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Building and Emtr,mment.VoL 2-. No. I. pp. 2-'~30.1992. 0360-1323 92 $5.00-0.00Pnnted n GreatBntain. 0 1902PergamonPresspie.

E nvironm enta l Aud it ing for Bui ld ing

C onst ruct ion: Energy and A ir Po l lu t ionIndices for Building Materials

R AY M O N D J . C O L E *D AV I D R O U S S E A U *

The design community has a reasonable understanding of the fact ors wh ich affect operationalenergy in buildings and has a rariety o f computational tools fo r assessing it. By contrast, thebroader encironmental consequences of producing an d operating buildings are poorly d efined.Since op erating energy represents the current exten t o f em'ironmental attditing, a significantadvance is to inchtde the energy and emissions associated with the production o f constructionmaterials. This paper o utlines the key issue s associated with environmental assessment of theproduction and use of materials and presents exam ples of energy and ah po llution audits fo r fou rcomparable commercial building assemblies with similar thermal resistances.

1 . I N T R O D U C T I O N

F R O M T H E e a r l y 1 97 0s u n t il t h e m i d -1 9 8 0 s t h e re w a s as t e a d y t r a n s f o r m a t i o n f r o m v i e w i ng e n e rg y a n d r e s o ur c euse as an eco log ica l i ssue to an e conom ic one [1] .H o w e v e r, w i t h t h e b r o a d - b a s e d r e s u rge n c e o f e c o l o g ic a lpreserva t ion concerns in the l a te 1980s th i s t rend i srevers ing . Resource use is now d iscussed wi th in a b roade re n v i r o n m e n t a l a g e n d a , p a r t i c u l a r l y i n t h e c o n t e x t o f g l o -b a l w a r m i n g , o z o n e d e p l e t i o n a n d l o c a l a n d r e g i o n a lpo l lu t ion .

C h a n g i n g t h e e c o n o m i c e q u a t i o n t o i n c l u d e c u r r e n th i d d e n e n v i r o n m e n t a l c o s t s a n d t o r e s t r a i n t h e r a p i ddeple t ion of ce r ta in resources wi l l r ad ica l ly a ffec t the wa ybui ld ing con s t ruc t ion i s v iewed [2] . The s ign i f icance fort h e c o n s t r u c t i o n i n d u s t r y w i l l b e t h e e x p a n s i o n o fe n v i r o n m e n t a l a u d i t i n g f r o m a s i m p l e a s s e s s m e n t o fo p e r a t i n g e n e rg y t o i n c l u d e a b r o a d e r a s s e s s m e n t o fresources used in bu i ld ing [3] . Th is wi l l necess it a te bo tha n i m p r o v e d g e n e r a l u n d e r s t a n d i n g o f t h e e n v i r o n m e n t a lconsequences o f bu i ld ings by des ign profess iona l as wel l

a s a c c e s s t o c o m p a r a t i v e e v a l u a t i o n s o f t h e e n v i r o n -m e n t a l i m p a c t o f v a r io u s b u i l d i n g c o m p o n e n t s a n dassembl ies . In th i s regard , a s ign i f ican t s tep i s to com pi let h e e n e rg y u s e a n d e n v i r o n m e n t a l e m i s s i o n s a s s o c ia t e dw i t h t h e p r o d u c t i o n o f c o n s t r u c t i o n m a t e r i a ls .

This paper ou t l ines the key i s sues assoc ia ted wi the n v i r o n m e n t a l a s s e s s m e n t o f t h e p r o d u c t i o n a n d u s e o fmate r ia l s , de f in ing which a re cur ren t ly qua nt i f i ab le , andp r e s e n ts a p r a c t i c a l f r a m e w o r k f o r e n e rg y a n d a i r p o l lu -t i o n a u d i t s . T h e p a p e r c o n c l u d e s w i t h e x a m p l e e n e rg ya n d a i r p o l l u t i o n a u d i t s o f fo u r c o m p a r a b l e c o m m e r c i a lbu i ld ing assem bl ies wi th s imi la r therm al res i s tances .

* Environmental Research G rou p, Scho ol of Architecture.University of British Columbia, Vancouver, BC. Canada. V6TIW5.

2. E N V I R O N M E N TA L A U D I T I N G

A n e n v i r o n m e n t a l a u d i t f o r b u i l d i n g c o n s t r u c t i o n i s a na c c o u n t i n g o f t h e q u a n t i f i a b l e e n v i ro n m e n t a l f a c to r s t h a twi l l be incur red in bu i ld ing produ c t ion and use . reduc ingthem to equ iva len t t e rms and presen t ing them in mean-ingfu l ca tegor ies . The purpose of the aud i t i s to add anenvi ronmenta l d imens ion to des ign dec i s ions .

A n e n v i r o n m e n t a l a u d i t i n c l u d e s b o t h e n e rg y a n d n o n -energy re la ted fac tors , each of which has d i rec t andi n d i re c t c o m p o n e n t s :

Di rec t env i ronm enta l e ffec t s inc lude :

Emiss ions o f ca rb on ox ides , ox ides o f su lphur, ox ideso f n i tr o g e n , p a r t ic u l a t e s a n d u n b u r n e d h y d r o c a r b o n sf r o m c o m b u s t i o n .

A i r, w a t e r a n d s o l i d w a st e i m p a c t s o f m a t e ri a l p r o -cess ing and handl ing .

Dep le t ion of l imi ted rese rves o f non- renew ables .

Ind i rec t env i ronm enta l e ffec t s inc lude :

D a m a g e t o t e r r e s t r ia l a n d a q u a t i c h a b i t a t s d u e t oe n e rg y p r o d u c t i o n a n d i n d u s t r i a l d e v e l o p m e n t .

P r o d u c t i o n o f h a z a r d o u s w a s t es w i th l o n g - t er m c o n -sequences .

T h e d i r e c t e n v i r o n m e n t a l e f f ec t s o f e n e rg y p r o d u c t i o na n d i n d u s t r y a r e t y p i c a l ly m o r e r e a d i l y q u a n t i f ia b l e t h a nthe indirect effects .

2.1 Quan t i f i ab l e enc i ronmen ta l e f f ec t sE n v i r o n m e n t a l s t u d i e s h a v e p r o d u c e d c o n s i d e r a b l e

da ta on the env i ronmenta l e ffec t s o f the p rocesses andm a t e r i a l s a s s o c i a t e d w i t h b u i l d i n g c o n s t r u c t io n , h o w e v e rvery l i t t l e i s ava i lab le in a fo rm which i s use fu l to thedes ign profess ions . Some o f the s ign i f ican t env i ron men ta lf a c t o r s a ss o c i a t e d w i th t h e p r o d u c t i o n a n d m a i n t e n a n c e

BAE 27:1 C 23

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24 R. J . C o l e and D . Rous seau

of bu i ld ings fo r which there i s env i ron men ta l da ta ava i l -ab le , bu t which canno t se t be used comp ara t ive ly inb u i l d i n g d es i g n a n d o p e r a t i o n a l d e c i s i o n m a k i n g a r e :

The consum pt ion of non- rene~vable energy and min-era l resources incur red in the p rodu c t ion of con-s t ruc t ion mate r ia l s , components , and bu i ld ings

The po l lu t ion of a i r, wa te r and so i l incur red in thet rans form at ions o f energy and m inera l resources in a l ls t ag e s o f m a t e r i a l s a n d b u i l d i n g p r o d u c t i o n

The resources consum ed and po l lu t ion incur red in them a i n t e n a n c e a n d r e p l a c e m e n t o f b u i l d i n g m a t e r i a l sand assembl ies over the l i fe - span of the bu i ld ing

The recove rab i l i ty o f resources con ta ine d in bu i ld ingsa t the t ime o f the i r dem ol i t ion .

The ind i rec t consequences a re ex t remely d i ff i cu l t toq u a n t i t ) a n d p r o b a b l y a r e b e st c h a r a c t e r iz e d as l o s s o feco log ica l cap i ta l [4] .

The work presen ted in th i s paper per ta ins on ly to thed i rec t env i ronmenta l e ffec t s o f bu i ld ing produc t ion andopera t ion . Wi th in th i s f ramework the scope i s fu r therl imi ted to the energy consumpt ion and a i r po l lu t ion fac -tors .

3 . E N E R G Y- R E L AT E D FA C T O R S

Energy re la ted fac tors inc lude a l l t r ans format ions o fe n e rg y in t h e p r o d u c t i o n a n d u s e o f b u il d i n gs . T h o u g hresearch in the mid-1970s c lea r ly dem ons t r a ted tha t s ig -n i f ican t amoun ts o f energy a re requ i red to p rod uce abu i ld ing [5 , 6 ] , energy account ing over the pas t f i f t eenyears has focused a lmos t exc lus ive ly on o pera t iona lenergy use in bu i ld ings and the deve lopm ent o f s t ra teg iesto reduce i t . In the 1990s i t is becoming increasingly

i m p o r t a n t t o r e s um e t h e w o r k o n e v a l u a t i n g t h e e n e rg yfor p roduc ing bu i ld ings and to ex tend i t to emb race ab r o a d e r e n v i r o n m e n t a l a g e n d a .

3.1 Emb odied eplergyA co mple te au d i t o f a bu i ld ing wi l l inc lude the energy

u s e d t o c r e a t e b u i ld i n g m a t e r ia l s a n d c o m p o n e n t s a n d t ocons t ruc t a bu i ld ing , i .e . the embo died energy. Emb odie denergy i s the 'd i rec t and ' ind i rec t energy used tom a n u f a c t u r e , t r a n s p o r t a n d i n s ta l l b u i l d i n g p r o d u c t s .

Di rec t energy is the energy ac tua l ly consu med in thecons t ruc t ion of bu i ld ings . I t r epresen ts the f ina l t rans -p o r t a t i o n a n d i n s t a l la t i o n o f a c o m p o n e n t o r

assembly. D i rec t energy i s a re la t ive ly smal l por t i on o fem bodie d energy. Europea n and U.S . f igures es t imatet h e c o n s tr u c t i o n p o r t i o n t o b e a b o u t 7 - 1 0 % o f t o t a lembodied energy [7, 8] .

Ind i rec t energy represen ts the energy consu med in thep r o d u c t i o n o f b u i l d i n g m a t e r ia l s a n d t h e i r a s so c i a t e dt ranspor ta t ion dur ing process ing . Ind i rec t energy i sthe l a rges t por t ion of embodied energy. I t r epresen tsthe produc t ion of a component exc lus ive of i t s t rans -por ta t io n to and ins ta l l a t ion on s i te .

E m b o d i e d e n e rg y t h u s r e p r e s e n t s t h e c o m p o n e n t o rassemb ly in p lace . How ever. w hen fu l l l i f e -cyc le ana lys i si s unde r taken , e mbo died energy should r igh t fu l ly beex tended to a l so inc lude the energy assoc ia ted wi th m ain-ta in ing , repa i r ing and rep lac ing mate r ia l s and com-ponen ts ov er the l i fe time of the bu i ld ing .

3.2 Energy intensio' vahwsEnergy In tens i ty i s the energy used on ly in the p ro-

duc t ion of a bu i ld ing mate r ia l o r component . I t r ep-resen ts the ind i rec t energy in un i t t e rms e i ther expresseda s e n e rg y / m a s s o r v o l u m e s u c h a s M J k g o r M J m 3 o rener gy /s ta nda rd un i t such as M J / shee t o r b lock e tc .Energy in tens i ty i s a l so ca lcu la ted , f rom s ta t i s t i ca l da ta ,

in M J, $.L imi ted in te rna t iona l research over the pas t 15 years

in the f i e ld o f energy in tens i t i es o f bu i ld ing mate r ia l s hasp r o d u c e d r e a s o n a b l e a g r e e m e n t o n a c c e p t a b l e v a l u es f o rsome m ater ia l s , bu t i t has a l so produ ced som e s ign i f ican td i ffe rences fo r o thers ( see Table I ) . There a re severa lreasons fo r these d i ffe rences :

S y s t e m b o u n d a r i e s Da ta source re l i ab i l i ty In te rna t iona l d i ffe rences Therm al energy conten t o f feeds tock mate r ia l s .

3.2.1 System boundaries.There i s no abso lu te o r cor-

rec t energy in tens i ty o f a mate r ia l [9 ] . A s ta ted va lue i s ad i r e c t f u n c t i o n o f w h a t w a s i n c lu d e d a n d w h a t w a se x c l u d e d f r o m i t s d e r iv a t i o n . A n e x a m p l e o f t h e i m p o r-tance of sys tem boundar ies i s read i ly found in com-p a r i s o n s o f a l u m i n u m . F i g u r e s f o r t h e C a n a d i a n a l u m i -num indus t ry in 1976 ind ica te a va lue of 236 .3 MJ /kg[10]. Al thou gh subs tan t ia l e ffic iency impro vem ents havebeen m ade s ince 1976 the f igure is s t il l r eason able tod ayi f one inc ludes the energy cos t s o f min ing , conc ent ra t ingand sh ipp ing ore , mos t o f which i s p rod uced in the Car ib-b e a n . T h e C a n a d i a n f i g ur e c o m p a r e s w e l l w i t h t h o s e o fSwitzerland [11], Finland [12], and the U.S. [13] . NewZeala nd s tud ies [14] howe ver p lace a lum inum a t on ly 145

M J / k g b a s e d o n s o m e l i m i te d r e p o r t in g b y i n d u s t r y a n dsome ana lys i s o f the p rocesses . New Zea land ' s o re , l ikeCa nad a ' s , i s a l so impor te d , bu t na t io na l s ta t i s t ics on thef lo w o f e n erg y a n d m a t e r i a l s in t h e a l u m i n u m i n d u s t r yc a n n o t b e d i s a g g r e g a t e d fr o m o t h e r n o n - f e r r o u s m e t a ls .

Assessm ent o f energy in tens i ty f igures mus t , the re fore ,b e a c c o m p a n i e d b y d e f i n i ti o n s a n d c l e a r b o u n d a r i e s . T h ecommonly accep ted l imi t inc ludes ana lys i s o f a l l o f thei n d u s t r i a l p r o c e s s e s o f e x t r a c t i o n , t r a n s p o r t a t i o n a n dprocess ing of a m ate r ia l . Th is l imi t typ ica l ly cap turesa b o u t 9 0 % o f t h e g ro s s e n e rg y r e q u i r e m e n t s o f a m a n u -fac tured i t em [15] , bu t there may be imp or tan t excep t ionsto th i s . For example in a case where h ighway t ranspor t

o f r a w m a t e r i a l s i s a k e y ( o r d e d i c a t e d ) c o m p o n e n t o f am a n u f a c t u r i n g s y s t e m , a p o r t i o n o f t h e e n e rg y c a p i t a land main tenance energy for the h ighways and veh ic lesshould be inc luded , and ma y s ign i f ican t ly a ffect theana lys i s .

The choice o f l evel o f ana lys i s depen ds on the ob jec t iveof the ana lys i s , the ava i lab le da ta and the type of eva lua-t i o n m e t h o d s . I d e a l l y th e s y s t e m b o u n d a r i e s m u s t i n c l u d ethe fo l lowing in o rde r to reaso nably re f lect the embo diedenergy of m ate r ia l s and assembl ies :

. The energy requ i rem ents fo r ex t rac t ion , benef ic ia t iona n d t r a n s p o r t a t i o n o f r a w m a t e r i a ls .

The energy requ i rements fo r p r im ary process ing such

as smel t ing , mi l l ing , d ry ing , machin ing , chemica lsyn thes i s e tc . as wel l as the t ranspor ta t ion energyto the second ary s tages .

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Environm ental Audi t ing for Bui ld ing Con st ruction 2 5

Table 1. Energy intensities of selected materials (M J/kg)

Material Canada U.S. N.Z. S ~ i t z . Finland

MetalsAluminum 236.3* 192.0 14 5. 0 261.7 189.0,Nickel 168.3 58.0* 468.0tSteel (general) 25.7* 39.0* 32.0* 27.7tZinc 64.1 68.4* 68.4* 43.2t

Non-metallic mineralsGlas s (shee t) 10.2 , 19.8 16.7 21.6* 16.5+Gy psu m 7.4 1 7.2* 1.4+Brick 4.9:~ 5.8* 3. l't 2.8tGlas s wo ol 22.3:[; 14.0 18.0t 23.4 t

Cement productsCe me nt 5.9:~ 9.4* 7.4* 4.9 ] 4.9 tCon crete 1.2+ 1.3 2.0* 0.9tM or ta r 2.2:1: 1.4 t

PlasticsPolyethylene 87.0~ 49.3tPo lys tyr en e 105.0+ 122.8 t 118.8+Pain t (wa ter base ) : dry 76.0:[: 77.7* 76.7 t

* Mid 1970s data,f Early 1980s data.++Mid 1980s data.

The energy requi rements for secon dary fabr ica t ion ,assembly e tc ., wh ere appl icab le .

The therm al energy poten t ia l o f the raw mater ia lfeedstock if i t was to be used as a fuel ( this appliesspecif ical ly to petroleum based products) .

A more de ta i led ana lys i s wi l l a l so inc lude the energyc o s t o f p r o d u c i n g e n e rg y. F o r e x a m p l e t h e e n e rg y c o s to f p e t r o le u m r e fi n in g i n C a n a d a i s 11 .5 % o f p r o d u c t i o n

[16] . As the use of bu i ld ing mater ia l s wi th recyc led con-ten t expands there mus t a l so be c red i t s appl ied to theaudi t to re f lec t the energy and resource cap i ta l sav ings aswell as po l lu t ion reduc t ions f rom the use of recoveredmaterials .

There a re prac t ica l l imi ta t ions howev er, par t icu la r ly inrap id ly emerg ing a reas such as recyc l ing where re l iab ledata is difficult to find.

3.2.2 Data sources and reliability.T h e d a t a s o u r c e s f o renergy in tens i ty ana lys is a re a l so problemat ic . The re a ret h r ee m a i n s o u r c e s o f e n e rg y a n d p r o d u c t i o n d a t a f o rmo st indus t r ies , thou gh a l l a re no t necessar i ly ava i lab le .

These a re : N at iona l s ta t i s t ics : Reco rds comp i led by na t iona l

agenc ies f rom indus t ry repor t ing . Process ana lyses : Engineer ing ana lyses of p rocesses

accou nt ing for energy use s tep-by-s tep . Indu s t ry s ta t is t ics : Record s kept in te rna l ly by p lan ts

or compi led by indus t ry assoc ia t ions .

E a c h d a t a s o u r c e h a s i ts s h o r t c o m i n g s i n a p p l i c a t io n t oe n e rg y i n t e n s i t y a n a l y s i s a n d m a y n o t a l o n e p r o d u c erel iable results . By using several types of analysishowever, on e can judge the re l iab i l ity of resu l ts th ro ughcom par in g the cons is tency o f figures der ived f ro m d i ffe r-

en t da ta sources .

3.2.3 International differences.There a re severa l

imp or tan t fac tors which a l so a ffec t in te rna t iona l f iguresand, to some extent , even national f igures. These are :

Fue l type : The mos t reg iona l ly ava i lab le and in-expensive fuel source is l ikely to be used, withinregula tory boundar ies . For example , v i r tua l ly a l l o fCanada's aluminum is produced with hydroelectr ici ty,while prod uct ion in the U.K . uses some thermal e lec-tr ici ty. This leads to ve ry signif icant increases in gros senergy input th rough the thermal convers ion lossese n c o u n t e r e d i n t h e U . K .

Raw mater ia l s impor t s : Some indus t r ies re ly onimpor ted raw mater ia l s for which the overseas ex-tract ion costs may be diff icult to assess. The trans-por ta t ion fac tor a l so becomes more s igni fican t. Again ,in the a luminum indus t ry, Canada ' s p roduct ion re l ieso n o r e i m p o r t s f r o m J a m a i c a w h e r e s o m e o f t h epr imary process ing a l so takes p lace . Energy cos t sand pollu t ion f igures are diff icult to get .

Di ffe ren t accou nt ing meth ods : For example , as no tedb e f o r e i n N e w Z e a l a n d , m a n y n o n - f e r r o u s m e t a lstat is t ics are lumped together making i t diff icult tod is t inguish copper f rom a luminum, e tc . A s imi la rprac t ice i s used in Ca nada .

3.2.4 Energy content o f feedstocks.A n o t h e r p r o b -lemat ic dec is ion i s the inc lus ion of the thermal energyconten t o f the feeds tock in the gross energy requi rement .For those mater ia l s which a re pe t ro leum based i t seemsclear tha t the thermal va lue of the i r feeds tocks , had theybeen burned as fue ls , mus t reason ably be inc luded . How -ever should one use the i r theore t ica l thermal va lue , o rthe i r ac tua l va lue when burne d in a process of averageeff ic iency? Many researchers have opted for the theo-re t ica l va lue a nd th i s expla ins the re la tive ly h igh energyintensi ty fo r mos t synthetic resins [17].

3.3 Direct environ mental consequences of e ner#y ,tseEnergy use en ta i l s emiss ions of carbo n d ioxide , par-

t icu la tes , ox ides of su lphur, ox ides o f n it rogen , car bon

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26 R . J . C o l e a n d D . R o u s s e a u

m o n o x i d e a n d u n b u r n e d h y d r o c a r b o n s f ro m c o m b u s -t ion . The charac te r i s t i cs and a i r po l lu t ion consequencesof these emiss ions a re :

C O : - - o f p r i m a r y c o n c e r n as a g r e e n h o u s e g as . P a r t i c u l a t e s - - p r i m a r i l y, c a r b o n , w i t h a r a n g e o f

a s s o c i a te d m i n e r a l a n d m e t a l c o m p o u n d s , p r i m a r i l y aloca l a i r po l lu tan t .

SO_, - -urban and reg iona l e ffec ts bo th as an a i r po l -lu tan t and precu rsor to ac id ic p rec ip i ta t ion .

N O ~ - - u r b a n a n d r e g i o n a l e f fe c ts b o t h a s a n a i r p o l -l u t a n t, p h o t o c h e m i c a l o x i d a n t a n d p r e c u r s o r t o a c i d icprec ip i ta t ion .

C O - - o f p r i m a r y c o n c e r n a s a l o c al a i r p o l lu t a n t . H C - - a b r o a d r a n g e o f fu g i ti v e v o l a t i le o rg a n i c c o m -

p o u n d s f r o m u n c o m b u s t e d f u el , p r i m a r i l y o f c o n c e r na s p h o t o c h e m i c a l o x i d a n t s .

The p ropo r t ion s o f these vary s ign i f ican t ly wi th thetype of fue l and the com bus t io n e ff ic iency. Table 2 show styp ica l emiss ions expressed as g, MJ for com mo n s ta t ion-

a r y ( n o n - t r a n s p o r t a t i o n ) u s es o f c o n v e n t i o n a l f u e ls[18-21] :

3.4 Air emiss ion indexOpe ra t ing energy au di t s have the re la t ive s impl ic i ty o f

be ing reduc ib le to a com mo n ene rgy un i t s . I t is c lea r lymo re d i ff i cu l t to c om pare the re la t ive e ffec ts o f d i ffe ren tpo l lu tan t s wi th in a par t i cu la r medium (e .g . a i r ) as wel las be tween m edia (e .g . a i r, wa te r an d so i l ) . Severa l Euro-p e a n r e s e a r c h e r s e m p l o y a n a c c o u n t i n g s y s t e m b a s e d o nvolume equ iva len ts in which accep ted l imi t ing va lues a reu s e d t o d e t e r m i n e t h e v o l u m e o f a i r w h i c h i s p o l l u t e dwi th a ce r ta in con tam inan t up to a l imi t ing va lue [22].

T h e r e s u l t i n g p o l l u t e d o r c o n s u m e d v o l u m e s o f a i r a r et h e r e fo r e e q u i v a l e n t u n it s a n d c a n t h e n b e c o m b i n e d a n dused as s imple ind ices to ev a lua te the degree o f env i ron-m e n t a l a i r p o l l u t i o n a s s o c i a t e d w i t h t h e m a t e r i a l o r c o m -p o n e n t . F o r e x a m p l e , w h e r e th e o u t p u t o f S O , i s y m gand the a dmiss ib le l eve l o f SO, . i s x mg /m 3 of a i r, i tc a n b e t r a n s f o r m e d i n t o m 3 o f a i r c o n t a m i n a t e d t o t h ea l lowab le l imi t by :

U s e d v o l u m e o f a i r =y / x (m 3)

A cr i t i ca l dec i s ion wi th in th i s app roac h to agg rega t inga i r con taminants i s the cho ice o f accep tab le l imi t s [23] .Legis la ted l imi t s , which a re inev i tab ly der ived th roughcompromise ra ther than d i rec t hea l th c r i t e r ia , can re la teto e i ther emiss ion ra tes f rom the p lan t o r, more s t r in -gen t ly, to ambien t a i r qua l i ty. In the work repor ted int h is p a p e r. C a n a d i a n a m b i e n t a i r q u a l i t y s t a n d a r d s h a v e

been chosen prov is ion a l ly un ti l in te rna t io na l c r i t e r ia t \~ re n v i r o n m e n t a l a u d i t i n g h a v e b e e n a g r e ed u p o n .

The vo lume equiva len ts approach i s su i tab le fo r touro f t h e m a j o r a i r c o n t a m i n a n t s w h i c h a r e u s u a l ly r e g u l a te di n n a t i o n a l a m b i e n t a i r q u a l i t y p r o g r a m s : S u s p e n d e dp a r t i c u l a te s ( f ro m c o m b u s t i o n ) , S O : , N O , a n d C O , T h eambien t a i r qua l i ty ob jec t ives se t by ' theCanadian

Envi ronmenta l P ro tec t ion A c tare p resen ted in Table 3 .Al though the concent ra t ions spec i f ied in theNat iona l

Ambien t Ai r S tandardsare very low and thus y ie ld veryh i g h v o l u m e s o f c o n t a m i n a t e d a i r , th e y d o p r o v i d e ausefu l re la t ive bas i s fo r weigh t ing the impor tance ofd i ffe ren t a i r po l lu tan t s . The impor tan t c r i t e r ia i s c lea r lythe re la t ive accep tab le concent ra t ions o f the var iousc o n t a m i n a n t s .

4 . N O N - E N E R G Y R E L AT E D FA C T O R S

Energy re la ted emiss ions account fo r on ly a por t io n ofovera l l env i ronm enta l e ffec ts f rom an indus t r ia l p rocess .

Process emiss ions re fe rs to those emiss ions which a rethe d i rec t resu l t o f sm el t ing , k i ln ing , d i s t il l ing , d ry ing .gr ind ing , cas t ing and a l l o ther indus t r ia l p rocesses exc lus -ive o f fue l combus t ion . These inc lude bo th the sameca tegor ies o f emiss ions assoc ia ted wi th fue l combus t ionas wel l as a very wide range of o ther par t i cu la te andg a s e o u s c o m p o u n d s . T h e s e a d d i t i o n a l c o m p o u n d s e a c hhave the i r own charac te r i s t i cs and en vi ronm enta l conse-quences , rang ing f rom re la t ive ly ben ign dus t s f rom o ver-burde n rem oved f rom mines , to h igh ly tox ic ha logenc o m p o u n d s a n d h e a v y m e t a l s .

In some cases , such as the cement indus t ry, the energyemiss ions a re the mos t s ign i f ican t fac tor in the overa l l

assessment , because the p rocess emiss ions inc lude on lysome du s t s (which a re re la t ive ly low r i sk) and some w ate rcontamina t ion (mos t ly wi th low r i sk so l ids ) . Meta l ssmel t ing , on the o ther hand , p roduces a wide range ofa i r emiss ions such as su lphur ox ides f rom ore redu c t ion ,and f luor ides , which a re h igh envi ronm enta l s t ressors .

4.1 Quan t i fvin 9 non-ene ryy related emissionsNon -energ y re la ted a i r emiss ions a re re la t ive ly easy

to charac te r ize wi th some accuracy, bu t a re d i ff i cu l t toq u a n t i f y. F o r e x a m p l e d u s t s o f p r e d i c t a b l e t y p e s a r einev i tab ly produc ed by d ry mi l l ing processes , bu t vary in gd e g r e es o f d u s t c o n t r o l s a r e i n p l a c e a n d v a r y i n g a m o u n t sof t rapped dus t s a re re tu rned to the p rocess . Da ta i sa v a i l a b l e o n u n c o n t r o l l e d e m i s s io n s [ 2 4 ] w h i c h a r eder ived f rom process s tud ies , bu t da ta on the e ffec t ivenessand app l ica t ion of con t ro l measures i s more d i ff i cul t to

Table 2. A ir emission by fu el and use

CO , Part. SO: NO , CO HCFuel use (g/MJ) (g/M J) (g/M J) (g/M J) (g/M J) (g MJ)

Distillate oil (conventional). 0.5% S 72.1 0.00 65 0.23 0.2 0.0 15 0.00 20Natural gas 50 .5 0 .0 0 6 0 .0002 0 .09 0 .007 0 .0080Coal (bituminous), 3% S 87.5 0.11 0.85 0.27 0.0 60 0.0 03 0Coal fired electricity 248.9 0.31 2.36 0.75 0.1 70 0.0 08 0

Canadian electricity* 52.3 0.07 0.50 0.16 0.0 40 0.0 01 7* Electricity productio n: Canadian split (62% hy dro, 20.1% coal, 16% thermonuclear; 0.5% gas and 1.4%

oil). Based on 35% overall efficiency for thermal production.

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Env i ronm en ta l Aud i t i ng fo r Bu i ld in9 Cons t ruc t ion 27

Table 3. Na tional Am bient Air Qu ality Objectives

Particulates SO: NOx CO

Concentration Limit (g'm~) 0.00012 0.0 00 03 0.0 00 06 0.006

f ind [25 , 26]. There a re a l so rap i d deve lopm ents in p lan te m i s s io n s c o n t r o l s w h i c h a r e d r i v e n b y r e g u l a ti o n . F o re x a m p l e Statistics Canadar e p o r t s t h a t c o p p e r a n d z i n csmel t ing a re , by fa r. the l a rges t indu s t r ia l sources o f SO~e m i s s i o n s i n C a n a d a [2 7] , h o w e v e r p l a n t i m p r o v e m e n t sa re expec ted to a l t e r tha t p ic tu re in a very shor t t ime .

Other d i ffe rences , such as the compos i t ion of rawmater ia l s , a l so in t roduc e var iab les which a re d i ff i cu l t toquant i fy. O ne br ick k i ln , fo r example , wi l l p rod uce m ark-e d l y d i f f e r e n t e m i s s i o n s f r o m a n o t h e r d u e t o t h e c o m -pos i t io n of the c lay.

T h e c h a r a c t e ri s t ic s a n d a i r p o l l u t i o n c o n s e q u e n c e s o fthese non-energ y re la ted emiss ions a re :

P a r t i c u l a t e s - - a v e r y b r o a d r a n g e o f c a r b o n , m i n e r a la n d m e t a l c o m p o u n d s e a c h w i t h s p e ci fi c u r b a n a n dregional air and soi l effects .

S O z - - u r b a n a n d r e g i o n a l e f fe c ts b o t h a s a n a i r p o l -l u t a n t a n d p r e c u r s o r t o a c i d ic p r e c i p i t a t io n .

C O - - o f p r i m a r y c o n c e r n a s a lo c a l a i r p o l l u t a n t . H C - - a b r o a d r a n g e o f v o l a t i le o rg a n i c c o m p o u n d s ,

m a n y o f w h i c h a r e e n v i r o n m e n t a l t o x i n s a s w e l l a sp h o t o c h e m i c a l o x i d a n t s .

T h e n a t u r e , e x t e n t a n d p r o p o r t i o n s o f t h e s e e m i s s i o n sare spec i fic to each o f severa l thousan d processes wi th inthe mate r ia l s indus t r ies .

5. C O M P O N E N T S O F A I R E M I S S I O N S I N D I C E SA n u n d e r l y i n g p r e m i s e o f t h e w o r k p r e s e n t e d i n t h i s

p a p e r i s t h a t t h e l a rge b o d y o f c o m p l e x d a t a o n t h e e n e rg ya n d e n v i r o n m e n t a l i m p l i c a t i o n s o f p r o d u c i n g b u i l d i n gm a t e r i a l s m u s t b e r e d u c e d t o m a n a g e a b l e t e r m s i n o r d e rto be usefu l in env i ro nm enta l aud i t ing of bu i ld ings . Som ed a t a c a n b e r e a d i l y r e d u c e d t o a c o m m o n u n i t w h i leo t h e r s c a n n o t , a n d a r e m o r e a p p r o p r i a t e l y l e ft d is c r e te .Given the commonal i t i es and d i ffe rences o f energy-re la ted and non-energy re la ted emiss ions , the fo l lowinga p p r o a c h h a s b e e n a d o p t e d f o r s u m m a r i z i n g t h e m o n ac o m m o n b a s i s .

5.1 Ca rbon dioxideCO., re lease f rom fue l com bus t ion ca n be s imp ly sum-

m a r i z e d a s th e m a s s o f C O : c r e a t e d b y t h e p r o d u c t i o n o fa u n i t o f b u i l d i n g m a t e r i a l . C o n c e n t r a t i o n l i m i ts a r e n o tappl icab le in the case o f CO: , so i t is s imply presen ted ast h e g r e e n h o u s e g as c o n t r i b u t i o n o f t h e m a t e r i a l o rassembly.

5.2 Air em ission indexT h e f o l l o w i n g c a n b e r e d u c e d t o a c o m m o n i n d e x

b y t h e a p p l i c a t i o n o f t h e v o l u m e e q u i v a l e n t s m e t h o dd e s c r i b e d i n 3 .4 u s i n g A m b i e n t A i r Q u a l i t y S t a n d a r d s i nTable 3 :

P a r t i c u la t e s f r o m f ue l c o m b u s t i o n S O , f r o m b o t h e n e rg y a n d n o n - e n e rg y r e l a t e d p r o -

cesses

NO~ f rom energy re la ted processes

C O f r o m b o t h e n e rg y a n d n o n - e n e rg y r e l a te d p r o -cesses.

The Ai r Emiss ions Index presen ted in th i s work i s thea g g r e g a t e o f t h e v o l u m e e q u i v a l e n t s g e n e r a te d f r o m t h efour emiss ion ca tegor ies above . Given tha t the s ig -n i f icance of an a i r po l lu t ion index i s no t in the ac tua lun i t s (m 3 for example) u sed , bu t in com par i son s be tweent h e m a g n i t u d e o f t h e i n d e x d e r i v e d f o r v a r i o u s m a t e r i a lso r a s s e m b l i e s , t h e y h a v e b e e n r e d u c e d b y a n a r b i t r a r yfac tor o f 10- '. Th is g ives the Ai r Em iss ions Index a morem a n a g e a b l e s c al e .

5.3 Other air pollution indicesOther a i r po l lu tan t quan t i t i es a re mo re d i ffi cu l t to con-

ver t in to a com mo n index because they compr i se a co llec -t i o n o f a n u m b e r o f d i ff e r en t c h e m i c al c o m p o u n d s w i t hwide ly vary ing envi ronmenta l r i sks , each of which hasto be eva lua ted separa te ly. At th i s s tage in the deve lop-m e n t o f t h e a i r p o l l u t i o n i n d i c e s t h e s e a r e g r o u p e dtoge ther in two ca tegor ies and presen ted in assoc ia t ionwi th the f ina l Ai r Emiss ions Ind ex . The c a tegor ies a re :

Par t i cu la tes f rom non-energy re la ted processes F u g i t i v e h y d r o c a r b o n s f r o m b o t h e n e rg y u se a n d

non-energ y processes .

F u r t h e r d e v e l o p m e n t o f t h e a i r p o l l u t i o n i n d i c e s w i l ll e a d t o a m o r e d e t a i l e d e v a l u a t i o n o f t h e e n v i r o n m e n t a limpac t o f the var ious par t i cu la te emiss ions and fug i t iveh y d r o c a r b o n s t h r o u g h a s s e ss i n g th e i r v a r i o u s c h e m i c a lca tegor ies and u t i l i z ing app l ica b le conce nt ra t ions fo reach . Once th i s i s accompl i shed they wi l l be in com-p a r a b l e t e r m s t o t h e A i r E m i s s i o n s I n d e x a n d c a n b eadded to i t .

6. E N E R G Y A N D A I R P O L L U T I O N A U D I T S O FWA L L A S S E M B L I E S

Mater ia l se lec t ion in the bu i ld ing indus t ry i s ra re ly

m a d e i n i s o l a t io n . M a t e r i a l s u s e d i n b u i l d i n g s c an o n l yr e a s o n a b l y b e c o m p a r e d i n t h e c o n t e x t o f t h e i r p e r -f o r m a n c e i n b u i l d i n g a s s e m b l i e s . F o r p u r p o s e s o fe n v i r o n m e n t a l a u d i t i n g , o n e m u s t i n v a r i a b l y c o m p a r ea l te rna t ive bu i ld ing assembl ies o ffe r ing s imi la r per-forma nce charac te r i s t i cs [28] .

F i g u r e 1 s h o w s s e c t i o n s o f f o u r n o n - l o a d b e a r i n g w a l lassembl ies used in commerc ia l cons t ruc t ion which a l la t t a i n a n a p p r o x i m a t e R S I = 3 .6 m 2 D e g C / W :

W al l # 1 i s a p recas t concre te pane l c lad wal l wi thr i g id p o l y s ty r e n e b o a r d i n s u l a t i o n a n d g y p s u m b o a r dinter ior f inish.

W al l # 2 i s b r ick c lad cons t ruc t ion wi th l igh tweigh ts tee l f raming conta in ing f ib reg lass insu la t ion andgypsum board f in i shes .

W al l # 3 i s an ex te r io r insu la t ion and f in ish sys tem

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28 R . J . C o l e and D . Rous seau

M a t e r i a l M a s s / m 275mm precast concrete panel 180.0 kg/m 2Steel reinforcement 7.2Steel anchors (galvanized) 3.0Weather barrier (polyolefin) 0.07Steel flashings (galvanized) 0.5Steel furrings (galvanized) 2.575ram polystyrene insu l, board 3.815mm interior gwb. (finished) 11.83 coats latex pain t (0.3 litres) 0.4TOTAL 209.3 kg/m2

.I ~ __

i

. ,

i U ~ m

W a l l # 1

M a t e r i a l M a s s / m 2lOOmm face brick (clay) 165.0 kg/m2Mortar 28.0Steel shelf ang le (strut. steel) 4.0Steel ties and screws (galvanized) 1.0Wea ther barrier (polyolefin) 0.07Sheathing (wp . gwb.) 9.8150ram steel studs (galvanized) 10.0150ram fiberglass batt insulation 5.4Vapour barrier (polyethylene) 0.0512.5ram interior gwb. (finished) 10.03 coats latex pain t (0.3 litres) 0.4TOTAL 233.8 kg/m2

[,

>-< . . . j

.

i / i : : i : ?

Wa l l 2

M a t e r i a l M a s s / m 22 coats acrylic rood. stucco 6.0 kg/m2Glass fiber mesh 0.819ram polystyrene insul, board 0.6Steel fasteners and flashings (galv.) 1.0Weather barrier (oolyolefin) 0.07Sheathing (wp.gwb.) 9.8100ram steel studs (galvanized) 6.9100ram fiberglass batt insulation 3.6Vapour barrier (polyethylene) 0.0512.5ram interior gwb. (finished) 10.03 coats latex paint (0.3 litres) 0.4TOTAL 39.3 kg/m2

Wa l l 3

M a t e r i a l M a s s / m 2Porcelain steel, or 9.6 kg/m 2Anodized aluminum, or 5.36ram glass sheet 16.0Aluminum mullion/rail/spandrel 22.0Wea ther barrier (polyolefin) 0.07150ram steel studs (galvanized) 10.0150ram fiberglass batt insulation 5.4Vapour barrier (,polyethylene) 0.0512.5ram interior gwb. (finished) 10.03 coats latex pain t (0.3 litres) 0.4TOTAL 57.6 kg/m2 (Steel)

53.3 kg/m2 (Alum.)64.0 kg/m2 (Glass)

Fig. 1. Sections of non -loa d

. .

bearin g wall assemblies used in comm ercial construction .

Wa l l 4

u s i n g a c r y li c st u c c o , p o l y s t y r e n e b o a r d i n s u l a t i o n a n dl i g h t w e i g h t s te e l f r a m i n g w i t h g y p s u m b o a r d f i n is h .Wa l l # 4 i s a n a l u m i n u m c u r t a i n w a l l s y s te m w i t ht h r e e a l t e r n a t i v e c l a d d i n g p a n e l s : p o r c e l a i n s t e e l,a l u m i n u m , a n d g l a s s . I t i n c o r p o r a t e s f i b r e g l a s s i n s u -

l a t i o n a n d g y p s u m b o a r d i n t e r i o r fi n is h .

Ta b l e 4 p r e s e n ts t h e t o t a l m a s s / m 2 a n d s u m m a r ye n e rg y u s e a n d a i r p o l l u t i o n c h a r a c t e r is t i c s f o r t h efour w a l l a s sembl ies in F ig . 1 .

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E n v i r o n m e n t a l A u d i t i n g f o r B u i l d i n g C o n s t r u c t i o n

Table 4. Environmental characteristics of different wall assemblies

29

Energy Emissions

Part. :Total Ref. Nat. ,Air Non-

Mass en er gy Feedst. Pet. Gas Coal El ect . Other CO: Emi ss. Ene rgy HCkgm-' MJ/m 2 MJ:m z MJ/m: M J/m: M J/m: MJ/m 2 MJ/m 2 g Index g g

Wall I 209.3 1148 317 125 254 246 169 37 52200 2810 1230 310Wall 2 233.8 1799 115 221 930 214 297 22 90260 2850 2230 560Wall 3 39.3 929 300 90 263 95 166 16 36700 1610 420 220Wall 4 : steel 57.6 6235 42 691 543 236 4715 8 113200 7710 630 370Wall 4: alum. 53.3 7263 42 766 4l l 170 5866 8 110700 7640 560 260Wall 4 : glass 64.0 5974 42 639 510 120 4656 8 94500 7240 580 260

Notes: Total Energy;energy of wall assembly including feedstock energies. Feedstock: gross thermal content of petroleum used in feedstocks for synthetic resins. Fuels; fuel use, by type, used in production of the component materials. C02 ; total mass of CO., created by fuel combustion in the production of the assembly. Air Emissions Factor:mass of particulates SO,, NO~, and CO, divided by their respective Canadian national ambient air quality

maximum concentration limits. Non-energy related particulates ;summary, of all particulates from processes. H C ; all fugitive hydrocarbons from both energy and non-energy related processes.

The energy summary includes :To t a l The total embodie d energy of 1 m 2 of wallE n e rg y : assembly includ ing feedstock energies.F e e d s t o c k: The feedstock energy represents the gross

thermal content of petroleum used in syn-thetic resins. Feedstock energy is notincluded in the calculations of emissionsfrom energy use.

Fue l s : These represent fuel use by type con-sumed in production of the componentmaterials. Other fuels represents mainlythe wood waste used in paper productio nfor gypsum wall board and the waste rub-ber, wood etc. bu rne d in cement kilns.

are presented according to the fourhe emissionscategories :

C 0 2 :

A i rEmis s ionsIndex :

N o n - e n e rg yre l a t edpa r t i cu l a t e s :H C :

A summary of the mass of CO2 createdby fuel combusti on in the production ofthe assembly.Generated by summing all particulatesand NO~ from energy use, SO2, and COfrom both energy and non-energy proces-ses, and dividing them by their respective

Canadian national ambient air qualitymaxim um concen tration limits (Table 3).A su mmary of all particulates from pro-cesses based on the emission factors andtypical contr ol efficiencies from the da ta.All fugitive hydrocarbons from bothenergy an d non- ener gy related processes,also incorporating typical controlefficiencies, These reflect emissions fromboilers, coal coking, polymer production,degreasing etc. Both particulates andHCs represent far too wide a range ofchemical compounds to readily convert

to air emissions factors at this time, andare therefore presented separately.

Emissions from fuel use are calculated from the fuel

factors given in Table 2 except the electricity used inprimary aluminum production which is assumed to beall hydro in Canada.

6.1 Key obse rva t ionsThe following observations can be made :

It is often assumed that low mass constructionimplicitly has low en viro nmen tal consequences. Thiscomparison shows that, although the lowest massassembly (Wall 3) does indeed demons trate thispoint, others with similar mass (Wall 4) have energyand air emissions that are greater by an order of mag-nitude.

Even with in the family of non-metalli c mineralmaterials with similar mass, there are distinct differ-ences in energy intensity and CO_, emission. Wall 1,for example, entails the emission of 52.3 kg of CO.,.Wall 2, despite having similar mass, entails 90.25kg. However the Air Emissions Index of these twowall assemblies is almost identical.

The very high embodied energy figures for the wallswhich are largely composed o f steel and al umi num arealso reflected in pr opor tion ally higher COz pro duct ion

and Air Emissions Index. However, what is notreflected in these figures is the inherent capacity toeventually reduce a significant portion of futureenviron mental costs th rough recycling.

Altho ugh the selection of a glass cladding panel inWall 4 has little effect on mass, there are distinctreductions in embodied energy, CO: emission and theAir Emissions Index.

7. CONCLUSION

This paper has presented key characteristics ofenviron mental auditing as well as examples of audits inuse. It is clear that embodied energy is only one part ofenvironmental auditing: environmental emission fromboth en ergy use by fuel type and non -energ y related

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3 0 R . J . C o l e a n d D . R o u s s e a u

p r o c e s s e m i s s i o n s a r e . i n m a n 5 c a s e s , m o r e s i g n i f i c a n ti n d i c a t o r s o f t h e e n v i r o n m e n t a l c o s t o f m a t e r i a l s .

E n v i r o n m e n t a l a u d i t s , i n c l u d i n g e n e rg y u s e f o rm a t e r i a l s p r o d u c t i o n a n d i n s t a l l a t i o n a s w e l l a s a ir p o l -l u t i o n i n d i c e s c a n p r o v i d e c r i t e r i a f o r d e s i g n d e c i s i o n sw h e n c h o o s i n g m a t e r i a l s a n d a s s e m b l i e s o f f e r i n g s i m i l a rp e r f o r m a n c e f o r a g i v e n a p p l i c a t i o n . G e n e r a l i t i e s a b o u t

t h e e n v i r o n m e n t a l i m p a c t o f m a t e r i a ls c h o i c e s d o n o ts t a n d u p w e l l d u e t o t h e d i st i n c t a n d m a r k e d l y d i f f e r e n te n v i r o n m e n t a l a t t r i b u t e s o f t h e f a m i li e s o f m a t e r i a l s u s e d

f o r c o m p a r a b l e a p p l i c a t i o n s , e .g . n o n - m e t a l l i c m i n e r a l sa r e f u n d a m e n t a l l y d i f f e r e n t f r o m m e t a l s .

Ackno wledgem ents--Funding for on-going research is providedby an operat ing grant f rom The Natural Sciences and Engin-eer ing Research Counci l of Canada (NSE RC). The authors a lsowish to acknow ledge the research assistance of Beate Nem eth-Winther, Rober t Boyd and Gary Helps , and extend th isacknow ledgemen t to Dr Niklaus K ohler a t LESO. Swiss FederalInstitute of Tec hno logy Lausanne. for offering direction in theform ative stages o f the project.

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