Publications

A literature review of cross ventilation in buildings

Published in Energy and Buildings, 2023

There is a growing body of literature that recognizes that natural ventilation plays a vital role in indoor air quality, thermal comfort and building energy consumption. This paper systematically reviews the previously published research of the most efficient and typical natural ventilation type - cross ventilation, aiming to present the main research topics in contemporary research and provide an agenda for future studies. The methodologies, airflow pattern, ventilation models and influencing parameters of cross ventilation were comprehensively summarized and discussed. The chained analysis and data-driven methods are the potential approaches to study cross ventilation more efficiently. The comparisons of different ventilation models of cross ventilation help to better understand the basic mechanisms that drive the cross ventilation airflow.

Recommended citation: Jiang, Z., Kobayashi, T., Yamanaka, T. and Sandberg, M., 2023. A literature review of cross ventilation in buildings. Energy and Buildings, p.113143. https://doi.org/10.1016/j.enbuild.2023.113143

Analysis of single-sided ventilation flows of a generic isolated building using particle tracking method in LES simulation

Published in Building and Environment, 2023

The main objective of this study is to investigate the airflow patterns in single-sided ventilation of isolated buildings in which the ventilation rate can not be easily predicted by the conventional Orifice equation. The research focuses on buildings with two openings located either at the front or back external wall, with building aspect ratios of 1:1 and 1:2.The study utilizes Large Eddy Simulation (LES) with the particle tracking technique validated by velocity data obtained from a wind tunnel experiment. Ventilation performance is evaluated by Airflow Rate (AFR) and Purging Flow Rate (PFR). AFR was obtained based on the instantaneous velocity over the openings, and PFR was determined by the tracer gas method. The results show that the influence of pulsation flow and eddy penetration both exist in single-sided ventilation. The comparison of AFR and PFR indicates part of the airflow through the opening does not contribute to effectively removing the indoor contaminants, which is quantitively evaluated by ventilation efficiency defined as the ratio of PFR and AFR. In order to explicitly observe and depict the airflow, the massless particles were emitted at the opening, and the trajectories were analysed. The Probability Density Function (PDF) of indoor residence and indoor travel distance was calculated. The high probability of short indoor travel distance and the residence time, which is mainly caused by the eddy at the openings and time-variant pulsation flow, can explain the difference between AFR and PFR.

Recommended citation: Jiang, Z., Kobayashi, T., Sandberg, M., Yamanaka, T., Kobayashi, N., Choi, N., Sano, K. and Toyosawa, K., 2023. Analysis of single-sided ventilation flows of a generic isolated building using particle tracking method in LES simulation. Building and Environment, 235, p.110230. https://doi.org/10.1016/j.buildenv.2023.110230

Validity of Orifice equation and impact of building parameters on wind-induced natural ventilation rates with minute mean wind pressure difference

Published in Building and Environment, 2022

Natural ventilation is gaining more popularity in recent decades as a sustainable strategy to reduce energy consumption and improve indoor air quality. Due to variable turbulent characteristics, there is a lack of a practical guide that helps engineers accurately predict and maximize wind-induced ventilation rates. The current work intends to investigate the factors that influence the ventilation rates by focusing on cases that have a minor wind pressure coefficient difference. This paper presents an experimental study of single- and double-sided wind-induced ventilation mainly through two openings of a reduced scale building with three different building aspect ratios in a boundary-layer wind tunnel. A continuous dose method of tracer gas technique was used to evaluate the ventilation rate. Important factors that affect ventilation rates such as velocity in the vicinity of the wall where the opening is assumed to exist (expressed as “nearby velocity”) and surface wind pressure were measured. Flow visualization was also performed to help to understand the ventilation mechanism caused by turbulence.

Recommended citation: Jiang, Z., Kobayashi, T., Yamanaka, T., Sandberg, M., Kobayashi, N., Choi, N. and Sano, K., 2022. Validity of Orifice equation and impact of building parameters on wind-induced natural ventilation rates with minute mean wind pressure difference. Building and Environment, 219, p.109248. https://doi.org/10.1016/j.buildenv.2022.109248

Papers

Internaltional Proceedings

日本国内会議