Single-sided Ventilation Research Articles

Statistical Analysis Approach of Single-sided Ventilation Based on Particle Track Technique Using Large Eddy Simulation

The main objective of this study is to investigate the airflow characteristics in single-sided ventilation. A CFD method of large eddy simulation (LES) using particle track technique was conducted in this study, and the simulation results are validated by experiment results. The mostly used ventilation efficiency indicators of natural ventilation are Air Flow Rate (AFR) and Purging Flow Rate (PFR). AFR is the volumetric airflow exchange rate through the openings and PFR is the effective airflow rate that removes indoor air pollutants. The ventilation efficiency (εν) of natural ventilation, which is defined as the ratio of PFR and AFR, is not well investigated in previous research, therefore, this study discusses the case of the εν of single-sided ventilation and tries to explain the distinction between AFR and PFR by statistical analysis approach based on particle movements. Particles are emitted from the opening and the particles’ movements are tracked by tracing their locations at different time steps. The residence time measures the time between the time that particles enter the room and the time that particles leave the room, and indoor travel distance indicates the sum of the displacement when the particle travels in the room. The Probability Density Function (PDF) of the residence time and indoor travel distance is used to depict airflow characteristics of the ventilation path of single-sided ventilation. The analysis method of study might be another useful approach to studying natural ventilation in detail.

Investigating natural ventilation performance on apartment units in Jakarta based on field test measurements

The COVID-19 pandemic has changed the way of living of many people across the planet. In the beginning of the pandemic, when the strict lockdown was implemented, numbers of individual were encouraged to work from home. In the city living, high rise living were apparent and became a global phenomenon. This paper evaluates natural ventilation performances of existing apartment units in Jakarta, Indonesia by measuring the indoor temperature, indoor airflow and relative humidity. This research studied three different apartment units in Jakarta in the form of single-sided ventilation or cross ventilation. This study conducted by field test measurement on three different apartment units across Jakarta with various natural ventilation strategy and room volume. Statistical analysis was carried out to investigate the relationship and influence between the results of field test measurement and external weather data collected from ERA5. The results of the analysis suggested that external weather influence the indoor air condition, especially indoor temperature where significant influence was apparent. Furthermore, the field test data measurement in this paper contributed to validation study in predicting indoor airflow.

Numerical studies on Re-independence and influence region definition for flow and dispersion within street-indoor scale model

To reduce modeling errors and save computing resources, the reduced-scale numerical models may sometimes be used. This study conducted the numerical models validated by wind-tunnel tests to investigate Re-independence issue and influence region definition for flow and dispersion within the target street-indoor scales. The window Re (Rew) was specified to characterize the indoor flow and dispersion, and the indicator of DR was applied to quantitatively determine Rew,crit. The ventilation modes (cross ventilation, CV or single-sided ventilation, SSV) and the surrounding building effect on Re-independence of indoor flow and dispersion were examined. Then ACH (air exchange rate) varying with the increasing layer number (n) of surrounding buildings was applied to derive the required size of influence region. Results show that it needs different Rew,crit to ensure the indoor flow structures at different positions to enter the Re-independence regimes, that is, the Rew,crit is a position-dependence quantity. Taking difference ratio (DR) ≤ 5% as the threshold, Rew,crit (=15,000) at the most unfavorable position should be selected as the optimal value to ensure Re-independence of indoor flow and dispersion, and the suggested Rew,crit is independent of ventilation modes and surrounding buildings. The ACH distributions show the required size of influence region to ensure the flow structures within the target street-indoor scales remain unchanged is n = 5. The contours of normalized velocity and pollutant concentration further confirm this required layer number. This study can provide significant guidelines for accurately modeling the flow and dispersion within the coupled indoor-outdoor scales by reduced-scale numerical model.

EFFECTS OF SINGLE-SIDED AND CROSS-VENTILATED SLIDING GLASS WINDOW OPENINGS ON THE INDOOR ENVIRONMENT OF A ROOM IN A HOT AND HUMID CLIMATE

There are two natural ventilation strategies, namely single-sided and cross ventilation. For a building with a deep layout plan and where cross ventilation is impossible, single-sided ventilation is used. This study aimed to compare the performance of both strategies using sliding glass windows. The method used was field measurement, which was executed in one room of a double-storey detached house. The predicted indoor thermal comfort was calculated using the Adaptive Thermal Comfort index. The main finding from the study agreed with those of previous studies, whereby cross ventilation was found to provide greater indoor airflow than single-sided ventilation. However, with each strategy, indoor thermal comfort could only be achieved only during the morning hours. The findings also show that the wind velocity decreased upon approaching the window opening and reduced further when the indoor space was reached. Another interesting finding is that cross ventilation had the capacity to enhance the indoor air velocity at one of the measurement times. This study is significant as it will stimulate future exploration and investigation of both natural ventilation strategies in hot and humid climates.

Turbulence-induced ventilation of an isolated building: Ventilation route identification using spectral proper orthogonal decomposition

Turbulence dominates the natural ventilation of a building when openings are parallel to the external wind, and multiple factors associated with turbulence simultaneously affect natural ventilation. This study applies spectral proper orthogonal decomposition (SPOD) to quantitatively identify the main ventilation routes produced by turbulence in an isolated building with two symmetric openings. The turbulence data are obtained from large-eddy simulations of various wind directions and window casements. Two major turbulence-induced ventilation mechanisms are observed when the wind is parallel to the openings: The first is in the low-frequency region and is characterized by a slight change in the wind direction of the external flow, which contributes to cross ventilation. The second is in the high-frequency region and is characterized by a flow separation on the side of the building, which contributes to single-sided ventilation. The ventilation routes are visualized using SPOD modes and animations. In addition, the impact of window casements on turbulence-induced ventilation is investigated. The installation location of the window casements can either enhance or weaken the cross ventilation depending on whether the turbulence is efficiently utilized in the ventilation and can significantly affect the indoor cross ventilation route. However, regardless of the side that they are installed on the window, the casements may slightly improve single-sided ventilation by limiting the occurrence of separated eddies near the openings. • Visualization of turbulence-induced ventilation in an isolated two-opening building. • Quantitative analysis of the contributors to natural ventilation. • Cross ventilation induced by external wind direction changing. • Single-sided ventilation induced by flow separation. • Impact of window casements on turbulence-induced ventilation.

Wind tunnel experiments on pumping ventilation through a three-story reduce-scaled building with two openings affected by upwind and downwind buildings

Periodic vortex shedding from the building can induce pumping ventilation (PV) and promote the ventilation rate of single-sided ventilation with well-arranged open windows. The present study aims to investigate the influence of sheltering conditions (presence of upwind and/or downwind buildings) on pumping ventilation using wind tunnel experiments. Different building gap aspect ratios and sheltering conditions were considered as main influencing factors.The mean streamwise velocity and velocity fluctuation around the target building were measured. The oscillation frequency of pumping ventilation was obtained from the time history of window center velocity. The effective ventilation rate was utilized to quantify the ventilation effectiveness of pumping ventilation through constant-injection tracer gas method.The experimental results show that the influence of upwind building on the mean velocity and velocity fluctuation are much more significant than that of downwind building. The presence of upwind or downwind building can reduce the pumping ventilation frequency compared with the isolated case. The downwind building has larger reduction effect on PV frequency of the target building compared with the upwind building. Increase of gap aspect ratio could linearly promote the PV frequency. Sheltering could promote the effective ventilation rate of pumping ventilation compared with the isolated case and the ventilation rate could be overall the highest when sheltered by both upwind and downwind building. Upwind building has much larger effect on the concentration fluctuation inside the target building than downwind building. The findings of this study may help to better understand pumping ventilation mechanism in urban areas.

Assessment of ventilation rates inside educational buildings in Southwestern Europe: Analysis of implemented strategic measures

The pandemic caused by COVID-19 has highlighted the need to ensure good indoor air quality. Public buildings (educational buildings in particular) have come under the spotlight because students, teachers and staff spend long periods of the day indoors. This study presents a measurement campaign for the assessment of ventilation rate (VR) and ventilation strategies in educational buildings in Southwestern Europe, Portugal and Spain. A representative sample of the teaching spaces of the Azurém Campus (Guimarães, Portugal) and the Fuentenueva Campus (Granada, Spain) have been analyzed. Natural ventilation is the predominant ventilation strategy in these spaces, being the most common strategy in educational buildings in Europe. VR was estimated under different configurations, using the CO2 decay method. Subsequently, the CO2 concentration was estimated according to occupancy and the probability of infection risk was calculated using the Wells-Riley equation. The obtained VR varied between 2.9 and 20.1 air change per hour (ACH) for natural cross ventilation, 2.0 to 5.1 ACH for single-sided ventilation and 1.8 to 3.5 for mechanically ventilated classrooms. Large differences in CO2 concentrations were verified, depending on the analyzed ventilation strategy, ranging from 475 to 3903 ppm for the different scenarios. However, the probability of risk was less than 1% in almost all of the classrooms analyzed. The results obtained from the measurement campaign showed that the selection of an appropriate ventilation strategy can provide sufficient air renewal and maintain a low risk of infection. Ventilation strategies need to be reconsidered as a consequence of the health emergency arising from the COVID-19 pandemic.

Impact of shading louvers on wind-driven single-sided ventilation in a multi-storey building

As a passive building energy-saving technology, shading systems are usually used to reduce the solar radiation into the unit and reduce the energy consumption of air conditioning system. For multi-storey buildings, shading devices can not only change the indoor thermal environment, but also change the indoor wind environment and air quality because their impact on airflow patterns of natural ventilation. In this paper, the numerical simulation method was used to investigate external shading louvers on the single-sided ventilation performance and indoor air quality of units at different positions in a multi-storey building. Three approaching airflow directions and three rotation angles of louvers were considered and analysed. The results show that the evaluation of ventilation performance of shading louvers in multi-storey buildings is important for shaded buildings, which provide a new perspective for the geometry design of shading louvers and ventilation design of buildings.

Inverse identification of source location in a single-sided natural ventilation building

Natural ventilation is a common way of ventilation for urban residents, which is simple and energy-efficient. However, this ventilation not only introduces fresh air from outdoors into the indoor environment but also brings various pollutants from outdoors into the indoor environment, thus reducing indoor air quality and causing a series of human respiratory diseases in severe cases, such as asthma, pneumonia, bronchitis, etc. In a high-density urban environment, the proximity of rooms within a building can easily lead to cross-infection between occupants in the event of a public health emergency. Therefore, it is of great significance to quickly and accurately find the source of viruses or pollutants. The objective of this study is to accurately locate pollutant source which spread between units by wind effect. A model with three-storey building of wind-driven single-sided ventilation was built. Carbon dioxide (CO2) was used as a tracer of indoor pollutants. Computational Fluid Dynamics (CFD) is used to accurately simulate and predict airflow and concentration fields in and around the building. The results indicated that the location of the predicted pollution source is close to the position where the pollutant is released. The results of this paper can provide vital information for preventing the spread of contaminants in buildings.

Dynamic compartmentalization of double-skin façade for an office building with single-sided ventilation

In this study, a compartmentalized double-skin façade (DSF) is developed for an office room with single-sided ventilation to enhance the performance of the passive design strategy. We designed a DSF that has both an inlet and an outlet to ensure compatibility with single-sided natural ventilation, increased the air cavity heights to overcome the effects of limited ventilation rate, and compartmentalized to suit seasonal conditions. The performance of the dynamically compartmentalized DSF was evaluated using four key parameters: cavity height, cavity depth, opening-to-glazing ratio (O/G ratio), and solar heat gain coefficient (SHGC). Two different seasons, namely summer and winter, were targeted. The results revealed the interdependency of each parameter and indicated the potential energy savings in terms of both cooling and heating. In summer, a greater cavity depth with a higher O/G ratio was helpful when the cavity height was increased. A higher SHGC increased the airflow rate, but it increased the room temperature because the solar heat gain was more influential than the increased airflow rate. In winter, the interdependency between the parameters increased with the SHGC. When airflow rate was restricted to fulfill the minimum ventilation requirement, a higher inlet cavity height helped increase the room temperature by 2 °C on average in winter.

Ventilation Characteristics and Performance Evaluation of Different Window-Opening Forms in a Typical Office Room

As most existing office buildings in China lack fresh air systems for ventilation, natural ventilation with windows remains the main means of improving indoor air quality and adjusting indoor thermal comfort. However, knowledge of the ventilation characteristics of various window-opening forms in actual buildings is limited and current methods for evaluating ventilation performance lack a comprehensive consideration of ventilation rate and thermal comfort. In this study, the ventilation characteristics of different window-opening forms were systematically compared by conducting computational fluid dynamics (CFD) simulations. A full-scale experiment was conducted in a typical office room in a university in Tianjin to validate the CFD simulation. Two ventilation modes (wind-driven cross-ventilation and temperature-driven single-sided ventilation), three window-opening angles, and seven window types were investigated. Additionally, the ratio of the ventilation rate to the absolute value of thermal sensation was used to quantify the indoor natural-ventilation performance. The results showed that a sliding window with a full opening has the highest discharge coefficients of 0.68 and 0.52 under wind-driven cross-ventilation and temperature-driven single-sided ventilation, respectively, and top-hung windows opening both inwards and outwards have better ventilation performance than other window types under the two ventilation modes. This study is applicable to the design and practice of natural ventilation.

Impact of Ventilation Strategy on the Transmission of Outdoor Pollutants into Indoor Environment Using CFD

The transition to remote working due to the pandemic has accentuated the importance of clean indoor air, as people spend a significant portion of their time indoors. Amongst the various determinants of indoor air quality, outdoor pollution is a significant source. While conventional studies have certainly helped to quantify the long-term personal exposure to pollutants and assess their health impact, they have not paid special attention to the mechanism of transmission of pollutants between the two environments. Nevertheless, the quantification of infiltration is essential to determine the contribution of ambient pollutants in indoor air quality and its determinants. This study evaluates the transmission of outdoor pollutants into the indoor environment using 3D computational fluid dynamics modelling with a pollution dispersion model. Naturally ventilated buildings next to an urban canyon were modelled and simulated using Ansys Fluent and validated against wind tunnel results from the Concentration Data of Street Canyons database. The model consisted of two buildings of three storeys each, located on either side of a road. Two line-source pollutants were placed in the street, representing traffic emissions. Three internal rooms were selected and modelled on each floor and implemented with various ventilation strategies. Results indicate that for a canyon with an aspect ratio of 1, indoor spaces in upstream buildings are usually less polluted than downstream ones. Although within the canyon, pollution is 2–3 times higher near the upstream building. Cross ventilation can minimise or prevent infiltration of road-side pollutants into indoor spaces, while also assisting in the dispersion of ambient pollutants. The critical configuration, in terms of air quality, is single-sided ventilation from the canyon. This significantly increases indoor pollutant concentration regardless of the building location. The study reveals that multiple factors determine the indoor–outdoor links, and thorough indexing and understanding of the processes can help designers and urban planners in regulating urban configuration and geometries for improved indoor air quality. Future works should look at investigating the influence of indoor emissions and the effects of different seasons.

Improving Indoor Air Quality in Classrooms via Wind-Induced Natural Ventilation

Student performance in classrooms is related to the indoor environmental quality. High air change rates are necessary to secure an acceptable level of indoor air quality and provide fresh air, which require large amounts of energy and technical installations. Mostly, mechanically supplied air is partially mixed with the return air. In warm climates, the capacity for natural ventilation is not fully exploited in modern buildings. During periods of acceptable outdoor temperatures, buildings need to adapt and employ available free renewable resources, such as wind. In this context, the building form, orientation, and envelope openings are crucial to enable an increased air change rate, user satisfaction, and energy savings. Owing to the difficulty of providing cross-ventilation in buildings with double-loaded corridors, single-sided ventilation is the most common approach. This study investigates the methods to improve the wind-driven air exchange of classrooms in warm climates, where naturally ventilated corridors help increase air movement. This study examines the potential of a set of alternatives within the context of a generic model regarding the pressure distribution, thermal sensation, air velocity, and air change rate. The study suggests that no single opening scenario can be applied to all façades at any time. Each façade requires special treatment. Decisions on natural ventilation need to be made during the early design stages for each façade. It was found that with the aid of low-tech modifications, remarkable increases in air change rates, in some cases up to 14.5 times that of the typical single-sided ventilation case, could be achieved.

Natural ventilation strategy and related issues to prevent coronavirus disease 2019 (COVID-19) airborne transmission in a school building

The World Health Organization (WHO) announced that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may spread through aerosols, so-called airborne transmission, especially in a poorly ventilated indoor environment. Ventilation protects the occupants against airborne transmission. Various studies have been performed on the importance of sufficient ventilation for diluting the concentration of virus and lowering any subsequent dose inhaled by the occupants. However, the ventilation situation can be problematic in public buildings and other shared spaces, such as shops, offices, schools, and restaurants. If ventilation is provided by opening windows, the outdoor airflow rate depends strongly on the specific local conditions (opening sizes, relative positions, climatic and weather conditions).This study uses field measurements to analyze the natural ventilation performance in a school building according to the window opening rates, positions, and weather conditions. The ventilation rates were calculated by the tracer gas decay method, and the infection risk was assessed using the Wells-Riley equation. Under cross-ventilation conditions, the average ventilation rates were measured at 6.51 h−1 for 15% window opening, and 11.20 h−1 for 30% window opening. For single-sided ventilation, the ventilation rates were reduced to about 30% of the values from the cross-ventilation cases. The infection probability is less than 1% in all cases when a mask is worn and more than 15% of the windows are open with cross-ventilation. With single-sided ventilation, if the exposure time is less than 1 h, the infection probability can be kept less than 1% with a mask. However, the infection probability exceeds 1% in all cases where exposure time is greater than 2 h, regardless of whether or not a mask is worn. Also, when the air conditioner was operated with a window opening ratio of 15%, power consumption increased by 10.2%.

Effects of sunshields on vehicular pollutant dispersion and indoor air quality: Comparison between isothermal and nonisothermal conditions

The effects of horizontal sunshields on the vehicular pollutant dispersion and indoor air quality of single-sided ventilation windward rooms along a street canyon is investigated in this study under both isothermal and nonisothermal conditions. A one-way coupling method is developed, i.e., an energy balance model is coupled to a CFD (computational fluid dynamics) simulation model. The simulation is performed for 3 p.m. on a hot summer day in Wuhan, China for cases under nonisothermal conditions. Three street canyon aspect ratios (AR: 0.5, 1, and 2) and two ambient wind velocities (0.5 m/s and 3 m/s) are investigated. The simulation results show that the use of sunshields on windward façades can prominently reduce the façade surface temperature by up to 5 K for each type of street canyon. Neglecting buoyancy effects generally results in an underestimate of the pollutant concentration and air exchange rate (ACH). Buoyancy increases the average ACH by 115.8%–1753.0% under weak ambient winds. Using sunshields under nonisothermal conditions increases the average ACH by approximately 20% for AR = 0.5 and 1 over not using sunshields. Sunshields are a widely used passive architectural design for thermal comfort that show promise for improving indoor air quality by increasing the air exchange rate under certain conditions and reducing pollutant concentrations around building openings. The study results also indicate that buoyancy cannot be neglected, especially in the presence of weak ambient winds.

Keeping Cool in the Desert: Using Wind Catchers for Improved Thermal Comfort and Indoor Air Quality at Half the Energy

In hot arid climates, air conditioning in the summer dominates energy use in buildings. In Kuwait, energy demand in buildings is dominated by cooling, which also determines the national peak electricity demand. Schools contribute significantly to cooling demand, but also suffer from poor ventilation. This paper presents analysis of a ventilation and cooling system for school classrooms using a wind catcher for natural ventilation and evaporative cooling. A school classroom in Kuwait with single-sided ventilation was modelled using the DesignBuilder V5.4/EnergyPlus V9.1 software and calibrated using field data. The model was used to analyse the performance of a wind catcher, with and without evaporative cooling, in terms of energy use, thermal comfort and indoor air quality. Compared to the baseline of using air-conditioning only, a wind catcher with evaporative cooling was found to reduce energy use by 52% during the summer months while increasing the comfortable hours from 76% to 100% without any supplementary air conditioning. While the time below the ASHRAE CO2 limit also improved from 11% to 24% with the wind catcher, the indoor air quality was still poor. These improvements came at the cost of a 14% increase in relative humidity. As the wind catcher solution appears to have potential with further development; several avenues for further research are proposed.

Analysis of Ventilation Efficiency and Effective Ventilation Flow Rate for Wind-driven Single-sided Ventilation Buildings

Natural ventilation can be categorized into single-sided ventilation and cross-ventilation. Based on the air flow mechanism of a single-sided wind-driven natural ventilation, the effective ventilation flow rates in buildings are different from the air flow rates through openings. The mixing coefficient or ventilation efficiency is defined by the ratio of these flow rates, indicating the effective ventilating ability of a single-sided ventilation, similar to the effect of penetration depth of fresh air. This paper provides a detailed analysis of ventilation effectiveness in a building with a single opening based on numerical simulations. The simulation was validated by a study of an existing case. By numerical calculation, the air flow rates through openings and the effective ventilation flow rates in buildings were compared. Effects of various influencing parameters, such as wind speed, opening location, opening area and aspect ratio of windward wall on ventilation efficiency were evaluated. An estimated mixing coefficient has been established by the modelling, which would be beneficial for the predication of the short-circuit ratio of ventilation rate through openings.

Thermal Performance of Single-Story Air-Welled Terraced House in Malaysia: A Field Measurement Approach

The provision requirement of 10% openings of the total floor area stated in the Uniform Building By-Law 1984 Malaysia is essential for natural lighting and ventilation purposes. However, focusing on natural ventilation, the effectiveness of thermal performance in landed residential buildings has never been empirically measured and proven, as most of the research emphasized simulation modeling lacking sufficient empirical validation. Therefore, this paper drawing on field measurement investigates natural ventilation performance in terraced housing with an air-well system. The key concern as to what extent the current air-well system serving as a ventilator is effective to provide better thermal performance is to be addressed. By adopting an existing single-story air-welled terrace house, indoor environmental conditions and thermal performance were monitored and measured using HOBO U12 air temperature and humidity, the HOBO U12 anemometer, and the Delta Ohm HD32.3 Wet Bulb Globe Temperature meter for a six-month duration. The results show that the air temperature of the air well ranged from 27.48 °C to 30.92 °C, with a mean relative humidity of 72.67% to 79.25%. The mean air temperature for a test room (single-sided ventilation room) ranged from 28.04 °C to 30.92 °C, with a relative humidity of 70.16% to 76.00%. These empirical findings are of importance, offering novel policy insights and suggestions. Since the minimum provision of 10% openings has been revealed to be less effective to provide desirable thermal performance and comfort, mandatory compliance with and the necessity of the bylaw requirement should be revisited.

A full-scale field study for evaluation of simple analytical models of cross ventilation and single-sided ventilation

In this study, we evaluated several simple natural ventilation models of cross ventilation and single-sided ventilation with data measured in a full-scale field study in London. In the field study, the ventilation rate in a naturally ventilated office was measured using a tracer gas technique with CO2. Internal temperatures were measured using a vertical temperature array. The external temperature, wind speed and direction were measured at a nearby weather station. In addition, a 1:200 scale model of the urban area within 300 m of the test room was built in a wind tunnel to measure the pressure coefficients. The ventilation models were evaluated with input data from two sources. Wind data from a nearby airport and pressure coefficients from the literature were used, as is common practice. Alternatively, wind data measured at the local weather station and the pressure coefficients measured from wind tunnel experiments were used. The results showed that, regardless of the input data sources, the cross-ventilation model in general gives reasonable predictions. For single-sided ventilation, several empirical models were evaluated and poor predictions were obtained using the models. We discuss ways in which models of natural ventilation might be improved in the future.

CFD simulation of natural ventilation of a generic building in various incident wind directions: Comparison of turbulence modelling, evaluation methods, and ventilation mechanisms

Single-sided and cross- ventilation of a cube-shaped building at various incident wind directions were stimulated using computational fluid dynamics (CFD). The simulation used either the Reynolds-averaged Navier-Stokes (RANS) equations in conjunction with a 2-equation turbulence model (Standard k-ε model (SKT), Realizable k-ε model (RLZ), or Renormalization group k-ε model (RNG)), or Large Eddy Simulation (LES) with the Wall-Adapting Local Eddy-viscosity model (WALE). LES showed good agreement with wind tunnel data when modeling indoor and outdoor wind fields; RLZ had slightly better results than SKT and RNG. Two evaluation methods were examined: the integration of opening velocities method under-estimated single-sided ventilation rates but over-estimated cross-ventilation rates; the tracer-gas decay method was more computationally demanding of the two. When the tracer-gas method and LES were used in combination, their estimations were most accurate especially if the ventilation was driven by wind flow fluctuations. RANS and LES predicted steady decreases of 92.5% and 81.8% (single-sided ventilation), and 52.6% and 37.2% (cross-ventilation) in ventilation rate as incident wind direction varies from 0° to 90°. Discrepancies between the RANS and LES predictions of ventilation rates were mainly attributable to their respective turbulence-modeling methods.