Natural Ventilation In Residential Buildings Research Articles

Enhancing thermal comfort and natural ventilation in residential buildings: A design and assessment of an integrated system with horizontal windcatcher and evaporative cooling channels

In this study, researchers investigated the efficacy of natural cooling in a residential building employing a horizontal windcatcher alongside a direct evaporative cooling system featuring a cross-flow pattern. ANSYS Fluent was used to model the three-dimensional airflow, while MATLAB measured the system's thermal performance. The study assessed thermal comfort and natural ventilation in accordance with the Adaptive Thermal Comfort Standard (ATCS) and ISO/EN7730 Standard. The impact of environmental conditions and window aperture on the hybrid system's functionality was scrutinized, culminating in design guidelines dictating the acceptable range of window openings to ensure compliance with thermal comfort conditions. The passive system demonstrated the capability to maintain thermal comfort within the test building under a maximum cooling load of 12,000 W (ATCS) and 6000 W (ISO/EN7730). Moreover, the natural cooling system decreased hourly electricity consumption during hot seasons in Tehran, Iran, by 0.0155 (kW/m2) compared to split air conditioners and 0.00087 (kW/m2) compared to evaporative coolers. The study also investigated the influence of neighboring buildings positioned at specific distances relative to the test building on the system's performance. Furthermore, adopting the suggested horizontal windcatcher instead of conventional vertical windcatchers resulted in a 50 % reduction in energy consumption.

Energy consumption behaviors and the potential of natural ventilation emission reduction in residential building

ABSTRACT China is the largest Carbon Emissions country in the world. The data analysis and simulation of the sampled residential buildings reveals that there exists a large gap between the monitoring data and energy simulation. Based on the thermal comfort theory, we further explored the relationship between the energy consumption behaviors of residents and building ventilation emission reduction. This study constructed a questionnaire to analyze the use habits of existing residential buildings and equipment. The results show the range of suitable outside temps. In this paper, the findings of the survey were combined with the probability of summer outside temp range profiles to derive the thermal comfort satisfaction of the sample population. In the summer high temperature environment, natural ventilation can help to reduce indoor temperature and reduce the concentration of pollutants in the indoor air, thereby improving indoor air quality and reducing energy consumption. The findings can evaluate the emission reduction potential of natural ventilation. The study provided directions for the implementation of low carbon natural ventilation in residential buildings: natural ventilation can be used to reduce residential energy consumption and carbon emissions, reducing the need for mechanical ventilation. This enables environmentally friendly and sustainable buildings and uses renewable energy sources such as solar and geothermal energy as an energy supply. In addition, the study examined the emission reduction potential of natural ventilation measures in the summer temperature range of 26°C to 28°C, which could reduce carbon dioxide emissions by 1.61 kg per square meter.

Critical Factors Contributing to Poor Natural Ventilation of Residential Buildings

The air tightness of buildings has the greatest potential for energy savings. Reduced fresh air intake raises concerns about natural ventilation systems and the need to provide users with a comfortable indoor climate. The pace at which heat is expelled from a building's interior surfaces increases with vent size, putting residents' health at risk and causing discomfort. The study aimed to evaluate critical factors that contribute to poor natural ventilation in residential buildings, and its associated effects. A quantitative research approach was adopted using purposive sampling for data collection due to undefined residential buildings. 215 questionnaires were distributed to occupants of residential buildings within six (6) selected communities within the Atwima Nwabiagya Municipality. 210 completed questionnaires were collected and analyzed using mean and relative importance index (RII) score ranking. From the findings, nineteen (19) identified variables categorized into three (3) main factors contribute to poor natural ventilation of residential buildings. The most critical factor is unplanned building design and usage with an average RII of (0.955). Most privately owned residential buildings were built with no professional consultation aiming to avoiding professional cost. Eleven (11) variables grouped under four (4) main effects were identified as effects associated with poor natural ventilation, the top-ranked ranked effects were Health risk with an average RII of 0.930. Good natural ventilation is a determinant factor for sustaining occupants’ satisfaction and wellbeing. Therefore, it was recommended that purpose of room space should be well defined before its design and construction. Public education on the need to engage experienced professionals in design and construction should be intensified. The paper affirms to the relevance of natural ventilation for occupants in residential buildings; also, usefulness to engage construction professionals and clients.

Investigation of Natural Ventilation in the Existing Buildings of Qasimabd, Hyderabad

Environment is one of the biggest concerns around the globe as it affects every aspect of our lives, including the buildings used for residential and commercial purposes. A majority of people spend about 90% of their time indoors. In residential buildings, the existence of natural ventilation is essential to ensure the comfort level of residents. Recently, greater significance has been accorded to natural ventilation in building codes and planning policies. Today, many planning policies provide guidelines that stipulate the need for adequate natural ventilation in residential buildings. This paper aimed to investigate the occupants’ level of satisfaction with natural ventilation in residential buildings of Qasimabad, Hyderabad. Twenty (20) houses with a different opening design individuality were selected as sample for the current study. In terms of the occupants’ level of satisfaction with natural ventilation, the majority was neither satisfied nor unsatisfied. Further investigation demonstrated that the level of satisfaction is significantly related to the size of the openings. This study explored the residents’ satisfaction level using the questionnaire survey and case study methodology. Data was collected from the study area of Qasimabad in Hyderabad from 290 respondents. The results vouched for the implementation of building bye-laws in the designing of residential buildings in order to achieve the comfort level of their occupants.
 Keywords: Building bye-laws, natural ventilation, occupants, residential building, satisfaction level

Study on measurement and design strategy of residential room natural ventilation in calm wind climate zone -- a case study of household in chengdu

It is found via the analysis of the meteorological data in Chengdu that the number of annual average calm wind days is more than 240. In the non-calm wind time, the dominant wind direction is not obvious, while the annual average wind speed is about 1.0 m/s. In consequence, problems arise as to indoor ventilation in residential buildings without mechanical ventilation in this climate zone and the way how local residential wind has adapted and improved natural ventilation for a long time. In this paper, the state of indoor ventilation in this zone is studied by measuring the concentration of carbon dioxide in the house for a long time. And the long-term adaptive improvement strategy of local residents to the ventilation of residential buildings in calm climate zone is investigated. So are strategies and experiences of local residents in improving natural ventilation in residential buildings.

Outdoor Airborne Transmission of Coronavirus Among Apartments in High-Density Cities

The coronaviruses have inflicted health and societal crises in recent decades. Both SARS CoV-1 and 2 are suspected to spread through outdoor routes in high-density cities, infecting residents in apartments on separate floors or in different buildings in many superspreading events, often in the absence of close personal contact. The viability of such mode of transmission is disputed in the research literature, and there is little evidence on the dose–response relationship at the apartment level. This paper describes a study to examine the viability of outdoor airborne transmission between neighboring apartments in high density cities. A first-principles model, airborne transmissionviaoutdoor route (ATOR), was developed to simulate airborne pathogen generation, natural decay, outdoor dispersion, apartment entry, and inhalation exposure of susceptible persons in neighboring apartments. The model was partially evaluated using a smoke tracer experiment in a mock-up high-density city site and cross-checking using the computational fluid dynamics (CFD) models. The ATOR model was used to retrospectively investigate the relationship between viral exposure and disease infection at an apartment level in two superspreading events in Hong Kong: the SARS outbreak in Amoy Gardens and the COVID-19 outbreak in Luk Chuen House. Logistic regression results suggested that the predicted viral exposure was positively correlated with the probability of disease infection at apartment level for both events. Infection risks associated with the outdoor route transmission of SARS can be reduced to <10%, if the quanta emission rate from the primary patient is below 30 q/h. Compared with the indoor route transmission, the outdoor route can better explain patterns of disease infection. A viral plume can spread upward and downward, driven by buoyancy forces, while also dispersing under natural wind. Fan-assistant natural ventilation in residential buildings may increase infection risks. Findings have implication for public health response to current and future pandemics and the ATOR model can serve as planning and design tool to identify the risk of airborne disease transmission in high-density cities.

Study on Design Strategies About Single-sided Natural Ventilation in Residential Buildings

Natural ventilation is an effective measure to reduce energy consumption and improve indoor environment. The enlargement of the depth of high-rise residential buildings allows only single-sided natural ventilation, which makes the problem of poor natural ventilation itself more serious. In this study, CFD numerical analysis was used to verify the optimal design strategy of one-sided ventilation residence in a practical case, and the results showed that the design strategy could improve the ventilation effect of one-sided ventilation houses [1].

Effects of vertical farming on natural ventilation of residential buildings

While vertical farming can promote sustainable living and mitigate urban heat island, vegetation could worsen the cross natural ventilation due to additional drag force on air flow. This study aims to investigate the impact of vertical farming on ventilation performance that is important to the thermal comfort especially at tropical/subtropical cities. The Computational Fluid Dynamics (CFD) simulation was first validated against the wind tunnel experiment in the street canyon with tree planting. The vegetable was modelled as porous medium in CFD simulation. In the parametric study, six configurations of facades module were investigated with respect to the vegetable block ratio, arrangement, and vegetable species. The results indicate that the natural ventilation performance is highly affected by the block ratio of vegetable. When three forth of the façade is covered by vegetable, i.e. block ratio of 0.75, the natural ventilation of the façade is very limited, with minimum leeward wind speed of 0.2m/s for incoming air flow of 2.0m/s. For the façade with a block ratio of 0.5, half of incoming air flow, i.e. minimum wind speed of 1.0m/s, can reach the near field downstream of the façade to promote indoor thermal comfort. Therefore, in the design process of the vertical farming, the block ratio of vegetable should be carefully determined regarding the ventilation performance. Furthermore, the natural ventilation with the same block ratio of vegetable could also be improved by appropriately modifying the vegetable arrangement and vegetable species. This study provides important understandings on vertical farming to enable architects to make the evidence-based decision in the architectural design.

Optimisation of Heat Loss through Ventilation for Residential Buildings

This study presents the results of research on heat loss from various types of residential buildings through ventilation systems. Experimental research was done to analyse the effectiveness of ventilation systems of different types and determine the parameters of air discharged via the ventilation ducts. A model of heat loss from the discharge of exhaust air outside through air ducts has since been developed. Experiments were conducted on three experimental systems of building ventilation: gravitational, mechanical, and supply-exhaust ventilation systems with heat recovery. The proposed model dependencies were used to chart the daily fluctuations of the optimum multiplicity of air exchange for precise control of the parameters of mechanical ventilation systems in residential buildings. This study proves that natural ventilation in residential buildings fulfils its function only by increasing the air flow into the building, and that this incurs significant heat loss from buildings during the heating season.

Wind suitability in site analysis of coastal concave terrains using computational fluid dynamics simulation: a case study in East Asia

The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better natural ventilation of residential buildings, external comfort, and pollution dispersion. The main purpose of this study was to develop a set of methods for wind environment assessment in coastal concave terrains. This set of methods can be used to provide quantifiable indicators of preferable wind conditions and help site analysis. Firstly, a total of 20 types of coastal bays with concave terrains in East Asia were characterized to find ideal locations. The selected areas were divided into five categories according to the main terrain features. Then a sample database for the concave terrains was compiled for modelling comparisons. Secondly, a number of key wind variables were identified. Computational fluid dynamics (CFD) models of the typical coastal concave terrains identified as a result of the study were created, and the local wind environments were simulated with input from geographic information system (GIS) and statistic package for social science (SPSS) analysis. A measure of wind suitability was proposed that takes wind velocity and wind direction into account using GIS. Finally, SPSS was used to find the relationship between wind suitability and key terrain factors. The results showed that wind suitability was significantly associated with terrain factors, especially altitude. The results suggest that residential building sites should be selected such that their bay openings face the direction of the prevailing wind and that the opposite direction should be avoided.

SIMULATION OF FREE CURRENT FLOWS IN BUOYANCY-DRIVEN VENTILATION SYSTEMS

Objectives . The aim of the study is to analyse the effect of the design and methods for heating the ventilation duct of a buoyancy- driven system on the formation of free convective air currents in it. Methods. The study of free convection under the conditions of interior problem was carried out using the CFD software, based on the finite volume method with unstructured grid. Ansys Fluent software was used as a calculation tool in the study, due to its having a high convergence of numerical solutions offering full-scale measurements of convective currents.To evaluate the reliability of the results obtained, a validation procedure was carried out, allowing us to determine how accurately the selected conceptual model describes the investigated flow through a comparison of experimental and numerical data. Results . The results of numerical modelling of free convective currents occurring in the heated channel of the ventilation system of the top floor of a multi-storey residential building are presented in the article. In the course of the study, the air velocity at the entrance to the ventilation duct was found to depend on the calculated temperature difference θ ˚C for various heating methods. A gradual increase in the discrepancy between the numerical simulation and experimental results is observed if the calculated temperature difference > 20 ° C. This phenomenon is due to the fact that with increased duct temperature, it is quite difficult to achieve even heating under actual conditions; this is especially noticeable when considering the variant when the vertical part of the vent duct and the take-off are both heated. The maximum deviation of the results is 4.4%. The obtained velocity profiles in the calculated sections indicate the impact of the ventilation take-off on the nature of the air flow motion. Conclusion . One of the drawbacks of the existing systems of natural ventilation of residential buildings is the low efficiency of work in the warm and transitional periods of the year, especially in bathrooms. The use of buoyancy-driven ventilation with vertical heating of the vent duct combined with the take-off allows a stable air exchange in the rooms to be provided.

EVALUATING NATURAL VENTILATION PROVISIONS AND OCCUPANTS’ VENTILATION BEHAVIOR IN FIVE TERRACE HOUSING TYPES IN PUTRAJAYA, MALAYSIA

This study investigates the natural ventilation provisions of residential buildings in the hot-humid climate of Putrajaya as well as the occupants’ utilization and overall satisfaction of these provisions. Five terrace house design types were selected for the study and natural ventilation (NV) provisions were identified through acquired building documents. Computer simulations were carried out on all house types to determine the ventilation rates delivered by the NV provisions. Furthermore, a total of 298 households from the selected house types were surveyed. Two house types were found not to comply with the Uniform Building By-Law (UBBL) governing NV provisions in Malaysia and those house types that complied were found to exhibit higher ventilation rates. Occupants’ level of satisfaction when utilising NV was found to be significantly related to opening sizes complying with UBBL, longer duration of opening windows, and occupants’ means of achieving comfort. This paper informs designers on the importance of complying with the required law governing NV in residential buildings. It also highlights the need for a strict effective enforcement of UBBL compliance for the purpose of building approvals.

Design optimization and field demonstration of natural ventilation for high-rise residential buildings

Natural ventilation in residential buildings has a great potential for conserving energy and improving the health of occupants. This paper first presents a design strategy for optimizing natural ventilation in high-rise residential buildings in Chongqing, China, a region with unfavorably low wind speed. Through the use of CFD modeling, building orientation and spacing were adjusted, wind paths were created into internal zones, and two windows were constructed in each bedroom. The optimized design reduced the age of air to less than 6min in 90% of the rooms, as compared to an age of greater than 30min in 50% of the rooms in a conventional design. Natural ventilation was found to be effective in the Chongqing area with the optimized design. This investigation also measured the local age of air and air change rate in a building with the optimized design using a tracer-gas method. The measurements confirmed the reliability of the CFD results.

Proposing a More Efficient Model to Enhance Natural Ventilation in Residential Buildings

Increase in population is one of the main reasons for human to live in height but in construction of tall-buildings the energy supply has been ignored; moreover mismanagement of natural resources in Iran during recent years has been led to raise concerns among authorities. This article seeks to provide a model which is proposed to use wind-catchers which exists in traditional Iranian architecture to enhance natural ventilation in residential buildings. Therefore, wind catcher performance is analyzed by Carrier software in one proposed model in Tehran. The research approach is simulation, modeling and applied techniques to calculate a proposed model. [1] Collecting information method also is library searching and physical studies. According to the data collected about the features and usage of the wind-catchers in Tehran, only some parts of this tall-building are naturally ventilated. Therefore, the traditional natural ventilation systems cannot be adequate unless the building mechanical systems are used.

Simulation and Analysis of Natural Ventilation of Residential Building's Arrangement

Natural ventilation of residential buildings not only affects the comfort of people` s outdoor areas, but also has an influence on the pressure distribution in front of or behind a single building. Based on the natural climatic conditions in Hefei, the most common three arrangements are referred in this paper, and their ventilation will be simulated and analyzed by the computer. The advantages and disadvantages of different arrangements will also be compared.

The assessment of the performance of a windcatcher system using computational fluid dynamics

Natural ventilation is increasingly being used in modern residential buildings to minimize the consumption of non-renewable energy and the reliance on active means for environmental control. Innovative green features such as the windcatcher has made use of natural ventilation in residential buildings for increasing ventilation rate. This paper presents a numerical study of assessment of the performance of windcatcher using computational fluid dynamics. A 500 mm square windcatcher system connected to the room has been modeled for different wind speeds in the range of 0.5–6 m/s and four different wind directions. The numerical results generally agree with the published experimental results of a wind tunnel experiment. The numerical results demonstrate that the windcatcher performance is greatly influenced by the external wind speed and direction with respect to the windcatcher quadrants. In all cases studied, the maximum velocity of air entering the room is close to the external wind speed and the windcatcher system is found to be an efficient way to channel fresh air into the room. The study also shows that the airflow rate of the air entering the room increases with the wind speed and slightly decreases with the wind incidence angle when the wind speed is lower than 3 m/s. In addition, the results show that the uniformity of air inlet decreases with increasing the wind speed and the incidence angle.