DOCSLIB.ORG

Analysis of a Low Energy Wind Catcher with Horizontally-Arranged Heat

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Analysis of a Low Energy Wind Catcher with Horizontally-Arranged Heat Available online at www.sciencedirect.com ScienceDirect AvailableAvailable online online at at www.sciencedirect.com www.sciencedirect.com Energy Procedia 00 (2017) 000–000 www.elsevier.com/locate/procedia ScienceDirectScienceDirect EnergyEnergy Procedia Procedia 14200 (2017) (2017 )2095–2101 000–000 www.elsevier.com/locate/procedia 9th International Conference on Applied Energy, ICAE2017, 21-24 August 2017, Cardiff, UK Indoor environmental quality (IEQ) analysis of a low energy wind catcherThe with 15th International horizontally Symposium-arranged on District heat Heating transfer and Cooling devices JohnAssessing Calautita, Angelo the feasibility Aquinob*, Dominic of using O’Connor the heatb, Sheen demand Cabaneros-outdoorb, Sally temperatureShahzadc, Saeedfunction Wazed forb, Tom a long Garwood-termb, Katrinadistrict Calautit heat ademand,Ben Hughes forecastb a Departmenta,b,c of Architecture aand Built Environment,a University of Nob ttingham, Nottingham NG7c 2RD, UK c I. Andri ć b*Department, A. Pina of Mechanical, P. Ferrão Engineering,, J. FournierUniversity of Sheffield,., B. LacarrièreSheffield S10 2TN,, O.UK Le Corre cCollege of Engineering, University of Derby, Derby DE22 3AW, UK aIN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal bVeolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Abstract Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France Windcatchers are natural ventilation systems based on the design of traditional architecture, intended to provide ventilation by manipulatingAbstract pressure differentials around buildings induced by wind movement and temperature difference. Though the movement of air caused by the wind catcher will lead to a cooling sensation for occupants, the high air temperature in hot climatesDistrict willheating result networks in little arecooling commonly or thermal addressed discomfort in the to literature occupants. as Inone order of the to improvemost effective the cooling solutions performance for decreasing by wind the catchers,greenhouse heat gas transfer emissions devices from were the buildingincorporated sector. into These the systemsdesign. Thisrequire work high will investments investigate which the indoorare returned environment through qualitythe heat performancesales. Due toof athe roof changed-mounted climate cooling conditions windcatcher and integratedbuilding renovationwith horizontally policies,-arranged heat demand heat transfer in the devices future (HHTD)could decrease, using Comprolongingputational the Fluid investment Dynamics return (CFD) period. and field test analysis. The windcatcher model was incorporated to a 5mx5mx3m test roomThe mainmodel. scope The of stu thisdy paper employed is to assess the CFD the feasibilitycode FLUENT of using with the heatthe standarddemand –koutdoor- model tempeto conductrature functionthe steady for-state heat demandRANS simulation.forecast. The For districtthe indoor of Alvalade,CO2 concentration located in analysis, Lisbon a(Portugal), simplified exhalationwas used asmodel a case was study. used andThe the district room iswas consisted filled with of 12665 occupants.buildings thatThe varyCO2 inconcentration both construction analysis period showed and thattypology. the system Three was weather capable scenarios of delivering (low, medium, fresh airhigh) inside and the three space district and loweringrenovation the scenarios CO2 levels were. Thermal developed comfo (shallow,rt analysis intermediate, using the deep). Predicted To estimate Mean theVote error, (PMV) obtained was heatconducted demand whereby values werethe measurementscompared with ranged results from from slightly a dynamic-cool heat (-0.96) demand to slightly model, warm previously range developed(0.36 to 0.60). and validatedField test by measurements the authors. were carried out inThe the resultsRas-Al showed-Khaimah that (RAK), when onlyUAE weather during changethe month is considered, of September. the marginNumerical of errormodel could was bevalidated acceptable using for experimental some applications data and(the good error agreement in annual was demand observed was betweenlower than both 20% methods for all of weather analysis. scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). ©The 201 value7 The ofAuthors. slope Publishedcoefficient by increased Elsevier onLtd average. within the range of 3.8% up to 8% per decade, that corresponds to the Peerdecrease-review in under the number responsibility of heating of the hours scientific of 22 -committee139h during of the 9thheating Intern seasonational (depending Conference on on the Applied combination Energy .of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the Keywords:coupled scenarios).Built environment; The values Computational suggested Fluid could Dynamics be used (CFD); to heatmodify trnasfer the devicesfunction; natural parameters ventilation; for passivethe scenarios cooling considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. * Corresponding author. E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy. 10.1016/j.egypro.2017.12.582 10.1016/j.egypro.2017.12.582 1876-6102 2096 John Calautit et al. / Energy Procedia 142 (2017) 2095–2101 2 Author name / Energy Procedia 00 (2017) 000–000 1. Introduction and literature review The way in which energy is generated and used has a direct impact on greenhouse gas (GHG) emissions and the economy. The built environment is one of the main end-user of energy; therefore, the use of new technologies to reduce the energy consumption of buildings is a key issue in the design and planning of more sustainable cities. The rapid growth of countries in the Middle East such as UAE and Qatar placed them at the top of the global carbon footprint. The extreme hot climate, the low cost in these regions and the demand for higher levels of comfort has led to the use of mechanical cooling units in both residential and commercial buildings, where most units are operated for 24 hours per day, all year round. Heating, Ventilation and Air-conditioning (HVAC) is responsible for up to 60% of the energy consumed by buildings and even higher during summer months [1, 2]. Reducing the substantial energy requirements of mechanical HVAC services has the potential to significantly lower the energy consumption of the built environment heavily reliant on such systems such as commercial buildings, schools and office spaces [3]. An example of a passive ventilation technology is a windcatcher which is an architectural component of traditional Middle Eastern buildings which captures the outdoor wind at high elevation and directs it to the interior [4, 5]. Windcatchers have been installed in buildings in temperate climates such as the UK, particularly in schools and offices [5]. Windcatcher ventilation is particularly effective for night time cooling as this is when there is the greatest differential between indoor and outdoor temperatures. However unlike mechanical cooling, windcatchers are ineffective at reducing the temperature of supply air [6]. It primarily relies on the outdoor temperature for cooling and in warm or hot climates, this could cause further discomfort to occupants during summer if the air is not pre-cooled before entering the occupied space. This places a limit on the application of windcatchers in warm or hot climates. Several works have attempted to address this by integrating evaporative cooling and heat transfer devices [6-8]. The windcatcher with evaporative cooling have shown promising results particularly in dry conditions, for example reductions up to 15°C were observed, depending on the local climatic conditions [7]. However, there are several drawbacks associated with evaporative cooling such as high operation and maintenance cost, ineffectiveness in warm, moderate to high humid conditions [8]. In addition, evaporative coolers use a substantial amount of water to run which could be considered wasteful in arid climates [8]. Several works [8,9] have incorporated heat transfer devices into the internal channel of the windcatcher to reduce the supply airflow temperature (Figure 1). Several researchers have attempted to improve the operation of the wincatcher in different climates; cold [10] and humid [11]. Fig. 1. (a) A roof mounted windcatcher with heat transfer devices (b) schematic diagram of the windcatcher operation. In our previous works [2,8-9], a cooling system that combines passive ventilation and cooling was developed to the
Load more

Recommended publications
  • Thermal Assessment of a Novel Combine Evaporative Cooling Wind Catcher
    energies Article Thermal Assessment of a Novel Combine Evaporative Cooling Wind Catcher Azam Noroozi * and Yannis S. Veneris School of Architecture, National Technical University of Athens, Section III, 42 Patission Av., 10682 Athens, Greece; [email protected] * Correspondence: [email protected]; Tel.: +30-210-772-3885 (ext. 3567) Received: 5 January 2018; Accepted: 13 February 2018; Published: 15 February 2018 Abstract: Wind catchers are one of the oldest cooling systems that are employed to provide sufficient natural ventilation in buildings. In this study, a laboratory scale wind catcher was equipped with a combined evaporative system. The designed assembly was comprised of a one-sided opening with an adjustable wetted pad unit and a wetted blades section. Theoretical analysis of the wind catcher was carried out and a set of experiments were organized to validate the results of the obtained models. The effect of wind speed, wind catcher height, and mode of the opening unit (open or closed) was investigated on temperature drop and velocity of the moving air through the wind catcher as well as provided sensible cooling load. The results showed that under windy conditions, inside air velocity was slightly higher when the pad was open. Vice versa, when the wind speed was zero, the closed pad resulted in an enhancement in air velocity inside the wind catcher. At wind catcher heights of 2.5 and 3.5 m and wind speeds of lower than 3 m/s, cooling loads have been approximately doubled by applying the closed-pad mode. Keywords: wind catcher; cooling system; experimental validation; thermal modeling 1.
    [Show full text]
  • The Wind-Catcher, a Traditional Solution for a Modern Problem Narguess
    THE WIND-CATCHER, A TRADITIONAL SOLUTION FOR A MODERN PROBLEM NARGUESS KHATAMI A submission presented in partial fulfilment of the requirements of the University of Glamorgan/ Prifysgol Morgannwg for the degree of Master of Philosophy August 2009 I R11 1 Certificate of Research This is to certify that, except where specific reference is made, the work described in this thesis is the result of the candidate’s research. Neither this thesis, nor any part of it, has been presented, or is currently submitted, in candidature for any degree at any other University. Signed ……………………………………… Candidate 11/10/2009 Date …………………………………....... Signed ……………………………………… Director of Studies 11/10/2009 Date ……………………………………… II Abstract This study investigated the ability of wind-catcher as an environmentally friendly component to provide natural ventilation for indoor environments and intended to improve the overall efficiency of the existing designs of modern wind-catchers. In fact this thesis attempts to answer this question as to if it is possible to apply traditional design of wind-catchers to enhance the design of modern wind-catchers. Wind-catchers are vertical towers which are installed above buildings to catch and introduce fresh and cool air into the indoor environment and exhaust inside polluted and hot air to the outside. In order to improve overall efficacy of contemporary wind-catchers the study focuses on the effects of applying vertical louvres, which have been used in traditional systems, and horizontal louvres, which are applied in contemporary wind-catchers. The aims are therefore to compare the performance of these two types of louvres in the system. For this reason, a Computational Fluid Dynamic (CFD) model was chosen to simulate and study the air movement in and around a wind-catcher when using vertical and horizontal louvres.
    [Show full text]
  • Download at April 2009 CIBSE Journal 25
    April 2009 Is this eco-house our best hope? THE INTERVIEW FROM ENGINEER TO FACILITIES MANAGER LIGHTING UP NEW HANDBOOK FOR PROFESSIONALS FAÇADES GERMAN LESSONS ON INTEGRATION www.cibsejournal.com CIBSEapr09cover.indd 1 2/4/09 16:30:12 With more than 1,500 schools, colleges and universities already benefiting from Monodraught Windcatcher, SunPipe, SunCatcher and Sola-boost systems no company is better placed to advise on the health, welfare and energy saving benefits of natural ventilation and natural daylight. So whether you are an education professional, architect, consultant or contractor, this experience and our knowledge of current legislation and the latest guidelines makes Monodraught the perfect partner when you are building schools for the future. Call or email us for a copy of our new schools brochure. 2 CIBSE Journal April 2009 www.cibsejournal.com p02_CIBSEMagApr09.indd 2 30/3/09 08:55:36 Contents April 2009 22 38 32 News Features 50 Lighting: Handbook A Society of Light and Lighting first – 6 News 22 The Interview a new handbook for generalists and Round-up of the latest news from Ewen Rose reveals how Eddie Myles specialists. across the sector. went from a hardman contractor to an accommodating facilities manager. 12 CIBSE News Classified Read the latest member news from 28 People: Terry Wyatt CIBSE. Industry leader Terry Wyatt tells 52 Products Carina Bailey why buildings are failing Products and services in the industry. to be energy efficient and what needs Opinion 54 Directory to be done to reverse the trend. 14 Letters A guide to suppliers across the Topical opinions and views from 32 COVER STORY building services sector.
    [Show full text]
  • Towards a Computational Fluid Dynamics-Based Fuzzy Logic Controller of the Optimum Windcatcher Internal Design for Efficient Natural Ventilation in Buildings
    Hindawi Mathematical Problems in Engineering Volume 2021, Article ID 9936178, 10 pages https://doi.org/10.1155/2021/9936178 Research Article Towards a Computational Fluid Dynamics-Based Fuzzy Logic Controller of the Optimum Windcatcher Internal Design for Efficient Natural Ventilation in Buildings Ashraf Balabel ,1 Mohammad Faizan,2 and Ali Alzaed3 1Mechanical Engineering Department, Taif University, Taif, Saudi Arabia 2Mechanical Engineering Department, Aligarh Muslim University, Aligarh, India 3Architectural Engineering Department, Taif University, Taif, Saudi Arabia Correspondence should be addressed to Ashraf Balabel; [email protected] Received 8 March 2021; Revised 23 March 2021; Accepted 29 March 2021; Published 12 April 2021 Academic Editor: G. Muhiuddin Copyright © 2021 Ashraf Balabel et al. 'is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Recently, increased attention has been given to the coupling of computational fluid dynamics (CFD) with the fuzzy logic control system for obtaining the optimum prediction of many complex engineering problems. 'e data provided to the fuzzy system can be obtained from the accurate computational fluid dynamics of such engineering problems. Windcatcher performance to achieve thermal comfort conditions in buildings, especially in hot climate regions, is considered as one such complex problem. Windcatchers can be used as natural ventilation and passive cooling systems in arid and windy regions in Saudi Arabia. Such systems can be considered as the optimum solution for energy-saving and obtaining thermal comfort in residential buildings in such regions. In the present paper, three-dimensional numerical simulations for a newly-developed windcatcher model have been performed using ANSYS FLUENT-14 software.
    [Show full text]
  • Windcatcher: a Passive Adaptive System for the New Climate
    WINDCATCHER: A PASSIVE ADAPTIVE SYSTEM FOR THE NEW CLIMATE Abstract Authors Reza Ramyar, Margaret Bryant, Human life has become heavily urbanized, and cities have become and Yao Wang State University of New York College more populated. Crowded cities have a greater urban metabolism, of Environmental Science and Forestry which results in hotter cities. Moreover, new, higher-density urban Keywords forms have the potential to reduce wind velocity in the streets. These Windcatcher, urban heat, adaptation, fundamental changes in urban climate have been accompanied street canyon by climate change. To cope with climate change, cities need to be prepared to adapt to changes. This paper proposes borrowing envi- ronmentally sustainable adaptation strategies for a hotter future climate in order to cope with climate threats. For this purpose, the windcatcher has been suggested as a passive cooling solution to penetrate more wind into street canyons; it may also increase the air turbulence and thus reduce the temperature and increase the outflow of pollutants from neighborhood environments. The wind- catcher is an Iranian traditional architectural element in arid climates to create natural ventilation for buildings and maintain comfortable indoor temperatures. In this paper we will introduce it as an urban element that not only could provide urban identity, but also could improve urban microclimates. Introduction have attracted significant research on making cooler envi- ronments in outdoor spaces. Some research examines how According to the World Meteorological Organization (Scott to lower air temperature, but only a fraction of this research et al., 2019), the 20 warmest years on record have been the focuses on improving wind velocity in urban canyons.
    [Show full text]
  • CFD Simulation and Analysis of a Two-Sided Windcatcher's Inlet\Outlet
    19th Australasian Fluid Mechanics Conference Melbourne, Australia 8-11 December 2014 CFD Simulation and Analysis of a Two-sided Windcatcher’s Inlet\Outlet Geometric Shape Effect in Ventilation Flow Through a Three Dimensional Room A.R.Niktash1 and B.P. Huynh1 1School of Electrical, Mechanical and Mechatronic Systems University of Technology, Sydney, NSW 2007, Australia Abstract computational fluid dynamics (CFD) for the windcatcher performance assessment has become a creditable tool for flow A windcatcher is a structure fitted on the roof of a building to analysis in the buildings [6,10]. According to the previous provide ventilation for the interior space employing wind power; numerical studies and simulations which have been done by the it exhausts the inside stale air to the outside and supplies the outside fresh air into the building interior space working by same authors using the standard RANS K-ε and LES methods, pressure difference between outside and inside of the building effects of a two-sided windcatcher’s location, the shape of the and using ventilation principles of passive stacks and wind tower, windcatcher at its bottom, inlet velocity, and the length of the respectively. windcatcher’s bottom on flow pattern and flow velocity have been considered for two dimensional and three dimensional In this paper, the effect of different geometric shapes of models [7 ,8]. inlet/outlet for a two-sided windcatcher on the flow velocity, flow pattern , and flow rate which affect on the ventilation quality through a three-dimensional and typical room fitted with a two- In this paper, effect of three different shapes of a two-sided sided windcatcher is observed numerically, applying a windcatcher’s inlet/outlet including square shape, rectangular commercial computational fluid dynamics (CFD) software shape and circular shape but the same areas on flow velocity, package.
    [Show full text]
  • Socio-Environmental Framework for Integration of Lightweight Tensile Structure Windcatchers in Contemporary Hot-Arid Urban Context of Tehran
    World Sustainable Built Environment Conference 2017 Hong Kong Transforming Our Built Environment through Innovation and Integration: Putting Ideas into Action 5-7 June 2017 Registration ID: 2527 Socio-Environmental Framework for Integration of Lightweight Tensile Structure Windcatchers in Contemporary Hot-Arid Urban Context of Tehran ABSTRACT A design framework for integrating windcatcher functions within the contemporary hot-arid urban Iranian context of Tehran responds to two major changes impacting their current utilization: 1) urban densification resulting in modified access to adequate airflows, and 2) sociocultural shifts towards dependencies on modern mechanical air- conditioning systems. Windcatchers are ubiquitous and integral to buildings throughout the hot-arid regions in the Middle East, and traditionally provide human comfort cooling functions through combinations of thermal mass, stack effect, and evaporation techniques. In historic context, the windcatcher is effective for passively moderating indoor temperatures by means of these natural ventilation cooling strategies. However, this passive technology is rarely used in recent decades due to emerging disadvantages such as maintenance difficulties, lack of urban air filtration methods, decline of cooling efficiency due to modified airflow patterns, habitable space utilization modifications, and the resulting dependencies on mechanical cooling systems. Modular lightweight tensile structures are identified as a potential method for integrating windcatcher functions to reduce energy use and engage regional textile industry. The beneficial aspects of this design strategy emphasize adaptability through inhabitant control for localized modulation to airflow through potential integration in existing multi-story apartment buildings. In addition, the framework suggests advancements for environmental performance of lightweight textiles, such as particulate matter filtration, kinetic energy transformation, and photo-response for passive shading or natural daylighting strategies.
    [Show full text]
  • Windcatcher Louvers to Improve Ventilation Efficiency
    energies Article Windcatcher Louvers to Improve Ventilation Efficiency Young Kwon Yang 1 , Min Young Kim 1 , Yong Woo Song 2 , Sung Ho Choi 2 and Jin Chul Park 1,* 1 School of Architecture and Building Science, Chung-Ang University, Seoul 06974, Korea; [email protected] (Y.K.Y.); [email protected] (M.Y.K.) 2 Graduate School, Chung-Ang University, Seoul 06974, Korea; [email protected] (Y.W.S.); [email protected] (S.H.C.) * Correspondence: [email protected]; Tel.: +82-2-820-5261 Received: 13 July 2020; Accepted: 21 August 2020; Published: 28 August 2020 Abstract: Windcatcher louvers are designed to capture air flowing outside a building in order to increase its natural ventilation. There are no studies that have designed the shape of the louver to increase the natural ventilation efficiency of the building. This study aimed to conduct a computational fluid dynamics simulation and mock-up test of a Clark Y airfoil-type windcatcher louver designed to increase the natural ventilation in a building. The following test results were obtained. The optimal angle of attack of the airfoil was calculated via a numerical analysis, which demonstrated that the wind speed was at its highest when the angle of attack was 8◦; further, flow separation occurred at angles exceeding 8◦, at which point the wind speed began to decrease. The results of the mock-up test demonstrated that the time required to reduce the concentration of fine particles in the indoor air was 120 s shorter when the windcatcher was installed than when it was not, which indicating that the time to reduce particles represents a 37.5%reduction.
    [Show full text]
  • Using Computational Fluid Dynamics to Study Flow Patterns of Egypt Windcatcher Named MALQAFS
    J. Basic. Appl. Sci. Res., 2(3)2405-2410, 2012 ISSN 2090-4304 Journal of Basic and Applied © 2012, TextRoad Publication Scientific Research www.textroad.com Using Computational Fluid Dynamics to Study Flow Patterns of Egypt Windcatcher Named MALQAFS Ali Hooshmand Aini1, Hossein Masoomi2, Faezeh Nejati2 1Department of Civil Engineering, Roudbar Branch, Islamic Azad University, Roudbar, Iran 2 Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran ABSTRACT Windcatcher structures have been utilized in some Middle East states and Egypt due to torrid and humid climates as air conditioners and cooling systems many centuries ago. There are different climate conditions, so, windcatcher structures have been developed based on altitude and windflaw direction in central cities and south of Iran as air conditioners and cooling systems. Various windcatcher has been developed in Egypt too. This is to present history of windcatcher and concerning performances by numeric system; then a usual pattern of windcatcher in Egypt named Malqaf is introduced. Therefore, firstly, Gambit software and then fluent software have been utilized to develop numeral and meshing models for the study of windcatcher and airflow direction. Thus, k-ε is selected as turbulent model. Obtained analysis results include flow pattern, distribution of velocity counters, kinetic energy and turbulent counters. KEYWORDS: Malqaf, CFD, Flow Pattern, Fluent, k-ε. 1. INTRODUCTION Difference of atmospheric pressure is named wind. It is an important element of temperature change, humidity and displacement of tiny suspended particles, thus, the developed natural air-conditioning and cooling through windflaw on windcatcher structures satisfy our natural welfare conditions; windflaw is also a remarkable disturbance of human welfare.
    [Show full text]
  • Natural Ventilation by Windcatchers: CFD Simulations and Experiments Castillo, José Antonio*1,2), Huelsz, Guadalupe1), Cruz, Miriam Verónica1)
    Natural ventilation by windcatchers: CFD simulations and experiments Castillo, José Antonio*1,2), Huelsz, Guadalupe1), Cruz, Miriam Verónica1) 1) Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco s/n Col. Centro, Temixco Morelos, México. 2) Building Physics and Services, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands *) presenting author, [email protected] ABSTRACT Natural ventilation can be improved by using a small structure on the roof, usually named windcatcher. This work presents the validation of computational fluid dynamics (CFD) simulations of the natural ventilation of a room with a windcatcher at the center of the roof; five different windcatcher configurations were analysed. Numerical simulations were performed using the software COMSOL and were validated using experimental results. Experiments were performed using a room scale model 1:25 in an open rectangular water channel. Stereoscopic Particle Image Velocimetry was used to measure the velocity vector field at the center plane of the room. A systematic procedure was employed to validate the numerical simulation with the experimental data. The average difference between experimental and numerical results of the wind speed a long the centreline of the room for all the windcatcher configurations is less than 10% and the difference between experimental and numerical results of the volumetric flow rate at the window is less to 7%. 1 INTRODUCTION Natural ventilation on buildings by driven wind flow is an important passive strategy to promote indoor air quality, hygrothermal comfort and health; mainly in warm climates. If cross ventilation by windows is not viable or is insufficient, alternatives based on the modification of building roof can be used, given that the roof is often the most exposed part to the wind (Blocken et al., 2011; van Hooff et al., 2011).
    [Show full text]
  • Airbase... [1544Kb]
    • AIVC BUILDING RESEARCH & INFORMATION (2000) 28(4), 234-244 #13041 Static split duct roof ventilators S. A. Gage1 and J. M. R. Graham2 1The Bartlett School of Architecture, Building, Environmental Design and Planning, University College London, Wates House, 22 Gordon Street, London, WClH OQB, UK E-mail: [email protected] 2Department of Aeronautics, Imperial College of Science, Technology and Medicine, Prince Consort Road, London, SW7 2BY, UK E-mail: [email protected] Split-duct roof ventilators or windcatchers are used to provide both supply and extract ventilation to the spaces which they serve. However, buildings are often erected in conditions where there is no prevailing wind direction. An investigation into four and six segment windcatchers to determine their relative perfor­ mances under different wind conditions was undertaken usind scale models in a wind tunnel. Conclusions indjciate that six segment windcatchers have a more predictable, reliable performance in uncertain or varia­ blewind conditions. However, a four segment windcatcher that is orientated 45 degrees to the prevailing wind will ge e ate the highest pressure differences and consequently the highest duct speeds in an installa­ n r tion. Further work on strategies for windless conditions are summarized, and scope for further research is in­ dicated. On utilise des ventilateurs de toit a fentes des capteurs de vent dans le but a la fois d'alimenter et d'evacuer OU l'air des locaux pour lesquels ils sont prevus. Cependant, les batiments sont souvent eriges clans des conditions ou il n'y a aucune direction de vent dominante. Des recherches ont ete menee en soufflerie sur des capteurs de s vent a quatre et a ix segments afin de determiner lew· fonctionnement relatif dans des conditions de vent dif­ s ferentes en se servant de ma111uettes en soufflerie.
    [Show full text]
  • Worlds Writ Small Four Studies on Miniature Architectural Forms in the Medieval Middle East
    WORLDS WRIT SMALL FOUR STUDIES ON MINIATURE ARCHITECTURAL FORMS IN THE MEDIEVAL MIDDLE EAST VOLUME I Margaret S. Graves Thesis submitted for the degree of Doctor of Philosophy University of Edinburgh, 2010 ii DECLARATION I hereby declare that this thesis is my own work and has not been submitted for any other degree or professional qualification except as specified. Signature:…………………………………………… Date:………………… iii iv ABSTRACT While academic discussion of ornament within medieval Islamic art has laboured much over the codification and meaning of certain forms, there has been relatively little research to date on the visual and iconographic function of architecture as ornament in this context. Those few authors that have dealt with this issue have focused overwhelmingly on two-dimensional architectural representations, largely ignoring the considerable body of portable objects from the medieval Middle East that imitate architecture through three-dimensional forms, whether in a mimetically coherent fashion or in a more elliptical or reconfigured manner. This thesis proposes, first and foremost, that there is significant cultural meaning inherent in the use of architecture as an inspiration for the non-essential formal qualities of portable objects from the medieval Islamic world. Through iconographic analysis of the relationships that such objects form with architecture, an understanding of both full-size architecture and its miniature incarnations in the medieval urban context is advanced within the thesis. To maximise the intellectual scope of the study whilst still enabling an in-depth treatment of the material, four discrete studies of different object groups are presented. All of these are thought to date from approximately 1000 to 1350 CE, and to come from the core Middle Eastern territories of Persia, Syria and Egypt.
    [Show full text]