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Building energy analysis - a look into the future
Barakat, S. A.
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Building Energy Analysis
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A Look
into the Future
by S.A. Barakat
ANALYZED
Reprinted from
Third International Congress on Building
Energy Management, ICBEM '87
Lausanne, Switzerland, Sept. 28- Oct. 2,1987
Vol. I, p. 90-101
(IRC Paper No. 1521)
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NRCC
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L'auteur dCcrit les recents dCveloppements et les tendances
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B U I L D I N G ENERGY ANALYSIS
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A LOOK INTO THE FUTURE S.A. B a r a k a t I n s t i t u t e f o r R e s e a r c h i n C o n s t r u c t i o n N a t i o n a l R e s e a r c h C o u n c i l Canada ABSTRACT Recent d e v e l o p m e n t s and f u t u r e t r e n d s i n b u i l d i n g e n e r g y a n a l y s i s t e c h n i q u e s and d e s i g n t o o l s a r e d i s c u s s e d i n l i g h t of p a p e r s p r e s e n t e d a t ICBEM'87 s e s s i o n on B u i l d i n g P l a n n i n g and D e s i g n T o o l s . The p r e s e n t a t i o n s c o v e r b o t h d e t a i l e d and s i m p l i f i e d t o o l s , and t h e i r u s e i n t h e a n a l y s i s of e n e r g y c o n s e r v a t i o n s t r a t e g i e s and t h e development of s i m p l e r e n e r g y c o n s e r v a t i o n g u i d e l i n e s . P r e s e n t a t i o n s r e l a t e d t o c a s e s t u d i e s on e n e r g y s a v i n g s i n p r a c t i c e , a s w e l l a s o c c u p a n t i n t e r a c t i o n , a r e a l s o summarized.1. THE NEED FOR ENERGY ANALYSIS
F o r t h e p a s t few d e c a d e s , t h e r e h a s been c o n s i d e r a b l e i n t e r e s t i n modeling and a n a l y s i s of t h e t h e r m a l b e h a v i o u r of b u i l d i n g s , i n o r d e r t o e s t i m a t e t h e i r e n e r g y r e q u i r e m e n t s a s w e l l a s t o p e r m i t s i z i n g a p p r o p r i a t e
h e a t i n g and c o o l i n g s y s t e m s t o m a i n t a i n t h e r m a l c o m f o r t . A'lthollgh a number , ~ f e a r l y manual methods a r e s t i l l i n u s e , c o m p u t e r i z e d methods i n t r o d u c e d i n t h e p a s t t w e n t y y e a r s have s t e a d i l y i n c r e a s e d i n a v a i l a b i l i t y , c o m p l e x i t y , s p e e d , f l e x i b i l i t y and more r e c e n t l y ( d u e t o t h e i n t r o d u c t i o n of m i c r o c o m p u t e r s ) , e a s e of u s e . I n i t i a l l y i n s p i r e d by a r e s e a r c h d r i v e t o g a i n b e t t e r u n d e r s t a n d i n g of a p a r t i c u l a r t h e r m a l p r o b l e m , e n e r g y a n a l y s i s and m o d e l i n g have l e d t o recommendations and g u i d e l i n e s f o r c o n s t r u c t i o n p r a c t i c e , i n s u l a t i o n
s t a n d a r d s
,
e n e r g y c o n s e r v a t i o n measures and n o v e l d e s i g n s of e n e r g y s y s tems ( 1 ) . D e s p i t e f l u c t u a t i o n s i n e n e r g y p r i c e s , che u s e of e n e r g y a n a l y s i s ( o r d e s i g n t o o l s ) * c o n t i n u e s t o be a v a l u a b l e a s s e t f o r a r c h i t e c t s , e n g i n e e r s and d e s i g n e r s , t o narrow t h e r a n g e of p o s s i b l e s o l u t i o n s t o a p a r t i c u l a r problem. Once a s e t of o p t i o n s i s c h o s e n , a n a n a l y s i s o r a d e s i g n t o o l c a n be used t o e v a l u a t e and compare t h e s e d e s i g n a l t e r n a t i v e s , i n t e r m s of t h e i r e n e r g y c o n s e r v a t i o n p o t e n t i a l , i m p a c t on t h e i n d o o r e n v i r o n m e n t and c o s t e f f e c t i v e n e s s .I n c o u n t r i e s s u c h a s Canada where government programs a r e e s t a b l i s h e d t o promote t h e c o n s t r u c t i o n of low e n e r g y b u i l d i n g s , t h e e l i g i b i l i t y f o r f u n d s u n d e r t h e s e programs i s u s u a l l y based on a maximum a l l o w a b l e e n e r g y
consumption. T h e r e f o r e , e n e r g y c a l c u l a t i o n methods a r e needed t o d e t e r m i n e t h e e l i g i b i l i t y of p r o p o s e d d e s i g n s o r t h e i r c o m p l i a n c e w i t h a n e n e r g y s t a n d a r d .
*
An e n e r g y a n a l y s i s may o r may n o t c o n s t i t u t e a ' d e s i g n t o o l ' . T h i s d e p e n d s upon w h e t h e r o r n o t i t i s f l e x i b l e , f a s t , e a s y and a c c u r a t e enough t o u s e a t t h e e a r l y s t a g e of d e s i g n , when i t i s most e f f e c t i v e .Extrait de "The Third International Congress on Building Energy Management" Val. I , a Presses polytechniques romandes, 1015 Lausanne, Suisse
Another i m p o r t a n t a s p e c t of a n a l y s i s and d e s i g n t o o l s i s t h e e d u c a t i o n t h e y o f f e r t h e d e s i g n e r . R e p e a t e d u s e a l l o w s t h e d e s i g n e r t o d e v e l o p a n i n t u i t i v e s e n s e of a p p l i c a b l e e n e r g y d e s i g n o p t i o n s . E v e n t u a l l y , d e c i s i o n s c a n be made b a s e d on p a s t e x p e r i e n c e , r e d u c i n g t h e need t o e v a l u a t e many d e s i g n o p t i o n s , and a l l o w i n g o n e t o c o n c e n t r a t e on t h e most p r o m i s i n g o n e s . Many p r a c t i t i o n e r s , however, a d m i t t h a t t h e y u s e e n e r g y a n a l y s i s o n l y i n t h e f i n a l s t a g e s of d e s i g n t o document t h e i m p a c t of t h e d e s i g n . Few u s e e n e r g y a n a l y s i s e f f e c t i v e l y e a r l y o n , when t h e c o s t of c h a n g i n g a d e s i g n d e c i s i o n i s s t i l l s m a l l . T h i s may i n d i c a t e t h a t most a v a i l a b l e e n e r g y a n a l y s i s t o o l s a r e n o t " d e s i g n t o o l s " , o r a r e n o t i n a form t h a t c a n be u s e d a t t h e c o n c e p t u a l d e s i g n p h a s e . T h e r e a r e many u s e s f o r b u i l d i n g e n e r g y a n a l y s i s a t d i f f e r e n t s t a g e s d u r i n g b u i l d i n g d e s i g n and o p e r a t i o n . Each one may demand a d i f f e r e n t t y p e o r c l a s s of a n a l y s i s w i t h a d i f f e r e n t c o m b i n a t i o n of p e r f o r m a n c e c r i t e r i a . The d e s i g n p r o c e s s i n v o l v e s many p l a y e r s , i n c l u d i n g o w n e r s , a r c h i t e c t s , e n g i n e e r s and b u i l d e r s . One might a s k , what t y p e s of d e s i g n t o o l s a r e a v a i l a b l e a n d what p r o p e r t i e s must t h e y p o s s e s s t o f a c i l i t a t e t h i s p r o c e s s ? What a r e t h e problems w i t h e x i s t i n g t o o l s and what a r e t h e f u t u r e t r e n d s f o r e n e r g y
a n a l y s i s t o o l s ? What a r e t h e y u s e d f o r now and what a r e t h e y t o be u s e d f o r i n t h e f u t u r e ?
T h i s p a p e r a t t e m p t s t o answer some of t h e s e q u e s t i o n s i n l i g h t of t h e p a p e r s p r e s e n t e d i n t h i s S e s s i o n on B u i l d i n g P l a n n i n g and Design T o o l s . The s e s s i o n i n c l u d e s 6 3 p a p e r s , d i v i d e d i n t o f o u r s u b - t o p i c s : 1. Design t o o l s , 2. Theory and a n a l y s i s of e n e r g y s a v i n g s t r a t e g i e s , 3. Energy s a v i n g s i n p r a c t i c e , 4. B u i l d i n g c o n c e p t s f o r h o t c l i m a t e s . T o p i c s 1 t o 3 a r e a d d r e s s e d i n t h e above o r d e r t o f o c u s on t h e development of d e s i g n t o o l s , t h e i r c h a r a c t e r i s t i c s and d i f f e r e n c e s , f o l l o w e d by p r e s e n t a t i o n and d i s c u s s i o n of examples where t h e y a r e u s e d t o a n a l y s e e n e r g y s a v i n g
s t r a t e g i e s , and f i n a l l y a n o v e r v i e w of p r a c t i c a l c a s e s of e n e r g y s a v i n g s i n b u i l d i n g s . S i n c e b u i l d i n g d e s i g n c o n c e p t s f o r h o t c l i m a t e s a r e a d d r e s s e d by D r . G i v o n i i n h i s Keynote p r e s e n t a t i o n , t h e l a s t t o p i c w i l l n o t be c o v e r e d i n t h i s p a p e r .
2. ENERGY ANALYSIS AND DESIGN TOOLS
C u r r e n t l y a v a i l a b l e a n a l y s i s and d e s i g n t o o l s may be d i v i d e d i n t o two c a t e g o r i e s : s i m p l i f i e d m t h o d s and d e t a i l e d methods. 2.1 D e t a i l e d Energy A n a l y s i s T h i s i s t h e most f l e x i b l e a n a l y s i s t e c h n i q u e f o r dynamic s i m u l a t i o n o f t h e t h e r m a l p e r f o r m a n c e of a b u i l d i n g and due t o c o m p l e x i t y of t h e c a l c u l a t i o n , u s u a l l y r e q u i r e s a computer. It i s a p o w e r f u l t e c h n i q u e , p a r t i c l i l a r l y s u i t e d f o r r e s e a r c h a p p l i c a t i o r l s i n which t h e o b j e c t i v e i s t o s t u d y a phenomenon i n d e t a i l o r t o e x t r a p o l a t e e x p e r i m e n t a l d a t a t o p r o d u c e more g e n e r a l i z e d c o n c l ~ ~ s i o n s . The complex c a l c ~ ~ l a t i o n s , however, r e q u i r e a g r e a t d e a l of i n p u t d a t a r e g a r d i n g t h e b u i l d i n g components and t h e c l i m a t e i n
The p r o l i f e r a t i o n and a d v a n c e s of m i c r o c o m p u t e r s i n t h e p a s t few y e a r s have b r o u g h t complex computer e n e r g y a n a l y s i s c l o s e r t o t h e d e s i g n s t a g e . However, t h i s i s s t i l l l i m i t e d by t h e c o m p l e x i t y of t h e r e q u i r e d i n p u t d a t a . An e x c e l l e n t r e v i e w of t h e c h a r a c t e r i s t i c s r e q u i r e d of computer t h e r m a l a n a l y s i s a s a d e s i g n t o o l was g i v e n by S o n d r e g g e r ( 2 ) who s u g g e s t e d ,
c o r r e c t l y , t h a t p a r a m e t r i c s t u d i e s a r e poor s u b s t i t u t e s f o r t h e r e a l power of c o m p u t e r s , t h e a b i l i t y t o a s k "what i f " w i t h r e g a r d t o d i f f e r e n t d e s i g n
a l t e r n a t i v e s and s e e t h e answer on t h e s c r e e n q u i c k l y . T h i s may be a c h i e v a b l e i n t h e n e a r f u t u r e t h r o u g h t h e i n t e g r a t i o n of a t h e r m a l modeling t e c h n i q u e , a g e n e r a l b u i l d i n g and s y s t e m s d a t a b a s e , and a n e x p e r t s y s t e m a s t h e i n t e r f a c e be tween t h e computer and t h e d e s i g n e r .
I n t h e domain of d e t a i l e d c o m p o s i t e modeling, a number of a n a l y s i s t e c h n i q u e s a r e w i d e l y u s e d ( 3 ) . These i n c l u d e network o r n o d a l a n a l y s i s , r e s p o n s e f a c t o r t e c h n i q u e s , and frequerlcy domain t e c h n i q u e s . N e i r a c * p r e s e n t s a method t o r e d u c e t h e c o m p l e x i t y of s o l u t i o n of n o d a l t h e r m a l a n a l y s i s
t h r o u g h t h e r e d u c t i o n of t h e number of nodes. Nodes a r e grouped n u m e r i c a l l y ( t h r o u g h l i n e a r r e g r e s s i o n ) t o r e d u c e t h e model o r d e r . T h i s r e s u l t s i n a much f a s t e r s o l u t i o n w i t h a s l i g h t r e d u c t i o n i n a c c u r a c y . Higgs examines t h e e f f e c t on t h e r e s u l t s p r o d u c e d by t h e l a r g e t h e r m a l a n a l y s i s program "DEROB", of d e c r e a s i n g t h e t i m e s t e p and i n c r e a s i n g t h e n o d a l r e p r e s e n t a t i o n of b u i l d i n g components. He f i n d s t h a t d e c r e a s i n g t h e t i m e s t e p s i s not s u f f i c i e n t l y r e p a i d by t h e i n c r e a s e i n a c c u r a c y . However, l i b e r a l u s e of nodes i s w a r r a n t e d . It i s w o r t h n o t i n g t h a t most of t h e improvement is
a c h i e v e d when 5 nodes a r e u s e d i n s t e a d of 2 ( f o r a high-mass w a l l ) . F u r t h e r i n c r e a s e t o 8 nodes d o e s n o t add any s i g n i f i c a n t improvement. T h i s , of c o u r s e , w i l l i n c r e a s e t h e c o m p u t a t i o n t i m e .
The p a p e r by Roux e t a l . s t r e s s e s t h e m e r i t s of t h e i n t e g r a t i o n of t h e h e a t i n g s y s t e m a n a l y s i s w i t h t h e dynamic a n a l y s i s of t h e b u i l d i n g a t t h e c o n c e p t i o n a l d e s i g n s t a g e . Such an i n t e g r a t i o n p e r m i t s t h e d e t e r m i n a t i o n of t h e e f f e c t of d i f f e r e n t h e a t i n g s y s t e m s t r a t e g i e s , i n c l u d i n g t h e s y s t e m t y p e and s i z e , on e n e r g y consumption and c o m f o r t . The a u t h o r s p r e s e n t a network a n a l y s i s method " B s t i m e n t " and i t s a p p l i c a t i o n f o r a p u r e l y c o n v e c t i v e h e a t i n g s y s t e m , a h o t w a t e r r a d i a t o r s y s t e m , and a h o t w a t e r f l o o r h e a t i n g s y s t e m .
Waters p r e s e n t s a methodology f o r modeling t h e t h e r m a l h e h a v i o u r of
i n d u s t r i a l b u i l d i n g s . He e m p h a s i z e s t h e i m p o r t a n c e of i n p u t p a r a m e t e r v a l u e s , which i n many c a s e s d o n o t r e p r e s e n t r e a l i t y .
D e t a i l e d t h e r m a l m o d e l i n g i s a l s o u s e d t o a n a l y s e s i n g l e b u i l d i n g components, s u c h a s w a l l s and windows, i n o r d e r t o p r e d i c t t h e e f f e c t of v a r i o u s c o n s t r u c t i o n s t r a t e g i e s on pe rformance ( t h e r m a l and h y g r i c ) . An
example i s p r e s e n t e d by Wright and S u l l i v a n f o r g l a z i n g s y s t e m s . The computer program " V I S I O N " c a n model a v a r i e t y of g l a z i n g d e s i g n s s u c h a s low e m i s s i v i t y f i l m s , I R t r a n s p a r e n t g l a z i n g s , and s u b s t i t u t e f i l l g a s e s , t o d e t e r m i n e t h e i r e f f e c t s on h e a t t r a n s f e r , s o l a r g a i n , s u r f a c e t e m p e r a t u r e , and hour-by-hour e n e r g y b a l a n c e .
Lewis, u s i n g t h e dynamic model HTB2, examines w h e t h e r t h e
r a d i a t i v e / c o n v e c t i v e c h a r a c t e r i s t i c s of t h e h e a t i n p u t and c o n t r o l s a f f e c t t h e impact of p a s s i v e s o l a r h e a t i n g on a u x i l l i a r y h e a t i n g r e d u c t i o n .
*
D e t a i l s of ICBEM p a p e r s may be f o u n d i n t h e p r o c e e d i n g s , t h e y a r e n o t r e f e r e n c e d i n t h i s p a p e r .Some b u i l d i n g e n e r g y a n a l y s i s models a r e b u i l t o r m o d i f i e d t o be u s e d f o r a p a r t i c u l a r a p p l i c a t i o n . Molle p r e s e n t s a r e s p o n s e f a c t o r model w i t h
p a r t i c u l a r emphasis on f l o o r h e a t i n g . The model i s u s e d t o examine t h e p e r f o r m a n c e of a f l o o r h e a t i n g s y s t e m u n d e r d i f f e r e n t s t r a t e g i e s f o r room t e m p e r a t u r e c o n t r o l and t h e r m a l i n s u l a t i o n . An i m p o r t a n t c o n c l u s i o n i s t h a t f l o o r h e a t i n g i s n o t p r e f e r r e d i n c o m b i n a t i o n w i t h i n t e r m i t t e n t h e a t i n g ; t h i s i s s u p p o r t e d by two o t h e r p a p e r s i n t h i s s e s s i o n d e a l i n g w i t h t h e r m a l mass e f f e c t
.
A good example of t h e u s e of d e t a i l e d computer a n a l y s i s i n d e s i g n i s g i v e n by Lanz. A computer a n a l y s i s (IGLOU-G) i s used t o examine t h e d e s i g n of t h e new a i r p o r t b u i l d i n g i n S t u t t g a r t . Compromises were r e a c h e d between t h e a r c h i t e c t u r e d e s i g n r e q u i r e m e n t s and t h e e n e r g y and e n v i r o n m e n t a l p e r f o r m a n c e of t h e b u i l d i n g .
2.2 S i m p l i f i e d Energy A n a l y s i s
It i s now g e n e r a l l y a c c e p t e d t h a t d e t a i l e d computer e n e r g y a n a l y s i s i s t h e most a c c u r a t e and v e r s a t i l e r e p r e s e n t a t i o n of a b u i l d i n g performance. T h i s makes computer s i m u l a t i o n a d e s i r a b l e d e s i g n t o o l , p r o v i d e d i t meets t h e o t h e r c r i t e r i a of s p e e d and e a s e of u s e . S i n c e most of t h e s e m d e l s a r e s t i l l c o s t l y and t i m e consuming, d e s i g n e r s a s k f o r s i m p l e t e c h n i q u e s t h a t c a n be u s e d on desk-top m i c r o c o m p u t e r s , c a l c u l a t o r s and sometimes e v e n manually. P r a c t i c a l a p p l i c a t i o n s a r e g e n e r a l l y n o t c o n c e r n e d w i t h d e t a i l e d modeling of a h e a t t r a n s f e r p r o c e s s , b u t w i t h o b t a i n i n g q u i c k a n s w e r s t o q u e s t i o n s on d e s i g n a l t e r n a t i v e s o r s a t i s f y i n g t h e r e q u i r e m e n t of a b u i l d i n g ( e n e r g y ) code.
Simple methods may be a c c u r a t e enough f o r t h e s e p u r p o s e s a n d , t h e r e f o r e , a r e u s u a l l y termed d e s i g n t o o l s , a s l o n g a s t h e y a r e e a s y t o u s e , r e a d i l y
a v a i l a b l e and i n e x p e n s i v e t o a p p l y . Some compromise of a c c u r a c y and v e r s a t i l i t y h a s t o be made t o a c h i e v e t h e d e s i r e d l e v e l of s i m p l i c i t y .
However, t h e l i m i t a t i o n s t o e n e r g y a n a l y s i s a r e more o f t e n due t o u n c e r t a i n t y of i n p u t d a t a t h a n t o t h e c a l c u l a t i o n method i t s e l f .
Simple methods i n c l u d e a n a l y s i s s i m p l i f i e d by r e d u c i n g t h e number o f b u i l d i n g components and z o n e s t o be h a n d l e d ( f o r example, s i n g l e zone a n a l y s i s w i t h a t h e r m a l s t o r a g e e f f e c t lumped i n o n e o r two n o d e s ) , a n d c o r r e l a t i o n methods where t h e e f f e c t s of p a r a m e t e r v a r i a b i l i t y a r e a c c o u n t e d f o r by s i m p l e c o r r e l a t i o n g e n e r a t e d by m u l t i p l e r u n s of a d e t a i l e d a n a l y s i s ( 4 ) .
Examples of s i m p l e a n a l y s e s a r e p r e s e n t e d i n t h e p a p e r s by R i a n c h i a n d G i l s o n , and by Matthews and J o u b e r t . Both p a p e r s t r e a t t h e b u i l d i n g a s a homogeneous i s o t h e r m a l body t h a t c a n be r e p r e s e n t e d by a s i m p l e RC e l e c t r i c a n a l o g u e . T h e o r e t i c a l l y , t h e lumped p a r a m e t e r method is a c c u r a t e i f t h e r a t i o of t h e b u i l d i n g t h e r m a l i n e r t i a t o e x t e r n a l t h e r m a l r e s i s t a n c e i s l e s s t h a n 0.1. The d i f f i c u l t y l i e s i n d e t e r m i n i n g t h e a p p r o p r i a t e v a l u e f o r t h e r m a l i n e r t i a . The v a l i d i t y of t h e method d o e s , however, i n c r e a s e w i t h i n c r e a s i n g t h e t h e r m a l i n s u l a t i o n of t h e b u i l d i n g e n v e l o p e . R i a n c h i and G i l s o n u s e t h e t e c h n i q u e t o examine t h e e n e r g y s a v i n g due t o i n t e r m i t t e n t h e a t i n g s y s t e m s . The a v e r a g e s e a s o n a l e f f i c i e n c y of t h e h e a t i n g s y s t e m i s used i n t h e a n a l y s i s . The a u t h o r s c o n c l u d e t h a t u n d e r t h e c o n d i t i o n examined, i n t e r m i t t e n t h e a t i n g i n h o u s e s w i t h t h e t h e r m a l i n e r t i a commonly u s e d i n I t a l y d o e s n o t l e a d t o l a r g e r e n e r g y s a v i n g s , a s had been e x p e c t e d .
Matthews and J o u b e r t added a n e x t r a r e s i s t a n c e t o t h e c i r c u i t t o a c c o u n t f o r n a t u r a l v e n t i l a t i o n . E m p i r i c a l c o n s t a n t s a r e used t o r e p r e s e n t t h e
method i s t h e n u s e d t o p e r f o r m a s t u d y of n a t u r a l l y v e n t i l a t e d b u i l d i n g s t o d e m o n s t r a t e t h e e f f e c t of c h a n g e s t o t h e d e s i g n on t h e i n d o o r a i r t e l n p e r a t l l r e and on t h e e n e r g y e f f i c i e n c y . The method i n c l u d e s e m p i r i c a l l y d e r i v e d
e q u a t i o n s which may, however, r e n d e r i t v e r y s p e c i f i c t o t h e c a s e s and c l i m a t e s s t u d i e d .
Cammarata e t a l . o u t l i n e t h e a d v a n t a g e s i n i m p r o v i n g t h e computer c o d e "BIOCLI", ( a lumped p a r a m e t e r model) by i n c l u d i n g c a l c u l a t i o n of w a l l h e a t t r a n s f e r u s i n g a d i s t r i b u t e d p a r a m e t e r model. They i n d i c a t e t h a t , compared t o t h e o r i g i n a l model, t h e g e n e r a t e d model p r o v i d e s n o r e a c c u r a t e r e s u l t s and a d e e p e r i n s i g h t i n t o t h e b u i l d i n g p h y s i c s , p a r t i c u l a r l y f o r s o l a r h e a t e d h o u s e s .
A s i m p l e e n e r g y a n a l y s i s i s p r e s e n t e d by L e f e b v r e a n d Neveu. Method H2E u s e s a c o r r e l a t i o n between t h e h e a t i n g r e q u i r e m e n t of a d w e l l i n g and t h e d e g r e e - h o u r s ( b a s e 19OC), t h e g a i n - ( s o l a r and i n t e r n a l ) t o - l o a d r a t i o and t h e b u i l d i n g p r i n c i p l e time c o r l s t a n t . A method t o c a l c u l a t e t h e t i m e c o n s t a n t i s a l s o g i v e n . Method H2E t a k e s i n t o a c c o u n t two t e m p e r a t u r e c o n t r o l s t r a t e g i e s : i n d o o r t e m p e r a t u r e f i x e d a t 19OC and a n i g h t s e t b a c k t o 15OC between 2 3 h and 6h. The method i s compared w i t h a d e t a i l e d computer e n e r g y a n a l y s i s . R e s u l t s a g r e e t o w i t h i n 5% f o r l a r g e e n e r g y r e q u i r e m e n t s . However, f o r lo^ e n e r g y r e q u i r e m e n t s , t h e d i f f e r e n c e i s i n t h e o r d e r of 20%. One s o u r c e of e r r o r , a c c o r d i n g t o t h e a u t h o r s , i s t h e c a l c u l a t i o n of u s e f u l s o l a r and i n t e r n a l g a i n s , which becomes a s i g n i f i c a n t f a c t o r p a r t i c u l a r l y f o r low e n e r g y b u i I d i ngs
.
E x t e n d i n g S u b b a r a o l s ( 5 ) s e a r c h f o r improved e n e r g y a n a l y s i s t o o Ls, Smart and H a l l i n g e r l s p a p e r p r e s e n t s t h e i r p r e l i m i n a r y a t t e m p t s a t p r e d i c t i n g t h e dynamic p e r f o r m a n c e of a p a s s i v e s o l a r house u s i n g a c t u a l p e r f o r m a n c e d a t a . The a n a l y s i s i s aimed a t u s i n g a few s i m p l e p a r a m e t e r s t o d e s c r i b e t h e b u i l d i n g t h e r m a l p e r f o r m a n c e .
I n a d i f f e r e n t a p p l i c a t i o n of t h e r m a l a n a l y s i s , S h a v i v p r e s e n t s a CAD
t o o l f o r t h e d e t e r m i n a t i o n of s o l a r r i g h t s ( t h e a v a i l a b i l i t y of s o l a r
i n s o l a t i o n o n t o a p r o p o s e d b u i l d i n g ) . The method g e n e r a t e s a nomogram o f t h e e n v e l o p e of a l l p o s s i b l e l o c a t i o n s Eor n e i g h b o r i n g b u i l d i n g s w i t h i n an a l l o w e d h e i g h t t o e n a b l e i n s o l a t i o n of a g i v e n p a s s i v e c o l l e c t o r f o r a s p e c i f i e d
p e r i o d and t i m e of day. The method i s e a s y t o u s e and c a n be implemented i n t h e e a r l y d e s i g n phase.
Energy a n a l y s i s c a n a l s o be u s e d t o g e n e r a t e t h e s i m p l e s t form of d e s i g n t o o l s , t h a t i s , r u l e s of thumb and g u i d e l i n e s . These a r e u s u a l l y t h e m s t u s e f u l t o o l s , p a r t i c u l a r l y a t t h e e a r l y s t a g e s of d e s i g n when t h e d e t a i l s of t h e b u i l d i n g a r e s t i l l b e i n g d e t e r m i n e d .
Canha Da P i e d a d e a n d R o d r i g u e s p r e s e n t r e s u l t s of a p a r a m e t r i c s t u d y , u s i n g a d e t a i l e d network computer s i m u l a t i o n , aimed a t e x a m i n i n g p a s s i v e s o l a r t e c h n i q u e s u s e d a s b u i l d i n g d e s i g n c o n c e p t s i n P o r t u g a l . The t e c h n i q u e s
examined i n c l u d e t h e r m a l i n e r t i a , n o c t u r n a l v e n t i l a t i o n and e v a p o r a t i v e
c o o l i n g . They c o n c l u d e d t h a t by u s i n g t h e s e p a s s i v e t e c h n i q u e s c o m f o r t l e v e l s c a n be met i n summer ( h o t / d r y c l i m a t e ) , and low l e v e l s of e n e r g y consumption c a n be a c h i e v e d i n w i n t e r .
Guppini e t a l . o u t l i n e a g u i d e produced f o r p l a n n i n g low e n e r g y
r e s i d e n t i a l h o u s i n g . The g u i d e combines t h e r e s u l t s of a n a l y s i s and f i e l d e x p e r i m e n t a t i o n i n Europe. It a i m s a t p r o v i d i n g means f o r r e a l i z i n g b u i l d i n g p l a n s t h a t o p t i m i z e s c o m f o r t and e n e r g y consumption.
G u i d e l i n e s mst t a k e economics i n t o a c c o u n t , s i n c e a n e n e r g y s a v i n g
measure w i l l n o t be u s e d u n l e s s i t i s c o s t e f f e c t i v e . G u s t a f s s o n and K a r l s s o n p r e s e n t t h e i r f i n d i n g s of a s t u d y on m i n i m i z i n g l i f e - c y c l e c o s t when
r e t r o f i t t i n g b u i l d i n g s . The methodology, a p p l i e d t o two b u i l d i n g s i n Malmo, Sweden, c o n s i d e r s a c o m b i n a t i o n of e n v e l o p e and h e a t i n g s y s t e m r e t r o f i t t i n g . They p r e s e n t some g u i d e l i n e s f o r c o s t e f f e c t i v e r e t r o f i t t i n g f o r t h i s c l i m a t e . I n g e n e r a l , t h e y f i n d t h a t t h e l o w e s t p o s s i b l e l i f e c y c l e c o s t a l m o s t a l w a y s emerges i f a h e a t i n g s y s t e m w i t h low r u n n i n g c o s t i s implemented i n t h e
b u i l d i n g . F o r low e n e r g y b u i l d i n g s , t h e i n i t i a l c o s t of t h e h e a t i n g s y s t e m i s a l s o a f a c t o r . Windows a r e found t o be m o s t l y u n p r o f i t a b l e t o change f o r e n e r g y r e a s o n s a l o n e .
2.3 E v a l u a t i o n of Energy A n a l y s i s and Design T o o l s
With t h e many a v a i l a b l e e n e r g y a n a l y s i s t o o l s t h e q u e s t i o n i s , which o n e t o c h o o s e ? The m e r i t s of one v e r s u s a n o t h e r a r e o f t e n judged a c c o r d i n g t o some c o m b i n a t i o n of t h e f o l l o w i n g p e r f o r m a n c e f a c t o r s ( 2 ) .
1. Accuracy: i f modelled b u i l d i n g and o p e r a t i n g c o n d i t i o n s were r e p l i c a t e d i n n a t u r e , how c l o s e would a c t u a l e n e r g y consumption be t o t h a t p r e d i c t e d by t h e model?
2. S e n s i t i v i t y : c a n t h e a n a l y s i s method show t h e e f f e c t , on e n e r g y
consumption, of v a r i a t i o n t o t h e d e s i g n a l t e r n a t i v e ( s ) t o be c o n s i d e r e d ?
3 V e r s a t i l i t y : what f r a c t i o n of r e a l world b u i l d i n g s can be modelled and w i t h what d e s i g n f e a t u r e s ?
4. Speed: how l o n g d o e s i t t a k e t o e n t e r d a t a f o r a b u i l d i n g , and how l o n g d o e s t h e c a l c u l a t i o n t a k e ?
5. R e p r o d u c i b i l i t y : i f 100 u s e r s e n t e r e d d a t a f o r t h e same b u i l d i n g , what would be t h e s t a n d a r d d e v i a t i o n of t h e r e s u l t s ?
6. Ease of u s e : how d i f f i c u l t i s i t t o l e a r n t o u s e t h e program, and how much p r e p a r a t i o n d o e s i t t a k e t o e n t e r a b u i l d i n g i n p u t ?
T h e r e i s always a c o n f l i c t i n g demand between a number of t h e s e f a c t o r s and t h e u s e r s h o u l d c h o o s e a n a n a l y s i s o r d e s i g n t o o l b a s e d on h i s own
r e q u i r e m e n t s . He may choose d i f f e r e n t t o o l s f o r d i f f e r e n t j o b s o r p u r p o s e s o r a t d i f f e r e n t s t a g e s of t h e d e s i g n . For t h i s r e a s o n t h e p r e s e n t a t i o n by
Cl6ment e t a l . i s q u i t e r e l e v a n t : a n o u t l i n e of a methodology f o r a common u n i f o r m p r e s e n t a t i o n of b u i l d i n g t h e r m a l m o d e l l i n g . T h i s may be a b e t t e r way t o a s s i s t d e s i g n e r s i n c h o o s i n g t h e a p p r o p r i a t e a n a l y s i s method.
A number of s t u d i e s h a v e a t t e m p t e d t o compare e n e r g y a n a l y s i s models, a s I f o r example, s t u d i e s t h r o u g h t h e I n t e r n a t i o n a l Energy Agency I E A Task V I I I . I I
These i n c l u d e s u r v e y i n g a n a l y s i s methods and d e s i g n t o o l s ( 3 , 4 ) and e v a l u a t i o n I I of d e t a i l e d computer models ( 6 ) a n d s i m p l e d e s i g n t o o l s ( 7 ) . I n g e n e r a l ,
m o s t l y due t o t i m e , r e s o u r c e and d a t a l i m i t a t i o n s , a l l v a l i d a t i o n s t u d i e s a r e l i m i t e d . A c o l l e c t i o n of many of t h e s e s t u d i e s may sometimes be needed t o examine a l l a s p e c t s of b u i l d i n g e n e r g y a n a l y s i s t e c h n i q u e s .
A s m e n t i o n e d , one oE t h e l i m i t a t i o n s t o many s i m p l i f i e d a n a l y s e s i s t h e i r r e s t r i c t i o n s t o t r e a t i n g a b u i l d i n g a s a s i n g l e zone. The e f f e c t of t h i s
a s s u m p t i o n i s examined i n t h e p a p e r by P e l l e t r e t . The p r e d i c t i o n s made by CSTB methods ( R S g l e s Th-K77, Th-G77 and Th-B85) of t h e t h e r m a l p e r f o r m a n c e of a m u l t i - z o n e ( 3 z o n e ) b u i l d i n g s i m p l i f i e d t o a s i n g l e zone i s compared t o r e s u l t s p r e d i c t e d w i t h a d e t a i l e d network model. D i f f e r e n c e s of up t o 30% ( 1 5 % on t h e a v e r a g e ) were o b s e r v e d between t h e a n n u a l h e a t i n g r e q u i r e m e n t s computed by t h e two methods, w i t h t h e s i n g l e zone model c o n s i s t e r l t l y
u n d e r e s t i m a t i n g t h e h e a t i n g r e q u i r e m e n t . The r e s u l t s were u s e d t o improve t h e CSTB s i m p l i f i e d method.
The p a p e r by E r i k s s o n e t a l . d e s c r i b e s t h e work p e r f o r m e d w i t h i n IEA/ECR Annex X I 1 t o compare t h e a n n u a l h e a t i n g r e q u i r e m e n t p r e d i c t i o n of s i m p l i f i e d e n e r g y a n a l y s i s methods w i t h e a c h o t h e r and w i t h a d e t a i l e d computer model. Most of t h e s i m p l i f i e d methods examined u s e t h e u t i l i z a t i o n f a c t o r a p p r o a c h t o a c c o u n t f o r u s e f u l s o l a r and i n t e r n a l g a i n s . S e v e r a l r u n s were made t o
examine t h e e f f e c t s on t h e h e a t i n g demand of v a r y i n g t h e window s i z e and o r i e n t a t i o n , t h e g l a z i n g t y p e , t h e b u i l d i n g mass, t h e i n h a b i t a n t ' s bellaviour p a t t e r n , and t h e h e a t i n g c o n t r o l . D i f f e r e n c e s of up t o 20% s e p a r a t e t h e r e s u l t s o b t a i n e d by d i f f e r e n t methods. The a u t h o r s e x p l a i n t h e s e i n t e r m s o f d i f f i c u l t i e s i n c a l c u l a t i n g a c t u a l i n d o o r t e m p e r a t u r e , s o l a r h e a t g a i n s and u t i l i z a t i o n f a c t o r s f o r s o l a r and i n t e r n a l g a i n s . On t h e l a t t e r , some of t h e models u s e t h e same u t i l i z a t i o n f a c t o r s f o r b o t h s o l a r and i n t e r n a l g a i n s . A
r e c e n t s t u d y ( 8 ) h a s shown t h a t t h e y c a n be q u i t e d i f f e r e n t , and g i v e s i n t e r n a l g a i n u t i l i z a t i o n f a c t o r s f o r t h r e e d i f f e r e n t g a i n p r o f i l e s .
Another a n a l y s i s p r e s e n t e d by Van d e P e r r e and Gendt e l a b o r a t e s on t h e u t i l i z a t i o n f a c t o r c o r r e l a t i o n used i n t h e Methode 5000. Using a d e t a i l e d s i m u l a t i o n , t h e e f f e c t of a number of p a r a m e t e r s on t h e u t i l i z a t i o n f a c t o r i s examined and compared w i t h M6thode 5000 c o r r e l a t i o n . The r e s u l t s have l e d them t o s u g g e s t t h a t t h e u t i l i z a t i o n f a c t o r depends on t h e h e a t g a i n s and t h e s e t p o i n t i n a d d i t i o n t o t h e p a r a m e t e r s a l r e a d y i n c l u d e d . The dependence on h e a t g a i n s i s e x p e c t e d , due t o t h e i n t e r a c t i o n between t h e s e g a i n s and t h e b u i l d i n g t h e r m a l mass.
Aghemo e t a l . p r e s e n t a comparison of c a p a b i l i t i e s and a c c u r a c y between two s i m p l i f i e d methods, B I L T E and t h e CSTB RSgles Th-R85. P r e d i c t i o n s by t h e two methods a r e compared t o e a c h o t h e r and t o d a t a c o l l e c t e d on a number of b u i l d i n g s , one of which i s c o m p l e t e l y i n s t r u m e n t e d . The a u t h o r s c o n c l u d e t h a t f o r e s t i m a t i o n of b u i l d i n g e n e r g y c o n s u m p t i o n , t h e s e methods c a n n o t r e a c h p r e c i s i o n s b e t t e r t h a n 10-15%, b u t t h e y a r e more u s e f u l i n e v a l u a t i n g t h e r e l a t i v e d i f f e r e n c e s a c h i e v e d by v a r i o u s d e s i g n a l t e r n a t i v e s . L a r g e r e r r o r s were n o t i c e d f o r " s o l a r d r i v e n " b u i l d i n g s ( w i t h h i g h g a i n - l o a d r a t i o ) . These e r r o r s i n c l u d e a l l e r r o r s i m p l i c i t i n t h e e x p e r i m e n t s , a l l e x t e r n a l e r r o r s
( i n p u t d a t a and w e a t h e r ) and i n t e r n a l e r r o r s of t h e a n a l y s i s method i t s e l f .
2.4 F u t u r e T r e n d s
The f a s t moving d e v e l o p m e n t s i n microcomputers and t h e improvement i n t h e i r s p e e d and c a p a c i t y a r e l e a d i n g t o a new l o o k a t a n a l y s i s t o o l s . The a p p l i c a t i o n s of computer-aided d e s i g n (CAD) and knowledge-based s y s t e m s i n t h e a r e a of b u i l d i n g d e s i g n and o p e r a t i o n a r e growing ( 9 ) . They w i l l g r e a t l y improve t h e i n t e r f a c e between t h e d e s i g n e r and h i s computer.
C u r r e n t CAD s y s t e m s i n c o r p o r a t e s e v e r a l f e a t u r e s t h a t c a n be u s e d o r enhanced t o s e r v e a s a n i n t e r f a c e w i t h e n e r g y a n a l y s i s t o o l s . F o r example, g r a p h i c i n f o r m a t i o n a b o u t t h e b u i l d i n g g e o m e t r y , l a y - o u t of t h e HVAC s y s t e m , d e s i g n d e t a i l s of e n v e l o p e s y s t e m s and a t t r i b u t e s f o r components cotild a l l be
e n t e r e d w i t h a CAD system. It s h o u l d t h e n be p o s s i b l e t o e s t a b l i s h t h e l i n k between t h e CAD s y s t e m and energy a n a l y s i s and d e s i g n t o o l s through d a t a i n t e r f a c e . Once t h i s i n t e r f a c e i s e s t a b l i s h e d , t h e i n t e g r a t i o n of o t h e r a s p e c t s of b u i l d i n g performance becomes e v i d e n t . These i n c l u d e thermal
c o m f o r t , d a y l i g h t i n g , a i r movement, i n d o o r a i r q u a l i t y and f i r e s a f e t y . Each of t h e s e a s p e c t s might r e q u i r e a new s e t of d a t a o r a t t r i b u t e s t o be added t o t h e b u i l d i n g d e t a i l s .
On t h e energy a n a l y s i s s i d e , t h e t h e r m a l a n a l y s i s of t h e b u i l d i n g would be combined w i t h a v e n t i l a t i o n and a i r movement a n a l y s i s , a s w e l l a s w i t h HVAC system a n a l y s i s t o a c c o u n t f o r t h e obvious i n t e r a c t i o n . Some of t h i s work i s a l r e a d y t a k i n g p l a c e ( 1 0 ) . The model 'ROYAL DEBAC', p r e s e n t e d by Bryn and Harsem i s a l s o a s t e p i n t h i s d i r e c t i o n . The computer program makes i t
p o s s i b l e t o t a k e a i r s t r a t i f i c a t i o n i n t o account d u r i n g t h e p l a n n i n g s t a g e , a l o n g w i t h energy a n a l y s i s . T h i s f e a t u r e , a s i n d i c a t e d i n t h e i r p a p e r , i s p a r t i c u l a r l y i m p o r t a n t f o r e x a m i n a t i o n of l o c a l c l i m a t e i n l a r g e g l a z e d s p a c e s . T h i s w i l l a l s o permit d e s i g n e r s t o o b s e r v e t h e consequences of a n energy r e l a t e d d e s i g n d e c i s i o n on t h e q u a l i t y of t h e i n d o o r environment and v i c e v e r s a .
I n t h e a r e a of Knowledge Based Expert Systems (KBES), s e v e r a l
developments have emerged i n a number of a r e a s which can be used a s examples f o r a p p l i c a t i o n i n t h e b u i l d i n g i n d u s t r y ( 1 1 ) . C u r r e n t examples f o r t h e u s e of KBES i n b u i l d i n g s i n c l u d e o p e r a t i o n , c o n t r o l and d i a g n o s t i c s of b u i l d i n g s y s t e m s , s t r u c t u r a l framing a d v i s o r s and window d i a g n o s t i c systems. KBES could be a powerful v e h i c l e t o t r a n s m i t energy g u i d e l i n e s , whereby t h e
d e s i g n e r can examine t h e impact of h i s d e s i g n d e c i s i o n s on e n e r g y consumption and i n d o o r environment, a s w e l l a s meeting t h e requirement of a p p l i c a b l e codes and s t a n d a r d s . A powerful a n a l y s i s method i n s t a l l e d i n t h e e x p e r t s y s t e m , t r a n s p a r e n t t o t h e d e s i g n e r , would perform t h e n e c e s s a r y c a l c u l a t i o n s .
An example of t h e u s e of e x p e r t systems i n t h e concept d e s i g n s t a g e of energy system d e s i g n i s p r e s e n t e d by Doheny and Monaghan. Although t h e i r r e s e a r c h mainly p r o v i d e s a b a s i c framework f o r f u t u r e developments, t h e p r e l i m i n a r y s t a g e s of t h e implementation a l r e a d y i n c l u d e a l i m i t e d group of energy systems. Other a p p l i c a t i o n s of KBES combined w i t h e n e r g y a n a l y s i s
t r e a t HVAC systems o p e r a t i o n and d i a g n o s t i c s . The eriergy a n a l y s i s p r o v i d e s t h e p r e d i c t i o n of t h e " i d e a l " s y s t e m performance and t h e e x p e r t s y s t e m compares t h i s t o t h e a c t u a l performance ( 1 2 ) . The o p e r a t o r i s t h e n l e d t o d i a g n o s e problems o r m a l f u n c t i o n s when t h e HVAC s y s t e m shows l e s s t h a n a n optimum performance.
It i s e v i d e n t t h a t emerging t e c h n o l o g i e s w i l l p r o v i d e a mechanism f o r i n c r e a s i n g t h e q u a l i t y of d e c i s i o n s made d u r i n g t h e b u i l d i n g d e l i v e r y and o p e r a t i o n . Energy a n a l y s i s s h o u l d be an i n t e g r a l p a r t of t h i s development.
3. THEORY
AND
ANALYSIS OF ENERGY SAVING STRATEGIESA s mentioned e a r l i e r , a major u s e f o r energy a n a l y s i s t e c h n i q u e s i s t o examine d e s i g n o p t i o n s and t h e i r e f f e c t on energy consumption. Repeated
examination of a p a r t i c u l a r a l t e r n a t i v e would r e s u l t i n t h e development of t h e g u i d e l i n e s t h a t d e s i g n e r s could r e l y on w i t h o u t r e s o r t i n g back t o d e t a i l e d a n a l y s i s a t t h e e a r l y d e s i g n s t a g e .
One d e s i g n o p t i o n t h a t i s s t i l l b e i n g examined i s t h e t h e r m a l s t o r a g e c a p a c i t y ( t h e r m a l mass) of a b u i l d i n g . The e f f e c t of t h e r m a l s t o r a g e on a n n u a l e n e r g y c o n s u m p t i o n i s examined f o r b o t h c o n t i n u o u s and i n t e r m i t t e n t h e a t i n g by E s d o r n e t a l . The c a l c u l a t i o n was done u s i n g a f i n i t e - e l e m e n t h o u r l y program a p p l i e d t o a p a r t m e n t u n i t s i n B e r l i n . F o r c o n t i n u o u s h e a t i n g , t h e r e d u c t i o n i n a n n u a l e n e r g y consumption f o r i n d i v i d u a l a p a r t m e n t u n i t s due t o a d d i t i o n a l t h e r m a l mass i s found t o be up t o 25%, d e p e n d i n g on t h e r a t i o of h e a t g a i n s t o h e a t l o s s e s . For e n t i r e a p a r t m e n t b u i l d i n g s , t h e o v e r a l l r e d u c t i o n i s up t o 7%. On t h e o t h e r h a n d , f o r i n t e r m i t t e n t l y - h e a t e d b u i l d i n g s , t h e a n n u a l e n e r g y consumption u s u a l l y i n c r e a s e s w i t h a n i n c r e a s e i n t h e r m a l s t o r a g e , up t o 5% f o r whole b u i l d i n g s . The r e s u l t c o n f i r m s c o n c l u s i o n s p r e s e n t e d e a r l i e r by B i a n c h i and G i l s o n . Bllrch and L i c i t r a e x t e n d e d t h e i r p r e v i o ~ i s e x p e r i m e n t a 1 f i n d i n g s on t h e t h e r m a l mass e f f e c t t h r o u g h a computer s t u d y t o examine s p e c i f i c a l l y t h e e f f e c t of p a r t i t i o n w a l l s and i n t e r i o r f u r n i s h i n g s on t h e e n e r g y c o n s u m p t i o n i n h o u s e s . The s t u d y u s e s t h e d e t a i l e d e n e r g y a n a l y s i s TARP f o r f i v e
l o c a t i o n s i n t h e USA. They c o n c l u d e t h a t t h e p r e s e n c e of a d d i t i o n a l mass h a s a s m a l l b u t b e n e f i c i a l e f f e c t on s p a c e h e a t i n g and c o o l i n g l o a d s . L a r g e r e f f e c t s were found f o r m i l d c l i m a t e r e g i o n s , where t h e h o u s e i s o p e r a t i n g n e a r t h e b a l a n c e - p o i n t t e m p e r a t u r e .
E s c u d i e e t a l . u s e modeling t o d e t e r m i n e t h e e f f e c t of u t i l i z a t i o n and management of t h e h e a t p r o v i d e d by a " c l o s e d " f i r e p l a c e on t h e e n e r g y
consumption and i n t e r i o r t e m p e r a t u r e i n a l i g h t and a heavy b u i l d i n g . T h e i r r e s u l t s a l s o show t h e s m a l l b u t p o s i t i v e e f f e c t of t h e r m a l mass.
The work by Haugen e t a l . combines t h e o r e t i c a l a n a l y s i s and f i e l d e x p e r i m e n t s t o examine t h e u s e of dynamic i n s u l a t i o n i n r o o f c o n s t r u c t i o n combined w i t h a s y s t e m f o r e l e c t r i c a l h e a t i n g and h e a t s t o r a g e . The d e s i g n i s examined i n b o t h c o l d and h o t w e a t h e r c o n d i t i o n s . The p a p e r a d d r e s s e s t h e i s s u e s of a i r f l o w , c o n d e n s a t i o n and h e a t s t o r a g e , a n d i n d i c a t e s t h a t t h e r o o f s t r u c t u r e d e s c r i b e d i s a n i n t e r e s t i n g a l t e r n a t i v e f o r r e d u c i n g d a y t i m e power pealcs and t o t a l e n e r g y demands, e s p e c i a l l y f o r o n e - s t o r e y b u i l d i n g s .
O t h e r u s e s of e n e r g y a n a l y s i s t e c h n i q u e s a r e d e m o n s t r a t e d i n t h e p a p e r s by Rozmiarek e t a l . , and P e t e r s o i l e t a l . The f i r s t u s e s a lumped p a r a m e t e r a n a l y s i s t o e x t r a p o l a t e t e s t c e l l r e s u l t s , on t h e p e r f o r m a n c e of a s o l a r component, t o o t h e r c o n d i t i o n s and c l i m a t i c l o c a t i o n s . The l a t t e r u s e s DOE 2.1C computer s i m u l a t i o n t o p r o p o s e a n a l t e r n a t i v e a p p r o a c h t o b u i l d i n g e n e r g y p e r f o r m a n c e s t a n d a r d s . The a n a l y s i s a d d r e s s e s m u l t i - z o n e b u i l d i n g s and t h r e e g e n e r i c HVAC s y s t e m t y p e s .
4. ENERGY SAVINGS I N PRACTICE 4.1 R e d u c t i o n o f Energy Consumption
B u i l d i n g e n e r g y a n a l y s i s methods a r e sometimes u s e d i n t h e form of e n e r g y a u d i t i n g p r o c e d u r e s t o g u i d e o p e r a t o r s i n e f f o r t s t o r e d u c e e n e r g y u s e i n t h e i r e x i s t i n g b u i l d i n g s . Although e n e r g y a u d i t i n g p r o c e d u r e s a r e n o t a d d r e s s e d i n t h i s p a p e r , i t i s w o r t h w h i l e m e n t i o n i n g , t h a t IEA Annex X I on Energy A u d i t i n g h a s produced a S o u r c e Book f o r Energy A u d i t o r s which c o n t a i n s v a l u a b l e i n f o r m a t i o n on t h i s s u b j e c t ( 1 3 ) .
A number of p a p e r s i n t h i s ICBEM S e s s i o n d e a l w i t h e n e r g y s a v i n g
p r a c t i c e s i n a v a r i e t y of b u i l d i n g t y p e s . O'Donnell and Doukas p r e s e n t t h e r e s u l t s of i n t e g r a t i o n and i m p l e m e n t a t i o n of e n e r g y and m a i n t e n a n c e programs a t t h e World T r a d e C e n t r e i n Melbourne. The program h a s a c h i e v e d a 15%
r e d u c t i o n i n e n e r g y consumption and a 12.7% r e d u c t i o n i n c o s t w i t h i n two y e a r s of i m p l e m e n t a t i o n . B a t t y e t a l . i n d i c a t e t h a t a n e n e r g y r e d u c t i o n of up t o 40% of c u r r e n t v a l u e s s h o u l d be a c h i e v a b l e i n new c a t e r i n g e s t a b l i s h m e n t s ( i n t h e UK) t h r o u g h improved b u i l d i n g and s e r v i c e s d e s i g n and improved management of k i t c h e n s . Vale and Vale d e m o n s t r a t e how a s m a l l o f f i c e b u i l d i n g ( f o r g e n e r a l p r a c t i c e s u r g e r y ) c a n be b u i l t w i t h i n s t r i c t c o s t l i m i t s and s t i l l a c h i e v e c o n s i d e r a b l e e n e r g y s a v i n g s ( 7 4 % i n s p a c e h e a t i n g l o a d a n d 80% i n l i g h t i n g l o a d ) . N i l s o n p r e s e n t s t h e r e s u l t s of i m p l e m e n t i n g e n e r g y
c o n s e r v a t i o n measures i n n i n e b l o c k s of f l a t s i n Sweden. Measurements were u s e d t o e v a l u a t e t h e s a v i n g s and p r o f i t a b i l i t y from d i f f e r e n t c o m b i n a t i o n s of s u c h measures. K e l l e r e t a l . p r e s e n t t h e d e s i g n of a l a r g e p u b l i c b u i l d i n g i n S w i t z e r l a n d . The d e s i g n u s e s a c o m b i n a t i o n of h i g h i n s u l a t i o n , p a s s i v e s o l a r c o n c e p t s , a n e n e r g y c o n s e r v i n g h e a t i n g s y s t e m a n d a n a c t i v e d o m e s t i c water h e a t i n g s y s t e m t o r e d u c e t h e t o t a l a n n u a l e n e r g y r e q u i r e m e n t s t o 1 5 3 M J / ~ ~ .
Pool and Brander h a v e u t i l i z e d t h e i r e x p e r i e n c e i n r e d u c i n g l i g h t i n g e n e r g y u s e i n a number of government b u i l d i n g s i n New Z e a l a n d , t o p r o d u c e a g u i d e f o r e n e r g y e f f i c i e n t l i g h t i n g d e s i g n and c o n t r o l .
Energy s a v i n g s t h r o u g h t h e u s e of h e a t pumps a r e d i s c u s s e d i n two d i f f e r e n t a p p l i c a t i o n s . S p a n t e e t a l . r e p o r t on t h e u s e of l a r g e c a p a c i t y ground c o u p l e d h e a t pumps w i t h a m u l t i p l e w e l l s y s t e m f o r t h e h e a t i n g of
a p a r t m e n t b u i l d i n g s i n Sweden. The s y s t e m examined d e m o n s t r a t e d t h a t t h i s i s a v i a b l e o p t i o n f o r a l a r g e number of a p a r t m e n t b u i l d i n g s i n Sweden. I n t h e h e a t pump a p p l i c a t i o n f o r h e a t i n g s e r v i c e ( o r d o m e s t i c ) h o t w a t e r , Gough r e p o r t s on t h e e f f e c t i v e u s e of a h e a t pump t o p r o d u c e h o t w a t e r by removing h e a t f r o m t h e c h i l l e d w a t e r r e t u r n of a n a i r c o n d i t i o n i n g w a t e r c h i l l i n g s y s t e m f o r a n a p a r t m e n t b u i l d i n g complex i n Honolulu. T h i s h e a t removal a l s o c o n t r i b u t e d t o a r e d u c t i o n of t h e c o s t of o p e r a t i n g t h e c h i l l e r .
I n a n o t h e r p a p e r , Adnot a n d Rabl examine improvements t o h o t w a t e r h e a t pump s y s t e m s t o b r i n g COP up t o between 5 and 8 (compared t o a c o n v e n t i o n a l v a l u e of a b o u t 3 ) . The two i d e a s proposed c o n s i s t of l o w e r i n g t h e t e m p e r a t u r e of t h e c e n t r a l s y s t e m c o u p l e d w i t h t r a c e h e a t i n g of t h e d i s t r i b u t i o n p i p e s and m o d i f i c a t i o n s of t h e i n t e r f a c e of h e a t pump and t a n k t o a l l o w o p t i m a l
c o n d i t i o n s f o r h e a t pump o p e r a t i o n .
Looking a t t h e f u t u r e of e n e r g y c o n s e r v a t i o n c o n c e p t s , Kroner p o i n t s t o some i n d i c a t o r s and developments which c o u l d l e a d t o w a r d s e n t i r e l y new
c o n c e p t s and d e f i n i t i o n s of b u i l d i n g d e s i g n s , b u i l d i n g s y s t e m s a n d e n e r g y - r e l a t e d t e c h n o l o g i e s . R e a l i z i n g t h a t " i n c r e m e n t a l improvement" i n t h e b u i l t - e n v i r o n m e n t w i l l remain a p a r t of t h e f u t u r e , h e a l s o l i s t s some " l e a p improvements" o r " v i s i o n a r y c o n c e p t s " t h a t s u g g e s t a d i f f e r e n t way of t h i n k i n g a b o u t b u i l d i n g r e s e a r c h and d e s i g n . 4.2 Occupant I n t e r a c t i o n U n t i l r e c e n t l y , t h e o c c u p a n t i n t e r a c t i o n was i g n o r e d i n p l a n n i n g o r p e r f o r m i n g b u i l d i n g e n e r g y a n a l y s e s . A s W i l l e y m e n t i o n s i n h i s p a p e r , o c c u p a n t were u s u a l l y c o n s i d e r e d o n l y i n t h e i r r o l e as r e c e i v e r s of t h e environment o r t e c h n o l o g y . T h i s i s b e g i n n i n g t o change w i t h t h e r e a l i z a t i o n
of i n d o o r e n v i r o n m e n t p r o b l e m s , w h e t h e r r e l a t e d t o t h e r m a l c o m f o r t , l i g h t i n g o r a i r q u a l i t y . P a r t i c u l a r l y i n commercial b u i l d i n g s , i t i s r e a l i z e d t h a t e n e r g y c o s t s a r e a v e r y s m a l l f r a c t i o n of t h e t o t a l c o s t of a b u i l d i n g o p e r a t i o n ( i n c l u d i n g s a l a r i e s ) . A number of s t u d i e s a r e emerging t o s t u d y t h e i n t e r a c t i o n between e n e r g y c o n s e r v a t i o n , t h e i n d o o r e n v i r o n m e n t and t h e o c c u p a n t . The g e n e r a l b e l i e f i s t h a t p r o p e r b u i l d i n g d e s i g n c a n a c h i e v e b o t h e n e r g y c o n s e r v a t i o n and good i n d o o r e n v i r o n m e n t . W i l l e y p r e s e n t s a number of d e s i g n s t r a t e g i e s f o r e n e r g y - e f f i c i e n t o c c u p a n t c o n t r o l of t h e e n v i r o n m e n t . T h i s a d d r e s s e s t h e two p e r c e i v e d i s s u e s of o c c u p a n t p r e f e r e n c e f o r some " n a t u r a l n e s s " i n t h e i n d o o r e n v i r o n m e n t and t h e d e s i r e t o c o n t r o l i t .
W i l l i a m s and Crawshaw, on t h e o t h e r h a n d , d i s c u s s d i f f e r e n t ways t o e n c o u r a g e o c c u p a n t s t o s a v e e n e r g y . They c o n c l u d e t h a t t h e r o u t e t o more e f f i c i e n t b e h a v i o u r l i e s i n e m p h a s i z i n g t h e i m p o r t a n c e of c o g n i t i o n , n o t m o t i v a t i o n . While e d u c a t i o n c o u l d improve e n e r g y management s k i l l s , t h e y s u g g e s t t h a t a more e f f e c t i v e and p r a c t i c a l s o l u t i o n would be t o r e - d e s i g n c o n t r o l s ( f o r more s i m p l i c i t y ) and p r o v i d e f e e d b a c k t o g i v e t h e o c c u p a n t t h e management t o o l s t o become more e n e r g y e f f i c i e n t .
B a i r d and P o o l a s s e s s e d t h e m o t i v a t i o n u n d e r l y i n g e n e r g y management i n 2 2 commercial b u i l d i n g s i n New Z e a l a n d . They d i s c u s s t h e r o l e and impact of
v a r i o u s l e v e l s of management and d i v i s i o n of r e s p o n s i b i l i t y on t h e a c t u a l e n e r g y c o n s e r v a t i o n measures and methods u n d e r t a k e n i n t h e s e b u i l d i n g s
.
Croome a n d Cheslam r e p o r t p r e l i m i n a r y r e s u l t s of a s t u d y of o c c u p a n t b e h a v i o u r i n two s i m i l a r s c h o o l s t o e x p l a i n a 30% d i f f e r e n c e i n e n e r g y consumption. They h i g h l i g h t t h e r o l e of management ( t h e h e a d m a s t e r ) , as a
" c o n s e r v a t i o n i s t " , a communicator and a problem s o l v e r , i n a f f e c t i n g t h e e n e r g y c o n s e r v a t i o n e f f o r t i n a s c h o o l .
The a s s e s s m e n t of i n d o o r e n v i r o n m e n t depends on p h y s i c a l measurements a s w e l l a s s u b j e c t i v e o c c u p a n t e v a l u a t i o n s . The p a p e r by A l b e r t i p r o p o s e s a method t o e v a l u a t e human c o m f o r t - r e l a t e d p e r f o r m a n c e of h e a t i n g a n d
c o n d i t i o n i n g s y s t e m s . The method u s e s s e v e n c r i t e r i a t o a s s e s s o c c u p a n t c o m p l a i n t s and r e l a t e them t o t h e c o n d i t i o n i n g s y s t e m , and t o h e l p t h e u n d e r s t a n d i n g of t h e t e c h n i c a l r e a s o n s f o r s a t i s f a c t i o n o r d i s s a t i s E a c t i o n . 5. SUMMARY Recent d e v e l o p m e n t s and u s e s of b u i l d i n g e n e r g y a n a l y s i s t e c h n i q u e s , a s r e p r a s e n t e d by p a p e r s i n t h i s s e s s i o n on B u i l d i n g P l a n n i n g and D e s i g n T o o l s , a r e d i s c u s s e d . The p a p e r a l s o summarizes p r e s e n t a t i o n s r e l a t e d t o e x p e r i e n c e s w i t h e n e r g y s a v i n g s i n p r a c t i c a l a p p l i c a t i o n s and t o t h e i m p o r t a n t r o l e of o c c u p a n t s i n r e a l i z i n g t h e e n e r g y s a v i n g s . I t i s e v i d e n t by t h e number of p a p e r s i n t h i s s e s s i o n ( 6 3 ) t h a t b u i l d i n g e n e r g y a n a l y s i s i s s t i l l of c o n s i d e r a b l e i n t e r e s t t o t h e b u i l d i n g r e s e a r c h and b u i l d i n g d e s i g n communities worldwide. C u r r e n t a d v a n c e s i n c o m p u t e r - a i d e d d e s i g n and knowledge-based s y s t e m s , and e f f o r t s t o i n t e g r a t e them w i t h more s o p h i s t i c a t e d e n e r g y a n a l y s i s t e c h n i q u e s , may l e a d t o a n i n c r e a s e i n t h e u s e of b u i l d i n g e n e r g y a n a l y s i s d u r i n g a l l s t a g e s of b u i l d i n g d e s i g n and
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T h i s p a p e r i s b e i n g d i s t r i b u t e d i n r e p r i n t f o r m by t h e I n s t i t u t e f o r R e s e a r c h i n C o n s t r u c t i o n . A l i s t of b u i l d i n g p r a c t i c e a n d r e s e a r c h p u b l i c a t i o n s a v a i l a b l e from t h e I n s t i t u t e may be o b t a i n e d by w r i t i n g t o t h e P u b l i c a t i o n s S e c t i o n , I n s t i t u t e f o r R e s e a r c h
