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USING THE ANALYSIS G RID IN ECOTECT Ju in tow L in Ass i s tan t Pro fessor | Ca l Po ly Pomona Depar tment o f Arch i tec ture 3801 W. Temp le Ave | Pomona CA 91768 | 909 869 6774 | j u in towl in a t csupomona do t edu November 4 , 2007 Day l ight ing The day l i gh t fac tor (D F) is a very common method to measure the sub jec t ive day l igh t qua l i ty in a r oom. I t represen ts the ra t i o be tween indoor and ou tdoor i l luminance leve ls , expressed in percen t . The h ighe r t he DF, the more na tura l l i gh t i s ava i lab le w i th in a space. Ecotec t use s the Bu i l d ing Research Es tab l i shment (BRE) Sp l i t -F lux method to ca l cu la te day l igh t fac tor s . Th is method assumes tha t there are th ree separa te components , ignor ing d i r ec t sun l i gh t , o f t he na tura l l igh t t ha t can reach any po in t w i th in a bu i ld ing . The DF is s imply t he sum of each o f these th ree components . DF = SC + ERC + IRC Sky Componen t (SC) - D i r ec t ly f rom the sky , th rough an open ing such as a w indow. Ex terna l ly Ref lec ted Componen t (ERC) - Re f lec ted o f f the ground, t rees or o the r bu i ld ings . In te rna l l y Ref lec ted Componen t ( IRC) - The in ter - r e f lec t i on o f 1 and 2 o f f sur faces w i th in the room. Day l igh t f ac tor va lues a re genera l ly ca l cu la ted unde r an overcast sky or in an a r t i f i c ia l sky wh ich s imu la tes a s tandard CIE ove rcast sky in o rder t o represen t a WO RST- CASE SCENARIO to be des igned fo r . Eco tec t c la ims there i s no po in t to “des ign a l igh t i ng sys tem based on the br igh tes t day o f the year as i t may on ly occur once or tw ice dur ing the year and peop le are very l i ke ly to c lose the b l inds anyway to pro tec t themse lves f rom heat and g la re ” . They c la im tha t i t i s “much more sens ib le i s t o des ign fo r the wors t -case scenar io . ” There fore : The va lues wi l l no t change w i th d i f fe rent da tes or t imes and , as the overcast sky mode l on l y var ies w i th

a l t i tude, Nor w i l l t hey be a f fec ted by ro ta t ing the Nor th po in t . These va lues are a proper ty o f the des ign i t se l f , no t the loca l env i ronmen t . The on ly parameters tha t a f fec t day l igh t f ac tor s are the geometr y o f the des ign and the mater ia l s i t i s

made o f . Average DF Appeara nce Energy impl icat ions

< 2 % Room looks g loomy. E lec t r ic l i gh t ing needed most o f the day

2% to 5 % Room appears predominan t ly day l i t . Ar t i f i c ia l l igh t i ng may be requ i red . Th is va lue s t r ikes a good ba lance between day l i gh t ing and therma l fac tors .

> 5 % Room appears s tong ly day l i t . Dayt ime e lec t r ic l igh t i ng is l i ke ly no t needed, bu t t here ex i s t s a po tent ia l fo r t hermal p rob lems due to overhea t ing in summer and heat losses in w in te r .

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Analysis Grid Open the f i le Thermal In t r o – new.eco f rom

http: / /www.too lsfo rsusta inabi l i ty .com/ f i l es /download/ecotect_mode ls /Thermal In t ro - new.eco . ▫ Go to the p lan v iew , se lec t the f loor o f Zone 1

- Hi t ok

In t he ana lys i s g r id t ab , c l ick “ Auto-F i t Gr id t o Ob jec ts ” ▫ Se lec t With in Type o f F i t ▫ Fi t g r i d t o Se lec ted Objec ts ▫ Se lec t XY Ax is w i th an Ax ia l Of f se t o f 2 ’ ▫ Se lec t Boundary Inse t o f 0 .5 fo r a l l axes

T h e re sh o u l d b e a b u f f e r , e sp f o r d a y l i g h t a n a l ys i s , t o a vo i d t o o h i g h a r e f l e c t i o n

Go to Gr id Management ▫ Play w i th the number o f ce l l s un t i l you ge t someth ing tha t looks square . For

example , x=30, y=12, z=5. ▫ Star t the Ca lcu la t ion

- Go to Ca lcu la t i ons and se lec t L igh t ing Leve ls → Per form Ca lcu la t i on . - Wizard Page 1 → Choose Natura l L igh t Leve ls - Wizard Page 2 → Se lec t Over the Ana lys is Gr id (don ’ t check 3D for now) - Wizard Page 3 → Choose medium ray t rac ing

T h e g r i d sh o u l d g e n e ra l l y b e 1 ’ o r 2 ’ sq u a re s , d e p e nd i n g o n yo u r p ro j e c t . T h e g r i d i n t e rp o l a t e s se p a ra te p o i n t s b e tw e e n t h e i n t e r se c t i o n s .

- Wizard Page 4 → Inpu t t he Sky I l l uminance . I f you don ’ t know the des ign sky , ca lcu la te i t by c l i ck ing on I ’m not sure – ca l cu la te i t fo r me . Then se lec t the t regenza fo rmu la . (Choose the C IE Overcast Sky Cond i t ion – make sure to check your va lues on the las t screen ( some t imes they don ’ t ge t updated)

S ky l u m i n a n ce va r i e s w i t h c l i m a te a n d c l o u d co ve r . B y a ss i g n i n g a d e s i g n s k y va l u e , i t i s p o ss i b l e t o o b ta i n i l l u m i n a n ce l e ve l s ( i n L u x ) f o r a p a r t i cu l a r l o ca t i o n . A l u x i s a u n i t o f m e a su re m e n t f o r t h e i n t e n s i t y o f l i g h t . I t i s e q u a l t o t h e i l l u m i n a t i o n o f a su r f a ce o n e m e te r a w a y f r o m a s i n g l e ca n d l e .

Go to the las t screen and h i t ok . V iew your resu l ts . - The va lues are re turned by defau l t i n day l i gh t fac tor - Note tha t the gr id da ta min imum, max imum, and con tours are automat ica l ly se t . - Try tu rn ing on the con tour l i nes . - Try tu rn ing o f f t he gr id l ines .

D a y l i g h t f a c to r i s t h e p e r ce n ta g e o f d a y l i g h t co m i n g i n , i n c l u d i n g 1 ) sk y co m p o n e n t , 2 ) e x te rn a l l y r e f l e c t e d co m p o n e n t , a n d 3 ) i n t e rn a l l y r e f l e c t e d co m p o n e n t ( o n l y o n e r e f l e c t i o n ) . R a d i a n ce u se s m u l t i p l e r e f l e c t i o n s .

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- Try chang ing the contour va lues - Refer t o t he tab le above and note those areas tha t a re no be tween the range o f

2 -5 % Day l igh t Factors .

E co te c t se n d s r a y s f r o m e a ch p o i n t . I f i t h i t s w a l l , i t w i l l l o o k a t i t s r e f l e c t i v i t y . I f i t h i t s a w i n d o w , i t kn o w s t o g o t o t h e s ky .

- Try chang ing the m in imum va lue t o 2 and then check Cl i ck to Min imum .

4 % d a y l i g h t f a c to r i s a d e q ua te f o r m o s t r e s i d e n t i a l b u i l d i n g s .

- Change to an axonometr i c v iew (F8) and t r y show ing va lues in 3D.

Change f rom Day l igh t Factor to Day l i gh t ing Leve ls to ge t I l luminance leve ls . I t jus t

mul t ip l i es the day l igh t fac tor by th e des ign sky .

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▫ Cl ick Show Average Va lue . Note the average lux va lue . ▫ Refer t o t he Szoko lay tab le fo r i l l uminance leve ls . ▫ Find the i l lum inance va lues you shou ld a im to des ign fo r . ▫ Add some w indows to ach ieve a sa t is fac tor y day l i gh t fac tor as we l l as sa t i s fac tory

i l lum inance leve ls . View resu l ts i n t he V isua l i se too lbar . Use the Sect ion Plane (z ax is ) too l in

V isua l isa t i on Set t ings .

Try chang ing the in te rna l r e f l ec t iv i t y on the mater ia l p rope r t i es Also change the re f r ac t i ve index o f g lass ( t ransparency f rom 0 .8 – 0 .3 ) Add a wa l l , i .e . across the s t r ee t , l i t t l e sky component , more ex terna l l y re f l ec ted

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Computa t iona l F lu id Dynamics (CFD) Ins ta l l W inAi r Use the Thermal In t ro Mode l . Se lec t a l l w indows and change them to vo ids . Ca lcu la te preva i l i ng w inds (show percentages and legend , choose a l l year )

Add a window to the leeward s ide o f t he bu i ld ing , i .e one w indow (8 ’w x 4 ’h wi th 3 ’ s i l l )

on the west end o f t he nor th wa l l . Turn the wind d iag ram o f f by c l i ck ing D isp lay → Mode l .

Go to the Ana lys i s Gr id Tab – d i sp lay the ana lys i s g r id Ad jus t g r i d ex tents and pu t a gr id on . Se lec t Auto -F i t Gr id to Ob jec ts and se lec t :

Around Al l V i s ib le Ob jec ts , XY Ax is , se t a boundary inse t o f - 25 . Make sure tha t t he z boundary i s zero . Then manua l l y change i t s he igh t . T ry t o make every th ing c lose to cubes.

Change gr id managemen t so tha t x=30 , y=26 , and z=24

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Se lec t CFD Ce l l B lockages and h i t Per fo rm Ca lcu la t ions, se lec t boundar ies Go to the Expor t Manager ( r igh t t ab) an d c l i ck on WinA i r4 , t hen c l i ck on the Save icon

▫ Save the f i l e as Simp leHouse ▫ Set t he Speed /d i rec t ion

- Use Wea ther Too l to de termine the speed/ d i r ec t ion , as we l l as tempera tu re . Use a webs i te such as http: / /www.ook ingdom.com/metr ic /ve loci ty t o conver t mph to mps and http : / /www.onl ineconversion.com/ temperatu re .htm to conver t f r om Ce ls ius to Fahrenhe i t .

Prevailing Winds

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- Check on ly the h or i zonta l a i r f low on ly box.

Open WinA i r . (C : \Wina i r \b in \w ina i r4 .exe)

▫ Load the .geo f i le . ▫ Load the con t ro l f i l e .CON ( do th is r i gh t away) ▫ Se lec t ou tput f i le (S impleHouse) ▫ Run the data . Se t t he number o f i te ra t ions. (200) ▫ Impor t t he CFD output .DAT f i le .

- Fi le → Impor t → Genera l Data F i les - Se lec t CFD Output Data F i les as the f i le type - Locate your S imp leHouse .dat f i le . - When prompted, se lec t the new format

▫ Examine the Ana lys is Gr id - Flow Vector

- Under g r id da ta and sca le , show f l ow vector - Uncheck Show Gr id l ines - Check Gr id Squa res - Uncheck Show con tour l ines

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- Ai r F low Rate

- Under g r id da ta and sca le , se lec t a i r f l ow ra te - Check Show Gr id l ines - Check Shade Gr id Squares - Check Show Contour L ines

- Cl ick on the ar row nex t t o con tour s , se lec t 3D vo lumet r i c r ender , se lec t

cubes, faded to m in imum va lues. P lay around wi th t he m in imum va lue unt i l you ge t some resu l ts .

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- Try to m in imize the wind speeds in the w in ter . T ry add ing t rees - Try to max imize the e f fec t s o f na tura l vent i la t i on . T r y add ing ano the r w indow

on the nor th wa l l . See wh ich locat ion works bes t . Use v iews (camera) t o s tay cons is ten t .

- For your ac tua l p ro jec t , you shou ld t i gh ten up the gr id more , so tha t you can see more accuracy in the f low vec tors , e tc .

- Try to v iew the w ind f low vectors in 3d . use the sec t i on p lane and the gr id axes and o f f se ts to ana lyze the wind vector s .

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Some in forma t ion on wind speeds .