Dissertations / Theses on the topic 'Natural ventilation'
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Kenton, Amanda Gail. "Natural ventilation in theatre design." Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/252011.
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Li, Rong. "Natural ventilation of atrium spaces." Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/6112/.
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This research is aimed to develop a series of design guidelines and relevant prediction tools for the incorporation of natural ventilation in atrium spaces as a passive cooling strategy. Focused on the geometrical and thermal characteristics of atrium buildings, four issues related to this purpose are investigated in this work including thermal comfort, wind-induced ventilation, buoyancy-induced ventilation and combined buoyancy and wind driven ventilation: In order to identify when passive cooling strategies are needed for atrium spaces, a new thermal comfort assessment method which enables the treatment of the solar radiation and non-uniform environment is developed using M.ATLAB as the data exchange platform. It is found that high mean radiant temperature (MRT) can be a more significant factor contributing to the thermal discomfort of the space when the internal occupants' level is irradiated by the sun rays. It is also shown that the air temperature at the occupants' level is mostly affected by the temperatures of the surfaces at lower levels and the temperatures at the roof level and the upper areas generally have little influence on the air temperature at the occupants' level. The study of wind-induced ventilation is concerned with the airflow through roof openings since the atrium is' often placed in the centre of a building and· as a result the openings at lower levels are not available. In this way the air movement in the space is actually driven by the recirculation rather than the direct main flow from the wind. Three. possible flow patterns, and related controlling forces for each flow pattern are defined first, based on which the impacts of the design parameters on the ventilation performance are investigated by CFD techniques and design guidelines are developed accordingly. The effects of the location of heat source and the control of the neutral level when bidirectional flow occurs are studied for buoyancy-driven natural ventilation of atrium spaces. The tendency of the heat source efficiency with the variation of. its location is examined and the optimised location for the heat source is suggested, based on which the guidelines for the selection of materials for the atrium internal surfaces are made. A series of new' algorithms are also developed for the prediction of neutral level when bi-directional flows occur and validated with CFD simulations. The investigation of the combined ventilation focuses on the condition where wind forces and buoyancy forces partly assist each other and partly oppose each other, and it is found that the phenomenon of solution multiplicity still exists for this condition and different solutions may have different ventilation performance depending on the initial conditions.
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Chen, Shaw-Bing. "Natural ventilation generates building form." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/65048.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1996.Includes bibliographical references (leaves 149-151).
Natural ventilation is an efficient design strategy for thermal comfort in hot and humid climates. The building forms can generate different pressures and temperatures to induce natural ventilation. This thesis develops a methodology that uses a computational fluid dynamics (CFD) program. The purpose of the CFD program is to assist architects to design optimum building form for natural ventilation. The design of a cottage in Miami, Florida demonstrates the application of this methodology. The first phase of this methodology is to create an input file for the CFD program. The input file uses wind velocity, wind direction, and air temperature of the site to simulate the weather. Different weather conditions can be generated through modification of the first input file. The second phase of this methodology is to develop building forms. The CFD programs can simulate airflow in different building forms by changing the building geometry in the input files. The program calculates the airflow pattern, velocity, and temperature for different forms. The printouts of the simulations allow architects to understand the airflow behavior in spaces with different forms. This thesis also uses the CFD program to study variance between the proposed and the actual results of a design. As demonstrated in a sports museum in Washington, DC, this case study clearly displays a difference between the intentions of the architect and the results of CFD calculation. Some problems appear in developing CFD models. However, when the input files are correctly defined, and the calculations converge, very few computational problems appear in developing building forms. Therefore, architects can easily use the CFD programs to develop building form after the input files are correctly defined.
by Shaw-Bing Chen.
M.S.
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Vad-Schütt, Klockervold Beatrice. "Natural ventilation and behavioural differences." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192156.
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To open a window can feel natural when experiencing frowsty air, a high room temperature, or stuffiness. Regardless of the purpose of the natural ventilation, heat is being let out and thereby energy. The problem with this arises for instance when planning new real estate constructions when ventilation of this kind is an individual behaviour dependent factor, and thereby impossible to exactly predetermine. Today, a relatively unevaluated standard value is used for annual energy losses at 4 kWh/m2, but considering that these losses are hard to measure it is uncertain how well this number matches reality. Besides, the natural ventilation behaviour and the use of energy differs from household to household. The purpose was to examine the average natural ventilation behaviour in households, whether some groups of people ventilate more than others, which the reasons of ventilating are, how large effect one person’s ventilation behaviour can have on his or hers neighbours, and also how the needs of ventilation and the amount of used energy will look in the future. To answer this a thorough literature study, a couple of preparing interviews for the survey template, a survey about ventilating behaviour, and a simple example calculation about heat transferring through partition walls was done. Important results obtained from this is that: · Natural ventilation behaviour depend on both age and property. · Older age groups ventilate more than younger. People between 30-50 years ventilate half as much as people between 30-50 years and a third as much as people over 50.People between 50-70 years and older ventilate approximately equally. · People living in buildings of 10-50 m2 and over 100 m2 ventilate approximately equally while people in buildings of 50-100 m2 ventilate 35% more. · Detached houses and apartments are naturally ventilated as often but apartments are ventilated more than an hour longer each session, which results in that apartments are ventilated 50 % more. · 71 % of all people does not shut off their heating sources during natural ventilation. · Frowsty air represents 47 %, high room temperatures represents 35 % and the want to get closer to the outside nature in any way represents 14 % of the reasons for ventilating. · Heat conduction from one apartment to another due to natural ventilation costs at the most 37,23 SEK a year. In the long run the results from this survey with more additional and extensive examinations, could lead to more accurate standard values used in energy calculations for new constructions. Depending on property and probable age of future inhabitants less uncertain calculations could be made. Studies and analyses was limited to Nordic climate and especially to the second and third climate zones of Sweden. The main reason for this was that the participants of the survey and interviews resided in this area. Beside this, the only properties which has been analysed are residences and therefore not office buildings or other real estate’s not resided by people.”Att öppna ett fönster” kan kännas naturligt vid upplevd dålig luft, för hög temperatur eller instängdhet. Men oavsett vad orsaken för vädring är så släpps värme ut och därmed energi vilket ger problem bland annat vid planering av byggnationer av nya fastigheter. Detta då vädring av detta slag är en individuell beteendeberoende faktor och därmed omöjlig att exakt förutbestämma. Idag används ett relativt outvärderat standardvärde från Boverket för energiförluster på 4 kWh/m2 per år men då dessa förluster är ytterst svåra att mäta är det oklart hur väl siffran stämmer överens med verkligheten. Dessutom skiljer sig vädringsbeteendet och energianvändningen åt från hushåll till hushåll. Syftet var att undersöka hur mycket bostäder vädras i genomsnitt, om vissa grupper av människor vädrar mer än andra, vad orsakerna till vädring är, vilken effekt en människas vädringsbeteende kan ha på intilliggande bostäders energianvändning, samt hur vädringsbehovet och mängden använd energi kommer se ut i framtiden. För att besvara detta gjordes en grundlig litteraturundersökning, ett antal intervjuer som förberedelse för en enkätmall, en enkätundersökning om vädringsbeteende, samt en enkel exempelberäkning om värmeöverföring från en bostad till en annan. Viktiga resultat som erhållits är att: · Vädringsbeteende beror av både ålder på de boende samt bostadstyp. · Äldre åldersgrupper vädrar i genomsnitt mer än yngre. Personer mellan 18- 30 år vädrar hälften så mycket som personer mellan 30-50 år och en tredjedel så mycket som personer över 50 år. Personer mellan 50-70 år och äldre vädrar ungefär lika mycket. · Personer i bostäder på 10-50 m2 och över 100 m2 vädrar ungefär lika mycket medan personer i bostäder på 50-100 m2 vädrar 35 % mer. · Friliggande villor och lägenheter vädras lika ofta men lägenheter vädras över en timme längre per vädringstillfälle vilket för den totala vädringstiden betyder att lägenheter vädras 50 % mer än villor. · 71 % i genomsnitt stänger inte av sina värmekällor under vädring. · Dålig luft, för höga inomhustemperaturer, och vilja att komma närmare naturen på något sätt står för 47 %, 35 % respektive 14 % av vädring. · Värmeöverföring från en lägenhet till en annan till följd av vädring kostar i extremfall max 37,23 kr per år. I det långa loppet kan resultatet från denna undersökning med fler kompletterande och omfattande sådana medföra mer korrekta standardvärden i energiberäkningar för nybyggnationer. Beroende på bostadstyp och trolig ålder för framtida inneboenden skulle mer riktiga beräkningar kunna göras. Undersökningar och analyser avgränsades till Nordiskt klimat och då främst till Sveriges 2a och 3e klimatzon. Orsaken till detta var främst att de tillfrågade i enkäten och intervjuerna var bosatta i detta område. Dessutom har endast bostäder analyserats och därmed exempelvis inte kontorshus eller andra fastigheter som inte innehar sådana.
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Pálsson, Daði Snær. "Hybrid Ventilation : Simulation of Natural Airflow in a Hybrid Ventilation System." Thesis, KTH, Installations- och energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146761.
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This thesis investigates the possibilities of using hybrid ventilation in an office building in Stockholm. The focus is on simulating the natural airflow to find out for which conditions it is sufficient. The thesis is done at White Arkitekter AB in cooperation and under the supervision of environmental specialists working there. A literature study is carried out to study what has been done before in Sweden as well as in other countries. Computer simulations are used to simulate the airflow to examine the conditions and architecture. A synthetic computer model representing a realistic office building is built up as a starting point. The ventilation method for the natural ventilation part is to take air in through the fa\c{c}ade and use the stack effects in an atrium for natural ventilation. By altering the architecture and the sizes of the openings according to the results from the simulations the building is dimensioned and formed to cope with the rules and requirements about the indoor air quality in workplaces. The simulations are done with a multi zone energy performance simulation tool that can simulate airflows and indoor air climate conditions in the zones as well as the energy consumption. Computational fluid dynamics calculations are then used to more closely simulate the conditions within the zones. The results from those simulations suggest that the natural ventilation as a part of a hybrid ventilation works for all the floors of the building for up to 10$\,^{\circ}\mathrm{C}$. The computational fluid dynamics simulations showed that the thermal comfort of all the occupants is fulfilled for these conditions but there is a risk of occupants experiencing draught because of to high velocities in the air especially for the colder outdoor temperatures. For the higher outdoor temperatures the airflow needs to be enforced to ensure sufficient conditions for the occupants and for the colder temperatures mechanical ventilation is needed to decrease heat losses and avoid the risk of draught.
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Wang, Bo. "Unsteady wind effects on natural ventilation." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11653/.
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Ventilation stacks are becoming increasingly common in the design of naturally ventilated buildings. The overall aim of the work described is ultimately to improve design procedures for such buildings. This thesis presents the experimental and theoretical investigation of unsteady wind effects on natural ventilation of a single envelope with multiple openings for both wind alone, and wind and buoyancy combined cases. There are two types of openings: namely the sharp-edged orifice and the long opening (stacks being treated as long openings). Two methods are adopted: 1) direct wind tunnel measurements using the hot-wire technique; 2) theoretical analysis using steady and unsteady envelope flow models. For the wind alone experiments, the influences of wind speed, wind direction and opening configuration on flow patterns are studied. For the wind and buoyancy combined tests, the transitional process between wind dominated and buoyancy dominated states are investigated. The direct velocity measurements provide the criteria for testing the validity of the theoretical models, and ways to improve them. Additionally, improvements are made to the experimental techniques: e.g. a precise unsteady calibration method of the hot-wire is developed; improvements of pressure measurements are also investigated. The experimental technique works well with multiple stacks. Even though small openings are used, some dependence of the mean pressure coefficient on opening configuration is observed. The theoretical models also work reasonably well with multiple stacks, yet it is observed that the accuracy of the theoretical models decrease with the increasing number of openings, and is sensitive to the chosen discharge coefficient which defines the characteristics of ventilation openings.
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Livermore, Stephen Richard. "Aspects of buoyancy-driven natural ventilation." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612789.
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BELLERI, Annamaria. "Integrated design methods for natural ventilation." Doctoral thesis, Università degli studi di Bergamo, 2014. http://hdl.handle.net/10446/30436.
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Natural ventilation is widely applied to new building design as it is an effective passive measure to reach the Net Zero Energy target. However, the lack of modelling guidelines and integrated design procedures that include technology solutions using passive design strategies to exploit climate potential, frustrate building designers who prefer to rely on mechanical systems.
Within the existing natural ventilation modelling techniques, airflow network models seem the most promising tool to support the natural ventilation design as they are coupled with the most widely used building energy simulation tools. This PhD work provides methods to integrate natural ventilation in the whole building design and to improve natural ventilation predictability overcoming some of the barriers to its usage during early-design-stages, such as model zoning, input data estimation, model reliability and results uncertainty.
A sensitivity analysis on parameters characterizing different natural ventilation strategies has been performed on a reference office building model considering key design parameters that cannot be clearly specified during early-design-stages. The results underline the most important parameters and their effect on natural ventilation strategies in different climate types.
The airflow network modelling reliability at early stage design phases has been tested by comparing early-design-stage model results with output results from a detailed model as well as with measured data of an existing naturally ventilated building.
Results underline the importance of an optimized control strategy and the need of occupant behaviour studies to define better window opening control algorithms to be included in building dynamic simulation tools. Early-design-stage modelling caused an overestimation of natural ventilation performances mainly due to the window opening control standard object implemented in building dynamic simulation tools, which assume all the windows within the same zone are operated at the same way.
With sufficient input data (identify in the research work), airflow network models coupled with building energy simulation tools can provide reliable informative predictions of natural ventilation performance.
Finally, natural ventilation design guidelines are proposed to explain how existing design tools and methods can be applied within the whole design process, taking into account technology solutions for triggering the natural ventilation.
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BELLERI, Annamaria. "Integrated design methods for natural ventilation." Doctoral thesis, Università degli studi di Bergamo, 2014. http://hdl.handle.net/10446/222111.
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Natural ventilation is widely applied to new building design as it is an effective passive measure to reach the Net Zero Energy target. However, the lack of modelling guidelines and integrated design procedures that include technology solutions using passive design strategies to exploit climate potential, frustrate building designers who prefer to rely on mechanical systems. Within the existing natural ventilation modelling techniques, airflow network models seem the most promising tool to support the natural ventilation design as they are coupled with the most widely used building energy simulation tools. This PhD work provides methods to integrate natural ventilation in the whole building design and to improve natural ventilation predictability overcoming some of the barriers to its usage during early-design-stages, such as model zoning, input data estimation, model reliability and results uncertainty. A sensitivity analysis on parameters characterizing different natural ventilation strategies has been performed on a reference office building model considering key design parameters that cannot be clearly specified during early-design-stages. The results underline the most important parameters and their effect on natural ventilation strategies in different climate types. The airflow network modelling reliability at early stage design phases has been tested by comparing early-design-stage model results with output results from a detailed model as well as with measured data of an existing naturally ventilated building. Results underline the importance of an optimized control strategy and the need of occupant behaviour studies to define better window opening control algorithms to be included in building dynamic simulation tools. Early-design-stage modelling caused an overestimation of natural ventilation performances mainly due to the window opening control standard object implemented in building dynamic simulation tools, which assume all the windows within the same zone are operated at the same way. With sufficient input data (identify in the research work), airflow network models coupled with building energy simulation tools can provide reliable informative predictions of natural ventilation performance. Finally, natural ventilation design guidelines are proposed to explain how existing design tools and methods can be applied within the whole design process, taking into account technology solutions for triggering the natural ventilation.
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Jerräng, Carlstedt Ludwig. "A comparison between emergency ventilation systems semi-transvers ventilation and natural ventilation in Road Tunnel A." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65671.
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Jones, Benjamin Michael. "Quantifying the performance of natural ventilation windcatchers." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4713.
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The significant energy consumption of non- domestic buildings has led to renewed interest in natural ventilation strategies that utilise the action of the wind, and the buoyancy of hot air. One natural ventilation element is the Windcatcher, a roof mounted device that works by channelling air into a room under the action of wind pressure, whilst simultaneously drawing air out of the room by virtue of a low pressure region created downstream of the element. A significant number of Windcatchers are fitted in UK schools where good indoor air quality is essential for the health and performance of children. The performance of a ventilation system in a school classroom is determined by its ability to provide ventilation in accordance with UK government ventilation, air quality, and acoustic requirements. However, there is only limited performance data available for a Windcatcher, particularly when operating in-situ. Accordingly, this thesis investigates the performance of a Windcatcher in three ways: First, a semi-empirical model is developed that combines an envelope flow model with existing experimental data. Second, measurements of air temperature, relative humidity, carbon dioxide, and noise levels in school classrooms are assessed over summer and winter months and the results compared against UK Government requirements. Finally, air flow rates are measured in twenty four classrooms and compared against the semi-empirical predictions. The monitoring reveals that air quality in classrooms ventilated by a Windcatcher has the potential to be better than that reported for conventional natural ventilation strategies such as windows. Furthermore, an autonomous Windcatcher is shown to deliver the minimum ventilation rates specified by the UK Government, and when combined with open windows a Windcatcher is also capable of providing the required mean and purge ventilation rates. These findings are then used to develop an algorithm that will size a Windcatcher for a particular application, as well as helping to improve the ventilation strategy for a building that employs a Windcatcher.
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Syrios, Konstantinos. "Natural ventilation of buildings in urban canyons." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420637.
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Harrington, Liam. "Computer modelling of night-time natural ventilation." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/7535.
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Wind-induced ventilation has the potential to reduce cooling energy use in buildings. One method this can be achieved is by the use of night-time ventilation to cool down the structure of a building, resulting in lower air and radiant temperatures during the day. To design effective naturally ventilated buildings, evaluation tools are needed that are able to assess the performance of a building. The primary goal of this work was to develop such a tool, that is suitable for use in annual building energy simulation. The model presented, is intermediate in complexity between a CFD numerical model and current single air node models, having seven nodes. The thesis describes how numerical and experimental data have been used to develop the structure and define the parameters of the simplified nodal model. Numerical calculations of the flow and temperature fields have been made with a coupled flow and radiant exchange CFD code. Numerically derived velocity dependent convective heat transfer coefficients are compared with experimental measurements made in room ventilated by cross-flow means, and with empirical correlations cited by other studies. Bulk convection between the air nodes of the simplified nodal model has been derived from a numerical study of contaminant dispersal. The performance of the model is demonstrated by making comparisons with the predictions of a single air node model.
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Simango, D. G. "Simulation of natural ventilation for livestock structures." Thesis, University of Aberdeen, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293987.
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Pig production in Malawi and in most of the developing countries is shifting increasingly from pasture or dirt lot to total confinement with improved housing facilities. Keeping pig level temperatures within the comfort zone in hot weather is a common problem in naturally ventilated intensive pig buildings. Automatically controlled natural ventilation (ACNV) has proved to be effective in reducing the problem of heat build up in pig houses and is becoming very popular. However, a method for reducing summer temperatures at animal level in non-automated naturally ventilated intensive pig buildings has not been developed. An attempt was made to develop a natural ventilation system which would maximise the cooling effect of wind at animal level by manual control in buildings suitable for the Tropics. The research project was conducted in three stages: (1) air flow pattern studies, using 1:20 scale two-dimensional models, (2) wind tunnel testing, using three-dimensional, 1:20 scale models with simulated pigs, and (3) validation of results from the wind tunnel studies made with a 1:4 scale model, put out in the field. Air deflectors were used as a means of increasing the effect of wind on the ventilation pattern in the models. Monopitch, duopitch and offest gable models were tested in the water table, and monopitch models were tested in the wind tunnel. The use of air deflectors in monopitch and offset gable models showed a marked increase in airflow towards the animal zone area and a reduction in the difference between the surface temperature of the model pigs and the outside air temperatures. The deflectors improved the performance of the models by about 10% with the front orientation and about 20% with the rear orientation. In the duopitch model an increase in the roof overhang improved flow circulation on the leeward side. The use of air deflectors also improved flow circulation on the leeward side. The wind speed and air temperature at the experimental site for the 1:4 scale model were used to validate the results from the wind tunnel tests. The measured temperature values showed similar response curves to the predicted values. Temperature differentials increased with an increase in the angle of the deflector.
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Partridge, Jamie Lee. "Natural ventilation : competing sources and background turbulence." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709122.
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Coomaraswamy, Imran Ajay. "Natural ventilation of buildings : time-dependent phenomena." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609863.
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Leung, Hugh, and 梁修賢. "Analysis of natural and hybrid ventilation in simple buildings." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26663107.
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Clark, Craig. "Use of hybrid ventilation techniques for improved energy efficiency of fan systems." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33962.
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The goal of this thesis was to improve the energy efficiency of building ventilation systems by exploring new methods of applying natural ventilation concepts. Strictly natural systems have limitations in which climates they can function or can provide optimal performance; these limitations lead to the use of mechanical or hybrid ventilation. This study looked at methods of combining the operation of the systems, such that the natural components improve the efficiency of the mechanical system.
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Elmualim, Abbas Ali. "Evaluating the performance of windcatchers for natural ventilation." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398291.
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Ip, Kiun Chong Karine. "Natural ventilation in buildings : modeling, control and optimization." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93829.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 192-195).
Natural ventilation in buildings has the potential to reduce the energy consumption usually associated with mechanical cooling while maintaining thermal comfort and air quality. It is important to know how building parameters, in particular its thermal mass properties and heat loads incurred, affect a building's transient thermal response to incoming outdoor air. A proper ventilation schedule is also needed to make optimal use of the free direct or night cooling. To investigate these factors, a first principles heat transfer energy model is developed to numerically simulate in MATLAB the air temperature profile of a single-zone cross-ventilated room. The physics behind natural ventilation at building level is also investigated using multi-zone modeling, as done in CoolVent, an existing MIT airflow modeling tool. In the process, the simulation capabilities of MIT Design Advisor, an existing building energy simulation tool, are expanded upon from shoe-box to interconnected multi-zone modeling. Optimal natural ventilation scheduling, with a view to maximizing thermal comfort, is then studied using two optimization techniques: dynamic programming and global search optimization, using the simple room energy model as the simulation engine. In the process, an algorithm framework is developed to optimize the ventilation scheduling on a rolling day-horizon basis based on input weather data and occupancy schedule. The use of rule-based control, as opposed to the aforementioned model-optimized control, is also explored due to its ease of implementation in building automation software. The former form of control is found to maintain comparable thermal comfort when separate rules for specific scenarios, such as night-overcooling or day-overheating, are gathered together to constrain the room air temperature. It is however critical to identify and calculate proper set-points for these rules.
by Karine Ip Kiun Chong.
S.M.
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Hamilton, Sephir D. (Sephir David) 1977. "Designing aero-acoustic wall openings for natural ventilation." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/88900.
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Tantasavasdi, Chalermwat 1971. "Natural ventilation : design for suburban houses in Thailand." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/70306.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1998.Includes bibliographical references (p. 93-95).
Natural Ventilation is the most effective passive cooling design strategy for architecture in hot and humid climates. In Thailand, natural ventilation has been the most essential element in the vernacular architecture such as the traditional house, but has become unused nowadays because of the urbanized conditions in big cities like Bangkok. This thesis explores the potential of using natural ventilation for modern houses by using a Computational Fluid Dynamics (CFD) program. The research investigates the characteristics of Thai houses from the past to the present that climate, culture and technology have influenced. The analysis of the climate data concludes that natural ventilation can be used approximately four months a year to create conditions within the zone of thermal comfort. In a suburban housing project, site planning has a significant impact on the wind pattern and velocity. The simulation results indicate that the wind has better characteristics in the houses with square shapes than those with rectangular shapes. The vegetation around the houses also has some effect on the wind by slightly reducing its speed. Lastly, the prevailing winds from the north and north-northeast have similar wind patterns in a large housing project. The final stage is to design a prototype by using some climatic characteristics from the traditional Thai house. The air movement is inadequate in a house with regular size windows. Therefore, the study tests three more cases with larger windows. The results demonstrate that the maximum size window provides better thermal comfort. Finally, the study finds that the stack effect is negligible. The study shows the possibility to use natural ventilation for the houses in this region. The investigation has developed comprehensive design guidelines for architects. Necessary further research is presented in the end to find more solutions for climate-responsive architecture in today's physical conditions.
by Chalermwat Tantasavasdi.
M.S.
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Chenvidyakarn, Torwong. "The fluid mechanics of pre-cooled natural ventilation." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614695.
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Adamu, Zulfikar A. "The feasibility of natural ventilation in healthcare buildings." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12600.
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Wards occupy significant proportions of hospital floor areas and due to their constant use, represent a worthwhile focus of study. Single-bed wards are specifically of interest owing to the isolation aspect they bring to infection control, including airborne pathogens, but threats posed by airborne pandemics and family-involvement in hospital care means cross-infection is still a potential problem. In its natural mode, ventilation driven by combined wind and buoyancy forces can lead to energy savings and achieve thermal comfort and high air change rates through secure openings. These are advantageous for controlling indoor airborne pathogens and external air and noise pollution. However, there is lack of detailed evidence and guidance is needed to gain optimum performance from available natural ventilation systems. This research is a proof of concept investigation into the feasibility and impact of natural ventilation systems targeting airflow rates, thermal comfort, heating energy and control of pathogenic bio-aerosols in hospital wards. In particular, it provides insights into the optimal areas of vent openings which could satisfy the complex three-pronged criteria of contaminant dilution, low heating energy and acceptable thermal comfort for occupants in a naturally ventilated single bed ward. The main aim of this thesis is the structured study of four systems categorised into three groups: Simple Natural Ventilation (SNV) in which single and dual-openings are used on the same external wall; Advanced Natural Ventilation (ANV) which is an emerging concept; and finally Natural Personalised Ventilation (NPV) which is an entirely new concept borne out of the limitations of previous systems and gaps in literature. The focus of this research is in the exploratory study of the weaknesses and potentials of the four systems, based on multi-criteria performances metrics within three architecturally distinct single-bed ward designs. In contributing to the body of existing knowledge, this thesis provides a better understanding of the performances of three existing systems while presenting the new NPV system. The analysis is based on dynamic thermal modelling and computational fluid dynamics and in the case of the NPV system, salt-bath experiments for validation and visualisation of transient flows. In all cases, wards were assumed to be free of mechanical ventilation systems that might influence the natural flow of air. The thesis meets three major objectives which have resulted in the following contributions to current knowledge: An understanding of the limitations and potentials of same-side openings, especially why and how dual-openings can be useful when retrofitted into existing wards. Detailed analysis of bulk airflow, thermal comfort, heating energy and room air distribution achievable from existing SNV and ANV systems, including insights to acceptable trickle ventilation rates, which will be particular useful in meeting minimum dilution and energy requirements in winter. This also includes qualitative predictions of the airflow pattern and direction obtainable from both systems. The innovation and study of a new natural ventilation system called Natural Personalised Ventilation (NPV) which provides fresh air directly over a patient s bed, creating a mixing regime in the space and evaluation of its comfort and energy performances. A low-energy solution for airborne infection control in clinical spaces is demonstrated by achieving buoyancy-driven mixing ventilation via the NPV system, and a derivative called ceiling-based natural ventilation (CBNV) is shown. A comparative analysis of four unique natural ventilation strategies including their performance rankings for airflow rates, thermal comfort, energy consumption and contaminant dilution or removal using an existing single-bed ward design as case study. Development of design and operational recommendations for future guidelines on utilising natural ventilation in single-bed wards either for refurbishment or for proposed designs. These contributions can be extended to other clinical and non-clinical spaces which are suitable to be naturally ventilated including treatment rooms, office spaces and waiting areas. The findings signify that natural ventilation is not only feasible for ward spaces but that there is opportunity for innovation in its application through further research. Future work could focus on related aspects like: impacts of fan-assisted ventilation for a hybrid flow regime; pre-heating of supply air; integration with passive heat recovery systems as well the use of full-scale experiments to fine-tune and validate findings.
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Ji, Yingchun. "Computational fluid dynamics modelling of displacement natural ventilation." Thesis, De Montfort University, 2005. http://hdl.handle.net/2086/4951.
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Natural ventilation is widely recognised as contributing towards low-energy building design. The requirement to reduce energy usage in new buildings has rejuvenated interest in natural ventilation. This thesis deals with computer modelling of natural displacement ventilation driven either by buoyancy or buoyancy combined with wind forces. Two benchmarks have been developed using computational fluid dynamics (CFD) in order to evaluate the accuracy with which CFD is able to model natural displacement ventilation flow. The first benchmark considers the natural ventilation of a single ventilated space with high and low level openings connected to the exterior driven by combined forces of wind and buoyancy. The second benchmark considers natural ventilation flow in a single space connected to an atrium driven by pure buoyancy. Simulation results of key ventilation parameters (stratification depth, temperature gradient and ventilation flow rate) have been compared with analytical and experimental models and close agreements have been achieved. The two benchmarks are defined using the RNG k-epsilon turbulence model. A pressure boundary is applied onto the ventilation openings directly and a porous medium boundary is used to assist the development of the thermal plume. This method has proved to be robust and the close agreement between the three modelling techniques indicates that CFD is able to model natural ventilation flows in simple geometries with acceptable accuracy and reliability. Using the benchmarks the influences of key CFD modelling parameters and building design issues have been investigated. For example, representing openings, heat source representation, stack height, and air inlet strategies. Natural displacement ventilation of a multi-storey building comprising an atrium is also addressed. Simple analytical models have been developed to describe the key air flow features within the ventilation system.
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Wu, Jiayi, and 吴佳诣. "Slope flows and thermal comfort for hospital natural ventilation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45159105.
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Fennessy, Kristian (Kristian M. ). "Addressing the problem with natural ventilation : producing a guide for designers to integrate natural ventilation into the early stages of building design." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92642.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Architecture, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 66-69).
Currently, the United States alone is responsible for approximately twenty percent of the world's total energy consumption. This consumption is equivalent to roughly 100 quadrillion Btu of energy, or in plainer terms, over $1 trillion in energy expenditures annually. This sector alone comprises nearly half of all the energy consumed in the United States. Additionally, about seventy-five percent of all electricity produced in the U.S. is consumed by building operations. This precedent has convinced me that finding an alternative is worth the investment. The purpose of my thesis project is to explore substitutes to mechanical heating, ventilation, and air conditioning (HVAC) building systems. My project revisits the concept of natural ventilation and explores and evaluates its feasibility as an energy-saving and comfortable alternative to mechanical ventilation systems. Additionally, my project focuses on how buildings can be designed to naturally condition the indoor environments of our buildings. More specifically, I would like to help architects discover how they can utilize natural ventilation effectively. Using the TRNSYS simulation environment, I methodically show how a designer would use TRNSYS to make informed decisions about natural ventilation in their designs. My research is meant to be a valuable tool for other designers who are unsure or uncomfortable with utilizing this natural process to condition their buildings. The final deliverable of my thesis project is a comprehensive strategy for designers to incorporate natural ventilation in the early stages of their building design.
by Kristian Fennessy.
S.B.
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Kleiven, Tommy. "Natural ventilation in buildings : architectural concepts, consequences and possibilities." Doctoral thesis, Norwegian University of Science and Technology, Department of Architectural Design, History and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-914.
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This thesis, “Natural Ventilation in Buildings -Architectural concepts, consequences and possibilities”, is the result of a PhD study financed by Hydro Aluminium/Wicona, The Research Council of Norway and the Norwegian University of Science and Technology (NTNU). The work was carried out at the Department of Architectural Design, History and Technology, Faculty of Architecture and Fine Art at NTNU in the period January 2000 to March 2003.
The study has been conducted in close collaboration with fellow researchers Bjørn J. Wachenfeldt and Tor Arvid Vik. Chapter 2 “Principles and elements of natural ventilation” is in its entirety written by the three of us together.
The main objectives of this work have been to identify and investigate the architectural consequences and possibilities of natural ventilation in office and school buildings in Northern Europe. Case studies and interviews with architects and HVAC consultants have been the most central “research instruments” in achieving this. Three buildings have been studied in detail. These are the GSW Headquarters in Germany, the B&O Headquarters in Denmark, and the Mediå Primary School in Norway. In addition, a larger set of buildings has been used to substantiate the findings.
The most important findings of this work are that:
- utilisation of natural ventilation in buildings has architectural consequences as well as possibilities.
- natural ventilation primarily affects the facades, the roof/silhouette and the layout and organisation of the interior spaces.
- the ventilation principle applied (single-sided, cross- or stack ventilation) together with the nature of the supply and extract paths, i.e. whether they are local or central, are of key importance for the architectural consequences and possibilities.
- designing a naturally ventilated building is more difficult than designing a similar but mechanically ventilated building. An interdisciplinary approach from the initial stages of design is mandatory for achieving successful natural ventilation concepts.
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Chiu, Yin-Hao. "Development of unsteady design procedures for natural ventilation stacks." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410175.
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Dean, Brian N. (Brian Nathan) 1974. "Natural ventilation possibilities for buildings in the United States." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/65726.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001."June 2001."
Includes bibliographical references (p. 171-172).
In the United States, many of the commercial buildings built in the last few decades are completely mechanically air conditioned, without the capability to use natural ventilation. This habit has occurred in building designs since the designers do not have the tools to understand the impact of using natural ventilation as an option in conditioning a building. Research has been conducted to create a better understanding of how natural ventilation can be used successfully in building designs. First, understanding the buildings that currently use natural ventilation and secondly by analyzing how buildings can operate in different climates. It is important in the building design industry to know the feasibility of designs, and is therefore important to see buildings that have used natural ventilation techniques. It is also important in the building design industry to know if the natural ventilation techniques that have been used, can be used in the climate that a building needs to be designed for. It was determined that increased airflow through natural means can significantly enhance the functionality of buildings in the United States. Throughout the United States there are numerous hours when outdoor conditions suggest using natural ventilation for a primary cooling system. Natural ventilation can help a building maintain comfort for the occupants, reduce energy usage, reduce cooling equipment size and increase indoor air quality. With the use of a natural ventilation design tool, designers can understand the impact that each of the buildings major features has on the overall comfort or energy required to make it comfortable.
by Brian N. Dean.
S.M.
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Allocca, Camille 1977. "Single-sided natural ventilation : design analysis and general guidelines." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/37561.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (p. 102-104).
Natural ventilation is an effective measure to save energy consumed in buildings and to improve indoor air quality. This study focuses specifically on the principles of single-sided natural ventilation design. Single-sided ventilation is very common in building designs and has been shown to produce very complicated, fluctuating airflow patterns at the openings of buildings. An ongoing challenge in natural ventilation design is therefore the ability to control the mechanisms of wind and temperature for desirable indoor environment conditions. Understanding these effects is important in determining the feasibility of natural ventilation designs. The current research approach used mainly (CFD) tools, together with analytical solutions, empirical models, and experimental results. CFD models were created and analyzed to determine the validity of using this tool for single-sided ventilation analysis and design. The impact of using computational modeling tools for the development of natural ventilation design is great to the building industry field. The focus of this CFD study was on a single room within a residential building in Cambridge, MA. Simulations were performed under varying conditions of temperature, wind speed, wind direction, opening layout and size, and internal heat load, in order to evaluate parameter trends. Airflow rates, velocity fields, and temperature distributions were derived from analytical equations and empirical models as well as from experimental measurements, in order to validate and perform further research in this area. Consequently, this investigation found CFD tools to be valid for studying single-sided natural ventilation strategies with respect to indoor, outdoor, and combined indoor and outdoor flow. From this validation, CFD was applied further to determine the effects of buoyancy, wind, and combined flow on natural ventilation rates and overall indoor conditions. For buoyancy driven flow, CFD performed well when modeling both the indoor and outdoor environment in the calculation, resulting in a 10% difference between semi-analytical and CFD results. However, for wind-driven flow, CFD was found to under predict empirical model results by approximately 25%. This under prediction was attributed to mean or time-averaged, rather than instantaneous calculations of the CFD technique applied to this study. In addition to evaluating the effects of buoyancy and wind on ventilationrates, this study also focused on the effects of wind direction, opposing buoyancy and wind forces, and mixed-mode ventilation. The results from these studies provided further insight into the field of single-sided ventilation and revealed the need for further research in this valuable area. To fully understand and utilize this natural ventilation strategy, the results from the complete single-sided ventilation study were compiled and developed into a computer design tool and a set of general design guidelines. These tools were created in such a way so that designers can use them to evaluate ventilation performance and see immediate results for an indoor environment that they propose to design. The level of analysis that is desired by designers in this area calls for a tool such as this one. This total investigation has been essential in evaluating and analyzing the important areas of the single-sided ventilation field and in providing a strong foundation for further research in improving natural ventilation design as well as in improving CFD and turbulence modeling.
by Camille Allocca.
S.M.
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Accili, Alessia. "Natural ventilation strategies for nearly – Zero Energy Sports Halls." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200892.
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In line with the article 9 of the EPDB, member states shall ensure that all new public properties are nearly zero energy buildings (n-ZEB) by December 31, 2018. Sports buildings account for a significant share of the European building stock consumption. More than half of their current energy needs are related to lighting, and a relevant energy use is due to domestic hot water. This work aims to test different energy measures to design nearly zero energy sports halls in Mediterranean climates. Under a holistic approach, the design of the base case sports hall includes the implementation of passive strategies in combination with renewable energy and energy efficient systems in order to meet the n-ZEB conditions. However, a special focus is put on the study of the sports hall ventilation requirements. A natural ventilation system is proposed as an alternative to a traditional mechanical one. The effectiveness of the analyzed ventilation strategies is validated using TRNSYS, a dynamic simulation tool. Therefore, natural ventilation impact on thermal comfort, air quality and energy needs is estimated. A cost effective evaluation is done following the methodology proposed by the European Directive. Additionally, the study is complemented with a short period of measurements in a selected existing facility according to which poor indoor air quality is the main cause of users discomfort during period of maximum occupancy. The obtained results show that the combination of reduction of thermal transmittance of the envelope, optimization of the windows surfaces, façades orientation, introduction of shading devices, installation of energy efficiency systems as LED lamps and use of natural and night ventilation, are advantageous for the reduction of heating, cooling and artificial lighting demand. Overall, consisted primary energy savings are achieved. Moreover, the described strategies ensure indoor thermal comfort, minimizing the period of overcooling and overheating, and provide good air quality conditions for most of the occupied time along one year simulation. Finally, it is verified that the PV system integration positively affects the sports hall performance toward n-ZEB standards.EUs direktiv om byggnaders energiprestanda (EPBD - 2002/91/EC) uppdaterades 2010 och har som mål att minska energianvändning i Europas fastighetsbestånd. Efter den 31 december 2018, ska alla nya byggnader som används av offentliga myndigheter vara nära-nollenergibyggnader.Idrottshallar står för en betydande andel av den totala energianvändningen i EU. Denna rapport syftar till att studera olika energieffektiviseringsåtgärder, förnybara energikällor och passiva strategier för att utforma n-ZEB idrottshallar i medelhavsklimat.Ett särskilt fokus läggs på att studera ventilationskraven i idrottshallar och användning av naturlig ventilation. Energiprestanda av de analyserade ventilation strategierna har studerats i programmet TRNSYS som är ett verktyg för dynamisk simulering av byggnader. Under projektet har mätningar genomförts i en idrottshall i Barcelona för att analysera de olika parametrarna som påverkar energianvändning i dessa byggnader.En ekonomisk analys att de olika energieffektiviseringsåtgärderna har utförts.Resultaten från projektet visar att lämplig naturlig ventilation i idrottshallar, kan säkerställa god luftkvalitet inomhus och termisk komfort. Dessutom kan naturlig ventilation minska energianvändningen och de totala kostnaderna.
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Zhang, Qin Ph D. Massachusetts Institute of Technology. "Modeling and characterizing bi-directional airflow in natural ventilation." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106427.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Architecture, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 98-105).
Bi-directional airflow in natural ventilation is an essential but not-well-understood scenario due to the complexity of airflow patterns as well as the strong coupling effect between temperature and ventilation. Neglecting bi-directional natural ventilation will result in problematic solutions and inaccuracy in estimation of ventilation performance. This work is focused on filling the knowledge gap by understanding the bi-directional airflow using computational fluid dynamics (CFD). Two important scenarios are simulated and analyzed: 1. Two-zone model with pure buoyancy forces, 2. Multi-zone model with combined wind and buoyancy forces. In the 1st model, a new concept of "local discharge coefficient" is proposed for its consistency under different boundary conditions. The influence of radiative heat transfer on simulation accuracy and ventilation performance is also investigated. In the 2nd model, the transient behaviors of airflow and the dynamics of wind and buoyant forces are analyzed and characterized. A new physical model is proposed based on simplified assumptions and nondimensionalization. This model is able to predicting the transient behavior of multi-zonal ventilation that involves bidirectional airflow patterns. The result of this study is to be integrated in CoolVent, the software designed by Building Technology Lab.
by Qin Zhang.
S.M.
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Khatami, Narguess. "Retrofitted natural ventilation systems for a lightweight office building." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/17820.
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This study aimed to develop retrofitted natural ventilation options and control strategies for existing office buildings to improve thermal comfort, indoor air quality and energy consumption. For this purpose, a typical office building was selected in order to identify opportunities and constraints when implementing such strategies. Actual performance of the case study building was evaluated by conducting quantitative and qualitative field measurements including physical measurements and questionnaire surveys. Based on the actual building performance, a combination of Dynamic Thermal Simulation (using IES) and Computational Fluid Dynamics (using PHOENICS) models were built to develop appropriate natural ventilation options and control strategies to find a balance between energy consumption, indoor air quality, and thermal comfort. Several retrofitted options and control strategies were proposed and the best retrofitted natural ventilation options and control strategies were installed in the case study building. Post occupancy evaluation of the case study building after the interventions was also carried out by conducting physical measurements and questionnaire surveys. Post refurbishment measurements revealed that energy consumption and risk of overheating in the refurbished building were reduced by 9% and 80% respectively. The risk of unacceptable indoor air quality was also reduced by 60% in densely occupied zones of the building. The results of questionnaire surveys also revealed that the percentage of dissatisfied occupants reduced by 80% after intervention. Two new products including a Motorized ceiling tile and NVlogIQ , a natural ventilation wall controller, were also developed based on the results of this study.
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Mozaffarian, Romina. "Natural ventilation in buildings and the tools for analysis." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024277.
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Camargo, Renata Martinho de. "Estudo da eficiência para a ventilação natural dos sheds em hospitais da Rede Sarah." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257759.
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Orientador: Lucila Chebel LabakiDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-19T06:39:40Z (GMT). No. of bitstreams: 1 Camargo_RenataMartinhode_M.pdf: 4984279 bytes, checksum: 362dc581c34f0a018e1778f146c62eab (MD5) Previous issue date: 2011
Resumo: A ventilação natural em regiões tropicais é uma eficiente estratégia de projeto para a obtenção de conforto térmico e para a redução do consumo de energia. O aproveitamento dos recursos naturais e das condicionantes do clima melhora a integração do edifício com o entorno e a obtenção do conforto através de sistemas passivos de condicionamento. Os efeitos do vento em um edifício são analisados através da dinâmica dos fluidos computacional (CFD, Computational Fluid Dynamics) ou de estudos em túnel de vento. É importante quantificar variáveis como: velocidade, pressão, temperatura e coeficiente de pressão. Os Hospitais da Rede Sarah Kubistchek, projetados por João Filgueiras Lima, Lelé, são considerados bons exemplos de arquitetura bioclimática, devido as suas soluções passivas de conforto, como a utilização dos sheds, que promovem a iluminação e a ventilação natural. Esses hospitais foram construídos em várias capitais brasileiras, com diferentes climas. Este trabalho tem como objetivo avaliar a eficiência da ventilação natural dos Hospitais Sarah localizados nas cidades de Brasília e Belém. Essas cidades foram escolhidas devido às características climáticas bastante diferenciadas - clima quente seco e quente úmido. Os sheds no hospital de Belém funcionam como extratores de vento, ao passo que no hospital de Brasília Lago Norte foram projetados como captadores de vento. A análise é feita através de ensaios em túnel de vento de camada limite atmosférica. Os testes incluem medições de velocidade do ar e pressão em vários pontos dentro e fora dos edifícios. O hospital de Belém é analisado em sua implantação real e na situação em que o vento predominante incide perpendicularmente à fachada. Os resultados mostram que, tanto o conjunto de aberturas e o sistema de sheds do hospital de Belém, quanto a sua implantação, proporcionaram maior velocidade do ar nos ambientes internos do que o hospital Brasília Lago Norte. Os resultados dos coeficientes de pressão permitiram confirmar que, para os dois hospitais analisados, o projeto de ventilação natural aproveita as áreas de maior pressão para posicionamento das aberturas de entrada e saída de ar
Abstract: Natural ventilation in tropical regions is an efficient design strategy for achieving thermal comfort and reducing energy consumption. The utilization of natural resources and climate conditions improves integration of the building with its surroundings and allows comfort conditions through passive systems of conditioning. The effects of wind on a building are analyzed using computational fluid dynamics (CFD, Computational Fluid Dynamics) or wind tunnel studies. It is important to quantify variables such as speed, pressure, temperature and pressure coefficient. The Sarah Kubitschek Network hospital, designed by João Filgueiras Lima, Lelé, are considered good examples of bioclimatic architecture, due to the passive solutions for comfort, such as the use of sheds, which provide natural lighting and ventilation. These hospitals were built in several Brazilian cities with different climates. This study aims to evaluate the efficiency of natural ventilation of Sarah hospitals located in the cities of Brasília and Belém. These cities were chosen because of the different climate characteristics of the two cities - mild dry and hot humid. The sheds in the hospital of Belem act as wind extractors, while those in in Brasilia Lago Norte hospital was designed as a means of wind catchers. The analysis is done through testing in atmospheric boundary layer wind tunnel. The tests include measurements of air velocity and pressure at several points inside and outside of buildings. The Belém hospital is analyzed in its actual implantation and in the situation where the prevailing incident wind is perpendicular to the facade. The results show that both the number of openings and the shed system in the hospital in Belém, as well as its implantation, provided a higher air speed in indoor environments than the hospital Brasília Lago Norte. The results for the pressure coefficients allow to confirm that for both hospitals studied, the design of natural ventilation takes advantage of the higher pressure areas for positioning of the income and exit of air
Mestrado
Arquitetura e Construção
Mestre em Engenharia Civil
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Acred, Andrew. "Natural ventilation in multi-storey buildings : a preliminary design approach." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/34322.
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Natural ventilation is a low-energy design strategy that has the potential both to significantly reduce energy usage in buildings and to provide a healthy and comfortable indoor environment. It has particular potential for use in tall, multi-storey buildings. However, the integration of natural ventilation into these large building designs has seen mixed success. Furthermore, there is a gap between simple 'rule-of-thumb' design guidance and detailed, computational design tools. This research attempts to bridge the gap between the simple and detailed with the broad aim of providing rapid and intuitive guidance for use in preliminary design. We use a simple mathematical approach to develop a coherent and easy-to-use framework for modelling ventilating flows, which quantifies the interactions between a core set of design variables. We focus in particular on buoyancy-driven ventilation in buildings with atria, ventilation stacks and/or similar vertical spaces that span multiple floors. Simple methods centred around hand calculations and design charts are developed to inform the sizing of vents in an 'ideal design' scenario, in which the desired ventilation flow rates and air temperatures are delivered to all occupants within a building. We define a measure of the ventilation performance of an atrium and use this to provide an indication of when an atrium is beneficial to a ventilation system design and when it is detrimental. We also use a transient flow analysis to consider 'off-design' scenarios, in which undesirable flow regimes may occur, and to place design tolerances on the building envelope. It is hoped that this work will form a point of reference for further research and for future revisions of design guidance literature.
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Spencer, Scott. "An experimental investigation of a solar chimney natural ventilation system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ59298.pdf.
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Shea, Andrew. "Research and marketing of natural ventilation in low energy buildings." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528275.
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Bensalem, Rafik. "Wind driven natural ventilation in courtyard and atrium-type buildings." Thesis, University of Sheffield, 1991. http://etheses.whiterose.ac.uk/3000/.
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This study investigated the effectiveness of wind-driven natural ventilation in courtyard and atrium-type buildings, particularly in the context of ventilative cooling. Courtyard and atrium buildings are currently enjoying great popularity. Perhaps a primary reason for their revival comes from the energy and environmental awareness of the current period, in which courtyard and atrium concepts are emerging as very promising. Wind-driven ventilation is one of the most basic and probably among the most efficient ways to prevent overheating, and provide cooling in the summer season, especially in humid climates. A review of previous works showed that little attention has been given to the wind-driven natural ventilation capability of these structures, and to the means of maximizing this ventilation. This study was thus aimed to fill part of the gap in this subject. In order to evaluate the wind-driven ventilation effectiveness of these structures, and to examine some of the influential parameters, experimental wind tunnel tests were made. Actual indoor air flows were measured in small replica models of four-storey courtyard and atrium buildings by means of small calibrated orifice plates. A parametric study of the geometry of the courtyard was made in isolation conditions, where the depth and breadth of the courtyard were systematically varied. Several atrium ventilation modes were tested both in isolation and in urban terrains. The tests involved different roof geometries and various roof porosities. The measurements were followed by a discussion on the validity of simple computational methods to predict airflow in atria. The investigation portrayed the importance of some factors, such as the wind orientation rather than the courtyard geometry, for enhancing the flow in these structures. The superiority of some atrium designs over the courtyard types, particularly in sheltered sites, was underlined. The study concluded with a discussion of design guide-lines and referred the reader to an application as an example, describing a simple step-by-step method to estimate the cooling benefits of these structures in a particular site, and making use of the measurement data obtained from the study.
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Zobayed, Sayed Md Akhter. "The use of natural pressurised forced ventilation in plant micropropagation." Thesis, University of Hull, 1996. http://hydra.hull.ac.uk/resources/hull:5898.
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A new, uncomplicated system for the forced ventilation of plants and cultures has been investigated in terms of both its efficiency of ventilation and its effects on the growth and physiology of various plant species, including cauliflower, tobacco, Annona (custard apple) and potato. This new system, which has no moving parts or artificial energy requirement, provides a sustained, pressurised stream of sterile, humidified air (RH = 70-94%) driven by humidity-induced diffusion. This process depends upon the maintenance of a gradient of water vapour across a microporous partition for inducing the diffusion of air into the apparatus. Flows up to 5 cm³ min¯¹ can be produced and the atmosphere in a 60 cm³ culture vessel can be renewed every 12 min Compared to the standard conventional diffusive method of ventilation, e. g. by capping the vessel with a polypropylene disc, this new system has proved to be 18X more efficient in removing accumulated ethylene and in keeping CO₂ and O₂ levels in culture vessels close to atmospheric. This forced ventilation system has also been shown to be very effective in the in vitro cultivation of seedlings or cuttings of cauliflower, tobacco, Annona and potato for improving growth and preventing symptoms of vitrification such as leaf epinasty, reduction of leaf area and production of abnormal stomata. In potato cuttings the induction and production of microtubers have been promoted and the growth of abnormal callus prevented. In Annona cuttings flower bud production, leaf and shoot growth and micropropagation have been promoted and leaf and flower bud abscission have been reduced. In cauliflower, tobacco and Annona the leaf chlorophyll contents, rates of photosynthesis and yields were improved by this forced ventilation. These beneficial effects have been variously attributed to the efficient removal of ethylene, the maintenance of near to atmospheric levels of CO₂ and O₂ by day and night and to the reduction of humidity levels in the vessels to below 100% RH. It is hoped that this new ventilation system, which is comparatively inexpensive and requires very little maintenance might have some useful applications in the field of tissue culture and perhaps particularly in developing countries.
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Carey, P. S. "Direct wind tunnel modelling of natural ventilation for design purposes." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422325.
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Luo, Qinzi. "Modeling of opening characteristics of an atrium in natural ventilation." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115629.
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Thesis: S.M. in Building Technology, Massachusetts Institute of Technology, Department of Architecture, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 97-99).
Atriums are widely applied in non-residential buildings to provide social contact, daylight, air circulation, and aesthetic requirements. Buoyancy-driven ventilation systems are common because they can maintain suitable thermal comfort and reduce energy. Modeling techniques used to simulate naturally ventilation include analytical models, full-scale and small-scale experiments, computational fluid dynamics(CFD) and airflow network tools, which have advantages and limitations. Investigations on atrium structure and opening characteristics have been limited up to now. This thesis studies the temperature stratification and air flow rates inside atrium buildings in purely buoyancy-driven ventilation. Ventilation effects in models with different heat sources, opening locations, opening sizes and numbers of floors are compared using CFD simulations. An airflow network tool, CoolVent, is used to compare the results with CFD models. Both temperatures and flow rates match well with discrepancies less than 10%. Therefore, the well-mixed temperature assumption in the atrium in the airflow network tool is suitable for single-layer atrium buildings. The full-scale experiment provides a detailed data set for further investigations. Air temperatures keep stable on every floor but increase with height. Therefore, the well-mixed temperature assumption over the entire height of the atrium in many analytical models is not applicable when the cross section of the atrium is small. The prediction of temperature distribution and flow rates in atrium buildings with buoyancy-driven ventilation is provided in details. Indoor air temperatures and flow rates can be calculated with known outside air temperatures and surface temperatures in the atrium. The estimation of heat transfer coefficients, especially the approximation of stairs can cause some discrepancies between calculated and actual results.
by Qinzi Luo.
S.M. in Building Technology
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Jiang, Yi 1972. "Study of natural ventilation in buildings with large eddy simulation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8512.
Full textAbstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2002.Includes bibliographical references (p. 186-194).
With the discovery of many economic, environmental, and health problems in sealed and mechanically ventilated buildings, the concept of natural ventilation has been revived. "Buildings that breathe" have become more and more desired by ordinary people and architects. Although natural ventilation is conceptually simple, it is difficult to design and control. At present, methods to study natural ventilation are either inaccurate or costly. This study aims at solving these problems by using large eddy simulation (LES). In LES, a three-dimensional, time-dependent method, the contribution of the large, energy-carrying structures is computed directly and only the smallest scales of turbulence are modeled. This investigation has identified a filtered dynamic subgrid-scale model of LES to study natural ventilation. The experimental data from a wind tunnel, a full-scale test chamber, and other research data have been used to validate the LES program. Methods have been developed to solve the problems encountered in validating LES models for natural ventilation studies. Studying the characteristics of different indoor and outdoor airflows helps to identify the best SGS model for those flows. By comparing the results of using large and small computational domains, an appropriate domain size is recommended to save computing time. It is also found that simulating the transient properties of incoming wind, such as the principal frequency of the turbulent fluctuations, influences the pressure distributions around buildings.
(cont.) The mechanism of natural ventilation is investigated using the numerical and experimental results. The fundamental impact of turbulence characteristics on ventilation rate is discussed and a new definition to calculate the ventilation rate is introduced. The distributions of velocities, pressures, temperature and energy spectra, and the computed ventilation rates, suggest that natural ventilation performance is significantly affected by thermal conditions and geometry of a building. LES provides the best tool to predict the effects under those conditions. Finally, with the implementation of a Lagrangian particle model, LES is applied to compute particle dispersion in buildings, which provides valuable information to improve indoor air quality. Good results were found for particles larger than 10 micrometers. Further work is needed for smaller particles.
by Yi Jiang.
Ph.D.
45
Durrani, Faisal. "Using large eddy simulation to model buoyancy-driven natural ventilation." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12488.
Full textAbstract:
The use of Large Eddy Simulation (LES) for modelling air flows in buildings is a growing area of Computational Fluid Dynamics (CFD). Compared to traditional CFD techniques, LES provides a more detailed approach to modelling turbulence in air. This offers the potential for more accurate modelling of low energy natural ventilation which is notoriously difficult to model using traditional CFD. Currently, very little is known about the performance of LES for modelling natural ventilation, and its computational intensity makes its practical use on desk top computers prohibitive. The objective of this work was to apply LES to a variety of natural ventilation strategies and to compile guidelines for practitioners on its performance, including the trade-off between accuracy and cost.
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Bova, Anthony Scott. "Modeling the Ventilation of Natural Animal Shelters in Wildland Fires." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274966386.
Full text
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Lishman, Ben Stanley Roy. "The control of natural ventilation with opposing wind and buoyancy." Thesis, University of Cambridge, 2007. https://researchportal.port.ac.uk/portal/en/theses/the-control-of-natural-ventilation-with-opposing-wind-and-buoyancy(97d0423b-9083-4078-bd8c-009141a8559e).html.
Full textAbstract:
This thesis is an investigation of the control of naturally ventilated buildings subject to opposing wind and buoyancy. Previous research shows that the interaction of wind and buoyancy can lead to complicated behaviour, and that this in turn can make it difficult to design controllers for naturally ventilated buildings. The aim of this research is therefore to aid in the design of such controllers.
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Chaudhry, Hassam Nasarullah. "The integration of heat pipe technology into natural ventilation systems." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5735/.
Full textAbstract:
The aim of this research was to integrate heat pipe technology into natural ventilation air streams to provide passive cooling in regions of hot arid climatic conditions without the use of mechanical assistance. The study used numerical and experimental techniques identified from literature to carry out the research. Design parameters of heat pipes including the working fluid and geometrical arrangement were investigated using Computational Fluid Dynamics (CFD). Flow and thermal behaviour of two-phase heat pipe working fluids including water, ethanol and R134a were investigated and their performance was quantified in terms of heat transfer and the overall effectiveness. The results showed that water has the highest cooling capability for the downstream airflow and its working performance was approximately 24% superior in comparison to refrigerant R134a and 42% higher in relation to ethanol. The analysis further determined that for low-speed hot airstreams, heat pipe working fluid properties play an important role in enhancing heat transfer and that the specific heat capacity of the fluid was the most influential parameter in increasing convective heat transfer by 39%. Subsequent to the working fluid, geometrical arrangements of the heat pipes were studied. Using a fixed physical domain, the findings displayed that the optimum spanwise thickness between the pipes was 50mm (spanwise thickness to pipe diameter ratio of 2.5) while the optimum streamwise distance was 20mm corresponding to the streamwise distance-to-pipe ratio of 1.0. In addition, the periodic time-dependant model determined the thermal response of heat pipes in relation to external temperatures and established the relationship between source temperatures and downstream profiles. The final part of the study validated the CFD findings through full-scale wind tunnel experimentation. Experimental testing was carried out on heat pipes using water and R134a as working fluids at varying spanwise configurations. The error patterns were found to independent of the heat pipe geometry and working fluid. The validation study determined the error range which varied between 0.6% and 18.1% for velocity, 0.7% and 18.8% for pressure and between 0.01% and 2.8% for temperature, showing a good correlation between the CFD and experimental techniques and with previous work found in published literature.
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Aboul, Naga Mohsen M. "Natural ventilation and cooling by evaporation in hot-arid climates." Thesis, University of Leeds, 1990. http://etheses.whiterose.ac.uk/4043/.
Full textAbstract:
In hot climates, outside air is too hot during the day. In hot arid climates, low humidity increases discomfort. For comfort, hot air should be cooled before flowing into dwellings and moisture in the moving air increased. For the poor, comfort must be sought cheaply. In places without electricity only 'natural' ventilation is feasible. The air temperature difference between the sunny and the shaded side of a building can be exploited to promote ventilation. Ventilation cooling can be enhanced with an 'evaporative cooling cavity' attached to a dwelling on its shaded side. The cavity has a top external inlet and a bottom internal outlet, and incorporates one or two wet partitions. The air within the cavity, being moist. descends. drawing the outside warm and dry air into the cavity. Evaporation cools the air and raises its humidity. The cool incoming air will reduce inside air temperature and improve comfort. The performance of a typical cavity to induce cooling ventilation by evaporation was investigated theoretically and experimentally with a full scale model. The temperature drop. velocity and relative humidity of the air were measured. The pattern of the air flow in the cavity was observed. The optimum dimensions of the cavity were established. Buoyancy air flow and fan-assisted air flow were analysed in the steady state. Since a convective heat transfer coefficient for air flowing between two parallel vertical surfaces was not found in the literature, appropriate convective heat and surface mass transfer coefficients were derived from measurements. The results show the convective heat transfer coefficient to be independent of the separation of the wet surfaces, and that with separation greater than 3Omm, each wet surface behaves as a 'free' surface. The optimum separation between wet surfaces was assessed, and the water removed by evaporation was determined, and found to be small. The Admittance Method was used to assess comfort. Ventilation and evaporation effectiveness were evaluated. An outlet air velocity of O.3m/s accompanied with a temperature drop of about 6K was achieved. Design proposals for hot arid climates are offered.
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Omrani, Sara. "Natural ventilation in high-rise apartments in hot-humid climates." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/116593/1/Sara_Omrani_Thesis.pdf.
Full textAbstract:
This thesis contributes to improvement of natural ventilation and thermal comfort in high-rise residential buildings in hot-humid climates. Case study approach along with full-scale experiments and Computational Fluid Dynamics formed the methodology of the current thesis. Two main outcomes of this study are: 1) a model for integration of different methods of natural ventilation evaluation at different design stages, and 2) a holistic model for implication of various design parameters to improve natural ventilation in buildings.