Natural Cross Ventilation Research Articles

Occupant’s behavior investigation related to the building openings in a rural pavilion: A case study of a bioclimatic designed building in a hot semi-arid climate

This study targets the building openings management as a sustainable, passive, cost-effective technique in a rural context with limited budget. Ensuring health and well-being and promoting energy-saving in building operation phase based on natural ventilation and sun management in interaction with the building design. The study utilizes thermo-aeraulic simulation through TRNSYS software, exploring the effects of altered seasonal day and night ventilation and vertical shading management. The findings highlight the significant impact of night natural cross ventilation on energy saving during June and September. Conversely, for July and August, early morning cross ventilation proves to be a more effective option for refreshing the indoor environment. During the cold season, minimizing or avoiding natural ventilation, especially cross ventilation, is advised; in addition, the mandatory overhangs on the south side and the vertical adjustable blinds enhance the energy saving inside the building. With a humidity interval ratio of 30 % to 70 % and two different set-point temperature ranges of 18 °C-28 °C and 20 °C-26 °C respectively, the annual thermal loads per square meter for two of the simulated scenarios are optimal, measuring 22.28 kWh/m2 and 22.85 kWh/m2 compared to 56 kWh/m2, respectively. These results can be further optimized by altering both types of ventilation mentioned earlier.

BIM-Based Simulation on Sustainable Housing Design Using Autodesk Revit

Abstract In the master plan of Trisakti University Nagrak Campus, the criteria for sustainable buildings are mandatory in its planning. One of the facilities in the master plan is the Lecturer Housing. In the modern era, sustainable housing design is needed because of the high energy consumption in modern housing design. This study aims to determine optimal strategies for implementing the Sustainable housing concept in lecturer housing design. Simulation methods are applied using Autodesk Revit to create the lecturer housing design. BIM models are more accurately analyzed and support the idea of more sustainable designs. Based on the simulation, the maximum power obtained from Photovoltaics is 26.181 kWh/year, saving Energy by IDR 62,102,167.05 on a payback period of 15 years. This design can also harvest 20.174,062 Liters of rainwater per year. In addition, applying solar chimneys maximized the penetration of natural daylight and cross ventilation process. Based on the modeling findings, it is evident that the average building daylight factor is 6.5%, above the minimum need of 5%, which will decrease reliance on artificial lighting during daylight hours. The fin-shaped shading device mechanism can reduce direct sunlight’s glare and radiation, increasing the reflected light that touches the side of the structure. When dealing with big openings, fin shading devices are utilized to get the optimal opening height-to-shade length ratio of 3:2. The rainwater harvesting management system is well-suited for toilet flushing and plant irrigation, and implementing bio pores may significantly enhance excess rainwater soil penetration., and maximize sustainable housing design.

Bioclimatic Design Strategies For Housing in Areas Affected by Natural Events

Objective: The objective of this study was a housing design with bioclimatic criteria and construction technology with traditional materials to propose an appropriate solution for families that suffered damage from the 2017 earthquakes in Oaxaca, Mexico. Method: A climatic characterization of the site was carried out to obtain bioclimatic strategies for the housing design. Analysis methods were used to validate these strategies such as comfort triangles and Mahoney tables. The housing was designed considering the resulting strategies and prioritized passive ones. Results and conclusions: It was obtained that for the study area the main strategies for the housing design are natural cross ventilation, thermal inertia in walls and ceilings and solar radiation during the cold months. The study highlights the importance of implementing bioclimatic design strategies according to the climatic context that promote the improvement of the habitability level of housing. Implications of the research: The research contributes to the design of a sustainable housing model for families affected in their patrimony by the action of earthquakes in the study area considering the environmental conditions, in addition to promoting the conservation of traditional architecture and construction systems. Originality/value: In the area of sustainability and the environment, a housing design was proposed that adopts practices that minimize the environmental impact and ensures that the new houses are energy efficient and environmentally friendly and adapt to climate change.

Optimizing wind-catching butterfly roofs to improve cross natural ventilation performance in apartment buildings

Abstract This study aims to enhance cross natural ventilation performance in multi-level double-loaded apartments by employing a wind-catching butterfly roof, specifically designed for apartments with a center-to-center opening configuration. A 2k full-factorial design of experiment (DOE) method with a center point is utilized for design optimization. Nine configurations, determined by roof height h and roof angle α, are assessed using Computational Fluid Dynamics (CFD). After the initial DOE assessment, three additional butterfly roof designs with varying α values are explored. The dimensionless flow rate (DFR) serves as the objective function for optimization. The optimal design features a butterfly roof with h = 0.01m and α = 30°, demonstrating improvements of 2.5%−4.9% in DFR and 5.3%−9.0% in the pressure coefficient C p compared to scenarios without a butterfly roof. Butterfly roofs also increased the velocity magnitudes in the rooms of the leeward block, with configurations h = 0.01m and α = 35° and 37.5° showing the most significant increases of 58.5% − 86.9% on levels 1 to 3. The discharge coefficient C d induced by all butterfly roof configurations are within 0.6 − 0.7 on levels 1 to 3, while the C d values for levels 4 to 6 are within 0.5 − 0.6. Although butterfly roofs can enhance indoor air quality, they require further research to meet all recommended guidelines. These findings provide valuable insights for architects and urban planners aiming to reduce the environmental footprint of apartment buildings. This research presents a comprehensive evaluation of the potential of butterfly roofs to enhance apartment ventilation and offers recommendations for future design improvements.

Validation of Dynamic Natural Ventilation Protocols for Optimal Indoor Air Quality and Thermal Adaptive Comfort during the Winter Season in Subtropical-Climate School Buildings

The need for energy-efficient buildings must be based on strong effective passive-design techniques, which coordinate indoor air quality and thermal comfort. This research describes the principles, simulation, implementation, and monitoring of two different natural cross-ventilation algorithm scenarios applied to a school-building case study affected by a subtropical climate during the winter season. These ventilation protocols, the steady and dynamic versions, can control the carbon dioxide concentration and actuate the window openings according to pre-defined window-to-wall ratios. The implementation of the monitoring process during three non-consecutive days in the winter of 2021 validates the opening strategy to maintain carbon dioxide below 800 ppm, described by the protocol Hygiene Measures Against COVID-19, and the temperature within the comfort ranges suggested by the adaptive UNE-EN 16798. The study shows that a steady opening of 2.16% window-to-wall equivalent ratio can be enough to maintain the requested comfort and carbon dioxide conditions. The use of the dynamic window ratios, from 0.23% to 2.16%, modified according to the measured carbon dioxide concentration, can partially maintain the carbon dioxide below the required limits for ASHRAE 62.1, Hygiene Measures Against COVID-19 and UNE-EN 16798 between 48.28% to 74.14% of the time. However, the carbon dioxide limit proposed by RITE, 500 ppm, is only achieved for 15.52% of the time, which demonstrates the inadequacy of the natural ventilation to fulfil the standard. Further improvements in the dynamic control of the openings in these buildings could lead to lower carbon dioxide concentrations while maintaining the thermal comfort in mild winter climates.

Opening configurations and natural cross ventilation performance in a double-loaded multi-level apartment building: A CFD analysis

This study investigates the impact of varied opening configurations on natural cross ventilation of a double-loaded multi-level apartment. Using computational fluid dynamics (CFD) simulations, twenty-five building models with combinations of top-top (TT), top-bottom (TB), center-center (CC), bottom-bottom (BB), and bottom-top (BT) opening configurations were analyzed in both windward and leeward building blocks. In the windward block, the BB configuration yielded the highest dimensionless flow rate (DFR) for levels 1–3, and BT was highest for levels 5 and 6. Air Exchange Efficiency (AEE) was optimal at 45–55% for TB configurations on levels 1–3, and for CC and BT on levels 4–6. Factor optimization (α) was introduced to balance DFR and AEE, favoring TB configurations for level 1–3 and BT configurations for levels 4–6. Additionally, the leeward block's ventilation was slightly influenced (±3.5%) by the windward block's configurations. Notably, the TT configuration achieved the highest α score at level 1 and TB at level 2, even with the lowest DFR. Conversely, the CC configuration, while having the lowest AEE for the first two levels, yielded the highest DFR values. Bottom inlet configurations recorded the lowest α scores for levels 3–6. The research suggests that the TT and CC configurations are the most effective for ventilation in the leeward block. The results indicate that building design can be optimized for ventilation performance at each level without significant impact to adjacent structures. This informs improved ventilation strategies in high-rise buildings, emphasizing design adaptability to enhance indoor air quality.

RISK OF BIOAEROSOLS IN SMALL AND POORLY VENTILATED INDOOR PLACES WITH LOW CONCURRENT USE

Natural cross ventilation has become one of the most effective and sustainable strategies to address respiratory pandemics in confined spaces. Air intake through windows, doors and other openings improves the Indoor Air Quality (IAQ) of a classroom, decreases the likelihood of respiratory disease transmission when social distancing of about 1.5 m is observed, and is affordable in terms of energy consumption. In this study, a comparison between types of cross ventilation from CO2 concentration, number of people and window and door surfaces of a school in a Mediterranean climate is carried out for 3 different cases of openings. For this purpose, CO2 levels were measured in two similar and annexed classrooms with different window and door openings (0%, 33% y 66%) with 2 loading and unloading sequences. Two types of cross ventilation were analyzed: cross ventilation with window and door in the same direction or direct (CDIR), and diagonal cross ventilation (CDIA), in a time period of 3 h. in December 2022. The results show an interaction between CO2 levels and the type of ventilation. Diagonal cross ventilation was more effective in terms of air renewal (ACH) than direct ventilation, in smaller opening ranges (33%), with direct cross ventilation being more effective globally and in larger opening ranges (66%), under the conditions of this case study. Keywords: natural ventilation; cross ventilation; indoor air quality; carbon dioxide (CO2) concentration; classroom.

Natural ventilation effectiveness in low-income housing to challenge energy poverty

The steady rise in global average temperatures due to climate change is leading to a significant increase in cooling energy demand worldwide. Despite having the least access to energy, the Global South will experience the greatest increase in cooling degree days (CDD), forcing the majority of the world’s population to endure highly uncomfortable temperatures in the buildings. As a result, it becomes crucial to prioritize passive design-based approaches to air conditioning, to mitigate the increasing demand for active cooling while ensuring equitable space cooling opportunities for all. This work, combing the CFD simulation with building energy modeling, evaluates the impact of natural cross-ventilation and building form on improving indoor thermal conditions in hot and arid climates. The analysis, focusing on low-income housing prototypes designed by Indian architect Charles Correa, demonstrates how proper building form design, by improving the ventilation and cooling efficiency of buildings, can ensure indoor thermal comfort even in challenging climatic conditions, helping to reduce energy consumption and prevent energy poverty. Natural ventilation provides an operative temperature reduction of up to 3.1 °C on the hottest day and up to 3.9 °C on the typical cooling period day. Even discomfort hours are drastically reduced by 31.3 % and 77.8 % respectively.

How much natural ventilation rate can suppress COVID-19 transmission in occupancy zones?

Previous research has emphasized the importance of efficient ventilation in suppressing COVID-19 transmission in indoor spaces, yet suitable ventilation rates have not been suggested. This study investigated the impacts of mechanical, natural, single-sided, cross-ventilation, and three mask types (homemade, surgical, N95) on COVID-19 spread across eight common indoor settings. Viral exposure was quantified using a mass balance calculation of inhaled viral particles, accounting for initial viral load, removal via ventilation, and mask filtration efficiency. Results demonstrated that natural cross-ventilation significantly reduced viral load, decreasing from 10,000 to 0 viruses over 15 minutes in a 100 m2 space by providing ~1325 m3/h of outdoor air via two 0.6 m2 openings at 1.5 m/s wind speed. In contrast, single-sided ventilation only halved viral load at best. Natural cross-ventilation with masks effectively suppressed airborne viruses, lowering potential infections and disease transmission. The study recommends suitable ventilation rates to reduce COVID-19 infection risks in indoor spaces.

Impacts of horizontal and vertical louvers on the natural cross-ventilation performance of a generic building

Wind-based natural cross-ventilation is defined as a process in which fresh air is injected into a building via a high-pressure windward window and exhausts into the atmosphere through a low-pressure leeward window. There are several parameters that affect the natural ventilation performance, which should be considered in detail to reach the maximum air quality inside the buildings. In the present study, the effects of horizontal and vertical louvers on the wind-driven natural cross-ventilation performance of a generic building are assessed using computational fluid dynamics. In this regard, horizontal and vertical louvers with installation louver angles of 15°, 30°, and 45° are compared with each other and corresponding non-louver cases. Computations are carried out for three different free-wind speeds of 1, 2, and 3 m/s to show the impact of the external conditions on the natural ventilation of louvered cases. The obtained results revealed that under a low free-wind speed of 1 m/s, the minimum age of air and maximum air exchange efficiency occur for vertical louvers with an installation angle of 15°, while at moderate and high free-wind speeds of 2 and 3 m/s, the horizontal louvers with an installation angle of 15° provide the best condition for a generic building. Highlights Effects of horizontal and vertical louvers on the wind-driven cross-ventilation were studied. At a free-wind speed of 1 m/s, the minimum age of air and maximum air exchange efficiency occur for vertical louver with α = 15°. At U H = 2 and 3 m/s, horizontal louver with α = 15° provides the best condition for a generic building.

Impact of planar area ratio and opening positions on natural cross ventilation performance in sheltered high-rise buildings: A simulation study

This paper studies the impact of planar area ratio (λP) and opening positions on natural cross ventilation performance of a sheltered three-level high-rise building through numerical simulations. Three building clusters of different λP and five different opening configurations each were assessed. To improve the accuracy of the numerical simulations, a novel calibration method utilizing 2k full-factorial design of experiment (DoE) approach was proposed to determine the closure coefficients of the Standard k−ε (SKE) turbulence model. Various parameters such as velocity profile (U/UH), pressure difference (ΔCp), turbulence kinetic energy (TKE), dimensionless flow rate (DFR), age of air (AOA) and air exchange efficiency (AEE) were examined. On level 1, distinct variations in DFR, AEE and AOA were observed for different λP values. Maximum DFR and AEE and maximum AOA are achieved when λP=0.25 for all opening configurations. Conversely, the impact of λP is minor for levels 2 and 3. Specific opening configurations, such as top-bottom and top-top on levels 1 and 2, and center-center and bottom-top on level 3, demonstrate favorable AEE of about 45–50%. The trade-off between AEE and DFR suggests that the bottom-bottom configuration performs best on level 1, while top-top and top-bottom configurations work best on level 2, and the center-center configuration is the best on level 3. The presence or absence of openings on levels 1 and 3 do not significantly affect the indoor airflow on level 2. The insights and recommendations derived from this study have practical implications for sustainable high-rise building design.

The impact of size in fenestration designon the airflow and temperature in natural cross ventilation, case study:A two-bedroom Polish multifamily home

In countries with cold winters such as Poland, there is growing evidence for proliferating overheating in summer times due to climate change. Hence, buildings become more uncomfortable for their occupants during hot summers. To tackle this challenge, we use the passive strategies potential to adapt buildings in line with their experimental and engineering analysis of the indoor environment. This paper demonstrates the results of both thermal and airflow simulation of existing naturally ventilated in double-bedroom homes in Poland. Thermal and airflow simulation is used to improve the natural ventilation system and to address summer thermal comfort problems due to excessive hot airflow caused by climate change. In the first step of the research, over 300 multi-family home plans all over Poland were categorized by size, ventilation type, facade organization, and fenestration type. In the second part, computational fluid dynamics (CFD) analysis is used on 3D models to predict indoor airflow velocities for different levels of the building envelope airflow permeability. Then, a coupled thermal and airflow simulation with 2 different window size, fully open, and with 3 integrated shadings options (base model or no shadings, 30 cm overhang with side-fin, and 10 cm depth horizontal louvers) are done to investigate whether the more opened envelope reduces a summer overheating problem. The results for the optimized natural ventilation through fenestrations successfully address houses' summer discomfort problem by reducing the indoor temperature between 2–3C and in some cases up to 4C cooler than similar model with small windows.

Quantifying natural cross-ventilation flow of a two-layered model used for terraced houses in tropical zones by particle image velocimetry

Wind-induced natural ventilation is a sustainable approach for improving the indoor thermal comfort, air quality, and energy consumption. Although numerous ventilation studies have addressed generic ventilation models, the cross-ventilation flow of a multilayered model (widely ingrained in a tropical climate zone such as Malaysia as a typical terraced house with a deep-plan layout) has not been studied well. Therefore, this study aims to investigate the flow patterns inside a simplified two-layered model separated by a second floor at the middle height with an opening using wind tunnel experiments. Two cases are considered based on the positions of the inlet and outlet openings on each floor. Two velocity components are measured using particle image velocimetry (PIV) and hot-wire anemometry (HWA). This study provides high-quality experimental datasets, which enables us to understand turbulent characteristics of indoor airflow, obtained using PIV and HWA for a generic two-layered cross-ventilation model. In addition, the results show that the ventilation performance of two-layered stratified buildings is significantly affected by the inlet opening positions. Moreover, the indoor flow direction is considerably changed owing to the multi-zoning of the indoor space. Although we employed only a generic two-layered model, this study clearly highlights the importance of considering multi-layered buildings for a better understanding of the ventilation performance.

Designing and testing the applicability of a natural green ventilation building block in an Egyptian Climatic zone using waste materials

Natural ventilation is one of the ways used to enhance building spaces' indoor air quality, especially after the COVID-19 pandemic. It also saves energy by utilizing natural wind forces to provide internal building spaces with fresh air instead of energy-consuming mechanical systems. For a multiple-floor building, adding external wall ventilation blocks can improve natural cross ventilation by catching and directing fresh air from the external prevailing wind into its internal spaces. This research aimed to enhance the building's natural ventilation by using environmentally friendly blocks. This was done by designing a green block using marble and granite waste materials as a partial substitute for conventional materials in the block. Styrofoam beads were added to the block’s mixture to reduce its weight. The block’s shape was designed to direct fresh air through building side walls by the use of natural wind pressure. The block was developed from the initial shape of the standard hollow block to a block with a wind catcher. Ventilation block shape simulations were done using (ANSYS fluent) computational fluid dynamics (CFD) software to determine the best inlet angle, catcher angle, and catcher length. The study revealed that by increasing the block inlet angle more than 45°, the block outlet air velocity starts to decrease due to the flow separation in the front part of the block inlet. The catcher angle ranged from 65° to 85°, and the catcher’s ability to redirect the airflow is decreased at a catcher angle greater than 85°. The best nondimensional catcher length-to-block length ratio (height /length) h/L was 0.625. Substitution of 5% of cement by granite in the presence of 0.15 Kg of Styrofoam (C5G) produced a lightweight green ventilation block of weight 19.3 kg. Whereas, the substitution of 15% of sand for marble in the presence of 1 Kg of Styrofoam (S15M) produced a lightweight green ventilation block of weight 15.9 kg. The produced block was tested in a building located in New Cairo City (a region currently having a tremendous increase in the building construction sector) as a study sample representing one of the Egyptian Climatic zones. The research concluded that it is preferred to allocate the building corners towards the prevailing wind direction to prevent airflow separation and to magnify the quantities of air along the building sides.

Influences of home kitchen designs on indoor air quality

Kitchen indoor air quality (IAQ) has not been well-addressed amongst other IAQ problems at home, despite the fact that cooking is one of the major home activities that can generate high levels of respirable particles and gaseous air pollutants. This study aims at investigating the effects of home kitchen designs on the performance of various ventilation strategies in reducing exposure to IAQ pollutants. The degree of natural ventilation was found to be dependent largely on the relative position of window and door opening, and using mixed ventilation with natural cross-ventilation and mechanical ventilation did not necessarily provide better ventilation. Natural ventilation with the added fume extraction by the exhaust fan could not protect the occupants from high levels of cooking pollutants. Range hood on the other hand could quickly and locally remove particles and gaseous cooking pollutants from the source. The study recommends using a range hood alone during cooking or with single-side natural ventilation to maintain an acceptable IAQ in the home kitchen.

Impact of Internal Wall Barriers on Airflow Pattern in Natural Cross-Ventilation of the Common Houses in Bhubaneswar City, India

Impact of Internal Wall Barriers on Airflow Pattern in Natural Cross-Ventilation of the Common Houses in Bhubaneswar City, India

EVALUATING THE EFFECT OF MASHRABIYA AND PERFORATED MALAY CARVING WINDOW ON THE INDOOR NATURAL VENTILATION PERFORMANCE OF LIVING SPACE

This study focuses on natural cross-ventilation improvements in terms of internal air velocity, measured in meter per second in the living room space in Malaysia, using two types of perforated windows namely, Mashrabiya window as well as perforated Malay carving window element to determine the performance of their internal air velocity. Cross ventilation has been proposed as one of the most effective natural ventilation methods for thermal comfort by several studies. It is, however, one of the most misunderstood aspects of passive design's approach to regulating interior temperature. In this study, the proposed design solution is by introducing the Mashrabiya (W1) and perforated Malay carving window (W2) as two predominant indigenous solutions for traditional houses that can be further developed and utilized in modern houses. The research involves three stages. The first stage includes the inventory exercise on five (5) different reference case studies of perforated windows. This is to ascertain the most fundamental and common pattern, as well as the dimensions of each W1 and W2. The second step involves computer simulations utilising Computational Fluid Dynamics (CFD) software known as Ansys fluent R2 2021. This program is used to simulate and evaluate natural air velocity and its performance in an interior context, and to determine the viability of a recommended design solution. Finally, an empirical method is used to predict the internal air velocity. The result shows that W1 and W2 represent effective passive design strategies for energy saving. The air velocity using W1 is three times higher than the normal speed which is 4.5/1.5 m/s, while using W2 makes the air velocity two times higher than the actual air speed which is 3/1.5 m/s. The simulation test and results are discussed based on the Malaysian region with a 1.5m/s wind speed. Understanding the different effects of the size of the voids and the placement of the patterns are significant to improve the indoor natural ventilation performance in a living room space.

Passive house design in temperate continental climate for increasing indoor comfort conditions

In the last couple of years, we have witnessed dramatic changes in the fabric of our society, with great impact on cities, neighborhoods and living conditions. Therefore, the contemporary architectural discourse tries to shift its attention towards these social, cultural and climatic changes, while trying to better respond to the challenges that occur in our society at different levels. The present paper analyzes a project for an energy efficient single-family house that integrates into a heterogeneous urban context, with specific constraints pertaining to local regulations and climatic regional conditions. The chosen site is situated in a historical area of Iasi, Romania, aspect that must be taken into account when proposing the overall volumetric concept. The passive design strategies have also been implemented in order to achieve the nZEB status. Among other energy and cost efficient solutions we mention: use of renewable energies along with a very efficient constructive system for an airtight house configuration; natural cross ventilation strategies and maximizing the daylight factor for all indoor spaces. Simulations in DIALux provided very good values for daylight factor, an important aspect for minimizing the energy consumption for electricity, especially during winter. For increasing the overall indoor comfort hours during summer and winter, additional systems/features were proposed for direct solar intake, shading and increase of thermal mass.

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.

Investigation of varying louver angles and positions on cross ventilation in a generic isolated building using CFD simulation

Louvers are an integral component of natural ventilation. This study presents a numerical analysis using computational fluid dynamics (CFD) on cross ventilation in an isolated building equipped with louvers. Opening configurations of (i) center-center, (ii) top-top, (iii) bottom-bottom, (iv) top-bottom and (v) bottom-top (whereby the configurations are defined as ‘windward’-‘leeward’) with varying louver configurations of No-Louver (NL), 0°, 15°, 30° and 45° are studied. Atmospheric Boundary Layer (ABL) condition is applied at the inlet of the flow domain and Renormalization Group (RNG) k-ε turbulence model with enhanced wall function (EWT) is employed for the numerical simulations. Grid sensitivity analysis is performed using Grid Convergence Index (GCI) whilst model validation is performed using Factor of two of observation (FAC2) analysis. The highest dimensionless flow rate (DFR) is achieved by configuration top-top without louvers at 0.719. The highest air exchange efficiency (AEE) is obtained by louver angle of 15° for center-center configuration at 53.4%. The lowest AEE obtained is obtained at louver angle of 0° for top-top configuration at 20%, indicating short-circuiting of air. For configuration bottom-bottom with louver angle of 30°, high AEE is obtained but at the cost of reduced DFR. The optimal balance between AEE and DFR can be obtained by factor-optimization (α) as presented in this paper. The study concludes that opening position alongside louver angle plays an integral role on the internal airflow, pressure coefficient, DFR and AEE in natural cross ventilation.