 mm (1.5 in) Semi- rigid glass ti ber

insulat i on Vapor Barrier

1 2 mm (0.5 in) Gypsum board Internal ｬｾ｡ＱＱＺ＠ 13 mm (0. 5 in) Gypsum board 92 mm (3.5 inl Metal studs 38 mm (1.5 in) Insulation blanket 13 mm (0.5 in) Gypsum board

C.Y. Shaw is a Senior Researcher and Robert

.T.

Magee is a Technical Officer at the Institute for Research in Construction, National

Research Council, Ottawa, Ontario, Canada. Jacques Rousseau is a Project Manager at Canada Mortgage and Housing Corp., Ottawa.

347

N

-Figure 2 Typical floor plan

. ｅ｡｣ｾ＠ ｩＺｮ､ｩｶｩｾｵ｡ｬ＠ apartment unit is heated by a fan coil umt eqwp_Ped wtth a hot water heating coil. There is no outdoor a1r supply to the fan coil unit or to individual

ｬｬｰｾｲｴｭ･ｮｴ＠ units. Ventilation air is drawu into the apartment

urut from the corridor by discharging the indoor air to the

outdoors through the kitchen and balhr oom exhaust fans when they are operated by the occupants.

TEST METHODS

The test methods were modified from those developed previously (Shaw et al. 1973; Tamura and Shaw 1976; Shaw 1980; Shaw et al. 1990). A brief description of these methods is given below.

Airtightness Value of the Whole Building

The overall airtightness value was measured using the fan depressurization method (Shaw 1980; Shaw et al.

1990). As shown in Figure 1, a large vane-axial fan was

used

I?

depressurize the test building. The fan airflow could

be adjusted between 0 and 23 m3_{/s (approx.imately 0 to}

50,000 cfm). The. fan inlet ｷｾ＠ ｣ｯｮｮ･｣ｴｾ＠ by 12m (39.3 ft)

of ＰＮｾ＠ m (3 ft). diameter ductmg to a plywood panel

tem-porarily replacwg a rear entrance door that connected to both stairwells. All interior doors to the stairwells were kept open to provide a free-flow path for the air drawn by the fan from the floor spaces through the stajrwells to the

ｯｵｴ､ｾｯｲｳＮ＠ Because the building was fully occupied, for

secunty reasons the entrance door to each apartment unit

was kept closed during the test. A previous study c0nducted on a similar building had indicated that opening or closing the entrance door to each apartment unit had no effect on the .measured overall airtightness values (Shaw 1980). Durwg the test, the building's ventilation system was shut down (with fresh air intake dampers closed) and the dampers in all window air conditioners were closed. Also, the garbage room exhaust fan was shut off and the vent sealed, as was the vent to the transformer vault.

. The ｾｩ ､ ｬｯｷ＠ ｲ｡ｾ･＠ was measured upstream of the fan

ｷｾ･＠ usmg a patr of total-pressure-averaging tubes.

Airflow rate measurements are accurate to within 5% of the

ｭ･｡ ｳ ｵｲｾ＠ ｶ｡ｬｾ ･ｳ Ｌ＠ as determined. during calibration by

c?mpan son With measurements usmg the pitot tube

traver-smg method. The pressure di fferences across the building envelope at both. the ground and roof levels were measured

using an ･ ｬ･｣ｴｾｾ｣＠ manometer with a strip chart recorder

(accurate to Within 5% of the measu red values as specified

by the manufacturer). The average of the pressure differen-ces measured at the ground and roof levels was used to

'

.

348

represent the mean pressure difference across the building

envelope. ｐｾｯｲ＠ to and. immediately after the test, the fan

was sealed w1th a plastic sheet and the pressure differences across the envelope at the ground and roof levels were

measured. ｾｨ･ｳ･＠ "base readings" were then avera-ged and

subtracted from the test results to minimize-weath_er effects (wind and stack action).

As an ｡ｬｾ･ｬｬ＿｡ｴｩｾ･＠ to 1!5ing a vane-ax.ial fan, the supply fan of the bmldmg s heatwg and ventilating system can be

used. for ｴｨｾ＠ test in some cases (Shaw et al. 1973). To

obtam ｭ･｡ｮｷｧｦｵｾ＠ results, the capacity of the supply fan

should be suffic1ent to produce a minimum pressure

､ｩｦｦ･ｲ･ｮｾ･＠ across the buildjng envelope of about 30 Pa. For conductwg such a test, the heating and ventilating system is operated under 100% outdoor air by closing both the main

return Ｈｾ､＠ exhaust, if any) dampers. Different airflow

rates, ｷｨｩｾｨ＠ are needed to produce four or five different

ｰｲ･ｳ ｾ ｵｲ･＠ ､ｩｦｦ･ｲｾｮｾ＠ across the building envelope, can be

obt:amed by adJUStmg the. outdoor or supply air damper.

This ｾ･ｴ＿Ｍｯ､＠ was also applied to measure the aixtightoess of

the butldmg envelope. Very poor results were obtained due to insufficient capacity of the supply fan of the building's heating and ventilating system.

Airtightness Values of Exterior Walls and Floor/Ceiling Separations

of Individual Stories

The balanced .

fll:'l

depressurization technique was used

to measure the a1rt1ghtness values of exterior walls and floor/ceiling separations of individual stories (Shaw 1980). As shown in Figure 3a, a variable-speed fan was used as the primary depressurization apparatus for a selected test

ｳｴｾｲｹＮ＠ The fan airflow could be adjusted between 0 and 1.3

m Is (0 and 2, 7 50 cfm). The fan inlet was connected by 7. 3

m (24 ft) of 0.46 m (1.5 ft) diameter ducting to a plywood

panel temporarily replacing a stairwell door on the ·test story. The outside stairwell door at the ground floor was kept open du?ng the test to allow the air from the test story to exhaust dtrectly to the outdoors. The airflow rate was

measured upstream of the fan intake with a pair of

total-pressure-averaging tubes.

Figure 3

ja) INDIVIDUAL STOREYS

1. ｆｎｾ＠

;:

ｾｴＧ｣Ｚｾｷｮ＠ f'1.0WCONTROl

4. Pltt..sW!lE LU:J.SIJO!UG DEVICE

5, PP.ES5unE OAL\JlCING FAN

('o) HfO!V.OUAL APAATMEIH ｕｾＯＱｔｓ＠

Test setup f or measuring airtightness values of building components

The pressure differences across the exterior wall of the test story and across the two floor/ceiling separations were

each measured using an electronic manometer with ｾ＠ strip

chart recorder. Two balancing fans with manual dampers were similarly installed in the stairwell doors to the stories above and below. These fans were used to control the pressures in these two stories and thereby control the flow of leakage air through the floor/ceiling separations into the test story.

For measuring the airtightness value of the exterior wall, the pressures in the test story and the stories above ar\d below were balanced using the two balancing fans (Figure 3a) to minimize the flow of leakage air through th.e tloorlceiling separations into the test story. For measuring the airtightness values of floor/ceiling separations, two additional tests were conducted immediately after the above test. During each test, only one balancing fan was used ; therefore, the pressure difference across only one floor/ceil-ing separation was reduced to zero. The pressure difference across the other floor/ceiling separation was measured

simultaneously with the p.ressure difference across the

exterio•· wall. The measured leakage rates during this test,

therefore, included the exterior wall leakage of the test floor and that of the' unbalanced floor/ceiling separation. By subtracting from the result the exterior wall air leakage rate at the same pressure difference across the exterior wall (this component could be calculated from U1e results of the first test), the airtightness value of the floor and ceiling tion at the measured pressure difference across the

separa-tion could be determined.

Airtightness Values of Interior Partitions and Floor/Ceiling Separations

of Individual Apartment Units

The balanced fan depressurization method was also

used to obt11in the airtightness values of interior partitions

and floor/ceiling separations of individual apartment units

(Shaw 1980). As shown

in

ｆｩｧｵｾＺ･＠ 3b, a fan was used to

depressurize a selected test apartment unit. The fan airflow

could be adjusted between 0 and 320 Lis (approximately 0

and 680 cfm). The fan inlet was connected by 3 m (10ft)

of 0.2 m (0.65 ft) diameter ducting to a plywood panel

temporarily replacing the entrance door of the test unit. All

interior doors in the apartment

unit

were kept open and all

exhaust fans (e.g. , kitchen and bathroom exhaust fans) were turned off and their grilles sealed. The airflow rate was adjusted with a manual damper and measured upstream of

the fan intake with a pair of total-pressure-averaging tubes.

The pressure differences across the exterior wall and interior partitions were measured using an electronic

manometer with a strip chart .recorder.

In

addition, four balancing fans with manual dampers

were installed, one for each adjacent unit (Figure 3b). By adjusting the airflow rate through each balancing fan until the pressure difference across the corresponding partition

wall or floor/ceiling separation was reduced to

zero,

the air

leakage through that component could be reduced to zero.

Ideally,

a fifth

balancing fan could be used to balance the

pressures between the corridor and the test apartment unit, thereby eliminating the leakage o'f air through the corrjdor

wall . In order to avoid occupant complaints, this application

of a fifth balancing fan was not carried out. As a result, the exterior wall airtightness values of individual apartment units were not measured .

Six

tests

were conducted, one after the other. The first

test was a simple fan depressurization test in which all four balancing fans were off and sealed. The results were,

349

therefore, the overall airtightness values of the test apart-ment unit (excluding its entrance door, which was replaced by a sheet of plywood for installing the pressurization fan) .

In the second test, all four balancing fans were used to

reduce the pressure differences between the test unit and its

four adjacent units to zero. The results were the combined

airtightness values of the exterior wall and the corridor partition (excluding the entrance door) at measured pressure differences across the exterior wall.

Four more tests were conducted immediately after the

second test. The test procedures were similar to those for

individual stories; i.e., in each test, only one balancing fan

was shut down and sealed and the pressure differences

across the Wlbalanced component ao,d across the exterior

wall were measured simultaneously. The results

of

these

four tests and those obtained from the second test were used to determine the airtightness values for the unbalanced building component using the same method as described for the floor/ceiling separations of individual stories.

Airtightness of Stairshafts

The method for stairwell leakage determination has been reported by Tamura and Shaw (1976). Similar to the test for the whole building (Figure 1), the fan with a

maximum capacity of 1.3 m3/s (2,750 cfrn) was ducted to

a

plywood panel temporarily replacing an outside stairwell

door. All other doors to the stairwell were kept closed (but · not sealed).

The airflow rate was measured upstream of the fan

intake using a pair of ｴｯｴ｡ｬｾｰｲ･ｳｳｵｲ ･ Ｍ｡ｶ･ｲ ｡ｧｩｮｧ＠ tubes. The

pressure differences across the stairwell wall were measured

at the ground, third, and

fifth

floors by inserting the probe

into the stairwell through the crack around the door. Again, an electronic manometer with a strip chart recorder was used. The roeasure.d values were averaged to represent the

mean

pressure difference across the shaft. Base readings to

correct for weather effects (wind and stack action) were

conducted as described for the measurement of overall

airtightness value.

RESULTS AND DISCUSSION

The airtightness of the building, three individual stories, ten individual apartment units, and two stairwells

was measured. The measured results are presented below.

Airtightness Value of the Whole Building

Figure 4 shows the overall airtightness values per unit area of exterior wall. Also shown are the results obtained with the alternate method of using the building's heating

and ventilating system to pressurize the building interior.

The results indicate that at the maximum flow rate of 1,280

Lis (2,700 cfm) available from the

HVAC

system, the

pressure difference across the building envelope was about

3 Pa (0.012 in. of water), which was inadequate to produce

meaningful

results.

For compariS<>D, the measured overall airtightness values of three other apartment buildings are also shown in F igure 4 (Shaw 1980; Shaw et al. 1990) . Buildings A, D,

and V are

5,

14, and 17 stories high, respectively. The

results indicate that the overall airtightness value of the test building is almost the same as that of Building V and is about 60% and 100% greater than those ofBuildings A anu

D at

50

Pa (0.2 in. of water) and 10 Pa (0.04 in. of water),

ｾ＠ 0 ·c v x w 0 0 ｾ＠ v a. v 0 0 >

Mean Pressure Diff eren c e Across Exterior Wall, In Water

0 .00 0 ,05 0 . 10 0 . 1:> 0 10 0 25 O, JO ｏ Ｌ ｊｾ＠ 0,"10 ｓｾｲＭＭＭＮＭＭＭＬＭＭＭＭＬ ＭＭｾ ＭＭＭＮｾＭＭＮＭ ＭＭｾＭＭＱ＠

Ｏｾ＠

1/

I

/

4.0 J.5 3.0 -2.5 0.9 0 .8 0.7 0. 6 0.5

''lfll_ .... /··· /

'/

ＯＭＺｾ＠

- - Building V

"""""" '

1_0 .It - Building D ＬＮ ｾ ｉｊ＠

...

e- Te::;l Building

if .& Test Building

0.5 } ••••• / (Supply Air Syslem)

t./

2.0 1.5 0.4 • 0.3 0.2 0.1 M M 0 I 0 20 JO 40 50 60 70 80 90 100

Mean Pressure Difference Across Exterior Wall, Po

Figure 4 Overall airtightness values

Airtightness Values of Individual Stories

N

"

.§ u 0 3o 0 ·o: ｾ＠ w ｾ＠ D 0

"

..{ ·c: ::::J ｾ＠ a. v ｾ＠ 0 > ｾ＠ " c . ;::

"'

ｾ＠ <Z ｾ＠

"

> 0

Exterior Walls Figure 5 shows the airtightness values of the exterior walls of the second, third, and fourth, stories. Again, the plotted results were normalized by the exterior wall area of the individual stories. As shown, the air-tightness value of the second story was about 25% smaller and, therefore, more airtight than lbat of the other lwo stories. Such a variation in results was likely caused by the conditions of windows and patio doors, which varied from apartment unit to apartment unit. For comparison, the overall airtightness value of the whole building was also included inFigure 5. The overall airtightness value per unit area of exterior wall was about the same as that of the second floor and was smaller than those of the other lwo stories. One reason for the discrepancy was that a ｳｩｧｾ＠

nificant part of the ground floor, occupied by commercial tenants, was separated from the building (i.e., no doors connecting the commercial units to the building). As a result, the exterior wall airtightness value of. the ground floor would be smaller than that of the upper floors . This, in tum, would result in a smaller overall airtightness value for the whole building.

Floor/Ceiling Separations Figure 6 shows the airtightness values of floor/ceiling separations for the ground/second, second/third, and third/fourth floors. All results were normalized by the floor area of the individual stories. The data showed a relatively high degree of scatter when compared with the results for the exterior wall airtightness determinations. This was probably because the exterior wall airtightness values were approximately nine times greater than those of the floor/ceiling separations. As the airtightness values of floor/ceiling separations were obtained indirectly by subtracting the ex erior wall leakage fcom the overall value, a small error in lhese measurements would result in a large error in the airtightness values of floor I ceiling separations.

Individual Apartment Units Ten apat1ment units on the third story were tested . Of the ten, permission was

350 N E ,; ... --' 0 ｾ＠ 0

ｾ＠

w 0 0 " < ·c ::::J v a.

"

ｾ＠ 0 > "' "' v c := "' ;.:: ｾ＠

Pressure Difference Ac r oss Ex teri or Wall, In Water 6_0 ,....o.,.o_1 _____ _ _ ｯｾＮｯ｟Ｓ＠ ___ o.,....o5_o.o..-7 __ 0.r1 o _ _ _ _ _ _ _ ｯｾ Ｌ ｊＭ ｯ ＮＮＮ｟ＬＮ＠ 50 4.0 l .O 2.0 1.0 0. 9 0.8 0 . 7

_•

o Overall nd 0 • 2 Fl. Exterior Wall rd 3 1h Fl . Exterior Wall ., 4 Fl. Exterior Wall 0 .6 ＧＭｾＭＭＭ ｾｾＭＭＧＭＭＭＭＭＭＭＭＭＧｾＭｾｾＭＮＮｵ＠ 10 JO 50 70 100

Pressure Difference Across Exterior Wall, Po

1.0 0.8 0.) 0.6 0.5 0.4 O.J 0. 2 N

ｾ＠

0 ｾ＠ ...,

Figure 5 Overall and individual floor exterior wall air-tightness values O.JO N E ,; ... _{0 .20} --' c· .!?

e

0

"-"

Vl 0 0

"

<

0.10 ·c 0.09 ::::J i; O.OB a. 0.07

"

0 0 0.06 > ｾ＠ " 0.05 .5 .c "' ｾ＠ <Z O.O ot 0 ,0.} 2

Pre ssure Difference Ac r oss Floor/Ceiling Separation, In Wate r

0 ,01 0.0) Ｐ ｾ ＰＵ＠ 0_07 0. 10

"'

1st/2 nd Floor

•

2nd/3rd Floor a Jrd/4th Floor

•

4th/5th Floor "' 0

•

•

0 6 7 8 9 10 10

Pressure Difference Across Fl oor /Cei ling Separation , Po

0.05() N

'

E 0.040.

u

O.OJO c ·2 ｾ＠ 0 a. " Vl 0 v 0 .020

<

0.010 0.009 0.006 0.007 0.006 JO ·c: ::::J

Figure 6 Airtightness values of floor/ceiling separation for individual swries

obtained to test six apa rtment units extensively to determine the airtightness values of individual interior ｰ｡ｲｴｩｴｩｯｾｳＬ＠

flo or/ceiling separations, and the exterior wall (which includes the corridor wall leakage). In addition, the overall airtightness values of these units were also measure<! independently. Figure 7 shows typical results of one of these series of tests. The sum of the individual component air leakage rates was approximately

equal

to ｴｨｾ＠ ｩｮ､･ｰ ･ ｮｾ＠

{ll ... ...J

"

0 a::

"

_"'

0 .:< 0

"

...J

Pressure Difference Across Partition, In Water

0.00 ｊＵＰ ｲＭＭＭ ＭＭＮＭＭＭＭＭＬＭ Ｐ Ｎ Ｐｾ＠ 0.10 ＭＭＭＭＭｹＭＭＭＭＭＬＭＭＭＭＭＭｲＭＭＭ 0.15 0. 20 0.25 ＭＭｾＭＬ＠ O,JO 0 Overall 17

•

Exterior Wall JOO 2 A Floor 3

..

Ceiling 4 0 Left Partition ＲｾＰ＠ 5

•

Right Partition 200

Pressure Difference Across Partition, Po

700 600 500 ｾ＠u <OO 2 0 0:: ｾ＠

"'

0 JOO .Y 0 ｾ＠ ...J 200 100

Figure 7 Overall and partition air leakages for apart-ment 307 c Ｚｾ＠ 0 0.. Q , 0 " .{ 8.0 7.0 6.0 5.0 4.0 J .O 2.0 1.0 0.9 0.8 0.7 0.6 0.5 0.4 O.J

•

A 0

•

v

..

0

•

A

Pressure Difference Acr os s Parlilion, In Water

Q_Q.J 0.05 0 07 0 10 301 North 301 South J05 South 306 No rth 306 South 307 North 307 South JOB North 0 JO 1.00 0 90 0 80 o 70 • c" 0 ,60 O.JO 0 ,20 0 10 0 .09 0 08 0 .07 ﾷｾ＠ t 0 0.. 0 ·c: ::J 0.06 ｾ＠ Ｐ Ｎ Ｐｾ＠ 0.2 ｌＭＮ ＭＭＭＭ ＭＭＭＧＧＭＭＭＭＭ ＭＭＭＭＭｾ Ｍ ＭＭＭＭＭＭ ｾ ＮＮＮＮｊ＠ 0.04 J Figure 8 5 6 7 a 9 to 20 Jo "o :.a 60 10 6090

Pressure Difference Ac ross Por\ilion, Po

Airtightness values of interior partitionfor in-dividual apartment units

dently measured ｯｶ･ｲＭ｣ｾｉｬ＠ value. Similar results were also

obtained for the other five tested apartment units.

F igure 8 shows the airtigh tness values for the interior

Jlarti tions . The result<> were normalized by the areas of the

partitions. As shown, the measured airtightness values for

interior partition walls at

50

Pa (0.2 in . of water) varied

from 0. 65 (Unit 308 South) to 3.1 L /s·m2 _{(Unit 306 Sou )}

(0 .13 to 0 .61 cfm/ftZ) . 351 N E ,;

:-:.

c Ｚｾ＠ 0 c._ 0 g .';: ·c ::J ｾ＠ 0. " ｾ＠ 0 > ｾ＠ ｾ＠ " c :c .'!' '<( 0 0.. 0 0

.

< ·c ::J

Pressure Differe nc e Across Partition, In Water

0 Ol Ｐ Ｐｾ＠ 0 0 7 010 0 ,)0 4.0 ｲＭＭＭＭＭ Ｍ ＭＭｾＭＭ ＭＭＭｾ Ｍ ＭＮＭＭ ＭＭＭＭＭ ＭＭＭＮＮＮＮＮＭＬ＠ l.O l .O 1.0 0.9 o.a 0.7 0.5

t

0.5 0.4 I 0 J l ! " 30t South ... .312 North o 307 So u1n • 388 No rth 0 ,70 0.60 N .::::, o.so E u o."o c" 0,)0 0.20 0. 10 0 . 09 008 0 01 0. 06 0.05 ｾ＠

.

0. u -=' ₀ > 0 2 _{ＬＧＭＭＭＭ ＬｾＮＭＬ Ｍ ＮＭ Ｙ＠ -'-, ｯ ＭＭＭＭ ＭＭｾＬＭＺＺＺｯ Ｍ ＭＬｯＭＭ Ｍ Ｌ Ｍ｣＠ ＭＭＺＭＺ ＬｯＭＭＺｯｯ ｾ Ｑｾ Ｐ ｾ ＸｯＧＭＧＹｯ＠} 0 04

Pr essure Oiflerencc Acros s ｐｯｾ｜ ｩ ｴｩｯｮＬ＠ Po

Pressure Difference Acro ss Partition, ln Wolcr

0 OJ 0 .05 0 .07 0 . 1 0 O.JO <.0 ｲＭＭＭ ＭＭＭ Ｍ ｾＭＭＭ ＭＭＭＮ ＭＭＭＭＭＭＬＭＭＭＭＭＭＭＭＭ ＭＭ ＬＮＮＮＮＮＮＮＬ＠ }0 2 0 1 0 0 9 08 Y 307 Norlh 0. 70 Q 6Q N 0_50 0 <O 0 )0 .::::, .§ u c ｾ＠ 0 a. ｾ＠ 0 1 " 0. 0.

"

ｾ＠ a > .

..,

0.6 0 5 04 OJ 0. 10 0 ,09 0 .08 0,07 0.06 0.05 " ｾ＠ a > "' "'

.

c .c. "' ;.:: 0 2 _{ｊｌＭＭｾＭ ＬＭＬ ｟｟ＮＮ Ｌ Ｍ Ｘｾ Ｙ＠} -'-1 ｯＭＭ ＭＭＭＭ Ｍｾｾｯ ＭＭ ＭｊｯＭＭ Ｍ ＴｾＰ＠ ｾｳｯｾＮｯ Ｍ Ｌｾ ｯ ｾ Ｘｯ Ｎ｟ｾ ｧｯ＠ o.o-4 Figure 9

Pressure Dirrerence Across Porlilion, Po

Repeatability of airtightness measurements for interior partitions

Four partitions were each measured twice during this

series of tests, as these partitions are each shared by two

adjacent apartment units. The two results of each of the

four partitions are shown in Figure 9. As shown, except for

the partition between apartment units 305 and 306, the results of the two tests agreed within 20% of each other at

pressure differences greater than 20 Pa (0.08

in.

of water) .

The discrepancy was likely caused by having obtained the

airtightness result indirectly by taking the difference

between the overall value and the overall value less that of the test component. As both values were much larger than

the airtightness value of the partition, a small error in these

measurements would result in a large error in the ftnal

Pressure Diflerence Across Floor. In Woler 0 01 0_0) 0 OS 0 ,07 0, 10 0 JO 1.00 0.90 O.B O

•

Apt. J 05 0.70

•

N 0 Api.J06 E 0.60 N ｾ＠

..

Apl307 _::::.

"

0.50 0.100 ｾ＠ -' D Apl ,JOB 0.090 0 0 . .40

.

ApU12 o.oao 0 0 c: • · · ·2nd/Jrd Storey 0.070 0 0 _O.JO c;: o FLOOR D

"0'

0.060 ₀

e

0 < 0.050 "'

<

·;: •'

..

::> 0.20 Ｌ ＬｾＧ ｾ Ｌ ＮＮ＠

.

.

0 .0 .. 0 c ｾ＠ ::> 0. ' ' 0 .030 ｾ＠ "' "' ｾ＠ "' 0 2 >

..

0 ｾ＠ > " 0.10 ' 0.020 ｾ＠ c O.C9 ｾ＠_"' :2 _{o.ca .s} 0' ;.=

.

£ 0.07 X ﾷｾ＠ 0.06 _·.:;: 0.05 0 0 10 0.009 00< 0,008

'

.

5

• '

B 9 10 10 )0 <0 so 60 70 8:>

Pressure Difference Across Floor, Po Pressure Difference Across Ceiling, In Waler

001 0 OJ 0 05 0.07 o. 10 O,JO I.CO 0.90 0.80 0.70 0 Apt.J06 N .... E _0.!50

..

Ap\.307 _::::. ｾ＠

'

-' 0.50

"

Apt.JOB 0,\00 .E u a.

..

Apt.312 0.090 c, . .§ _{ＰＮｾＰ＠} 0 .060 _Ｚｾ＠ ｾ＠ • -- ·Jrd/4th Storey _0.070 "' u 0 O.JO b CEILING 0 0 2 " o.oso

<

<

·c 010 0.040 _·;: ::> ::> ｾ＠ t; 0. 0.030 0. "' _"

,

D

.

_" 0

..

0 > _' > ｾ＠ 0.10

.

0 .020 "' " 0.0<; :1 c _' :2 0.06 _' ..5

"'

.

£ ;.: O.C7

.

_{' ;.=}

"'

ﾷｾ＠ O.C6

.

.

.

ｾ＠ ＰＮＰｾ＠ 0 010 O.OOQ 0.04 0.006

'

•

5 6

'

6 9 10 20 JO <0 50 60 70 80

Pres::;ure Oif:erence Across Ceiling, Po

Figure 10 Airtightness values of floo r and ceiling for individual apartment units

F igures lOa and lOb show the airtightness values of

floor and ceiling separations, respectively, for individual apartment units. The results also indicate that the measured

airtightness values for floor/ceiling separations at

50

Pa (0.2

in. of water) varied from 0.18 (Unit 306) to 0. 68 L/s·m2

(Unit 305) (0.035 to 0.1 3 cfm/ft2_{). The ceilings for this}

story seem to be much more airtight than the floors. The

measured floor and ceiling airtightness values for the third

story Rlso indicated the same trend. No obvious reason

could be found to explain the difference.

Stairwells The airtightness of two stairwells is shown

in Figure 11. The south stairwell, which contains the roof

access hatch, was approxinutely 40% leakier than the north

stairwell.

352

Mean Slairweii/Corridar Pressure Difference, In of waler

0.03 0,05 0.07 0.10 0.)0 2000 •ooo

•

Norlh Stoirwoll

•

South Stairwell 3000

"'

E

"

..J ₀ .; 1000 0 2000 ,; 900 0 oc oc

"

_"

"' BOO 0 "' -" 0 0 -" " 700 0 -' _, _"

ｾ＠

"ii 5()0 ｾ＠ ·c;

·"

u; 0 u; 500 1000 900 <00 aoo 700 JOO

•

ｾ＠

•

7 6 9 10 20 JO 40 50 •a 10 aogooo

Mean Sloirweli/Corridor Pressure Difference, Po

Figure 11 Airtightness values for stairshafts

Possible Applications of the Data

Strictly speaking, these kinds of data are valid only for the buildings or components tested. For applications where an accurate estimate of the air leakage characteristics of a

specific building is needed (e.g., airflow model validation),

the only way to obtain the data is by measurement. It is not

likely tbat a correlation between airtightness values and

designs of wall construction

can

be developed (Shaw and

Jones 1979). This is because most wall construction consists

of a vapor barrier and a painted interior fmish (e.g., a

painted drywall). As such a combination is much more

airtight than other materials (e.g., bricks or concrete blocks), the airtightness value of a wall assembly is

depen-dent on how well the vapor barrier/interior component is

installed. Therefore, the materials used to construct the exterior portion of a wall assembly would not likely have a

significant influence on its air leakage characteristic. As

indicated in Figure 4, the overall airtightness values of fO\If

buildings with different wall constructions are not very different from each other.

The leakage data, while specific to the building tested,

can be used for design purposes (e.g., estimating air

infi ltration rates for sizing HV AC equipment or p.redicting

air leakage rates through interior partitions for designing

smoke control systems) . For such applications, the

design-ers need a complete data set, such as the one reported for

conducting sensitivity studies . SUMMARY

The airflow capacity of the building's heating and

ventilating system was insufficient to be used for measuring

the airtigb.tness value of the building envelope. Before

planning to

use

the building' s HVAC system for such

measurements,

it is

advisable to measure

the maximum

airflow rate and the JlllLUraum pressure difference it can

Because windows and doors are not uniformly

distri-buted in the building envelope, tests to measure the overall

airtightness value (conducted on the whole building) and the exterior walL airtightness values of individual stories often produce different results. For this building, the overall

airtightness value for the whole building at 50 Pa w:as 3.1

L/s·m2 _{(0.6 cfm/ft'l). The measured exterior wall}

airtight-ness

values for individual stories at 50 Pa (0.2

in .

of water)

varied from 4.0 to 5.1 L/s·m2 _{(0.79 to 1.0 cfmJft'l.}

The measured airtightness values for the building

components of individual apartment units varied from

component to component. For this building, the measured

airtightness values for interior partition walls and

floor/ceil-ing separations at 50 Pa (0.2 in. of water) varied from 0.65

to 3.1 L/s·m2 _{(0.13 to 0.61 cfm/ft}2

) and 0.18 to 0.68

L/s·m2 _{(0.035 to 0.13 cfm/ff), respectively.}

ACKNOWlEDGMENTS

The authors acknowledge the cooperation of the Canada Mortgage and Housing Corporation, the Centretown Citizens (Ottawa) Corporation (CCOC), the tenants of the

test building, and the members of the CCOC Tenants

Committee for their cooperation in making this study

possible, particularly Mr. Glen Dunning and

his

staff at

eeoc

for their assistance during the lests. The authors also

wish to acknowledge the contribution of J.T. Reardon in the

preparation of this paper and the assistance of L.P. Chabot, M. Ferron, and L. Sans Cartier in the field tests and in the processing of the data.

353

REFERENCES

Kurabuchi, T., J.B . Fang, and R.A. Grot. 1990. "A

numerical method for calculating indoor airflows using a turbulence model." NISTIR 89-4211. National Institute of Standards and Technology, U.S. Depart-ment of Commerce.

Said,

M.N.

1990. 11 _{Air and smoke movement model for tall}

buildings." Internal Report, Institute for Research in Construction, NRC.

Shaw, C.Y. 1980. "Methods for conducting small-scale

pressurization tests and air leakage data of multi-story

apartment buildings." ASHRAE Transactions, Vol. 86,

Part 1, pp. 241 -250.

Shaw, C.Y., and L. Jones. 1979. "Air tightness and air

j.nfiltration of school buildings." ASHRAE

Transac-tions, Vol. 85, Part 1, pp. 85-95.

Shaw, C.Y., D.M. Sander, and G.T. Tamura. 1973. "Air

leakage measurements of the exterior walls of tall

buildings. " ASHRAE Transactions, Vol. 79, Part 2,

pp. 40-48.

Shaw, C.Y., S. Gasparetto, and J.T. Reardon . 1990.

"Methods for measuring air leakage in high-rise apart-ments." STP 1067, Air Change Rate and Airtightness in Buildings, pp. 222-229. Philadelphia: American

Society

of

Testing Materials.

Tamura, G.T., and C.Y. Shaw. 1976. ''Air leakage data

for the design of elevator and stair shaft pressurization