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Application of the Mechanical Ventilation in Elevator Shaft Space to Mitigate Stack Effect under Operation Stage in High-rise Buildings

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Even though the measures to minimize the stack effect in high-rise buildings were taken that include a revolving door on the lobby floor, additional barriers to the passage of air in the lower part of the building, and air-tightness reinforcement for elevator doors, the stack effect is still present during cold season in Korea. However, it is difficult to fully apply the measures for stack effect under occupied condition in high-rise buildings. In this study, as an advanced method to lower the stack effect in highrise buildings under occupied condition, mechanical ventilation in elevator shaft space, which cools the shaft space with outdoor air and reduces the temperature or pressure differences between indoor air in shaft and outdoor air, was proposed. In this paper, the application details and performance analyses of the installed shaft cooling system in a completed building in Korea were described. Also, as a measure to improve the performance of the applied system, concentrated cooling in the lower part of the elevator shaft where there is a main air flow passage was proposed. As a result, cooling effect of mechanical ventilation system in elevator shaft was improved and the extent of stack effect in winter was decreased effectively.
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DOI: 10.1177/1420326X13480055
2014 23: 81 originally published online 8 May 2013Indoor and Built Environment
Doosam Song, Hyunwoo Lim, Joonghoon Lee and Jungmin Seo
operation stage in high-rise buildings
Application of the mechanical ventilation in elevator shaft space to mitigate stack effect under
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I
I
ndoor
ndoor
and
and B
uilt
uilt
Environment
Original Paper
Application of the mechanical
ventilation in elevator shaft
space to mitigate stack effect
under operation stage in high-rise
buildings
Doosam Song
1
, Hyunwoo Lim
2
, Joonghoon Lee
3
and
Jungmin Seo
4
Abstract
Even though the measures to minimize the stack effect in high-rise buildings were taken that include a
revolving door on the lobby floor, additional barriers to the passage of air in the lower part of the
building, and air-tightness reinforcement for elevator doors, the stack effect is still present during cold
season in Korea. However, it is difficult to fully apply the measures for stack effect under occupied
condition in high-rise buildings. In this study, as an advanced method to lower the stack effect in high-
rise buildings under occupied condition, mechanical ventilation in elevator shaft space, which cools the
shaft space with outdoor air and reduces the temperature or pressure differences between indoor air in
shaft and outdoor air, was proposed. In this paper, the application details and performance analyses of
the installed shaft cooling system in a completed building in Korea were described. Also, as a measure
to improve the performance of the applied system, concentrated cooling in the lower part of the
elevator shaft where there is a main air flow passage was proposed. As a result, cooling effect of
mechanical ventilation system in elevator shaft was improved and the extent of stack effect in winter
was decreased effectively.
Keywords
High-rise building, Stack effect, E/V shaft cooling, Occupied state
Date received: 5 August 2012; accepted: 1 February 2013
Introduction
As the building height and temperature difference
between the indoor and the outside increases, the mag-
nitude of the stack effect in buildings also increases.
The stack effect could provoke a number of problems
as follows:
.Strong drafts through the doors in the building.
.Unpleasant noise through gaps in even
closed doors.
.Malfunctioning of the elevators and doors.
.Loss of conditioned (heated or cooled) air and
increase the heating and cooling loads.
.Lower the performance of fire safety systems.
1
Department of Architectural Engineering, Sungkyunkwan
University, Suwon, Republic of Korea
2
Department of Civil, Environmental and Architectural
Engineering, University of Colorado Boulder, CO, USA
3
Technology Research Center, Samsung C&T Corporation,
Seoul, Republic of Korea
4
Graduate School, Sungkyunkwan University, Suwon,
Republic of Korea
Corresponding author:
Joonghoon Lee, Technology Research Center, Samsung C&T
Corporation, Seoul 137–857, Republic of Korea.
Email: jh6925.lee@samsung.com
Indoor and Built Environment
2014, Vol. 23(1) 81–91
!The Author(s) 2013
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Many studies have been conducted to solve these
issues. Some studies have analyzed the characteristics
of the stack effect in high-rise buildings.
1–4
Tamura
5
disclosed the pressure distributions and smoke move-
ment caused by the stack effect in high-rise buildings.
Also, Tamura and Wilson
6
reviewed the relation
between the pressure differences on the building com-
ponents and the air-leakage areas of the building enve-
lope through field measurements.
In connection with the above researches, some stu-
dies have investigated the air-tightness of building com-
ponents. Persily and Grot
7
measured the air-tightness
of the envelopes of 8 office buildings in USA. Tamura
and Shaw
8
measured the air-tightness of the envelopes
of 8 buildings with 9–25 storeys and also they measured
the air-leakage rates from elevator doors and staircase
doors.
Meanwhile, studies have been conducted to propose
measures to reduce stack effect problems. Tamura and
Wilson
6
proposed strengthening the air-tightness of a
building envelope and installing vestibules. ASHRAE
research
9
proposed that strengthening the air-tightness
of building envelope is the most important measure for
reducing stack effect in tall buildings, and the next-best
method is strengthening the air-tightness of walls inside
buildings. Also, Hayakawa and Togari
10
suggested a
method to distribute stack effect pressure by installing
additional indoor partitions. Yu et al.
11
investigated the
stack effects in high-rise buildings according to the
layout of the lobby floor and the ratio of window
area. Koo et al.
12
examined the effects of architectural
plans on the stack effect for high-rise residential build-
ings. Lee et al.
13
suggested a design process to install
revolving doors in order to effectively reduce drafts
caused by stack effect in high-rise buildings. This
design process includes the method to determine the
installation location and air leakage areas of the revol-
ving doors that minimize the draft rate below the target
value. These architectural methods should be applied to
entire building for successful reduction of stack effect.
However, improving the air-tightness of a whole build-
ing envelope is almost impossible after completion of
building and installing additional indoor partitions in a
whole building needs much cost and time.
As an active control strategy using equipment to
reduce the stack effect problems, Tamblyn
14
proposed
the method of indoor pressurization with AHU and
Takemasa
15
demonstrated through a field survey and
simulation that pressurization on all the floors of a
building can reduce the air pressure difference between
the outdoor and indoor on the lobby floor, and can
prevent the air flow rate from intruding indoors.
While these examples utilize a facility system to deal
with the stack effect, these methods are only partially
effective in lowering the air pressure and air flow rate in
applied areas, because they fail to consider the overall
pressure distribution in a building. The force that
causes the stack effect may be transferred to other
parts, resulting in secondary problems in unapplied
areas. Also, the measures mentioned above have the
limitations to apply under occupied condition in
terms of building design considerations, cost, and
builders work level.
Lee et al.
16
proposed an advanced method called the
mechanical ventilation in elevator shaft space. The idea
involves addressing a fundamental cause of the prob-
lem by reducing the air density difference or tempera-
ture difference between the elevator shaft space and the
outdoor environment, and as a result, weakening the
driving force of the stack effect.
Based on the preceding research by Lee et al.,
16
in
this study, the operation methods of the mechanical
ventilation system in elevator shaft, which was applied
restrictively to an occupied state in a high-rise office
building in Korea, were analyzed to find optimal per-
formance. The field measurements were performed to
verify the applied system performance, and the various
reasons why full performance of the system is
obstructed were examined. As a result, a concentrated
cooling method in the lower part of elevator shaft space
is proposed to maximize the performance of the applied
system which is limited in installed conditions.
Target building and mechanical
ventilation in elevator shaft space as
a countermeasure for stack effect
Stack effect behaviors in target building
Figure 1 is a section view of the target building. This
building is a large-scale office building located in Seoul,
which has eight underground floors and forty-one
ground floors; the floor area of the building is
197,428 m
2
. Vertical shafts as main air flow paths are
found in various parts of the building: customer eleva-
tors for lower floors (1 F–17 F), middle floors (1 F,
17 F–28 F) and upper floors (1 F, 28 F–40 F), shuttle
elevator to access the parking lot and lower floors
(B7–4 F), emergency elevator for all floors, and a stair-
well. Customer elevators are located at the centre of the
hall and are divided into six elevator shafts. A typical
floor contains an elevator hall and an office area is
designed as an open-type floor plan with no interior
partitions.
Considering the stack effect for a large-scaled build-
ing, architectural measures were taken that include a
revolving door on the lobby floor, additional partition-
ing in the lower part of the building, and air-tightness
reinforcement for elevator doors. However, the stack
effect was still present during winter, especially on the
82 Indoor and Built Environment 23(1)
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lobby floor and the 40th floor. Major related problems
are as follows:
.Strong draft when elevator door opens: lobby floor
(5–6 m s
1
), 38th–40th floors (3–4 m s
1
).
.Noise from elevator door: lobby floor (about 60 dB),
38th–40th floors (about 50 dB).
.Noise from emergency elevator door.
.Malfunctioning of elevator hall door (automatic
door): 40th floor.
.Poor heating performance on the lobby floor by
excessive outdoor air inflow.
.Malfunctioning of elevator on the lobby floor.
Mechanical ventilation in elevator shaft
space as a countermeasure
When the building situation that the building has occu-
pied was considered, the application of additional
architectural countermeasures on stack effect was
impossible. Moreover, the reduction effect on stack
effect problems of architectural countermeasures
applied locally is small. Therefore, elevator shaft cool-
ing with mechanical ventilation system that can reduce
stack effect evenly throughout a building was installed.
The factor that triggers stack effect and its magni-
tude, i.e., pressure gradient between the outdoor envir-
onment and indoor spaces, is determined by the height
of the building and temperature differences between the
outdoor environment and indoor spaces as shown in
equation (1).
P¼gðhhnplÞoðTiToÞ=Tið1Þ
where Pis the pressure difference (gradient) between
the outdoor environment and indoor spaces caused by
stack action (Pa), gis the gravitational constant
(m s
2
), his the building height of interest (m), h
npl
is
the height of neutral pressure level (m), is the air
density (kg m
3
), T
i
is the indoor temperature (K),
and T
o
stands for outdoor temperature (K).
As shown in Figure 2, the mechanical ventilation
system in elevator shaft reduces stack effect by reducing
the temperature difference between the outdoor envir-
onment and indoor spaces, which is one of the factors
that determine the magnitude of stack effect. That is, an
elevator shaft and the outdoor air are connected
through a duct to supply outdoor air into the shaft
space. The cold outdoor air in winter season flows
into the elevator shaft and is exhausted through the
top of the shaft. Through this process, the air in the
elevator shaft is cooled and consequently the air density
in the elevator shaft is increased and the slope of pres-
sure profile inside the shaft is increased, and in turn, the
pressure difference between outdoor and shaft is
decreased. As results, stack effect in the entire building
is reduced.
As a stack effect reduction measure under occupied
condition, strengthening the air-tightness of a specific
wall can be considered, but the draft reduction effect is
limited at the specific wall, and the other parts are
nearly unchanged. Moreover, secondary problems,
such as the pressure transition, can occur. Therefore,
in the case where the air-tightness of the wall compo-
nents is increased, all of the wall components in build-
ing should be increased. However, it requires additional
construction and cost. The mechanical ventilation
system in elevator shaft has the similar draft reduction
effect to strengthening the air-tightness of the all wall
components in the building and is more useful in terms
of the construction, cost, and application under occu-
pied condition in high-rise building.
17
There are two important things in applying the
mechanical ventilation in elevator shaft space. One is
to keep temperature inside the elevator shaft above the
dew point temperature. If the temperature goes down
below the dew point temperature, condensation may
occur on the inside wall of the elevator shaft, resulting
in indoor air quality (IAQ) problems.
18
The other is to
maintain the neutral pressure level.
5
If the neutral pres-
sure level of shaft varies vertically by operation of the
mechanical ventilation system, the pressure difference
by the stack effect would be increased on the opposite
side to the direction of movement of the neutral
Figure 1. Section of the target building.
Song et al. 83
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pressure level, resulting in side effect. To keep the neu-
tral pressure level, the supply air flow rate into the ele-
vator shaft and exhaust air flow rate from the elevator
shaft should be the same when the mechanical ventila-
tion system is operated. Also, the vertical distribution
of cooling temperature inside the elevator shaft should
be made uniform.
Even though the mechanical ventilation in elevator
shaft is a possible way to minimize the stack effect
under occupied condition in high-rise building, this
system was installed after completion of the target
building under limited conditions. As shown in
Figures 3 and 4, it was decided that the air supply
and exhaust ducts for the mechanical ventilation in ele-
vator shaft would be installed on the rooftop. The air
supply from the rooftop was branched to two sides of
the elevator shaft and the outside air was supplied at
eight points through the six internal vertical ducts, and
air was exhausted through the upper part. Table 1
shows the air flow rate of the two shafts measured
through Testing, Adjusting, and Balancing (TAB).
Performance analysis of the mechanical
ventilation system in elevator shaft
To analyze the performance of the installed mechanical
ventilation system, the temperature changes at various
positions in the shaft were examined through the mon-
itoring of the temperature sensors in the shaft.
Moreover, for the lobby floor and top floor (40 F),
where particularly large drafts occur due to the stack
effect, the passing wind velocity at the opening of the
elevator doors was periodically measured.
The temperature sensors were installed at 3 levels;
the 10th floor level, 20th floor level, and 30th floor
level, and were located inside the elevator shaft. The
measurement range was from 18 Cto+93
C and
its margin of error was from 0.3 C to + 0.3 C. The
data measured by the temperature sensors were moni-
tored and recorded once every hour by the building
controls system.
Figure 5 shows the average temperature (mean value
of 3 points) distribution in the elevator shaft (shaft A)
with and without shaft cooling (Figure 5(a)) and the
temperature distributions of three points in the shaft
when the mechanical ventilation system was operated
or not (Figure 5(b)).
As shown in Figure 5(a), when the elevator shaft
space was cooled, the average temperature of the
shaft space was lower by 2–3.5 C compared to the
case when the elevator shaft cooling was not activated.
On the other hand, when the outside air temperature
was 11.3 C, which is the design condition of the heat-
ing system in Korea, it was expected that the average
Shaft cooling by inflowing
outdoor air with mechanical
ventilation
*Absolute pressure
Neutral Pressure Level Reduce the building infiltration
and air flow rate(stack effect)
through elevator shaft
P1(Before cooling the elevator shaft)
Ambient
Mechanical ventilation (after cooling)
Mechanical ventilation (before cooling
)
Reduce the temperature and
pressure differences between
outdoor air and elevator shaft
P2(After cooling the elevator shaft)
Return air
Supply outdoor air with
mechanical ventilation
ΔP : driving force of stack effect
Elevator shaft
Air flowing into shaft
Air flowing out shaft
Pressure
Height
Supply duct
Figure 2. Principle of stack effect reduction using the mechanical ventilation in elevator shaft space.
84 Indoor and Built Environment 23(1)
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temperature of the elevator shaft would be cooled by
16.75 C. However, the average temperature measured
inside the elevator shaft was approximately 21 C, and
there was a difference of 4.25 C between the measure-
ment result and designed temperature. This could be
attributed to the insufficient amount of outdoor air
supply compared to the designed quantity. The
designed amount of air volume of the mechanical ven-
tilation system was 7,200 m
3
h
1
in the shaft A, but the
actual volume was measured at 6,733 m
3
h
1
.
Furthermore, as shown in Figure 5(b), the temperatures
of the upper part (30 F) of the shaft were lower than
those of the lower part (10 F) during the activation of
the mechanical ventilation system. This was because the
outside air supplied from the rooftop would acquire
heat while being supplied to the lower part of the
shaft due to the conduction between duct and shaft
space. As a result, the elevator shaft space was not
fully cooled and caused a performance difference
between initial designed system and actually installed
system in the target building.
Figure 6 shows the result of the inflow air velocity
(1 F) into the shaft and the outflow air velocity (40 F)
from the shaft to the interior caused by the stack effect
when the elevator door was opened. The draft at the
elevator door while the door was opened was chosen as
an evaluation item for stack effect reduction rate with
or without the elevator shaft cooling, because excessive
draft was one of the serious problems caused by the
Figure 3. Horizontal duct divergence (elevator engine room for upper floors).
Figure 4. Vertical duct distribution in elevator shaft.
Table 1. Amount of air supply and exhaust of the mech-
anical ventilation system (Testing, Adjusting, and Balancing
(TAB) results).
Shaft Supply (m
3
h
1
) Exhaust (m
3
h
1
)
Shaft A 6,733 6,385
Shaft B 10,036 9,337
Song et al. 85
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Figure 5. Temperature changes in high-rise elevator shaft (a) Average temperature distributions (b) Local temperature.
86 Indoor and Built Environment 23(1)
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stack effect in the target building. Also, wind velocity
was easily measured in the occupied building. A por-
table anemometer (TSI 9535-A) was used to measure
the wind velocities through the elevator doors. Its
measuring range was from 0 m s
1
to+30ms
1
and
its margin of error was from 0.15 m s
1
to + 0.16 m s
1
.
As shown in equation (2), the pressure difference due
to the stack effect is proportional to the air velocity
when the air leakage area is fixed.
Q¼Affiffiffiffiffiffiffiffiffi
2P
s/Av ð2Þ
where Qrepresents air flow rate (m
3
s
1
), is air flow
coefficient (dimensionless), Ais air leakage area (m
2
),
is air density (kg m
3
), Pis pressure difference (Pa),
and vis air velocity (m s
1
).
From the measurement results, when the mechanical
ventilation system in elevator shaft was operated, the
air velocity at the elevator door of the 1st floor
decreased by approximately 13%, and the air velocity
at the elevator door of the 40th floor decreased by
approximately 37%. The ratio was different between
the floors due to uneven cooling within the shaft; the
cooling efficiency was shown to be poorer in the lower
part of the shaft.
Operational method to improve
performance of the mechanical
ventilation system in
elevator shaft
Concentrated cooling in lower part
of the shaft
Regarding the measurements result, the mechanical
ventilation system in elevator shaft installed in the
target building did not achieve the proper cooling
effect. As a result, thermal stratification occurred in
the elevator shaft and the stack effect reduction by
the elevator shaft cooling was lower than expected.
Also, in the target building, the stack effect problem
on the 1st floor was worse than 40th floor; accordingly
the reduction rate of stack effect on the 1st floor was
relatively less than 40th floor due to poor cooling in
lower part of elevator shaft.
In order to improve the performance of the cooling
system and resolve stack effect problem on the 1st floor,
alternative methods were explored by the commission-
ing team and management team (Table 2). After dis-
cussions, it was decided that concentrating the air
supply in the lower part of the shaft was a viable solu-
tion, as it did not require additional engineering work.
Figure 7 illustrates the concept of concentrated cool-
ing in the lower part of the shaft. The former outdoor
Table 2. Measures to improve performance of mechanical ventilation system in elevator shaft.
Major problems Causes Measures
Lack of cooling efficiency in
elevator shaft A
Lack of O.A. supply: Increase supply air volume
Designed supply air volume: 7,200 m
3
h
1
,
TAB result: 6,733 m
3
h
1
Temperature difference
between upper and lower
part of the elevator shaft
Heat gain in O.A. supply duct Insulation of O.A. supply duct
Short-circuit at upper part of elevator shaft Add exhaust duct at the middle
level in elevator shaft
Concentrate the air supply in the
lower part of the shaft (adopted)
100 100
87
73
0
20
40
60
80
100
120
40F1F
Floors
OFF
ON
Rate of air velocity [%]
Figure 6. Rate of air velocity when the elevator door was
opened.
Song et al. 87
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air (O.A.) supply was condensed from 8 diffusers to
2 diffusers in the lower part of the shaft. This leads to
the increase in the cool air supply to the lower part of
elevator shaft, then decrease in the lower part tempera-
ture of the shaft, and the equalization of temperature
inside the shaft. Furthermore, this method could lead to
the average temperature drop inside shaft by reducing
short-circuit.
Analysis of the effect of concentrated
cooling in lower part of the shaft
Based on the meeting results, concentrated cooling
was applied to the target building. The outdoor air
supply was adjusted from the eight supply inlets to
two supply inlets in the lower part of the shaft. As
shown in Table 3, the total supply air volume by
mechanical ventilation in elevator shaft was not chan-
ged. But the infiltration rates of the whole building
caused by stack effect were changed due to the eleva-
tor shaft cooling method. The infiltration rates were
down by 13.2% when elevator shaft cooling was
accomplished with even air cooling compared to the
non-cooling condition. In case of the concentrated air-
cooling in lower part, the infiltration rates were
decreased by 13.8%.
Figure 8 shows the average temperatures (Figure
8(a)) in the elevator shaft (shaft A) and the tempera-
tures at various points (Figure 8(b)) after the adjust-
ment. Compared to the air supply through the eight
diffusers in the shaft (8ea), the concentrated air supply
from the two diffusers (2ea) in the lower part
decreased the average temperature inside the shaft
by approximately 1–1.5 C. In particular, since the
cooling effects in lower part in the shaft were
improved, temperature difference between lower
part (10th floor height in shaft) and upper part (30th
floor height in shaft) was decreased from 2.5 Cto
2.0 C. This was because the amount of cooled air
increased in the lower part of the shaft and the
short circuit of cooled air in the upper part of the
shaft decreased.
Figure 9 shows the reduction rate of wind velocity
when the elevator door was opened. The concentrated
cooling decreased the elevator door passing wind velo-
city on the 1 F and 40 F by 41% and 48%, respectively,
compared to the non-cooling condition. Moreover,
with the concentrated cooling at the lower part of the
shaft, the reduction effects on 1 F and 40 F had signifi-
cantly improved by 28% and 21%, respectively, com-
pared to those of even air-cooling (8ea air supply). As a
result, the lower part concentrated cooling improved
the stack effect reduction performance compared to
the even air-cooling (8ea air supply) in the target
building.
Figure 7. Concept of concentrated cooling in elevator
shaft. (a) Even air cooling (8 diffusers) (b) Concentrated
air cooling in lower part (2 diffusers).
Table 3. Air flow rate according to the elevator shaft cooling method.
Methods
Air flow rate (m
3
h
1
)
Reduction
rate (%)
Infiltration by stack
effect
Supply (shaft A) by elevator
shaft cooling system
Non cooling (Off) 6,703 6,733 0
Even air cooling (8 diffusers) 5,820 13.2
Concentrated air cooling in
lower part (2 diffusers)
5,780 13.8
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Figure 8. Temperature changes in high-rise elevator shaft (a) Average temperature. (b) Local temperature.
Song et al. 89
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Discussion and conclusions
As a measure to reduce the stack effect under occupied
condition in high-rise office buildings, the mechanical
ventilation in elevator shaft was applied to the
40-storey building in Korea. Field measurements were
performed to examine the performance of the applied
system, and its limitations were addressed to improve
the stack reduction effect in the target building. The
following summarizes the main findings and achieve-
ments of this study.
The designed mechanical ventilation was implemen-
ted to the elevator shaft of a target building. However,
the installed mechanical ventilation system proved that
it did not fully express the cooling effect due to the lack
of outdoor air volume, heat gain in the air supply path,
and short-circuit from the field measurements. Since the
thermal stratification was observed with a relatively
higher air temperature in the lower part of the shaft,
the magnitude of the draft decreased by 27% on the top
floor and 13% on the lobby floor, which differed from
the initial estimate.
As a measure to improve the performance of the
installed system, the concentrated air supply to the
lower part of the elevator shaft was examined consider-
ing the stack effect characteristics of the target building
and the conditions of the installed mechanical ventila-
tion system. The concentrated cooling improved the
performance of the mechanical ventilation system com-
pared to even air-cooling. Even though the infiltration
rates of the whole building were not significantly differ-
ent between even air-cooling and concentrated air cool-
ing, the major problem such as strong draft was
remarkably decreased when the concentrated cooling
was applied. As a result, the magnitude of the draft
decreased by 48% on the top floor and 41% on the
lobby floor, compared to the non-cooling condition.
The methods suggested in this study can be used to
reduce the problems with stack effect under occupied
condition in high-rise building. The findings of this
study would be useful for solving the stack effect pro-
blem in high-rise buildings under occupied condition.
Acknowledgements
This research was supported by WCU (World Class
University) program through the Korea Science and
Engineering Foundation funded by the Ministry of
Education, Science and Technology (R33-2012-000-10027-0)
through Sungkyunkwan University.
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... Lee et al. [6] proposed the shaft cooling technology by reducing the temperature difference between the elevator shaft space and the outdoor environment to weaken the driving force of the stack effect. Song et al. [7] improved the shaft cooling technology by using mechanical ventilation to cool elevator shaft space with outdoor air. Xie et al. [8] built a coupled multi-zone and CFD model to simulate the elevator shaft cooling system. ...
... The γ is a criterion of the tightness of the envelope and can also be used to calculate the air infiltration and leakage. An improved formula [1] of γ is given by Equations (6) and (7), and the pressure differences are replaced by the equivalent leakage area of the envelope and interior partitions. ...
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Energy loss and performance deterioration caused by the stack effect are emerging issues in high-rise office buildings (HROB). However, a single countermeasure may not completely remove the stack effect problems, so combinations of countermeasures are often considered in building commissioning or retrofit projects to achieve the desired results. Therefore, a comprehensive study on combinations is necessary for the final decision-making. In this study, a multi-criteria decision-making model is proposed, which is utilized to calculate the ranking of countermeasure combinations for the final decision-making index by assigning weights and conducting comprehensive analysis on four criteria: infiltration energy loss, maximum pressure difference, investment cost, and implementation resistance. Based on a two-level Fractional-Factorial design (FFD), the interaction effects between countermeasures were verified, and the regression models of infiltration energy loss and maximum pressure difference were obtained as well. The investment cost and implementation resistance were defined according to the investigation and survey. An Analytic Hierarchy Process (AHP) was applied to establish the weights of each criterion. A weighted Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method was applied to establish the decision-making index. Through the case study of a HROB located in northern China, it was concluded that the ideal combination can reduce infiltration and pressure difference by 26.88% and 87.58%, respectively, with low-level investment costs and implementation resistance. The results indicate that the multi-criteria model provides a comprehensive ranking of countermeasure combinations, which can serve as a quantitative basis for the final decision-making. Furthermore, this multi-criteria decision-making approach can be extended to other buildings in other regions.
... • Setting positive pressure ventilation in the elevator shaft: According to the International Building Code (IBC) and the Florida Building Code (FBC), elevator hoist ways shall be pressurized to maintain a minimum positive pressure of 0.10 inch of water (25 Pa) and a maximum positive pressure [50]. ...
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Recently, the Egyptian government has sought to create new urban spots. The New Administrative Capital was one of those new urban extensions. Architects and urban designers tended to vertical expansion in planning this city as a result of the high cost of the land. Accordingly, high-rise and super-high-rise buildings have been relied upon in the architectural design of the buildings. This study aims to evaluate the achievement of safe occupants' evacuation in case of fire for two high-rise and one super high-rise complex buildings based on a set of variables. Staircase design, the use of elevators, and the provision of refuge areas were evaluated, through simulating seven scenarios using Pathfinder software. The simulation results comprised an assessment of average stairs traffic jams, the occupant load density on emergency stairs, and the required safe evacuation time (R SET) for each scenario. It was concluded from the study that staircase design has a significant impact on (R SET) time. As well as, evacuation using elevators or relaying on refuge areas as auxiliary means with the emergency stairs may be safer for these types of buildings. Finally, the study provided technical requirements for using refuge areas and elevators in emergency evacuation in high-rise and super high-rise buildings.
... However, in summer, a reverse airflow process occurs, wherein cool indoor air flows towards the outside of buildings. Such an airflow phenomenon in a high-rise building is called the stack effect [3,4] and it may lead to severe problems in two aspects: one caused by strong flow, e.g., unpleasant noise [5][6][7] and the propagation of unwanted contaminants [8,9]; the other resulting from excessive pressure difference, e.g., malfunction in opening or closing elevator doors [10,11]. ...
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The stack effect in high-rise buildings, stemming from an inside/outside temperature difference, may produce a significant pressure difference on the elevator doors, potentially causing elevator malfunctions. This effect can also be influenced by wind action and human behaviors, e.g., opening/closing of building entrances. In this study, a wind tunnel test was conducted to determine the real wind pressure distribution on a high-rise building in northern China. A numerical simulation utilizing the Conjunction of Multizone Infiltration Specialists software (COMIS) was carried out to investigate the pressure difference of elevator doors under the effects of thermal buoyancy, wind action, and opening/closing of the first-floor lobby entrance. An alternative solution of a locally strengthened envelope is proposed and validated for the studied building zone. The study reveals that the opening of the first-floor lobby entrance increases the pressure difference regardless of the environmental conditions, and the increase of wind speed tends to increase the pressure difference in winter but decrease it in summer. The proposed countermeasure combination, involving using revolving doors instead of swing doors, increasing additional partitions, and strengthening the local building envelope, was found to be synergistic and effective in reducing the pressure difference inside the building. The research findings offer practical engineering solutions for mitigating elevator door pressure challenges in high-rise buildings.
... The main principle of these methods is to reduce the magnitude of the pressure difference by lowering the temperature difference between the shaft and the external environment. This can be achieved through techniques such as drawing outdoor air into the elevator shaft using a fan [12] or implementing a passive cooling system for the elevator shaft [13][14][15]. For example, Yu et al. [16] performed a set of simulation cases to find an effective HVAC operation scheme to reduce the excessive pressure difference acting on building components, and the scheme of pressurizing the upper zone of a building was implemented in the actual building. ...
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In high-rise buildings, the excessive pressure differences cause various problems, and architectural and mechanical measures are always applied. In this study, pressure measurements on a 67-story high-rise building were conducted to evaluate the effect of mechanical pressurization on the pressure distribution. Absolute pressure measurement devices were installed at 28 points on 10 floors, a full-scale pressure profile of the test building was derived, and the pressure distributions on the main floors were reviewed. Four pressurization modes for the test building were considered, and the variation in the pressure distribution for each mode was analyzed. The results showed that mechanical pressurization reduced the pressure difference on the lobby floor by approximately 18%. Although it did not exert an apparent impact on the pressure difference due to the stack effect, pressurizing the entire floor serves as the most effective way of reducing the excessive pressure difference.
... The PM reduction by the open-door intervention was an order of magnitude lower in the 1940s elevator compared to the 1960s and 1980s elevators. These observed differences during open-door intervention may be due to sampling on different floors of the building during the stationary phases, perhaps introducing a stronger stack effect [51]. Although an effective intervention in reducing particle concentration, leaving doors open between runs is not feasible because hard-wired elevator safety features [27] and safety codes [28] prohibit doors remaining open continuously. ...
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The objective of this study was to measure particulate matter (PM) total loss rates in three older (1940s, 1960s, and 1980s) elevators in California during two phases and three low-cost intervention modes. Tracer gas decay and <2 μm aerodynamic diameter nontoxic NaCl particles (PM2) were used to calculate PM2 loss rates. The NaCl particles were considered surrogates for smaller particles carrying SARS-CoV-2. Empirical PM2 loss rates were paired with modeled dynamic scenarios to estimate SARS-CoV-2-relevant PM2 removal. Mean loss rates (hr-1) ranged from 1.8 to 184. Compared to a closed-door, stationary elevator, the moving elevators had a fourfold increased mean loss rate (hr-1), while an air cleaner in a stationary elevator increased the mean loss rates sixfold. In a dynamic particle removal simulation of a ten-story elevator, PM was removed 1.38-fold faster with an air cleaner intervention during bottom and top floor stops only (express ride) and 1.12-fold faster with an air cleaner during every other floor stops. The increase in removal rates due to the air cleaner was modest due to the higher moving and open-door removal rates, except during stationary phase. The half-life of PM2 particles in a stationary elevator after all passengers have left can be 8-12 minutes following a single emission and 2-5 minutes with an air cleaner. The low particle removal rate in the stationary elevator requires an intervention so that the particle removal rate will be high to eliminate infectious aerosol. If codes permit, keeping the door open when the elevator is stationary is most effective; otherwise, an air cleaner in a stationary elevator should be used. While an air cleaner is commonly seen as a substantial improvement in reducing potential virus concentration in air, in the moving elevator scenarios, the effect is quite modest. This paper provides empirical particle loss rates inside elevators, the effectiveness of air cleaners in a dynamic elevator space, two approaches to control infectious agents while the elevator is stationary, and support for a precautionary approach towards elevator use amidst a pandemic.
... Pressurizing the shaft [26,27] can suppress the upward spread of smoke. To minimize the chimney effect, the shaft can be ventilated and cooled [28]. However, these studies mainly focused on the chimney effect itself without consideration of the movement of elevator cars. ...
Article
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An elevator shaft provides passage for air exchange across floors and thus imposes infectious disease transmission risk. The moving elevator car generates positive air pressure in the shaft section to which the car approaches, while negative air pressure is generated in the section where the car leaves away. This investigation adopted computational fluid dynamics (CFD) to model the exchange airflow between the lobbies of each floor and the shaft accompanying the car movement. Dynamic distributions of the air pressure, velocity, and airborne pollutant concentration inside both the shaft and the lobbies were solved. The modeling results were verified with some experimental test data. The results revealed that the alternatively changed air pressures inside the shaft while the car was moving caused significant airflow exchange via the clearances of the protecting doors and, thus, the transmission of airborne pollutants across floors. The sudden changes in the airflow rates could be due to the elevator car passing by the protecting door’s opening on the concerned floor or the generated water hammer when the car was parked. To minimize the transmission of airborne pollutants across floors, the pressures inside the shaft must be better controlled, and the clearance of the elevator’s protecting doors shall be further minimized.
... Airflows in high-rise buildings affect indoor environments, air quality, and cooling and heating energy consumption [1]. There is a strong airflow through the doors [2], sometimes preventing elevator and front doors from opening and closing [3]. The airflow results in unpleasant noises [4], the diffusion of smoke [5], odors [6], pollutants [7], and viruses [8], and an increase in heating loads [9] on some floors. ...
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The stack effect is dominant in multifamily high-rise buildings (MFHRBs) in winter because of the considerable height of MFHRBs, which causes a difference in the infiltration amount between floors. This difference causes a heating load difference between floors in a MFHRB. However , there are no indicators to quantify the heating load differences in previous studies. In this article, an indicator-the thermal draft load coefficient (TDLC)-is proposed that can be used to estimate and evaluate the differences between floors in a MFHRB. The TDLC is built on a theoretical model of the stack effect and leakage area of the airflow paths, considering the entire building air-flow in a MFHRB. The theoretical model was validated by comparison with a simulation model. The winter average coefficient of variation of the root mean square error and the normalized mean bias error of the theoretical model were acceptable (17.1% and 9.3%, respectively). The TDLC resulted in a maximum of 2.5 and a minimum of approximately 0.1 in the target MFHRB. The TDLC can pre-evaluate the load difference in the building design stage and can be utilized to build design standards or guidelines.
Article
The literature review discusses state-of-the-art studies regarding strategies for smoke control in high-rise buildings and provides a comparison of prescriptive rules used in several countries. The literature review was conducted on high-rise building safety methods and concerned literature regarding smoke control strategies. This study focused on smoke management, and particularly on the movement of smoke in the elevator shaft, ventilation shaft, and stairwell. The objectives of this review were to introduce the fundamental concepts of smoke movement in high-rise buildings as obtained from the literature, summarize the practical applications of smoke control strategies based on pressurization or extraction systems, investigate the impacts of using a lift as a means of evacuation, and suggest future advances and potential research related to performance-based safety schemes for smoke ventilation control in tall buildings. Many fire safety strategies and proper smoke management guidelines (e.g., for the minimum level of safety in several countries) were considered. A total of 163 academic publications were included in this review; these publications are distributed between 1964 and 2021. Although many previous studies and experiments have provided solutions for smoke control, human creativity in design always evolves faster than any code or guideline from past studies. Therefore, a performance-based approach should be considered when designing a smoke control system.
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Drafts in high-rise buildings caused by the stack effect can cause noise and reduce the performances of ventilation, cooling and heating systems as well as the building’s energy efficiency. Revolving doors are generally used as a method to reduce drafts; however, the effect would only be limited to the main entrance on the lobby floor. Revolving doors have two main advantages; that their opening areas are seldom changed by people passing through the doors, and the doors do not have the pressure-related functional problems. Considering these advantages, this study examined a quantitative draft reduction method using revolving doors in high-rise buildings. This method would contribute to the design process to install revolving doors to buildings and consists of 10 steps with two key steps of selecting the installation locations of revolving doors and to calculate the air leakage area of revolving doors. Verification through simulations showed that, based on this process, the use of revolving doors could reduce the drafts in buildings by a quantified target value. Furthermore, the possibility of problems due to the stack effect in the other walls of buildings would decrease due to the pressure sharing of the additional walls fitted to revolving doors.
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Building occupants can enjoy a healthy and comfortable indoor environment and use less cooling energy if sufficient natural ventilation is available in their dwellings. Assessing the natural ventilation performance of building designs requires modelling of the external wind environment, the natural ventilation rate and the thermal environment in individual rooms, and reduction in the use of air-conditioning equipment. These are complicated processes. A practical approach for assessing the natural ventilation performance of residential building designs is presented in this paper. The method includes prediction of wind pressures upon window openings in the building façade by computational fluid dynamics simulation, natural ventilation rate prediction using a flow network simulation model, and indoor free-float temperature and air-conditioning energy-use predictions using a building heat transfer and an air-conditioner performance simulation programme. Additionally, the method includes a simplified statistical approach to deal with the random variations in the speed and direction of the wind. This method has been applied to assess the natural ventilation performance of a standard public housing block design widely used in Hong Kong, taking into account when the wind wing walls were incorporated into the building façade and when the separation distances among the building blocks were widened by 25% and 50%.
Chapter
Description The result of a changing technology, STP 904 presents the latest information on air infiltration. There are 23 papers in this book which is divided into four sections: residential; commercial and industrial; techniques for measurements and infiltration reduction; and analysis.
Article
1. Pressure distribution in the region of typical floors caused by stack effect can be easily explained with "Exterior wall pressure load ratio K'" which is defined as |ΔP_w|/(|ΔP_w|+|ΔP_s|), whereΔP_w andΔP_s are pressure differnce across exterior wall and elevator shaft. 2. K' is equal in principle to "Tamura's Actual/Theoretical (=K)", that was confirmed through measure-ments and computer simulation. Therefore, K has become to show more physical characterestics. 3. Specific problems generated by pressure difference, which are noise resulting from air flowing through cracks, the difficulty of opening doors, flow rate variation of air conditionning system are explained quantaively and an effective solution to the noise problem was proposed.
Article
The authors describe the results of field studies to measure overall air leakages and the pattern of pressure differences caused by the chimney effect, both alone and in combination with building ventilation systems. The zone in which the interior pressure equalled the exterior pressure in the buildings was at a level ranging between 35 and 52 per cent of building height. Pressure differences across entrances were lower with ventilation systems off than would be calculated from the ASHRAE Handbook because of the low height of the zero pressure-difference zone and the significant pressure losses across first-floor ceilings. The ratio of actual to theoretical draft varied between 0.6¤ 3 and 0.82. and This paper describes the results of a study on the pattern of pressure differences caused by the chimney effect and mechanical ventilation. For this purpose, the authors used a mathematical model representing a building. They determined the effects of variations in airtightness of the exterior walls and partitions and of the number of storeys on the pattern of pressure differences. They also examined the way in which imposed pressure differences, whether uniform or not, affect the pattern of pressure differences caused by the chimney effect. These data provide the basis for the prevention of air leakages caused by chimney action. They also help in interpreting the practical measures referred to in the companion paper entitled " Pressure Differences Caused by Chimney Effect in Three High Buildings". Les auteurs exposent les résultats de recherches menées sur place en vue de mesurer les fuites totales d'air et la ré partition des pressions engendrée par l'effet de tirage, tant seul qu'en conjonction avec l'appareillage de ventilation des immeubles. La région des édifices où la pression interne égalait la pression externe atteignait de 35 à 52 pour cent de leur hauteur. Les différences de pressions de part et d'autre des entrées étaient plus faibles lors de l'arrêt de l'appareillage de ventilation que le manuel de l'ASHRAE ne permettait de les calculer, en raison de la faible altitude de la région à différence pié zométrique nulle et des importantes pertes de pression aux plafonds du rez-de-chaussée. La proportion centésimale du tirage réel par rapport au tirage calculé atteignait entre 0. 63 et 0.82. et Le présent article communique les résultats d'une étude sur la répartition des différences de pressions engendrées par l' effet de tirage et la ventilation méchanique. Les auteurs se sont servis pour cette étude d'un modèle mathématique représentant un bâtiment. Ils ont déterminé les effets de variations d'étanchéité des murs extérieurs et des cloisons et du nombre des planchers sur la répartition des pressions. Ils ont également étudié la manière par laquelle l'établissement de différences de pressions uniformes ou non affecte la répartition des pressions causées par l'effet de tirage. Ces données fournissent la base de la prévention des fuites d'air causées par l'effet de tirage. Elles aident également à interpréter les mesures pratiques contenues dans l'article conjoint intitulé "Différences de pressions causées par l'effet de tirage à l'intérieur de trois édifices élevés." RES
Article
This paper considers the requirements for investigation of sick buildings including some guidelines for assessment of exposure risks with a particular focus on dampness, proliferation of moulds, and dispersion of fungal spores in indoor environments. Building pathology, indoors air quality management and management of bio-deterioration, and health problems in buildings are complex issues requiring multi-disciplinary investigations and environmental monitoring. Lack of maintenance, chronic neglect, and building defects leading to water ingress, condensation, and dampness in the building fabric will often produce proliferation of pathogenic toxic moulds, and other microbial and biological effects that could cause allergic response in sensitive people and generally lead to ‘‘sick buildings.’’ A general guide has been provided by this paper for environmental assessment of toxic moulds in indoor environments, including a suggested guideline for assessing the threshold levels for fungal spores in indoor air.
Article
Ventilation design has a long history in China. The ancient pioneers used engineering skills to change the indoor environment. In this review, basic natural ventilation design ideas are introduced from both a historical and modern viewpoint. Attention is paid to new natural ventilation system developments, such as the design and testing of natural ventilation inlets and outlets for the stack and solar chimneys. Theoretical aspects of ventilation design are also considered. Today, the use of mechanical ventilation systems in China is growing for both domestic and non-domestic buildings. The use of mixed-mode or hybrid ventilation systems as a response to needs for indoor comfort and energy efficiency is increasing, and such systems are now widely used.
Article
The enclosed lift lobby distinguishes itself as a unique form of region categorised under building transitional spaces. This paper reports on an evaluation of thermal comfort conditions in a prominent transitional space in buildings which is the enclosed lift lobby of an educational institution in Malaysia, using field survey which included objective measurement and subjective assessment. The temperature set-point of air conditioner was increased and maintained at 26 degrees C to investigate the human thermal perceptions in the enclosed region. Comparison was made on the percentage of thermal sensation, preference, acceptability and general comfort votes obtained from field survey. The outcomes clearly indicated that the human thermal perception in the enclosed lift lobby would be directly proportional to the level of human occupancy, and any sudden temperature change could lead to thermal discomfort of occupants. The respondents generally preferred to have cooler environment, rather than warmer one. Also, comfortable temperature can be obtained even with higher air conditioner thermostat settings. These findings may serve as a guide for building operators in the tropics to control the energy consumption of cooling equipment attached to the enclosed transitional spaces.