Stack Effect In High-rise Buildings Research Articles

Combined Effects of Thermal Buoyancy, Wind Action, and State of the First-Floor Lobby Entrance on the Pressure Difference in a High-Rise Building

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.

Analysis of vertical movement of particulate matter due to the stack effect in high-rise buildings

Outdoor particulate matters (PM) enter the indoors with airflow due to wind pressure, temperature differences, and variable pressures from HVAC systems. PM introduced into the indoor space is deposited on the surface according to the indoor environmental conditions to reduce the indoor particle concentration. In particular, in high-rise buildings in winter, the stack-induced driving force, which is a function of the height of the building and the temperature difference between indoor and outdoor, is dominant. High-rise buildings have vertical pathways for the transport of PM between floors within the building, and eventually distribute it to households.This study aims to analyze the characteristics of PM transport in the vertical shaft in a high-rise building, and to propose a method to calculate penetration and deposition properties to predict indoor particle concentration. An optimization method was proposed to calibrate the multi-zone airflow and particle transport model using field measurement, multi-zone airflow/contaminant simulation, and genetic algorithm (GA)-based optimization techniques. The target building was a 43-story high-rise residential building, and CONTAM was used for multi-zone simulation. The results showed that the PM concentration in the vertical shaft decreased toward the upper floors due to wall deposition. The deposition rate in the vertical shaft was calculated to be less than 0.3 h−1, was the smallest at the Neutral Plane Level (NPL), and increased toward the upper and lower floors. In other words, the deposition rate in vertical space was inversely proportional to the airflow rate. The deposition rate of the vertical shaft was calculated to be smaller than that of the horizontal space. The reliability of the PM concentration prediction results calculated using the proposed method in this study was valid, and satisfied ASTM D5157.

동절기 고층건물에서 연돌효과로 인해 발생하는 엘리베이터문을 통한 기류 유입 및 외피를 통한 침기 저감을 위한 공조가압방안의 적용

Purpose: This study aimed to investigate optimization of mechanical pressurization using HVAC system to reduce airflow outflow of elevator doors and infiltration through envelopes due to stack effect in high-rise buildings in winter Method: For this study, air leakage rate into office room through elevator door and building envelope in a high-rise office building were calculated through simulations in several pressurized and de-pressurized conditions. With a network simulation model(CONTAM 3.1), the effect of pressurization/de-pressurization positions was evaluated. As results of simulations, the pressurization method with differential pressurized air volume from the top floor to the final pressurized floor was concluded as the best solution to reduce the pressure difference across the elevator doors. Result: As a result of applying the differential pressurization method for each floor, the amount of inflow of indoor air flow through the elevator door before and after pressurization was reduced by 77% and the amount of infiltration through the skin by 92% under the design outdoor air condition in winter. However, it was found that the amount of additional outdoor air introduced through the air conditioner increased by 39% compared to the previous one, resulting in an increase in the cost of air conditioning heating energy.

Characteristics of Revolving Door Use as a Countermeasure to the Stack Effect in Buildings

Efficient control of ventilation and cooling/heating systems in buildings is integral to making adjustments to indoor environments and to minimizing energy use. In high-rise buildings, however, the stack effect is generated through vertical shafts in the buildings, and the air flow due to the stack effect greatly affects the efficiency of air-conditioning systems used for ventilation, cooling, and heating. Therefore, attenuating the stack effect in high-rise buildings is a critical aspect of HVAC operations as well as a solution for direct problems related to the stack effect, such as high-velocity draft, high-level noise in the buildings, and so on.In general, as a method to attenuate the stack effect in high-rise buildings, revolving doors are installed at the lobby entrance. However, while this method may be effective on the floors where revolving doors are applied, the efficiency is very low when considering the entire building due to the existence of many air flow paths and the fact that revolving doors applied to only part of a building can control only a portion of the air flow. Numerical simulation analysis was performed in this study to quantitatively examine the stack effect attenuation characteristics of revolving doors on both a partial building level and for the entire building. In addition, the effects of building height and airtightness on the performance of the building envelope were considered.

Stack Effect in High-Rise Buildings: A Review

This technical paper presents a detailed review of the stack effect phenomenon and of the associated implications pertaining to the design and construction of high-rise buildings in regions of extreme climatic conditions. The present review is focused on both the classical 'chimney' effect as well as on the reverse stack effect, which are respectively related to cold and hot climates. For the purposed of the work here presented, the ASHRAE (2013) design conditions of Astana (Kazakhstan) and Riyadh (Kingdom of Saudi Arabia) were selected. A 230 m tall residential building of rectangular floor plan was numerically modelled in the context of the climatic conditions of the two abovementioned cities and a number of sensitivity analyses were performed, covering parametric changes of: temperature, facade air tightness, site wind speeds and wind directions.

Characterization of Stack Effect in High-Rise Buildings Under Winter Conditions, Including the Impact of Stairwell Pressurization

To characterize the magnitude of stack effect within stairwells and elevator shafts, differential pressure measurements were taken in fifteen (15) high-rise buildings in four (4) different cities (Cleveland, Baltimore, Minneapolis, and Philadelphia) during the winter months of January–March, 2013. Test buildings ranged in height from 44 m to 150 m (143 ft–492 ft). Outside temperatures during testing ranged from −12°C to 15°C (10°F–59°F). Based on the differential pressures measured, there was evidence of winter stack effect in all buildings tested. On the lower levels of all buildings, air was observed flowing from the building into the stairwells and elevator hoistways with pressure differential magnitudes ranging from −2.7 Pa to −24.9 Pa, −12.0 Pa average (−0.011 in. w.g. to −0.100 in. w.g., −0.048 in. w.g. average). Similarly, in most buildings (excluding Buildings 6 and 7) air was observed flowing from the stair and elevator hoistways into the building on the upper levels with pressure differential magnitudes ranging from 0.5 Pa to 34.9 Pa, 11.2 Pa average (0.002 in. w.g. to 0.140 in. w.g., 0.045 in. w.g. average). Under winter conditions, the data suggests that large quantities of air can migrate, floor-to-floor, via unprotected elevator shafts. Data further suggests activation of the stairwell pressurization system can increase vertical air movement via unprotected elevator shafts. This behavior is expected to impact the movement of smoke floor-to-floor during a fire, as airflow is indicative of smoke migration. The exterior stack force on the building’s envelope (governed by the building’s height and temperature differential between the building interior and exterior) does not always translate proportionally to shaft-to-building differential pressures (i.e., “stack effect”), as each building is unique. Although a building’s height and outside temperature play important roles in determining vertical airflow movement within a building, height alone was not found to be a good predictor of vertical airflow (or smoke movement) within the building due to stack effect. Other variables, such as architectural layout, architectural leakage, wind effects, and ventilation systems should all be considered. Simplified algebraic calculations (i.e. hand calculations) do not treat the building as a complete system, and do not account for all variables involved. Therefore, simplified algebraic calculations may result in inaccurate shaft-to-building differential pressure predictions. Based on this analysis, unless conservative leakage values are used, the simplified algebraic calculations may underpredict the shaft-to-building differential pressures. Using simplified algebraic calculations may be suitable for preliminary approximations, however, for design purposes a more complex analysis is recommended. The more complex analysis should consider other variables that affect pressure differentials such as changes in architectural layout and envelope leakage from floor-to-floor, HVAC systems, and wind.

제주지역 고층건축물에서의 바람의 영향이 굴뚝효과에 미치는 영향 분석 (서울과 제주지역간의 비교 분석)

This study used CONTAM modeling to analyzed analyze the stack effect in high-rise buildings for the terrain and weather conditions of Seoul and Jeju. The differential pressure caused by the stack effect is a function of the indoor and outdoor temperature difference and the height of the vertical shaft. Jeju is considered more stable than Seoul, because it is warmer than Seoul in winter. The differential pressure in Jeju is about 60% that of Seoul in for the same height of buildings in winter. However, Jeju is an island and the neutral plane is raised by over 56% by strong winds, although there is less differential pressure caused by the stack effect in Jeju than in Seoul. Due to the raised neutral plane, the region and magnitude of negative pressure in the lower part is larger in Jeju than in Seoul.

Application of the mechanical ventilation in elevator shaft space to mitigate stack effect under operation stage in high-rise buildings

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.

A STUDY ON PREVENTION OF STACK EFFCT IN ELEVATOR SHAFT OF HIGH-RISE BUILDING CAUSED BY OPENING ENTRANCE

For the prevention of the stack effect in high-rise buildings in winter, this paper studied a method to cool the shaft by natural ventilation through the opening between the shaft and out air. It was shown theoretically that the shaft is effectively cooled by putting the opening in the lower level of the shaft and thus the stack effect can be effectively prevented. By the calculation for a high-rise building based on the airflow network model and the steady heat balance analysis, it was shown quantitatively that the studied method is effective for general high-rise office buildings and that a careful survey is necessary before introducing this method for the following cases: 1)a case in which the down flow occur in the shaft influenced by the existence of another shaft, 2)a case in which there is no opening to the outside in the upper level of the shaft, 3)a case in which the humidity of the building is high.

A study on the development and application of the E/V shaft cooling system to reduce stack effect in high-rise buildings

This study suggests the E/V(Elevator) shaft cooling system as a new approach to reduce the stack effect and the related problems in high-rise buildings. The basic characteristics on its application were analyzed with some simulations in this study. Moreover, the system was applied to an actual building and its performance was evaluated through the measurements. The system can reduce the stack effect itself and the related problems simultaneously and it can reduce the pressure and the air flow rate in each part of a building in the same ratio. These features were shown in the results of the simulations; for the examples, when all the E/V shafts were cooled from 22 °C to 12 °C, the stack effect and the pressure in each part of the modeled building were decreased by about 27%. In the field measurements, the wind velocity through the E/V door was decreased effectively in the whole building; its reduction ratio at the lobby floor was about 25% and at the upper floors (37F, 38F) about 10% respectively. But, the neutral pressure level at the E/V shaft was moved by the vertical temperature difference in the E/V shaft because of the inflow ducts concentrated in the lower part of the E/V shaft. This movement was also shown in another simulation on the same conditions as the measured ones. It is very important to minimize the vertical temperature difference in the E/V shaft to maximize the reduction effects on the problems.

AIRFLOW PATTERNS AND STACK PRESSURE SIMULATION IN A HIGH RISE RESIDENTIAL BUILDING LOCATED IN SEOUL

Buoyancy forces due to air density difference between outdoor air and indoor air cause stack effect in high-rise buildings in cold climates. This stack effect occurs mainly at the core of the building such as the stairway and elevator shafts and causes many problems such as the energy loss caused by air flow, the blocked elevator door and discomfort due to inflowing of strong outdoor air. The main purpose of this work is to model the airflow pattern in a highrise building during the winter period by mean of COMIS. The presented building which is situated in Korea contains 30 floors above the ground level and 5 basement floors. Using COMIS, the simulation has been carried out for the entire building. However, the simulation failed due to the huge number of zones and interactions between them. Therefore, a model of building which contains 14 floors with 5 floors in the basement has been considered; and a simplified model based on the considered one has been constructed and compared with the 14 floors model. The simplified model consists on reducing the number of floors by combining a certain number of stories into one so that to enable the simulation to be carried on with a minimum number of zones and links. The result of the simulation shows that this approach could be used with accuracy still being satisfied. Therefore, the simplified procedure has been extended and applied to the high rise building model with 30 stories above the ground level and 5 stories in the basement. The effect of the exterior wall air-tightness of the building with 30 stories on the stack pressure and airflow by infiltration and/or by exfiltration has been investigated. The result shows that the total air by infiltration and/or exfiltration within the elevator shafts increases with the decrease of the level of the air-tightness of the exterior wall of the building. It has been also shown that a huge amount of air infiltrates through the shuttle and emergency elevator shafts from the basement.