Green Design 

CFD for Green Building Design with QGBC and GBCI Europe S2

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hello and welcome to the second and lastsession of our workshop CFG for greenbuilding by sim scale in collaborationwith the Carter Green Building Councilin the German Green Building Associationtoday we will talk about thermal comfortfor occupants and continue our journeythrough the world of engineeringsimulation how it can be used for greenbuildingmy name is millet and today I will beone of your co-hosts for today's webinarI'm a product marketing manager at somescale and as a part of my role I ampreparing and hosting different kind oflearning opportunities like workshopsand webinars on a regular basis todaywith me is hammer da Yosef he is a hatof communication at the Carter GreenBuilding Council and as the greenbuilding and engineering veteran he isan expert when it comes to talk aboutstandards or different strategies forgreen building and today he will sharewith us his deep knowledge about thermalcomfort and how it can should beconsidered during the design period of abuilding before we start with ourtoday's topic let's take a quick look atours agenda so I will just quicklydiscuss with you some very feworganizational things and then hamadawill introduce you to the principles ofthermal comfort you will learn aboutdifferent standards differentventilation strategies and how andthermal comfort is impacting theperformance and productivity of peopleinside buildings after that we willincrease our knowledge aboutcomputational fluid dynamics and I willintroduce you to some very importantfundamental concepts of physicalmodeling so you will learn how to treatturbulence wallrelated effects and also how to avoidsome very popular mistakes when it comesto you CFD after that we have again avery nice life demo in this time it's areal industrial project by a biginternational building companyand they agreed that we can show theresults with you which is really niceand I'm sure you will learn a lot aboutthe practical applications of CFD photonwill come for and finally we'll haveagain a Q&A session so when the case youhave questions just write them into ourquestion box and Hammoud on e will tryto answer them on the fly in the chat orduring the end at the Q & A yes let'slet's not lose too much time to talkabout organizational things just to towrap it up so you can basically earn twothings joining this workshop the firstthing is elite C II our and to receivethis you need to join the live webinarsession and today we are tomorrow realsent out the first bunch of certificatesto two participants of last weeksessions and you can also qualify forbrief of free professional trade Simmstraining by SIM scale with a value of500 euro for this you need to fill outand submit both courses and we alreadyhad a session last week where we send itaround the link to a recording the linkto the quiz so you have still time tosubmit the quiz and for next week'ssession we will send out the materialand off this week all rightand no and I would like to announceHamada's presentation about theprinciples of thermal comfort Mura yesthank you very much for joining and thestage is yourshello Mila another everyone and thanksfor joining us today for the secondsession or of our safetylet me show my screen and go for thefull stream yeahto talk to society so last week we spokeabout the energy efficiency and passivedesign principles this week as Malia hasmentioned we will focus more into moreof the indoor environmental quality andlater on Malad will showcase more of theCFD of thermal comfort so to cover moreof that topic we will discuss twodifferent topics in general but we haveto fully connected one its the indoorair quality and how to measure it whatkind of benchmarking do we need to useand references and then how this leadsto thermal comfort and again thereferences of its practices and thingsto consider from a design principlesbefore going to simulation so why do youcare about buildings around the indooroverall it's very basic because wesimply spend more than 90 percent of ourlife time indoors and for that we havelots of actually pollution sources thatare more concentrated wouldn't bend overand that's the tricky part that manyparameters of the indoor air mayactually be worse than outdoor air dueto the concentration lack of airmovement or poor ventilation in generalbut the good side of the story that wehave more control over as an indoorenvironment and that hence theimportance of understanding theventilation principles and how we designour indoor ventilation system andmechanical systems so yes we can havemore issues with the indoor air qualitybut in the same time we have morecontrol of actually mitigating theseissues andspeaking of negative impacts the poorair quality actually impact lots ofthings in our bodies and that's part ofthe trend now if you are aware of thewill rating system and other ratingsystems that focus more in to witnessand will being and directly connectingthe building physics with the buildingwith our body block or building sis bodysystems so from the respiratory systemto immunity and unity and otherreproductive system we have lots ofimpacts that can be affected by poor airquality and contaminated air things likesick building syndrome allergic wintershypersensitivity phenomena have manymore other pollutants of concern like acarbon dioxide and depends on the amountof concentration of carbon dioxide andthat's very important because we willdiscuss it later with reference to theASHRAE standard at the minimum fresh airrequirements they exposed long exposureto high concentration of co2 within theindoor environment actually has beenproven to have moderate to high levelvikraman to decision making to attentioninitiative task orientation and lots ofcognitive additional cognitive skills ofour body so and you can feed it there ifyou are any poor fully ventilated spacewhich equals to having a higher level ofcarbon dioxide you can feel more oflaziness feeling more tendency to sleepit's not sleeping but it's way of yourbody not getting enough oxygen enough todeal with it other sources of poorindoor air quality comes from inadequateinadequate ventilation as a main reasonthen you have for termination from theinside of the buildings or from outsideair like arable dust and others andmicrobial combinations over the buildingfabric itself which is something that wetend to forget about overall the whu-ohestimates that more than twelve pointseven percent of that is could beavoided by improving the ambient airquality withinless space and that's by decreasing theburden of respiratory diseases decreasehealthcare costs decrease lost workforceproductivity and people in the positiveside increasing product productivityfrom staff and of course increasing lifeexpectancy so it's to sum up this partit's to say it simply improves airquality actually impact offset basicbuilding syndrome and increase ourproductivity and we'll will being withinthe space if we take it further tothings like lead and lead before forbuildings and construction similar tolast week we are looking at thebreakdown of the topic from eliteperspective from a rating systemperspective so for instance elite andindoor environmental quality you havemany topics that are coveredspeaking from making sure of providingthe minimum indoor air qualityperformance linking it withenvironmental tobacco smoke control orlimiting smoking within the building asa source of contamination then taking itto the enhancement strategies mitigatingair pollutant sources sources of airpollutant like low emitting materialsand construction indoor air qualitymanagement plans then doing properindoor air quality assessment later onthen going for designing for thermalcomfort and life and comfort andacoustic performance as well so thereare several topics to cover here fromindoor air quality to lighting acousticsand occupied the experience but fortoday's sake we will be just focusing onindoor air quality and thermal comfortso to go to the principles and thereferences of first the indoor airquality principles let's go for whateverventilations are we starting with andthat's one of the very early stagesdesign says that we need to take withyour architects and your electromechanical engineers what how are wegoing to ventilate the building can wedo it as a natural ventilation is itmechanical is mixed-mode it depends onthe weatherthe culture the function of the buildingthe expectation of the usability thelots of decisions that need to be takenfor mechanically ventilate space we havea reference to references if it dependson where you live the ASHRAE standard62.1 2010 that's the American Standardand you have the CN standard theEuropean home fifteen twenty fifty oneand thirteen seven seven nine these arethe European equivalents of course ifyou are in a country and you haveanother alternative or anotherequivalent you can still use the same aslong as you maintain the main principlesand benchmarks and I believe this willbe something that will add yourdifference more as we go for the settingup the model for thermal comfort atlater stage if you are going for anaturally ventilated space you have theAshley 62.1 as well and the Sipsey myman you attend of March 25 so there isnice reference in the sip see sip C isthe Charter Institute of buildingservices engineer so they haveapplication manual which was the am 10in there there is a nice a very goodflow chart that I would highly recommendthat even if you are not mechanicalengineer or an architect to have a lookat because it's help in settinganswering that question what kind ofventilation is suitable to our buildingso it's flowchart which decisionsyes ro and once you start following ityou will end up in the show videopointer at the end of it yes you can gofor natural ventilation order need themixed mode or you need to come for justfor cooling and so onit depends of course in the maximum hegains another building has a narrow planconsideration for parameter zones is itdoable for mix for exit will not so it'sit's a nice guideline which I highlyrecommend that you check if you haven'tdone beforeso for eachroom and space and that and that's a waythat you can do that you don't need tohave a single ventilation system for thewhole building but you can do it perspace and room it depends againpartition strategy and design so you canhave a mix of both between differentsystems in the building the samebuilding so for each human space and forspace it's up to the function of goes tothe space then you set up yourventilation strategies your ventilationzones you need to understand that yournet occupied space and occupancycategory and function and activities anddesign occupancy as well what how manypeople are expected to work and functionwithin that space for mechanicalventilation you need to consider someoptionscan we bring 100% percent outside air ornot the amount of fresh air within thesystem the system capacity for dealingwith fresh air is it's the the eightdisplacement is it who's under flooroverhead or side distribution and thelocation of the turn grid supply airtemperature your setback temperature isit a variable air volume language forshort is Vav or constant volume supplyis it doesn't know is it more dynamic isit more responsive or is more constantand from there comes the standards againback to the standards that we have seenfrom early on so for instance if you gothrough the LEED project to comply withthe indoor environmental quality qualityprerequisite for minimum indoor airquality performance you haven't in twooptions either to go with the Americanstandard was Ashley 62.1 and completethe ventilation air procedures for itssystem or go for the european standard15 25 1 and follow the calculations atannex b it's for both of them it's wayof doing the calculation depends onwhere you are so to keep the to keep thehighlight or the highlight the mainissues and in this calculation firstcompared the calculation with the designairflow making sure that you meet theminimum 10 CFM per person cubic feet perminute per person ensure minimumrequirements are met incorporateequipment into your HVAC design sotaking these kind of design requirementsand integrating them into the HVACdesign the main thing is maintain 10 CFMminimum per person for all occupiedspaces this is the minimum amount offresh air that you need to provide perminute which is cute the creep minutesper person so this is a minimum that youneed to maintain at all time to avoidissues that we mentioned earlier likethe increase of carbon blocks ourconcentration and negative impact fornaturally ventilated spaces you need toprovide the mechanical ventilationbackup in case there was not enough airmovement or the temperature is going toohigh or there is a extreme climatechange in the weather conditions youneed to have monitors to monitor theventilation systems from the directexhaust air flow measurement devicesalarmed opening for national air spacesand carbon dioxide motives so again weneed to maintain as we mentioned fromthe ayleid slides that you need tomaintain good air quality within thespace so the regardless of the yoursystem is it not ship insulated ormechanically limited or mixed we need tomonitor the carbon dioxide we need tomonitor the air flow and making surethat we have enough required so in thereI didn't fire the ceiling heights andopening performance ventilationprocedures and again this is where itwill come in handy similar to whatMillett showed last week for the airmovement using a CFD simulation toactually assess the feasibility ofnatural ventilation is a doable or notwithout taking the risk to actuallydiscover it on-site so making use ofyour simulation tools to take thisdecision on a design stages you haveenhancedtrivets when you follow these principleswhich is to provide enhanced indoor airquality strategies and for that you havea mix depends on your system in themechanical natural or mixed mode sopicking a couple of strategies that cancomfort from using entryways systemspreventing cross-contamination betweeninterior spaces adding extra filtrationdoing extrication for naturalventilation and so on increasedventilation rates beyond the 10 CFM andstoring carbon dioxide monitoring anddoing my own calculations so that's moreor less is the part of the indoor airquality now let's take it to the nexttopicand the final flow back from my endtoday is the thermal comfortso speaking of thermal comfort andpeople tend to confuse thermal comfortwith air quality and these are twodifferent topics but thermal comfortactually if it's too warm or too coldand within the space you can actuallylink it to increase of productivity andperformance in in different spaces andactually they have different referencesand different standards so for thermalcomfort design you need to follow ashley55 2010 or later or the ice UN sentstandards irrelevant ice once andstandards so you need to select anddesign condition strategies so itdepends with your article to complianceconsiderations what kind of functionsare we doing within the space andconnecting that with how are weproviding the air and temperature andair movements and that's these are thekind of considerations so you haveactually five considerations take careof one is the surface temperature two isthe air temperature and second is thehumidity then the air movement or aspeed within the space and finally themetabolic rate and clothing so thefunction and clothing within the spaceso whether these five complianceconsiderations you can thendesigned for a proper server comfortsputting them together in line so formechanical conditioning we need tounderstand or design for what's theindoor opera operative temperature thehumidity levels the airspeed levels orkeep and clothing and activity levels aswe mentioned beforeexamples of thermal control fromthermostats to ceiling fans adjustableunderfloor diffusers glass mountedcontrols operable windows people need tohave control on that space of coursethere's person subjectivity between eachperson people some people might feel abit warmer than others people othersmight be more welcomed with a colderenvironment so we need to provide thiskind of control ability for eachoccupant within the trance places soagain to put it to keep it in our mindwhat kind of consideration that woulddetermine the thermal comfort of thespace as we mentioned with the Balacreate clothing humidity air speed andrated temperatureso with these in mind we need to bringthese two concepts or not to forget thatthis these two concepts are totallyconnected to everything that we havediscussed so far even last week from thepassive design principles promotingdaylight promoting proper indoorenvironmental quality is truly connectedwith your site is fully living with yourenergy strategies and water strategiesand so on and material selections and soon so there are lots of synergies andyou can't isolate a design strategy fromanother especially impacting buildingsdone so that's mostly it from my end beloud and thank you everyone and pleaselet me know if you have any questions byin the if you can drop a question in themenu or drop us an email thank youmeet up some the samevery much for this exciting presentationand let me just make myself againit's a presenter all right you guys cansee my screen yep perfect okay thenlet's continue thank you very muchRamudu and we will talk later during theQ&A so now let's talk a little bit aboutCFD and some further fundamentals lastweek we got an introduction to the ideaof computational fluid dynamics and howit can be be used for green buildingprojects and first of all let's todaytalk about some aspects which becomevery important when it comes tosimulating internal air flows andsimulator more comfort on the firstthing is turbulence modeling andturbulence is basically not nothing moreor less than a chaotic change of thefield values in space and times and alot of people's has some misconceptionbecause they think that vortices andturbulence is the same but that's notactually true and a good example for aturbulence floor is if you take a lookat the water tap and when you open it alittle bit you will see that there is aflow come float it's water coming outand if you take a look at at the profileof the boundary and face between thewater and the air it's like very smoothand sin and it's more you open the tapas small you are increasing the massflows through the tap and thereforethere's a fluid flow velocity and if youopen it up more and more you will noticeat some point that first of all the thecross section will become wider and thenalso the surface becomes more rough andas more you open the water tap as morechaotic andrough the boundary layer all that says afast like a fast boundary between thewatching the air will look like and thisis a very good example because actuallythere is not something like unit forturbulence but there is a Reynoldsnumber which is a dimensionless numberand it's basically the ratio of theinertial forces which are the product ofthe velocity the characteristic lengthof the flow and density of the fluid andthe viscous force are represented by theviscosity and the viscosity and identityour material properties of the waterphasing based on the temperature and ifyou increase the velocity the rain Adamawill become bigger and bigger and thereis a critical number around 2300 andabroad this normal flow become turbulentand basically all the flows which areused in technical devices and also whichare relevant and buildings are turbulentflows and turbulence is massivelyimproving the distribution for exampleof heat and therefore it's something weneed to very careful simulate and andadjust you to finish this example if helets a change there's a fluid and youwould use oil which has a must mass muchhigher viscosity set of water the flowwould still become again become La Minasince now the Reynolds number will dropand if we think about turbulence and Itold you that basically all technicallyreal flows are turbulent flows it bringsus to a problem because let's say thisis the value of the any value forexample the velocity or temperature atthe point and then this is a graphrepresenting house as well you changedover time and one way to deal with thatis to say well I will calculate anaverage velocity and now well Eldred Iwill introduce something new which Icall the flux of velocity and this isbasically a function which isrepresenting the fluctuation around thisaverage well are you depending on timeand this is quite smart and but it comesstill with another problem thisoscillations here they are cure on verydifferent time on land skates and what Imean with that is that at some point thevalue will change very rapidly atquickly and some others very slow so wehave different time scouts and landscales means that we have maybe a verysmall fluctuation at the point of theflow field where like independence fromthe hive how fast is changing theamplitude of the oscillation is verysmall and we will have some regionswhere this amplitude is quite high andthis brings us to a problem because thewind since we have very small lengthscales it would take us audible comewith a very very high effort to solveall the small scales and this kind ofsimulation where you solve all the kindof small scales is called DNS directnumerical simulation and it comes withso much calculation effort thatbasically not not available today forany technical relevant flow there aresome some some research projects wherethey try at you do DNS may be ofsimplified car and it takes them likemonths or years to to solves thesimulation and so what can we do onething we cannot do at all is rituresolves and fluctuations but there is avery smart approach and this is based onreplace the oscillation so we will notconsider them further and introducesomething else called a turbulentviscosity and how does it workwell I have from last week you know thatwe use different equations or theirdifferent governing equations which needto be solved including the conservationof mass energy and momentum and in themomentum equation the viscosity is usedour it's depending on viscosity let'ssay this way and now what we do insteadof using the physical viscosity for thisequation system we will introducesomething you calledacta viscosity where we will addsomething called turbulent viscosity andthe idea now is that the effect of thisoscillations will be consideredindirectly through the effectiveviscosity and this turbulent viscosityhas no physical meaning so it's not amaterial property of of the fluidit's just artificially introduced tosimplify the problem and the only thingwe need to do now is to introduce atleast one additional transport propertybecause the equation system it's notclosed and this is this is fulfilled byintroducing this turbulent viscosity andthere are dr. balance model availablewhich makes which enable us to simulateturbulent flows in a affordable was infor noble effort the only thing youshould know that turbulence modeling isa simplification and therefore there isno turbulence model with the generallyvalid for all kinds of flows for examplethere are some turbulence models whichare very strong for shear flow someothers are very strong far away from thefrom the body and during all for errorAEC applications we recommend by the wayto you so the so called k ami gases teammodel which is quite strong for Phobosregions far far field and and near fieldof of the flow another aspect which canbecome very important as well modelingbecause as you might know we havesomething called boundary layer and it'sthe result of the fact that the airwhich is directly in contact with thesurface of the object is basicallysticking on it and this will deceleratethe flow engineer off of the wallcompared to the free stream velocity andthis will lead to here's an imagevisualizing the boundary layer at theopposite of airfoil and here you can seeschematically like how the velocityprofile is looking so this is the wallhere the velocity is zero and then wehave this profile ateverywhere where we reach 99.6% of theambient flow velocity we have the freestream in everywhere words below its theboundary layer by definition and what ishappening is that this boundary layerhas a strong effect on the global flowfield and the problem is said as youknow we use this elements itself toresolve gradients and and the engineerof the wall in the boundary layer wehave a special effect which me and thiseffect is said and we have a very strongvelocity change in y direction in thisdirection in the vertical direction butin the horizontal direction it's veryvery small the change of velocity andtherefore we need to resolve directionalchanges of velocity and one option wouldto be use a lot of small elements butsince this is a weight of computationalresources instead we use this flat cellswhich optimal optimal for resolving asis let's say a major a gradient in onedirection the only important thing youneed to know is that you should you needto apply this elements on all outerwalls but never on physical on physicalwalls like unless so outlets and who inwhenever you use it cells it's veryimportant to use this same the righthate for the elements and this hate ismainly depending on Uranus number andthis also comes with another problembecause if you take a look at how thevelocity is changing against the walldistance you will notice that you wouldneed a lot of small elements to reallyreally resolve this complex profile andthis usually also increasescomputational effort on the other handfor a lot of effects you can simplify itby using wall models and one thing weuse a lot of times is the so-called lawof wall it was like it's I think atnearly hundred years old or 60 at leastand the great thing about a very uniqueand interesting idea because what's awhat I actually did this researchersexperimented a lot and measured followedor floss the the velocity profile in theboundary layer and they found out thatthere is a generic way to describevelocity close to the wall and that youcan use the function which will give youthe dimensionless velocity depending oras a function of the dimensional walldistance so what we have here isbasically velocity was this walldistance and if we make bothdimensionless it will give us a relationwhich we can reuse and now the idea isinstead of resolving this complexprofile with a lot of cells we'll justuse one flat cell which will completelycover the whole so-called fiscalsoftware so we have three layers insidethe boundary layer and this viscous sublayer that can be replaced where we havethe biggest change actually replacedwith a velocity profile and this willsolve this will reduce the computationaleffort there is just one thing itrequires a very specific by plus numbersso a very specific distance of the firsttell to the wall which is depending onon the velocity and some some otherthings and if you don't have a wallfunction you need to reach a wall y plusof one from the first layer which willlead you to much more cells all rightnow let's talk a little bit about verycommon errors and see if Li and just tomake it clear it's the biggest source oferrors is basically the user and themost the biggest kind let's say oferrors made by users are modeling andsetup errors which means that youoversimplify something which isphysically not possible and anotherthing which happens a lot and just togive you an example if you for exampleuse there's a turbulence model if youdon't use a turbulence model or use ifyou use features and turbulence modelwhich is made forsay laminar flows and flows troublingthis is a typical or if you try tosimulate some saying as a steady statesimulation which is a transient processso next I let's say the second biggestsource of errors are so-calleddiscretization errors and this isrelated with the inadequate or bad mashand this basically can have two reasonsone is that your measures to cause andyou're not able to resolve gradientswhich is a physical very important andin every case it will lead to bad resultin the in the worst case this can evenlet your simulation crash and anotherthing which people usually do wrong issay that they use wrong domainapproximation so let's say there's ataking example if you do a naturalventilation simulation like we did lastweek if the bounding box reminds thebuilding is too small and the third kindof error which is not happening so oftenor let's say it's not very usual for forsimulations which are not super complexis to use wrong America settings andactually just to simplify it amindifference to what analytic methods dowe work with numbers here and thisnumber needs to be rounded and sometimesduring the simulation we need to solvenumerically a Gaborik equation systemand if we use the wrong settings it canhappen that we get an error and just toshow you some some prominent example sothis is a typical error made by bybeginners let's say your job is tosimulate the flow on a step and a lot ofpeople do wrong actually is that theywant to save elements so they cut thedomain very early after the step andwhat will happen is that the vortice isoutside the domain and this will readyour to a problem because and theboundary condition will also notproperly work and in this case a lot oftimes you get wrong results or even asimulation crash and the right solutionwould be to dolike this to at least make sure thatthere's big awake behind the stair isfully developed and yes also whathappened a lot of time and this quitesimilar is that people puts the inlet orthe outlet tube close to the area of ofdistance so this problem usually happensfor external aerodynamics and ifinternal aerodynamics internal flowlet's say we have this pipe systems HXstep and we're interest what's happeninghere we need to make sure that the flowcan't fully develop because usually youdon't add the boundary layer to exit tothe inlet boundary condition it's a flowdevelop itself and you have to make surethat there is enough way upstream forthe flow to develop and there's anexample which you maybe will not dealwith since multi-phase simulation isit's not very common for green buildingbut this is a good example for reallyphysics for not taking physics intoaccount let's say you want to simulatehow a fuel fuel cell is filled with withfresh fuel and let's say what youobviously need is Inlet for the fluidentering some container but a lot ofpeople forget that you actually alsoneed to outlet for the air in thecontainer to to escape if you forgetabout this at some point your flow willstop and stop because numerically ormathematically it's so much air insidethis that it can't leave and this is bythe way not then the the result doesn'tneed to be physical by the way becausesome people would say well but inreality what if I don't have an openinghere well that's a good point but it's asimplification and um if you for examplewant to simulate the case where there isalso physically not an outlet here itwill become much more complex and youreally have to think about how then youhave to do a compressible simulation forexample soand in the end of the day why I'mtelling you this I'm telling you thisbecause it's you know very easy tocreate some some colorful smoothcontours and they can be basicallyproduced by any model even if it's anyparent if it's good or bad for examplein a lot of movies if they have CGI oranimations including fluid flow it's notbased on a physical simulation so whatwill look super nice but the resultsusually are absolutely not physical andit's your responsibility as a user tofirst understand the problem and thenmake some some let's say inherentassumptions before setting up thesimulation and usually before startingto use the same scale platform youshould sit down for half an hour thinkabout the problem and write down how youwant to solve it and in the end of theday whenever you get a simulationresults don't trust them don't trustthem in the blind or something like thatso try to compare the results make surethat they make sense from a physicalpoint of view and if possible try tocompare them as in ellipticalcalculations hands-on proximation solet's say well you space or based onyour experience and now let's switch tothe live demonstration and I would liketo show you a very interesting projectwe did on a consulting base for theInternational construction companyramble which is known for a lot of veryimportant and famous buildings like theFerrari World and I think there in theEmirates or football stadiums Copenhagenor period house or the Jakarta FourSeasons and this time Rambo was workingon new building from the Coons fairyQueens very high school and as you cansee this is a school in Scotland was aquite modern concept and and here youcan see the sketches of how theclassroom should look like also withwith chairs and the tables inside on theright side you can see the the initialdesign for the HVAC systemand synthesis is school term will comefor was a big issue and so theycontacted us because before they wereusing only hand calculations and theyasked us to help them if we can simulatethe mixing box system case and they wentto scenario where the windows are closedand the sinus on and to to help them weprovided them with qualitative andquantitative results which wereincluding the velocity distribution thetemperature distribution and so termwill come for inside the room basedcalculation calculated based on theASHRAE fifty standard and in the caseyou've missed your last week session Iwould suggest you should watch after thewebinar the recording and because sincewe all just have 20 minutes left I wantto explain everything again which wediscussed last week but just to put in anutshell so we have against three stepsthe first step was that we needed CADmodels so tramble provided us with rhinocap model and it was quite easy to youto to simplify it so we made sure it waswatertight and we introduced some dummybodies to simulate the heat transferfrom from the students the next step weprepared the simulation so we mashedeverything and run the simulation withsame scale and finally we proposedprocess the results visualized make somecountable and used this results togetherwas a customer to take design decisionlet's now take a look at the cap modelso and we have different things includedhere so first of all we are simulatingthe humans inside the room as well asobstruction obstructions likes chairsand we also have some some inlets withgrills where we and you can see what Itold you that we actually had to addsome some volume to the domain here atthe inlet to make sure the flow candevelop so we have two inlets withgrills herewe have outlet tax here sorry this otheroutlet tax so here's and three yearsother inland select act we have someradiant panels and in addition also wehave some light which also released someheat and for the cat preparation as Imentioned we extended inlet and outletsthe model was closed and very importantalso to two-thirds of our keep bodies asand parts a separate solid set so thatwe can assign different boundaryconditions and also to make sure or tounderstand that we need the volumeinside the room and not the volume ofthe walls etc so it's kind of a negativeoff of the cap domain so the first stepwas to create a proper mash we usesurface and feature of refinements toadapt the mesh refinement in in regionswhere we expect to have high gradients achange of the flow field and you can seelike we refined the actress of smallparts and the surface of obstructionslikes chairs and and the tables and weended up in a trending million sounds 3dmesh so in the end we will have 4/9 on90 million 490 million points we willknow the pressure individual pressureand temperature value and it just tookus 40 minutes to calculate the mesh andsince we can use up to 96 computingcosts here you can see in all overviewthe simulation setup so for sure it wasair we used to convective heat transfersolver which is steady state andincludes turbulence we also includedgravity which is important when it comesto natural convection effects and as youcan see you at the inlets we'reintroducing and the air was one pointtwo five meters per second which willreduce in a in a mass flow based on thecross-section and the outlet we are likesucking out the air with 0.03 mod cubicmeter per second the sidewalls have noslip they have a constant temperature of294 Kelvin the humans are like asubmarine releasing some heat as well aswindows lights and the radiantand now let's take a look at the CFDresults of the design so first of allyou can see a slice and in X directionwe're visualizing the velocity and whatis quite interesting is that first ofall the high velocity flow through thediffuser grills creates a kind of strongdraft which we can see here and you cansee here that we have some buoyancyeffect so the air around the humans aresitting up so then the two drops andtheir foot rises up and get andby the PI's outlet and and you can seewe basically have three thresholds forthe flow velocity so the flow isentering the room was 1.25 meters insidethe grills since the cross-section isdropping the the flow velocity increasesup to 2.1 m/s and in the region where wehave y&z draft it's quite low from 0.1to 0.25 is a little bit and then we canagain see that there is a strong by NZeffect around bouncers occupants andthat we have natural convection do youchoose occult windows and this is alsointeresting if you want to do suchanalyzed as a Simona mentioned you needactually should do several simulationsconsidering different ambienttemperatures and and and at least you doto do a simulation for winter summerautumn and so on and it's basicallyquite similar what is happening here andand if we even move to slide to the endof the room it's everywhere the samelike we have again this draft regions wehave the sine will offer to here whichis not very comfortable if you jewelrydirectly like stand here but here is notsure from that point of view it could befair and we can have sponsee and naturalconnection now let's rotate the slidesby 90 degree and now we have why normalslides and let's take a look at this twosections again via visualizing thevelocity and you can see that thediffuser growth actually work quite wellin that manner that they alike ensurethat the flow is spreading andthe outlet that you can see that theyactually like taking air from everywhereso even from the walls especially choosea convection and some air get sucked innow let's again rotate it by 90 degreearound the y-axis and now we can see itsets lies against velocity for theshoulder and the belt hat London for theshoulder level you can see that we havesome high velocities in the near alsoinlets because they interact with thewalls and then we have such waters andyou can also see that the average flowvelocity around through humansespecially a short level is between zeropoint one and zero or that is below zeropoint two meter per seconds at least nowwe can use some streamlines to visualizea path of the flow for each side and theinlets are released from as the paththat are released from the illness andyou can see how the air just firstslowly goes through the room and thengets sucked and Biser by the outlets andthe some other views where you canreally see the complex and structureoffs and you can like and what I reallylike is the visualization of those fastascending air columns for the inlets andhow they are mixing inside the room nowlet's take a look at the temperature andyou will use the same slices and hereyou can see like the cold air and how itbecomes warmer when we sing with we'reinside the room you can like see thevelocity profile and the warmth isreduce reserve heat flux was theoccupant and we have a very eventemperature at people level yesbasically it's the same again if we movethe slice and what doesinteresting here is that the outlet airis quite warm and that's exactly what wewant the outlet air is around 300 Kelvinwhy the air in the room is around 295degree or Kelvin sorry now we can take alook at why normalize the sense thetemperature distribution you can seeagain that it's coming cold air from xinlanguage which is mixing and that wehave heat from the radiance panels hereand here which are and this could alsobe a good explanation for for the airwhich is going from the walls and andinside the easy outlet and now this isvery interesting we can see thetemperature distribution at but abovehead level and about shoulder level andat shoulder level it's more or lessaround Chonan 896 Kelvin why at AutoOutlet head level it's it's a little bita little bit higher around 297 298Kelvin and actually we have a largedifference in the average temperatureespecially here so we have a lot of hotspots on on above half level and it'snot as extreme as as on the left sidebefore the right side we also have someof the seat islands and yes when if weknow we can like acolyte averagetemperature of occupants and it's like315 Kelvin and now let's try to take alook at the contours for a temperatureof 296 Kelvin and you can see like wehave this hot air above the people andlike at the last 30 person of the hateof the of the room and that the warm airfrom occupant bodies Rises which is goodand we want to keep the air where discnow you can see a simpler to slice 20seemed to me different ground lovewhere the temperature is quite low andnow let's at the same point do ahorizontal take approach theirperspective and you can really see thetemperature profile on how itsinfluenced by the heat released from thehuman bodiesnow let's take a look at the temperatureprofiles for four different places forthe room below the inlet grill at thecenter and below the outlet and here youcan see it's very similar to thevelocity velocity profile so we areplotting it is all the way around wasexchanged axis and you can see thatactually below the inlet equals a muchdifferent profile and for the center andand below all that it does make a bigdifference now what we also did is wecalculated the effective drafttemperature which is described in theASHRAE fifty-five standard and this canbe calculated based on the local areatemperature the average room temperatureand the local air stream strand to linevelocity and it's a great thing I saidas long as the CDT is between minusthree and two it's comfortable and youcan see that everything which is darkreally which is orange for our and tolight blue is okay and you can see thatthere is just one guy in a uncomfortableregion the student directly sittingabove both sirs as a outlet and for surehere where the inlet is it's quiteuncomfortable because of the combinationof high velocity and low temperature andwe have the same effect if we go andanother point of the room for this twooccupants and again this uncomfortableregion at the above head level where wehave the inlets and if we now use the Yslice we can see again that we have suchuncomfortable regions below then let'salso from the other side but on theother hand where the people sits it'sbasically everywhere comfortableand now we again use the slice at abouthalf level and one at shoulder levelwhich shows that shoulder level unum ofuniformly comfortable but above thatlevel there are some spots which aren'tcomfortable here for example or here butthey seems to be far away from thepeople since they're sitting most of thetime yes the simulation was performed insurgery - cause it took 22 hours tofinish so Sam on the call was at all andtogether with the mesh it took seven onthat 80 call hours to run the simulationand in return we received a lot ofinteresting insights about thetemperatures velocity distribution andbased on the simulation we can first ofall we now are sure that the concept towork and we can further improve it achance of further increase the thermalcomfort or decrease the energy needed byincreasing the flow rates answer thetempters and yes all right I hope youenjoyed the second session and Ibasically answered most of the questionbut there is some some some unansweredquestion which I would like to discusswas you know and feel free to addfurther questions all right I think thefirst question is from where is by LuisMontoya and he wants to know if you canuse sims girl with a Revit file that yesLou is it absolutely possible we alsosupport direct Autodesk import regardinga direct gravity impart it will beavailable soon but in the meantime youcan use a lot of exchange formats whichwork well like step for example or outerdesk other Autodesk formats and needyMarotta wants to know if there is theonline training available and in thecase you missus needy that we haveseveral trainings and by submitting bothquizzes you can qualify for a freetraining andyes the other questions were answered onthe chat so if there's nothing leftwhere there is a question by rashik RIand the question is if naturalventilation necessary for on occupiedspace like storage troops maybe this issomething where hamura can give a goodanswer on I mean if any space or anyroom if it has one occupant or access byone occupant it need to have some sortof ventilation doesn't it mean to be inaction but you need to have some sort ofcross comparecross ventilation because if it's astorage room if you have any chemicalforeign say if you have any chemicals inthe room you need you must have aventilation either it's natural ormechanical you need to have some sort ofair movement within the space for otherstorage areas you might not need to butat least you need to have in case I meaneven from a health and safetyperspective you need to have airmovement you don't need to provideventilation but you need to have crossventilation from other rooms if neededso that's basically in principle the thedesign in requirements but of course youcan find more details if you go to theASHRAE standards with the same standardsfrom that case I would like to coveranother question as well that cameacross regarding the information aboutLEED for existing buildings credits forindoor air quality and I and thanks forthat question and I'll make sure to addNavy slide next time that covered thistopic but in principle they're both thesame in the main principles of minimumindoor air quality at controlling thesmoke and tobacco control additionallythere is a couple of thermal comfort thesame more or less the additional topicsthat need to be covered things relevantto green cleaning cleaning products andhow to make them more informativefriendly things regarding to the bestcontroller pest management the chemicalsthey are using the way of youchemicals or minimizing the use ofchemicals and providing more of Nanaqwave of dealing with it so these kindof topics are delivered to theoperational policies and how duringoperation you need to minimize yoursource protein source proteins and toget in touch with your occupants tounderstand unique like for instance indepth in operational maintenanceyou must have or you need to do anoccupancy survey to understand peopleper se perspective on the thermalcomforter there and their satisfactionwith it and what kind of correctivemeasures that you can put in place toput it in those matters all right thankyou very much it seems like we answeredall the question if you want to reachout to us you can also send me an emailand I will forward the question to amullah or I don't know how muda if youagree we can also provide the registerswith your email address all rightperfect we will edit choose an emailwhich includes a recording yes thank youvery much for joining we add a lot ofattendees and I know that it's quitelate for a lot of you and the weather isvery good so we really appreciate thathope to see you soon again and have awonderful rest of the week byeyou

Learn how to use fluid flow simulation to ensure compliance with ASHRAE 55 and other standards for thermal comfort in buildings. We will look into a case study where thermal comfort was optimized in on office.

A CFD simulation tool can help engineers in predicting and optimizing the performance of HVAC systems and buildings in the early stage of the design process. This can be especially beneficial for the planning of green building projects where sustainable design, optimized energy performance, and air comfort play a crucial role in obtaining a LEED certification.

To introduce everyone to cloud-based CAE, SimScale, Qatar Green Building Council (QGBC) and GBCI Europe joined forces to deliver a free online workshop focused on teaching the application of fluid flow simulation in HVAC and AEC industries, tailored to the needs of Mechanical, HVAC, Building, and Sustainability Engineers.

Official page: https://www.simscale.com/webinars-workshops/cfd-simulation-for-green-building-design/

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