Doosam Song

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.

Quantitative Reduction Method of Draft in High-Rise Buildings, Using Revolving Doors

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.

Prediction and evaluation method of wind environment in the early design stage using BIM-based CFD simulation

Drastic urbanization and manhattanization are causing various problems in wind environment. This study suggests a CFD simulation method to evaluate wind environment in the early design stage of high-rise buildings. The CFD simulation of this study is not a traditional in-depth simulation, but a method to immediately evaluate wind environment for each design alternative and provide guidelines for design modification. Thus, the CFD simulation of this study to evaluate wind environments uses BIM-based CFD tools to utilize building models in the design stage. This study examined previous criteria to evaluate wind environment for pedestrians around buildings and selected evaluation criteria applicable to the CFD simulation method of this study. Furthermore, proper mesh generation method and CPU time were reviewed to find a meaningful CFD simulation result for determining optimal design alternative from the perspective of wind environment in the design stage. In addition, this study is to suggest a wind environment evaluation method through a BIM-based CFD simulation.

A Strategies to Improve the Natural Ventilation Performance at Underground Parking Lot in Multi-Residential Buildings

ABSTRACT:Energy efficiency and indoor air quality have become main issue to develop healthy and sustainable building in these days. As an effort to reduce the energy consumption in multi- residential building, many attempts as like passive design strategies and renewable energy as well as active control method are tried. However, underground parking lot in multi-residential building seldom adopt the sustainable strategies and only mechanical system is installed as usual. Moreover, the mechanical system installed in underground parking lot is rarely operated due to the electric demand for operation after completion. In this study, as an energy efficient measure, natural ventilation system using stack effect as a driving force for underground parking lot will be proposed and the performance of the suggested system will be analyzed by simulation method.Keywords:Natural ventilation(자연환기), Stack effect(연돌 효과), Underground parking lot(지하주차장), Simulation(시뮬레이션), Contaminant concentration(오염물질농도)

Development of the TRNSYS Simulation Modules for System Air-Conditioner and Its` Verification

In these days, importance of HVAC system in office building is steadily growing in terms of thermal comfort and energy savings. As a energy efficient heating and cooling system, system air-conditioner which can be controlled distinctly and has a high COP is more widely adopted nowadays. However, the features and advantages of system air-conditioner were not reported well because system air-conditioner did not describe yet by conventional simulation methods such as TRNSYS, e-Quest, Energyplus, etc. In this study, by using the TRNSYS program which is able to show module implementation and building energy consumption analysis, system air-conditioner module will be proposed and validated through comparison between the simulation results and measurement results.

EVALUATION OF WIND ENVIRONMENT AROUND THE BUILDING IN THE EARLY DESIGN STAGES USING BIM-BASED CFD SIMULATION

Drastic urbanization and Manhattanization are causing various problems in the wind environments of urban areas. This study suggests a computational fluid dynamics (CFD) simulation method to evaluate the wind environment around urban buildings in the early design stages. The CFD simulation method suggested in this study is not a traditional in-depth simulation, but a method to immediately evaluate the wind environment for each design alternative and provide guidelines for design modification. The CFD simulation approach suggested in this study is based on the building information model. In addition, previous criteria for evaluating wind environments around buildings in urban areas are reviewed and criteria applicable to the proposed CFD simulation method are identified. Furthermore, a proper mesh generation method and appropriate CPU time were investigated to allow generation of a meaningful CFD simulation result in a limited time.

Appropriate conditions for determining the temperature difference ratio via infrared camera

The temperature difference ratio is used to measure the thermal performance of a building envelope. Calculation of temperature difference ratio requires temperature differences between indoor and outdoor environments and wall surface temperatures, obtained here using an infrared camera. This approach performs well when the temperature differential between indoor and outdoor environments is greater than 10℃ and when wind speed is less than 3.0 m/s. We identify periods suitable for accurate evaluation of thermal insulation performance with an infrared camera, based on eight cities in Korea. The number of measureable hours ranges between 3183 and 1317 annually. Optimum periods for measurement are between November and March, specifically between 01:00 and 09:00 h. Measurements obtained during these periods can therefore be regarded as relatively accurate. Practical application: A thermal imaging camera provides an easy method for checking the insulation performance and construction conditions of a building. Conventionally, this would be checked experimentally, but thermal imaging allows easy visualization of conditions.

Some Consideration on Derivative Approximation of Particle Methods

In this paper, the accuracy of the derivative approximation of the particle methods is discussed. Especially, we show that the issue of decreasing accuracy on a boundary area in the SPH method is due to the lack of the boundary integration. Through some numerical examples, the convergence of error norm of energy obtained by the SPH and the MPS methods is studied.