Academic literature on the topic 'Ventilated Envelope'

The proposal of energy efficiency measures in the residential sector in Argentina requires analyzing the architectonic possibilities of building rehabilitation using technologies that reduce energy consumption, that are feasible to implement locally. In regions with high solar radiation levels, as is the case of the city of Mendoza, heat fluxes transmitted inside can be reduced by the natural ventilation of the layers in the envelope, both on facades and roofs, thus obtaining significant savings in consumption for cooling purposes. This work evaluates the potential for improvement with the integration of ventilated envelopes. The work methodology is structured in two stages: i) survey of residential buildings by morphological typology and analysis of rehabilitation possibilities with ventilated facades, considering the exposed envelope surfaces by orientation; ii) simulation of a case study - previously validated with onsite measurements - using the EnergyPlus software. On integrating ventilated facades and roofs important energy savings of around 32% were achieved, considering the building without users (unoccupied). In the case of units on the top floor, with roofs exposed to the outside, energy savings of 260% were recorded.

Abstract Reducing the energy consumption needed for creating suitable indoor conditions has become a significant issue on a global scale. The building’s envelope and service systems have the most important influence over the amount of energy consumed. This aspect is related to reducing the heat flux across the building envelope in summer conditions and preventing the condensation and infiltration risk in the winter period. The research regarding ventilated façades has advanced taking into account these advantages, which emphasized the need to study and create constructive solutions adapted to the conditions. In this context, this paper represents a brief introduction to ventilated façades solutions, taking into account the definition, their characteristics, the principal constructive elements, the main types of ventilated facades, and last, but not least, their advantages and disadvantages. The authors believe that the study is critical in fully comprehending the characteristics of these systems and their primary components, as well as designing and implementing them in accordance with current environmental needs. It is anticipated that comprehending this concept, as well as its evolution and trends, can contribute in the resolving of a number of ecological and societal issues.

Abstract DTU has established a single-family three-level test house in Nuuk, Greenland. The main idea of the house was to have a relatively small heated area but a split building envelope, where a ventilated space behind the rain screen in some areas could be used as a sunroom. This paper describes the process of transforming the architectural ideas to a test building. Main issues have been how to design the rain screen and how to ventilate the space behind the rain screen.

Abstract The walls in a building envelope have the largest contact area with the exterior environment, and, therefore, a considerable portion of the thermal energy can be lost through the walls compared to the other parts of the building envelope. For energy-saving purposes, the thermal transmittance of walls is typically limited by building energy performance standards at the national level. However, the presence of a ventilated air-space behind the external cladding, which has variable hydro-dynamic behavior, can differently affect the total thermal transmittance of the entire structure. This paper aims to provide an experimental analysis of the total U-value of a ventilated wall assembly measured in a building prototype following the average and dynamic methods defined by ISO 9869-1. Differences between the calculated theoretical U-value and the measured U-value are compared. The contribution of the thermal resistance of the ventilated air-space in the total thermal transmittance of the wall assembly is also analyzed. The results show that the air movement and the enthalpy change in the ventilated cavity can affect the thermal performance of the wall structure to a certain extent.

The thermal performance of a phase change energy storage building envelope with the ventilated cavity was evaluated. CaCl2·6H2O-Mg(NO3)2·6H2O/expanded graphite (EG) was employed to combined with the building for year-round management. The energy consumption caused by the building under different influence parameters was evaluated numerically. The results indicated that CaCl2·6H2O-8wt %Mg(NO3)2·6H2O/EG should be installed on the south wall for the heating season, while CaCl2·6H2O-2wt %Mg(NO3)2·6H2O/EG should be integrated on the roof for the cooling season. When the air layer was ventilated and the south wall was coated with the solar absorbing coating, the room could save approximately 30% of energy consumption. Moreover, the energy consumption increased with an increase in the air layer thickness, and the air layers played a different role in the building envelope. The optimal value of the flow rate between air layer 2, air layer 3, and the room was 0.09 m3/s. To reduce the energy consumption, the phase change materials (PCMs) with large and small thermal conductivity should be installed in the south wall and roof, respectively. In general, the phase change energy storage building envelope with the ventilated cavity can save energy during the heating and cooling seasons.

This study aims to propose building envelope retrofit packages for existing naturally ventilated school buildings in the hot–humid climatic region of Chennai, India. Indoor thermal parameters were collected through field studies from nine sample classrooms of a selected school building in May 2019, between 9.00 am and 4.00 pm. The thermal performance assessment of the existing building was performed by examining the discomfort hours using the CBE thermal comfort tool. Envelope retrofit strategies gathered from the literature and building standards were applied and studied through simulation. The findings reveal the enormous potential to increase the thermal comfort of existing school buildings through envelope retrofit measures. The results demonstrate that the whole-building temperature can be reduced up to 3.2 °C in summer and up to 3.4 °C in winter. Implementing retrofit measures to the building envelopes of existing buildings will help school owners to increase the comfortable hours of whole buildings by up to 17%. In comparison, annual energy savings of up to 13% for the whole building can be made by enhancing the thermal performance of the building envelope. The findings will also help architects to optimise thermal performance and energy usage with minimal interventions.

Electricity generation on site is a design challenge aiming at supporting the concept of energy-autonomous building. Many projects worldwide have promoted the installation of photovoltaic panels on urban buildings, aiming at utilizing a large area to produce electricity. In most cases, photovoltaics are considered strictly as electricity generators, neglecting their effect to the efficiency and to the thermal behaviour of the building envelope. The integrated performance of photovoltaic ventilated fa?ades, where the photovoltaics are regarded as part of a complicated envelope system, provides design challenges and problems that cannot be overlooked within the framework of the Nearly Zero Energy Building concept. In this study, a finite volume model for photovoltaic ventilated fa?ades is developed, experimentally validated and found to have a significant convergence to measured data.

It is beneficial for designers to identify the most important design parameters of building envelopes. This study undertook sensitivity analysis integrated with EnergyPlus to assess the impacts of envelope design parameters for naturally ventilated industrial buildings. Sensitivity coefficients of six envelope design parameters for different internal heat intensities were analyzed and compared for buildings in the city of Xi’an, located in the cold climate zone of China. Our results showed that the heat transfer coefficient of the roofs had the most significant impact on indoor temperature. The weights were 32.29%, 33.71% and 30.71%, and the heat intensities were 5, 10 and 15 W/m3, respectively. The effect of the skylight-to-roof ratio was the second most sensitive. The impact of the solar absorptances of the walls and roof on the total number of hours was not sensitive. The results could be helpful for designers to efficiently form alternative design solutions in the design of new and retrofitting industrial buildings.

Ventilated façades are increasingly used for retrofitting of exterior walls but also as a passive strategy in the reduction of heat transfer through the envelope of new buildings. If correctly designed and constructed, ventilated façades can lead to energy savings and increased durability of exterior walls. Nevertheless, the main advantage of these constructive systems is the capacity to reduce heat load on the building during the warm season due to the air that flows inside the cavity. The total heat transported by convection is influenced by the temperature distribution inside the channel and depends on many factors, the most important being the channel thickness and the type of the exterior layer. This work presents an experimental study of the temperature reduction capacity for different channel thicknesses and exterior layer tightness on a real scale wooden ventilated façade wall.

La demande d'énergie consommée par les habitants a connu une croissance significative au cours des 30 dernières années. Par conséquent, des actions sont menées en vue de développement des énergies renouvelables et en particulier de l'énergie solaire. De nombreuses solutions technologiques ont ensuite été proposées, telles que les capteurs solaires PV/T dont l'objectif est d'améliorer la performance des panneaux PV en récupérant l’énergie thermique qu’ils dissipent à l’aide d’un fluide caloporteur. Les recherches en vue de l'amélioration des productivités thermiques et électriques de ces composants ont conduit à l'intégration progressive à l’enveloppe des bâtiments afin d'améliorer leur surface de captation d’énergie solaire. Face à la problématique énergétique, les solutions envisagées dans le domaine du bâtiment s’orientent sur un mix énergétique favorisant la production locale ainsi que l’autoconsommation. Concernant l’électricité, les systèmes photovoltaïques intégrés au bâtiment (BIPV) représentent l’une des rares technologies capables de produire de l’électricité localement et sans émettre de gaz à effet de serre. Cependant, le niveau de température auquel fonctionnent ces composants et en particulier les composants cristallins, influence sensiblement leur efficacité ainsi que leur durée de vie. Ceci est donc d’autant plus vrai en configuration d’intégration. Ces deux constats mettent en lumière l’importance du refroidissement passif par convection naturelle de ces modules. Ce travail porte sur la simulation numérique d'une façade PV partiellement transparente et ventilée, conçu pour le rafraichissement en été (par convection naturelle) et pour la récupération de chaleur en hiver (par ventilation mécanique). Pour les deux configurations, l'air dans la cavité est chauffé par la transmission du rayonnement solaire à travers des surfaces vitrées, et par les échanges convectif et radiatif. Le système est simulé à l'aide d'un modèle multi-physique réduit adapté à une grande échelle dans des conditions réelles d'exploitation et développé pour l'environnement logiciel TRNSYS. La validation du modèle est ensuite présentée en utilisant des données expérimentales du projet RESSOURCES (ANR-PREBAT 2007). Cette étape a conduit, dans le troisième chapitre du calcul des besoins de chauffage et de refroidissement d'un bâtiment et l'évaluation de l'impact des variations climatiques sur les performances du système. Les résultats ont permis enfin d'effectuer une analyse énergétique et exergo-économique<br>The demand of energy consumed by human kind has been growing significantly over the past 30 years. Therefore, various actions are taken for the development of renewable energy and in particular solar energy. Many technological solutions have then been proposed, such as solar PV/T collectors whose objective is to improve the PV panels performance by recovering the heat lost with a heat removal fluid. The research for the improvement of the thermal and electrical productivities of these components has led to the gradual integration of the solar components into building in order to improve their absorbing area. Among technologies capable to produce electricity locally without con-tributing to greenhouse gas (GHG) releases is building integrated PV systems (BIPV). However, when exposed to intense solar radiation, the temperature of PV modules increases significantly, leading to a reduction in efficiency so that only about 14% of the incident radiation is converted into electrical energy. The high temperature also decreases the life of the modules, thereby making passive cooling of the PV components through natural convection a desirable and cost-effective means of overcoming both difficulties. A numerical model of heat transfer and fluid flow characteristics of natural convection of air is therefore undertaken so as to provide reliable information for the design of BIPV. A simplified numerical model is used to model the PVT collector so as to gain an understanding of the complex processes involved in cooling of integrated photovoltaic arrays in double-skin building surfaces. This work addresses the numerical simulation of a semi-transparent, ventilated PV façade designed for cooling in summer (by natural convection) and for heat recovery in winter (by mechanical ventilation). For both configurations, air in the cavity between the two building skins (photovoltaic façade and the primary building wall) is heated by transmission through transparent glazed sections, and by convective and radiative exchange. The system is simulated with the aid of a reduced-order multi-physics model adapted to a full scale arrangement operating under real conditions and developed for the TRNSYS software environment. Validation of the model and the subsequent simulation of a building-coupled system are then presented, which were undertaken using experimental data from the RESSOURCES project (ANR-PREBAT 2007). This step led, in the third chapter to the calculation of the heating and cooling needs of a simulated building and the investigation of impact of climatic variations on the system performance. The results have permitted finally to perform the exergy and exergoeconomic analysis

La croissance démographique rapide et l'industrialisation ont entraîné une augmentation significative de la demande énergétique à l'échelle mondiale, malgré une baisse de 1 % en 2020 due à la pandémie de COVID-19. Malgré les progrès réalisés dans le domaine des énergies renouvelables, les combustibles fossiles restent prédominants. Le secteur du bâtiment, troisième consommateur d'énergie, contribue largement aux émissions de CO2. Les systèmes de chauffage, ventilation et climatisation (HVAC) représentent 50 à 60 % de la consommation d'énergie. L'intégration de la technologie photovoltaïque (PV) dans les bâtiments via le BIPV ou le BAPV permet de réduire la demande énergétique et les émissions de CO2. Cependant, l'efficacité des cellules PV est limitée par la génération de chaleur, ce qui rend nécessaire des méthodes de refroidissement passif telles que la convection naturelle pour maintenir les performances et la durabilité. Des technologies passives telles que les doubles façades, les murs Trombe et les cheminées solaires utilisent l'énergie solaire pour améliorer la ventilation dans les bâtiments. En particulier, les cheminées solaires murales offrent un refroidissement et une ventilation efficaces. S'appuyant sur le projet NAMICO, une cheminée solaire murale intérieure attenante à une pièce a été fabriquée à l'échelle au LOCIE pour recueillir des données fiables sur les systèmes BIPV double façade connectés à l'espace habitable via une ouverture d'entrée horizontale.Cette thèse évalue un banc d'essai modulaire en établissant des protocoles et des critères expérimentaux. Est investigué l'effet de la position et de la taille des fenêtres sur les performances de la cheminée solaire et du système de ventilation de la pièce. Sont également étudiés les effets de l'émissivité de surface, (0,08 ou 0,96) et du flux de chaleur injecté depuis le mur d'entrée du canal en forme de L(110 W/m², 235 W/m²). Les performances thermiques et cinématiques du canal sont évaluées en analysant les données de température des parois et en effectuant des mesures PIV une fois que le banc d'essai de la cheminée a atteint un état quasi stable. Le flux d'air moyenné dans le temps est mesuré et visualisé en deux dimensions spatiales. L'effet de la position et de la taille de la fenêtre de la pièce sur la ventilation est évalué en mesurant la température de l'air et en traçant la circulation de l'air avec un générateur de fumée. Un modèle simplifié unidimensionnel (SHBM) a également été développé. Il est validé à l'aide de données expérimentales.En conclusion, la géométrie de l'entrée de la cheminée affecte le champ thermique et la topologie du flux dans le canal vertical. L'augmentation du flux de chaleur renforce le champ thermique sur les parois et le flux d'air dans la cheminée sur les parois à émissivité faible et élevée. Une émissivité de surface plus élevée améliore le transfert de chaleur radiatif de paroi à paroi, modifiant les profils thermiques des parois et les flux d'air en passant d'un chauffage à une paroi à un chauffage asymétrique du canal. Par conséquent, la température de la paroi chauffée diminue d'autant que la température de la paroi opposée, recevant le rayonnement, augmente. De plus, le débit volumique d'air sortant de la cheminée est calculé comme étant plus élevé aux parois de cheminée à ε = 0,96 par rapport à ε = 0,08 sous le même flux de chaleur. Les arêtes des murs de l'entrée créent des zones de recirculation, la taille de ces structures étant affectée par le flux de chaleur et l'émissivité. Il a également été étudié que la taille et le placement de la fenêtre sur le mur de la pièce n'ont aucun effet notable sur les performances de la cheminée mais influencent la distribution de la température. L'approche de modélisation développée aide à prédire la ventilation mais surestime les températures des parois de la cheminée<br>Rapid population growth and industrialization have led to a significant rise in energy demand globally, though a 1% drop occurred in 2020 due to the COVID-19 pandemic. Despite advancements in renewables, fossil fuels remain predominant. The building sector, ranking third in energy consumption, contributes heavily to CO2 emissions, with HVAC systems alone accounting for 50-60% of energy usage. Integrating photovoltaic (PV) technology into buildings via BIPV or BAPV offers a promising solution to reduce energy demand and CO2 emissions. However, the efficiency of PV cells is limited by heat generation, requiring passive cooling methods like natural convection, especially in BIPV systems, to maintain performance and longevity. Solar-assisted passive technologies like double-skin façades, Trombe walls, and solar chimneys utilize solar energy to enhance air ventilation in buildings. Among these, wall-mounted solar chimneys offer effective cooling and ventilation. Building upon NAMICO project, a unique indoor wall-mounted solar chimney with scaled-down room model have been fabricated at LOCIE for gathering reliable data on BIPV systems integrated on double-skin façade connected via horizontal inlet opening with the dwelling space.This doctoral research assesses a modular test bench in a lab setting, establishing protocols and criteria for experiments. The research explored the impact of window position and size on the performance of the solar chimney and room ventilation system. Experiments also investigate the effects of varying surface emissivity, set at either 0.08 or 0.96, and uniform heat flux injected solely from the inlet-forming wall of the L-shaped channel, at rates of 110 W/m² or 235 W/m². The top window of the room remains open while maintaining constant aspect and extension ratios of the channel. Thermal and kinematic performance of the L-shaped channel is assessed by analysing wall temperature data and conducting PIV measurements on whole channel once the solar chimney test rig reached quasi-steady state. The 2D time-averaged flow field within the channel was measured, and spatial flow structures were visualized. Additionally, the impact of room window placement and aperture size on ventilation was evaluated by measuring room air temperature and observing airflow patterns using a smoke generator. A simplified one-dimensional model, the Steady Heat Balance Model (SHBM), is also developed to predict the thermal and ventilation performance, validated using experimental data.it has been concluded chimney inlet geometry affects thermal field and flow topology in the vertical channel. Increasing heat flux boosts thermal field on walls and flow field within the chimney on both low and high emissive walls of the channel. Higher surface emissivity enhances wall-to-wall radiative heat transfer, altering wall thermal profiles and airflow patterns by modifying the thermal conditions from one-wall heating to asymmetrical of the channel. Consequently, the temperature of the heated wall decreases notably while the temperature of the opposing wall, receiving radiation, increases proportionally. Additionally, the volume airflow rate out of the chimney is computed to be higher at ε = 0.96 chimney walls compared to ε = 0.08 under the same heat flux. No reverse is observed at the outlet of the chimney even at low emissive walls of the channel. Sharp corners of the inlet create recirculation zones, the size of these structures are being affected by input heat flux and wall emissivity. It is also investigated that the size and placement of the window on room wall have no visible impact on chimney performance but influences room temperature distribution. Lastly, the modelling approach developed aids in predicting ventilation but overestimates chimney wall temperatures

Many attempts have been made to design buildings that reduce the heat gain inside the building. In hot-humid region, architects deal with many forces of nature. These forces might be Rain, Humidity, and solar heat gain. Thermal mass was been used for centuries in hot-arid region as a way to limit the dry-bulb temperature swing inside the building. However, there are some architects who agree that thermal mass materials could be used in hot-humid climate. This thesis project suggests using ventilated envelope that incorporates thermal mass in the design of the ventilated envelope. The result of the experiment shows that using ventilated envelopes with thermal mass would allow the heat gained in the cladding and in the thermal mass to be released to the air cavity and therefore releasing the heat from the building to the exterior atmosphere. The ventilated facade could be improved by adding thermal insulation and by using reflective materials on the cladding.

博士<br>國立成功大學<br>建築學系<br>88<br>The sustainability issues of recent studies are mainly focused on the energy preservation, environment protection, and economical development etc. One of the most beneficial senses is to utilize the natural driven forces to emphasize the air-exchange through the openings of the enclosure, and to reduce the dependence on utilizing the mechanical ventilation. This study, therefore, intends to develop the quantitative assess method as a tool during the design period to predict the naturally ventilated performances of rooms. Based on the literature review, numerical simulation was performed using CFD (Computational Fluid Dynamics) techniques. A full-scale bedroom Chamber was used in the experiments. Two types of windows were studied on the performances of different window positions and rotational angles. Our major findings were as below: 1. Close congruence with the experimental results shows the validity of numerical models. Those show CFD turbulence models in this study can act reasonably the role to predict the nature ventilation of buildings. 2. In the airflow of the forced convection, the standard k- model and the low-Reynolds number k- model are suitable, it, however, saves more calculated time using the standard k- model. In the airflow of the free convection, low-Reynolds number k- model performs more accurate, but a fine grid distribution near the wall boundary was necessary, and it took more calculated time. 3. In the seasons benefit the natural ventilation (spring & autumn), it is recommended utilizing cross-ventilation induced from the wind-pressure difference across the bedroom. For the bedroom-unit cases, wind-induced airflow was suitable for all of the window positions at the inlet wind-speed below 1 m/s. It was to avoid the window positions caused the mainstream through the head zone at the speed about 3 m/s. And, it was caused violently uncomfortable flow across the head zone as the air-draft effect for all of the window positions at the speed above 5 m/s. 4. In the seasons unfavorable for natural ventilation, especially in winter, it is used to close the door to keep warm in the sleeping nighttime. The single-sided ventilation, however, was harmful to provide convection. One of the solution is to utilize the central horizontal pivot window to introduce airflow into bedroom. For the bedroom-unit cases, when the window angle at 0-90°(cosθ>0), the airflow path induced from wind was against from stack, the ventilation efficiency at outdoor wind-speed UE = 0 m/s was more obvious than which at the slight wind-speed (UE = 0.3-0.5 m/s), the wind force, furthermore, become the major influence at wind-speed above 0.5 m/s. When the angle at 90-180°(cosθ<0), the airflow path induced from wind was overlapped from stack, the ventilation efficiency was greater accompanied the greater wind-speed.

Echocardiography is the most clinically practical method of visualizing cardiac structures and directly observing changes of cardiac function during the respiratory cycle. This chapter will review heart–lung interactions and will focus on the effects of intrathoracic pressure variation on cardiac function that can be measured with advanced critical care echocardiography. These measurements are derived from observing respirophasic variation of stroke volume (SV) and help the intensivist to guide management of haemodynamic failure. The heart–lung interactions that occur with changes in intrathoracic pressure variation have utility in identification of preload sensitivity and adverse patient ventilator interaction. Measurement of the systolic velocity envelope with pulsed-wave Doppler is a requisite skill in order to identify SV variation, as is the recognition that the measurements may be difficult with transthoracic echocardiography.

This chapter deals with the analysis of the potential offered by the integration of smart solutions in dynamic glass façades to improve buildings’ energy performances. Dynamic solutions are here examined with reference to dry ventilated systems, active and passive cooling, solar gain, greenhouse effect, and technologies able to react and self-regulate, according to the environmental inputs. The first part is dedicated to the state of knowledge, assessing the performance evolution of dynamic and interactive architectural envelopes (smart skins). Then, the core of the chapter is divided into clusters according to different strategies that allow the building skin to react and self-regulate according to the environmental inputs: double-layer glass façades, solar shadings, PV integration, etc. The goal is to produce a sort of “smart skin guideline” divided by requirements/strategies of intervention to investigate a range of solutions able to regulate buildings’ behavior and characterize their image: from systems that allow to transform solar gain into heat to improve buildings’ energy performance in winter season, to others that integrate passive cooling, to systems that transform the façades in a real active element of energy production, thanks to the integration of renewable energy sources.

Using brick-concrete for building envelope is a common practice in India. These envelopes have high heat gains and experience large embodied energy. Agro-waste panels made up of sugarcane waste can significantly reduce cooling load for new construction due to its better u-value and also reduce carbon emission since it is produced from sugarcane waste, i.e., bagasse. A double storey naturally ventilated building has been simulated for Mumbai climatic conditions to understand the performance of agro-waste materials. The total cooling load and temperature profile for a year have been simulated using EnergyPlus software. Thermal comfort hours are calculated using the India model for adaptive comfort (IMAC) band to show the potential of the agro-based panel. The thermal cooling load of the simulated building incorporated with an agro-waste panel decreased by 28 % as compared to the brick-concrete envelope. There is a 16.4 % increase in annual thermal comfort hours compared to brick-concrete envelope.

In recent years, the adaptive model of thermal comfort has gained traction as a more robust alternative to fixed set-point-driven design, which considers various factors that impact human comfort, such as humidity, air velocity, mean radiant temperature, and ambient temperature. Nonetheless, it is crucial to recognize the limitations of such models and the potential for discomfort and stress. This research employs simulations to systematically evaluate WBGT as a parameter to measure heat stress in residential buildings in Bhubaneshwar, India, comparing ventilation scenarios. The study assesses three building envelope materials: Conventional (RCC and Brick) and Innovative (EPS Core). The ECBC-R standard and a dynamic method derived from regression analysis predicts heat stress, analysing natural ventilation in residential units using the IMAC-R and ISO 7243 benchmark. Heat stress profoundly affects well-being in hot climates. With the rise of energy-efficient, naturally ventilated buildings, understanding their impact on heat stress is crucial. This is particularly significant in countries like India that are grappling with climate change induced heat waves. The study focuses on the factor of heat stress in adaptive thermal comfort models, emphasizing the need for a more holistic approach to indoor comfort factors. Insights gained can lead to improved strategies for optimal thermal comfort and reduced heat stress risks, vital for occupant health. Indoor WBGT ranged from 16°C to 33°C for various envelopes, averaging 28°C (RCC), 24°C (Brick), and 22°C (EPS). Indoor air velocity of 0.9-1.8 m/s lowered WBGT by 0.15°C or 0.27°C annually. Discomfort hours were ~5,000 (RCC), 3,600 (Brick), and 3,200 (EPS), peaking in May-June at 40°C outdoor DBT. Proper insulation and ventilation are crucial for comfort and heat stress reduction. By considering diverse factors affecting indoor comfort, it offers insights to create safe and comfortable indoor environments, especially in regions prone to heat stress. The findings advocate a balanced approach that combines effective insulation and ventilation strategies for optimal occupant well-being.

This paper studies the real case of natural ventilated space with a convective/radiative heat source and non-adiabatic envelope. The real envelope and heat source are introduced into the ‘Emptying Filling Box’ model and then contribute to achieve a new developed one, Thermal and air Flow Natural Ventilation model. TFNV model combines the thermal and fluid mechanical characteristics of displacement natural ventilation. Two vertical zones of different temperature are divided as that in EFB model. But temperature in the lower zone is higher than outdoor. With TFNV model, natural ventilation parameters can be reasonably predicted — interface height, ventilation airflow rate, occupied zone temperature, etc. By comparison of the results of the two models, it is shown that EFB model underestimates the interface height as well as air temperature in the lower zone and overestimates the temperature difference between the upper and lower zone of the space. It is also observed that EFB model may improperly predict the ventilation airflow rate and ventilation load.

Several sour gas leakage accidents have occurred in the offshore platform during the past decades, such as the Kab 121 platform in 2007, which caused serious consequences mainly resulting from the lethal toxicity of hydrogen sulfide (H2S). Under the threat of H2S, it is a challenge to exploit resource in the sour gas filed. Especially during the drilling operation, an abrupt blowout or kick could bring huge amount of H2S, envelop the platform and disperse in the cabins. The present paper is aimed at introducing our analysis of H2S dispersion both in the outer deck and inner mud treatment cabin so as to fully assess the potential poisoning during well blowout. The method we chosen was computational fluid dynamics according to the spatial environment characteristics of the offshore platform. First, we drew a comparison between accident consequences deriving from the wellhead configurations of an opened bell nipple and a sealed rotary blowout preventer (BOP) in the outer deck under various wind directions and speeds. The instantaneous concentrations and hazard zone distributions show that the second configuration is much better from the view of accident control. And the accident severity is much lower when the wind blows from the larboard, not from the prow for both configurations. As a result, the potential hazard zone would not envelop the entire platform with suitable platform position and arrangements of the mud return ditch, accommodation, helicopter deck et al. Then, the simulations of H2S dispersion in the mud treatment cabin were conducted in case of the closed outlet doors, opened outlet doors and sealed cabin with air ventilator working. An immediately dangerous to life level may come up in a short break with the door closed. In such a dangerous situation, H2S can only be made to disperse to other areas through the opened door or effectively ventilated away by means of a ventilator. It is a good practice to isolate the cabins with the potential H2S leakage and install ventilator. And a simple model was proposed to calculate the working time for the ventilator.

The world's climate, natural systems, and public health are all negatively affected by conventional building materials and construction methods. Buildings are highly resource-intensive, resulting in over exploitation of raw materials. The evolution and use of alternative building components to improve thermal performance has witnessed an increasing trend due to the growing awareness of energy efficiency and sustainable building techniques worldwide. This research paper focuses on a comprehensive assessment and evaluation of alternative wall and roof assemblies, such as natural materials, biomaterials, and salvaged materials. A wide range of alternative materials for the wall and roof assemblies were chosen for a residential building in Vijayawada based on their availability, featuring diverse combinations of insulation materials, thermal masses, and cladding options. Detailed modelling of heat transfer processes within the building envelope, including conduction, convection, and radiation, analysis is possible with software, while accounting for external weather conditions. The U-value, Time lag, decrement factor and heat gain / loss of the assembly were assessed through Opaque 3.0, developed by the Society of Building Science Educators (SBSE). A comparative analysis of alternate materials with conventional materials in the field of construction was performed to improve thermal performance for indoor occupant comfort to reduce energy consumption in a naturally ventilated residential building in Vijayawada. Further, suitable wall and roof assemblies based on their compliance with ECBC (Energy Conservation Building Code) standards were identified. The findings offer useful information on how different wall and roof systems perform in comparison to the conventional materials. Straw bale with mud and lime plaster of U-value of 0.17 W/m2.K performs best with a time lag of 9.9 hr among the various alternatives analyzed. Similarly, Mangalore tile with Palymra beam, which has an inclination of 45°, performs best comparatively, with a lowest U-value of 2.2 W/m2.K and a time lag of 11 hours. It provides insight into the efficiency of advanced methods of construction in improving interior comfort, lowering energy use, and developing sustainable building design. In order to satisfy the demands of a continuously changing and energy-conscious built environment, the outcomes of this study provide architects, engineers, and policymakers with invaluable insights into the selection of suitable building assemblies.

One of the most important requirements for building performance is energy saving and recovering and they are chased developing new strategies for the reduction of energy consumption, due to the heat flux transmitted through buildings envelopes. This work examines a prototypal ventilated roof numerically using a two-dimensional model in Ansys Fluent. Only a single flap of the roof is analyzed because its structure is geometrically and thermally symmetrical. The objective of this work is to study the thermal and fluid dynamic behaviors of a ventilated roof for different configurations of the exit section of the ventilated channel. The model is evaluated in air flow, considering a k-ε turbulence model to give the governing equations. Results are a function of an assigned heat flux on the top wall of the ventilation layer. They are analyzed studying temperature and air velocity distributions. The profiles of wall temperature and air velocity along the cross sections and longitudinal sections of the ventilated layer consider the different effects of the various geometric configurations. The results for different considering configuration detect that the ridge form and the outlet reservoir dimensions do not influence the thermal behavior inside the channel whereas a smaller outlet section determines higher wall temperature and lower air velocity in the channel.

Double skin facades (DSFs) are building envelopes comprised of two glass facades, a ventilated air cavity and shading devices placed within the cavity. In this paper airflow and heat transfer simulation was conducted for a DSF system equipped with a venetian blind using computational fluid dynamics (CFD) with RNG turbulence model. Simulation was done for a three-level combination of slat tilt angle and blind position. The heat transfer coefficient was directly obtained from CFD simulation. The CFD prediction was validated using experimental data collected for a mechanically ventilated DSF (1.6 m wide and 2.5 m high and 0.15 m wide cavity) equipped with venetian blinds. The present study indicates that the presence of venetian blinds influences the surface heat transfer coefficients (SHTCs), the temperature and the air distribution in the DSF system. Specifically, for the cases considered, the position of the blinds is more important than the slat angles.

A ventilated supercavity consists of a large gas-filled bubble enveloped around an underwater vehicle that allows for significant drag reduction and an increase in maximum vehicle speed. Previous studies at the Saint Anthony Falls Laboratory (SAFL) of the University of Minnesota focused on the behavior of ventilated supercavities in steady horizontal flows. In open waters, vehicles can encounter unsteady flows, especially when traveling near the surface, under waves. In supercavitation technology, it is critical that the vehicle remains within the cavity while traveling through water to avoid unwanted planing forces. A study has been carried out in the high speed water tunnel to investigate the effects of unsteady flow on axisymmetric, ventilated supercavities. An attempt is made to duplicate sea states seen in open waters. In an effort to track cavity dimensions throughout a wave cycle, an automated cavity tracking script has been developed. Using a high speed camera and the proper software, it is possible to synchronize cavity dimensions with pressure measurements taken inside the cavity. Results regarding supercavity appearance, cavitation parameters and their relation to sea state conditions are presented. It was found that flow unsteadiness caused a decrease in the overall length of the supercavity while having only a minimal effect on the maximum diameter.