A Method for optimization of south window areas in houses

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

NRC Publications Archive

Archives des publications du CNRC

This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

A Method for optimization of south window areas in houses

Barakat, S. A.; Sander, D. M.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

NRC Publications Record / Notice d'Archives des publications de CNRC:

https://nrc-publications.canada.ca/eng/view/object/?id=6c39c9d4-e177-4f54-8d4a-950808835857 https://publications-cnrc.canada.ca/fra/voir/objet/?id=6c39c9d4-e177-4f54-8d4a-950808835857

no, 1183

~

National Research

Conseil national

C. 2

$

Council Canada

de recherches Canada

BW)G

A METHOD FOR OPTIMIZATION OF SOUTH WINDOW AREAS

I N HOUSES

by S.A. Barakat and D.M. Sander

ANALYZED

Reprinted from

ASHRAEIDOE Conference on Thermal Performance of the

Exterior Envelopes of Buildings

Las Vegas, Nevada, December 6

-

9, 1982

ASHRAE (SP 38), p. 993

-

1003

,,

7 - = . -

-

DBR Paper No. 1183

Division of Building Research

La mgthode graphigue s i m p l e pr'esents dans c e t t e e t u d e permet

d e _{calculer d h La} corlcepelon le b e a o l n en energte de chauffage

des maisons solalres passives 'a apports d i r e c t s afin de

dEterminer I'aire den Penatsea exposks au s u d st la maese ehemique de stockage qui diminueront le tofit de lT6nerpie

requise pour le chauffage. Cette mCthade s ' a p p l i q u e

a

tous les

types de maison, d e la matson solaire paestve 3 apporta d i r e c t s

d e masse 6lev'ee

a

la matson dc f a i b l e masse 3 ossature l"eg&re.

Un exemplc montre comment k t a b l i r la surface optimal.@ des fealtres exposges au aud B l'aide de cette d t h o d e .

Session X

No.

8

A Method for Optimization

of South Window Areas

in

Houses

S.A.

Barakat

D.M. Sander

ASHRA E Associate Member

ABSTRACT

A simple g r a p h i c a l procedure i s p r e s e n t e d f o r c a l c u l a t i n g t h e h e a t i n g energy requirement of d i r e c t - g a i n , p a s s i v e s o l a r houses d u r i n g t h e d e s i g n p r o c e s s i n o r d e r t o e s t a b l i s h t h e

combination of s o u t h window a r e a and thermal s t o r a g e mass t h a t w i l l minimize purchased s p a c e h e a t i n g energy. It i s a p p l i c a b l e t o t h e complete range of house c o n s t r u c t i o n t y p e s , from high-mass, d i r e c t - g a i n p a s s i v e s o l a r houses t o low-mass, l i g h t - f r a m e houses. An example i l l u s t r a t e s t h e u s e of t h e method i n e s t a b l i s h i n g t h e optimum south-facing window area. INTRODUCTION

The need f o r a simple method of e s t i m a t i n g t h e h e a t i n g energy requirement of a house i s widely recognized. Such a t e c h n i q u e could be used f o r comparing a l t e r n a t i v e s i n t h e d e s i g n p r o c e s s and f o r e v a l u a t i n g house d e s i g n s t o determine t h e i r compliance w i t h energy s t a n d a r d s . An i m p o r t a n t a s p e c t of such a method i s t h a t i t p r o v i d e s a means of e s t i m a t i n g t h e amount of s o l a r energy c o l l e c t e d through windows and u t i l i z e d t o o f f s e t h e a t l o s s e s .

A number of methods have been developed f o r e s t i m a t i n g t h e n e t s o l a r c o n t r i b u t i o n t o s p a c e h e a t i n g of d i r e c t - g a i n p a s s i v e s o l a r house designs. The s o l a r - l o a d r a t i o (SLR) method developed by t h e Los Alamos S c i e n t i f i c ~ a b o r a t o r ~ l , ~ i s widely used i n t h e United S t a t e s and Canada, but t h e range of parameters t h a t can be c o n s i d e r e d i s l i m i t e d t o t h o s e i n t h e

r e f e r e n c e d e s i g n s . I n p a r t i c u l a r , t h e SLR method cannot be used t o examine t h e e f f e c t s on a s p e c i f i c d e s i g n of f a c t o r s such a s number of g l a z i n g s and amount of thermal s t o r a g e .

Another approach t o e s t i m a t i n g s o l a r c o n t r i b u t i o n i s t h e " u n - u t i l i z a b i l i t y " method developed a t t h e U n i v e r s i t y of

is cons in.^

It r e l i e s on s o l a r r a d i a t i o n s t a t i s t i c s t o determine t h e non-useful f r a c t i o n of s o l a r g a i n t h a t must be e l i m i n a t e d t o p r e v e n t

overheating. More parameters can be c o n s i d e r e d w i t h i t t h a n w i t h t h e SLR method, b u t i t r e q u i r e s more c a l c u l a t i o n s i n v o l v i n g r a d i a t i o n d a t a . It i s , t h e r e f o r e , n o t s o widely used a s t h e SLR method. R e c e n t l y , however, t h e " u n - u t i l i z a b i l i t y " method h a s been made e a s i e r t o apply through t h e use of t a b l e s and graphs.4

The procedure p r e s e n t e d i n t h i s paper combines t h e s i m p l i c i t y of t h e SLR method w i t h t h e f l e x i b i l i t y of t h e " u n - u t i l i z a b i l i t y " method. It p e r m i t s c a l c u l a t i o n of t h e h e a t i n g energy requirements of c o n v e n t i o n a l a s w e l l a s d i r e c t - g a i n p a s s i v e s o l a r houses and i s a p p l i c a b l e t o t h e complete range of housing t y p e s , from high-mass, d i r e c t - g a i n t o l o w m a s s , sun-tempered houses. The c a l c u l a t i o n can be performed on a s e a s o n a l r a t h e r t h a n on a monthly b a s i s , making i t e a s i e r t o u s e and p e r m i t t i n g i t s i n c o r p o r a t i o n i n a g r a p h i c a l t e c h n i q u e t h a t can be a p p l i e d t o determine t h e optimum* combination of south-facing window a r e a and t h e r m a l s t o r a g e mass. The g r a p h i c a l t e c h n i q u e c a n a l s o be used t o i l l u s t r a t e t h e s e n s i t i v i t y of s e a s o n a l h e a t i n g energy requirements t o changes i n g l a s s a r e a , type of g l a z i n g , and thermal mass.

Examples f o r a Canadian l o c a t i o n (Ottawa) i n d i c a t e t h a t t h i s s e n s i t i v i t y i s l e s s t h a n might be expected.

*

Optimum i n t h e s e n s e of minimum h e a t i n g energy ( n o t a n economic optimum).

S.A. Barakat and D.M. Sander, Research O f f i c e r s , D i v i s i o n of B u i l d i n g Research, N a t i o n a l Research Council Canada, Ottawa, O n t a r i o

The energy consumption v a l u e s measured i n t h e NRCC p a s s i v e t e s t u n i t s d u r i n g t h e 1981-82 h e a t i n g season have been compared w i t h corresponding v a l u e s c a l c u l a t e d by means of t h e method p r e s e n t e d i n t h i s paper.5 C a l c u l a t e d v a l u e s were i n c l o s e agreement w i t h t h e measured

r e s u l t s , t h e maximum d i f f e r e n c e amounting t o l e s s t h a n 5%. UTILIZATION FACTOR

The c a l c u l a t i o n procedure i s based on t h e concept of t h e s o l a r u t i l i z a t i o n f a c t o r ,

ns,

d e f i n e d a s t h e f r a c t i o n of t o t a l s o l a r g a i n through a l l windows of a house t h a t c o n t r i b u t e s t o

r e d u c t i o n of t h e h e a t i n g requirement; t h a t i s ,

-

Useful s o l a r g a i n

'S

-

T o t a l s o l a r g a i n

The u s e f u l s o l a r g a i n f o r any hour i n c l u d e s t h e s o l a r g a i n used t o o f f s e t h e a t l o s s e s d u r i n g t h a t hour p l u s t h e p o r t i o n s t o r e d i n t h e thermal mass t h a t i s used t o o f f s e t l o s s e s a t a l a t e r time. It does not i n c l u d e excess g a i n t h a t must be d i s c a r d e d t o prevent room temperature from exceeding a p r e s e t maximum o r any g a i n u t i l i z e d t o o f f s e t a d d i t i o n a l l o s s e s caused by a r i s e i n room temperature above t h e t h e r m o s t a t s e t t i n g .

The s e a s o n a l h e a t i n g energy requirement, H, f o r a house i s given by:

where

L = n e t h e a t i n g l o a d

ns

= u t i l i z a t i o n f a c t o r f o r s o l a r g a i n Gs = t o t a l s o l a r h e a t g a i n through windows

The s o l a r u t i l i z a t i o n f a c t o r i s expressed a s a f u n c t i o n of two normalized parameters, t h e "gain-load r a t i o " (GLR) and t h e "thermal mass-gain r a t i o " (MGR). The gain-load r a t i o i s t h e r a t i o of s o l a r g a i n through windows, Gs, t o t h e n e t h e a t i n g load, L:

Cis GLR =

-

L ( 2 )

This gain-load r a t i o d i f f e r s from t h e s o l a r load r a t i o , a s d e f i n e d by Balcomb e t a1.,6 i n t h a t t h e GLR i n c l u d e s h e a t l o s s e s through windows w h i l e t h e SLR does not. Moreover, t h e GLR

i n c l u d e s s o l a r g a i n s through a l l windows, not j u s t t h o s e f a c i n g south.

The mass-gain r a t i o r e f l e c t s t h e thermal s t o r a g e c h a r a c t e r i s t i c s of t h e b u i l d i n g a s w e l l a s t h e a r e a , type, and o r i e n t a t i o n of t h e glazing. It i s d e f i n e d a s

MGR = C/gs ( 3 )

where

C = thermal c a p a c i t y of t h e b u i l d i n g i n t e r i o r , MJ/K gs = average hourly s o l a r g a i n f o r season, W / h r ,

(gs = GS/h i n h e a t i n g season)

The thermal c a p a c i t y , C , i s c a l c u l a t e d a s t h e " e f f e c t i v e mass" of t h e b u i l d i n g m u l t i p l i e d by i t s s p e c i f i c h e a t . The e f f e c t i v e mass i s t h e mass a c t u a l l y a v a i l a b l e f o r s t o r i n g h e a t from d i r e c t s o l a r g a i n o r from c l o s e c o n t a c t w i t h room a i r s o t h a t any change i n room a i r

temperature a f f e c t s t h e mass temperature. T h i s normally i n c l u d e s t h e mass i n s i d e t h e

i n s u l a t i n g l a y e r of t h e w a l l s and c e i l i n g s , but e x c l u d e s t h e exposed c o n c r e t e of u n i n s u l a t e d basement w a l l s and f l o o r s . T y p i c a l thermal c a p a c i t y v a l u e s f o r f o u r t y p e s of c o n s t r u c t i o n a r e given i n Tab. 1.

S o l a r u t i l i z a t i o n f a c t o r s were d e r i v e d by Barakat and Sander u s i n g hour-by-hour computer s i m l a t i o n of a l a r g e number of houses having d i f f e r e n t combLnations of space h e a t i n g load, thermal s t o r a g e mass, s o l a r g a i n , and a l l o w a b l e temperature swing f o r f i v e Canadian

location^.^

When t h e r e s u l t i n g u t i l i z a t i o n f a c t o r s were c o r r e l a t e d , u s i n g t h e parameters GLR

and MGR, they were found t o be independent of g e o g r a p h i c a l l o c a t i o n (Fig. 1). F i g u r e 1 shows t h e s o l a r u t i l i z a t i o n f a c t o r p l o t t e d a g a i n s t t h e GLR f o r v a r i o u s v a l u e s of MGR and a room temperature r i s e of 5.5 C deg. Curves f o r 0 and 2.75 C deg temperature r i s e a r e a l s o a v a i l a b l e .

CALCULATION OF HEATING REQUIREMENT

The b a s i s of t h e c a l c u l a t i o n method i s t h e simple h e a t balance e q u a t i o n of t h e house, a s g i v e n by Eq 1. The s e a s o n a l n e t h e a t i n g l o a d , L, i s c a l c u l a t e d a s

where

Lt = t o t a l h e a t l o s s due t o t r a n s m i s s i o n through e x t e r i o r w a l l s , windows, c e i l i n g s , e t c . La = t o t a l h e a t l o s s due t o i n d o o r o u t d o o r a i r exchange ( i n f i l t r a t i o n + v e n t i l a t i o n ) Lb = t o t a l below-grade h e a t l o s s

ni

= u t i l i z a t i o n f a c t o r f o r i n t e r n a l g a i n s

Gi = t o t a l h e a t g a i n s from i n t e r n a l s o u r c e s ( l i g h t s , equipment, people, e t c . )

The s e a s o n a l t o t a l h e a t l o s s e s due t o t r a n s m i s s i o n through t h e e x t e r i o r w a l l s , windows, and c e i l i n g may be c a l c u l a t e d a s

Lt = 0 . 0 3 6 ~ ( 5 ~

- g o ) z u ~

(components) (MJ) ( 5

where

N

= number of hours i n h e a t i n g s e a s o n

8. = s e a s o n a l average indoor a i r temperature

-

1

8, = s e a s o n a l average outdoor a i r temperature

UA = thermal conductance of each component, i n c l u d i n g a l l windows

-

The conductance v a l u e s , UA, can be c a l c u l a t e d a s d e s c r i b e d i n t h e ASHRAE

andb book,^

and 9, i s a v a i l a b l e f o r many l o c a t i o n s from weather d a t a records. l o The h e a t l o s s e s due t o indoor-outdoor a i r exchange, La, can be c a l c u l a t e d from t h e e q u a t i o n ,

where

ACH = average a i r change r a t e of house ( a i r changes per h o u r ) V = volume of house, m3

The t o t a l below-grade l o s s can be c a l c u l a t e d u s i n g a procedure r e c e n t l y developed by M i t a l a s . l l The magnitude of t h e i n t e r n a l g a i n s , Gi, depends on t h e occupancy of t h e house. While d a t a concerning t h e r a t e of h e a t r e l e a s e from v a r i o u s a p p l i a n c e s a r e a v a i l a b l e , i t i s always necessary t o make a r b i t r a r y assumptions r e g a r d i n g occupant behavior and, t h e r e f o r e , of i n t e r n a l gains. For most s i t u a t i o n s i n which G i s l e s s t h a n 25% of t h e h e a t l o s s , a l l i n t e r n a l g a i n s a r e assumed t o be u s e f u l ( s i = l f .

The s e a s o n a l t o t a l s o l a r g a i n through t h e windows i s c a l c u l a t e d a s

where

s u b s c r i p t i r e p r e s e n t s o r i e n t a t i o n of window, and A = g l a s s a r e a

shi

= s h a d i n g c o e f f i c i e n t of window

Qi = t o t a l s o l a r g a i n through u n i t a r e a of a s i n g l e s h e e t of s t a n d a r d g l a s s , g i v e n by

Qi = 0.83 Hi, where Hi i s t h e t o t a l s e a s o n a l s o l a r r a d i a t i o n i n c i d e n t on t h e window s u r f a c e

Values of t o t a l monthly s o l a r r a d i a t i o n i n c i d e n t on s u r f a c e s of d i f f e r e n t o r i e n t a t i o n s and t i l t s a r e t a b u l a t e d f o r a number of l o c a t i o n s . I n Canada t h i s i n f o r m a t i o n i s a v a i l a b l e from t h e Atmospheric Environment S e r v i c e a s 10-year a v e r a g e s f o r 130

location^.^

The s e a s o n a l s o l a r g a i n can be o b t a i n e d by summing t h e v a l u e s f o r t h e a p p r o p r i a t e months.

Equations 2 and 3 a r e used t o c a l c u l a t e t h e GLR and MGR. The u t i l i z a t i o n f a c t o r ,

ns,

can then be found from Fig. 1 and t h e space h e a t i n g requirement ( a u x i l i a r y h e a t i n g ) c a l c u l a t e d from Eq 1.

GRAPHICAL DESIGN METHOD

S o l a r u t i l i z a t i o n may a l s o be p r e s e n t e d a s t h e f r a c t i o n of n e t h e a t i n g l o a d t h a t must be s u p p l i e d by t h e h e a t i n g system. T h i s f r a c t i o n , Fh, w i l l be r e f e r r e d t o a s t h e "purchased h e a t i n g f r a c t i o n . " ( I t i s , i n f a c t , e q u a l t o one minus t h e s o l a r h e a t i n g f r a c t i o n . )

F i g u r e 2 shows Fh p l o t t e d a s a f u n c t i o n of t h e parameters GLR and MGR. The curves apply f o r a maximum a l l o w a b l e temperature swing of 5.5 C deg; graphs f o r o t h e r temperature swings have been given by Barakat and Sander.12

The h e a t i n g energy requirement f o r t h e house can be o b t a i n e d from

The above procedure can be i n c o r p o r a t e d i n a simple g r a p h i c a l method t o examine t h e e f f e c t of south-facing window t y p e and a r e a a s w e l l a s t h e r m a l s t o r a g e on t h e h e a t i n g requirement of a house. Figure 2 can be r e f o r m a t t e d a s shown i n Fig. 3 and t h e f o l l o w i n g p l o t t e d a g a i n s t s o u t h window a r e a f o r a p a r t i c u l a r house design:

1. S o l a r g a i n , Gs, c a l c u l a t e d a s a l i n e a r f u n c t i o n of s o u t h window a r e a , assuming t h a t t h e a r e a s of wlndows on t h e o t h e r o r i e n t a t i o n s remain f i x e d :

where

Go i s t h e s o l a r g a i n through a l l o r i e n t a t i o n s o t h e r t h a n s o u t h

2. Net house l o a d , L, c a l c u l a t e d a s a l i n e a r f u n c t i o n of s o u t h window a r e a :

where

L; i s t h e t r a n s m i s s i o n l o s s of t h e house w i t h a l l s o u t h windows r e p l a c e d by w a l l (Asouth= 0 )

3 . GLR, obtained by d i v i d i n g Gs by L a t a number of p o i n t s

4 . MGR, obtained by computing CN/Gs f o r a number of v a l u e s of Asouth

The procedure f o r c o n s t r u c t i n g t h e r e l a t i o n between window a r e a and purchased h e a t i n g requirement i s a s f o l l m s (Fig. 3 ) :

1. For any s o u t h window a r e a , draw a v e r t i c a l l i n e t o i n t e r s e c t t h e s o l a r g a i n l i n e , t h e n e t l o a d l i n e , t h e GLR curve, and t h e MGR curve a t p o i n t s A , B , C , and D,

r e s p e c t i v e l y .

2. Draw a h o r i z o n t a l l i n e from p o i n t C t o i n t e r s e c t t h e purchased h e a t i n g f r a c t i o n p l o t f o r t h e a p p r o p r i a t e MGR (measured a t D) a t p o i n t E (some i n t e r p o l a t i o n between MGR curves may be necessary). This determines t h e purchased h e a t i n g f r a c t i o n , Fh. The h e a t i n g requirement, H , i s then e q u a l t o t h e product of Fh and L. This i s o b t a i n e d g r a p h i c a l l y i n t h e next t h r e e s t e p s .

3. Draw a h o r i z o n t a l l i n e from p o i n t B t o i n t e r s e c t t h e v e r t i c a l l i n e of Fh = 1.0 a t X.

Connect a l i n e between p o i n t X and p o i n t Y ( p o i n t of i n t e r s e c t i o n of t h e v e r t i c a l l i n e through Fh = 0 and t h e z e r o energy l i n e ) .

4. Draw a v e r t i c a l l i n e from p o i n t E t o meet t h e l i n e XY a t F.

5. Draw a h o r i z o n t a l l i n e from p o i n t F t o meet t h e o r i g i n a l v e r t i c a l l i n e of S t e p 1 a t p o i n t G. The energy v a l u e a t p o i n t G r e p r e s e n t s t h e purchased h e a t i n g energy a s s o c i a t e d w i t h t h i s s o u t h window a r e a .

6. Repeat s t e p s 1 through 5 f o r o t h e r s o u t h window a r e a s and draw a curve through a l l G p o i n t s . T h i s curve r e p r e s e n t s t h e r e l a t i o n between Asouth and purchased h e a t i n g energy.

A change i n thermal s t o r a g e f o r t h e same house can be accommodated simply by c a l c u l a t i n g new v a l u e s of MGR and r e p e a t i n g t h e above. A change i n window type r e q u i r e s r e p e t i t i o n of t h e e n t i r e procedure, beginning by r e c a l c u l a t i o n of b o t h Gs and L.

SAMPLE CALCULATIONS

Examples a r e p r e s e n t e d i n Figs. 4 and 5 f o r two d i f f e r e n t house envelope c o n s t r u c t i o n s ( t h e r m a l r e s i s t a n c e ) i n Ottawa, Canada. For each example, t h r e e o p t i o n s were e v a l u a t e d :

1. l i g h t frame c o n s t r u c t i o n w i t h a l l windows double glazed 2. same a s 1 , but w i t h f o u r times t h e amount of thermal s t o r a g e 3. l i g h t c o n s t r u c t i o n with a l l windows t r i p l e glazed.

D e t a i l s of t h e s i x c a s e s examined a r e given i n Tab. 2 a l o n g w i t h t h e minimum purchased h e a t i n g r e q u i r e d f o r each c a s e and t h e optimum s o u t h window area.

SUMMARY AND OBSERVATIONS

A simple g r a p h i c a l procedure i s p r e s e n t e d f o r determining t h e optimum combination of s o u t h window a r e a , window t y p e , and t h e r m a l s t o r a g e mass f o r any house c o n s t r u c t i o n . The f o l l o w i n g o b s e r v a t i o n s r e g a r d i n g d i r e c t - g a i n p a s s i v e s o l a r houses i n t h e Canadian c l i m a t e were made by a p p l y i n g t h e method t o a number of house d e s i g n s f o r t h e Ottawa area.

The curves of purchased h e a t i n g v e r s u s south-facing window a r e a a r e very shallow around t h e optinum a r e a . I n g e n e r a l , a 50% change i n s o u t h window a r e a on e i t h e r s i d e of t h e optimum v a l u e r e s u l t s i n a s m a l l change i n purchased energy requirement ( a maximum of 4% i n t h e s i x c a s e s p r e s e n t e d ) .

The optimum s o u t h window a r e a d e c r e a s e s f o r t h e more energy conserving houses. For double-glazed windows and l i g h t w e i g h t c o n s t r u c t i o n t h e optimum a r e a i s about 8% of f l o o r a r e a f o r an 80 G J house (House 1 ) . This reduces t o 3.5% of f l o o r a r e a f o r t h e more energy

conserving (48 GJ) house (House 2 ) .

Although an i n c r e a s e i n thermal s t o r a g e allows u s e of more windows and r e s u l t s i n a r e d u c t i o n i n purchased energy, a l a r g e r r e d u c t i o n i n purchased energy can be achieved w i t h a s m a l l e r a r e a of t r i p l e - g l a z e d windows. Taking t h e optimum double-glazing c a s e s a s bases f o r comparison, a f o u r - f o l d i n c r e a s e i n mass r e s u l t s i n a 7% r e d u c t i o n i n purchased h e a t i n g f o r House 1 and 2% r e d u c t i o n f o r House 2. Use of t r i p l e - g l a z i n g r e s u l t s i n r e d u c t i o n s of 15% and 21% f o r Houses 1 and 2, r e s p e c t i v e l y .

REFERENCES

1. W.O. Wray, Design and Analysis of D i r e c t Gain S o l a r Heated Buildings, Los Alamos

S c i e n t i f i c Laboratory, LA-8885+lS, 1981.

2. J . D . Balcomb, e t a l . , P a s s i v e S o l a r Design Handbook, Vol. 2, P a s s i v e S o l a r Design A n a l y s i s , U.S., Department of Energy, DOE/CS-012712, 1980.

3. W.A. Monsen, S.A. Klein, and W.A. Beckman, " P r e d i c t i n g of D i r e c t Gain S o l a r Heating System Performance," S o l a r Energy, 27:2 (1981) p. 143-147.

4. S.A. K l e i n , e t a l . , "Tabular Data f o r t h e U n - U t i l i z a b i l i t y P a s s i v e S o l a r Design Method," Proc. of t h e 6 t h N a t i o n a l P a s s i v e S o l a r Conference, P o r t l a n d : ISES, (1981), p. 328-332. 5. S.A. Barakat, and D.M. Sander, U t i l i z a t i o n of S o l a r Gain through Windows f o r Heating

Houses, N a t i o n a l Research Council Canada, D i v i s i o n of B u i l d i n g Research, BRNote 184, 1982.

6. Balcomb e t a l . 7. Barakat and Sander. 8. I b i d .

9. ASHRAE Handbook

--

1981 Fundamentals Volume, Chapter 23.

10. Canada, Atmospheric Environment S e r v i c e , Downsview, O n t a r i o , Canadian Normals

-

Temperature, 1975.

11. G.P. ~ i t a l a s , Baselnent Heat Loss S t u d i e s a t

DBRINRC,

N a t i o n a l Research Council Canada, Ottawa, D i v i s i o n of B u i l d i n g Research, NRCC 20416, (1982), 63 p.

12. Barakat and Sander.

TABLE 1

Sample House Weights Thermal Capacity

p e r F l o o r Area (MJ/m2K)

C o n s t r u c t i o n

0.060 L i g h t

-

Standard frame c o n s t r u c t i o n ,

12.7-m gypsum board f i n i s h on w a l l s and

c e i l i n g s , c a r p e t over wooden f l o o r

0.153 Medium

-

A s above, b u t 50.8- gypsum board

f i n i s h on w a l l s and 25.4-mm on c e i l i n g

0.415 Heavy

-

I n t e r i o r w a l l f i n i s h of 101.6-mm

b r i c k , 12.7-mm gypsum board f i n i s h on c e i l i n g , c a r p e t over wooden f l o o r

0.810 Very Heavy

-

Commercial o f f i c e b u i l d i n g ,

304.8-m c o n c r e t e f l o o r

TABLE 2

Sample C a l c u l a t i o n f o r Ilouses i n Ottawa

Parameter House 1 House 2

Case Case Case Case Case Case

1 2 3 1 2 3

Floor a r e a , m2 207 207 207 207 207 207

Thermal c a p a c i t y , MJ/K 12.4 49.6 12.4 12.4 49.6 12.4

Wall thermal r e s i s t a n c e , m 2 * ~ / w 3.5 3.5 3.5 6.4 6.4 6.4 C e i l i n g thermal r e s i s t a n c e , m 2 * ~ / w 5.2 5.2 5.2 10.5 10.5 10.5

Glazing type Double Double T r i p l e Double Double T r i p l e

South s o l a r g a i n , MJ/m2 1814 1814 1670 1814 1814 1670 Basement h e a t l o s s , G J 20 20 20 17 17 17 I n t e r n a l g a i n s , G J 15 15 15 15 15 15 A i r change r a t e , l / h 0.25 0.25 0.25 0. l* 0.1 0.1 Heat l o s s c o e f f i c i e n t ( a t Asouth = O), m 2 * ~ / w 206 206 197 120 120 116 Optimum s o u t h window a r e a , m2 Minimum purchased h e a t i n g , G J

*

Equivalent t o 0.5 a i r changeslhour u s i n g a i r - t o - a i r h e a t exchanger of 0.8 e f f e c t i v e n e s s .

G L R

Figure 1. Seasonal solar utilization factor 0

(rocm temperature swing = 5.5 C)

Figure 2. Seasonal purchased heating fraction 0

(room temperature swing = 5.5 C)

F i g u r e 3 . I l l u s t r a t i o n of g r a p h i c a l p r o c e d u r e loo0

N A M E

D B F !

P R O J E C T

H O U S E

1

O T T A W A , C A N A D A

S O U T H W I N D O W A R E A ,

m 2

Figure 4 . Saniple c a l c u l a t i o n f o r House 1

(

N A M E

D B R

I

I

P R O J E C T

H O U S E 2

1

O T T A W A , C A N A D A

F i g u r e 5 . S a m p l e c a l c u l a t i c n for House 2

Discussion

P . B r u n e l l o , U n i v e r s i t y o f U d i n e ( I t a l y )

-

L a w r e n c e B e r k e l e y L a b . , B e r k e l e y , C A : Two q u e s t i o n s a b o u t y o u r i n t e r e s t i n g m e t h o d o l o g y f o r c a l c u l a t i n g r e q u i r e m e n t s , w h o s e p h i l o s o p h y s e e m s t o b e v e r y s i m i l a r t o a c o r r e l a t i o n p r o c e d u r e we h a v e d e v e l o p e d ( r e p o r t e d i n t h e P r o c e e d i n g s o f t h e f i r s t ASHRAE-DOE c o n f e r e n c e h e l d i n O r l a n d o , F L , i n 1 9 7 9 ) . F i r s t , how d o y o u t a k e i n t o a c c o u n t t h e v a r i a t i o n s o f t h e i n t e r n a l r a d i a t i o n - c o n v e c t i o n l a m i n a r c o e f f i c i e n t ? S e c o n d , e v e n t h o u g h t h e r e i s n o i n t e r n a l a i r t e m p e r a t u r e s w i n g , s o m e s o l a r e n e r g y i m p i n g i n g o n t h e i n t e r n a l s u r f a c e s i s l o s t , b e c a u s e i t m u s t b e a b s o r b e d b y t h e w a l l s , r a i s i n g t h e i r t e m p e r a t u r e a n d s o i n c r e a s i n g t h e c o n d u c t i v e h e a t l o s s e s . Do y o u a c c o u n t f o r t h i s p h e n o m e n o n ? S . S . BARAKAT: T h e v a r i a t i o n s o f t h e i n t e r n a l f i l m c o e f f i c i e n t a r e n o t a c c o u n t e d f o r i n t h e c a l c u l a t i o n s . T h e s e v a r i a t i o n s r e s u l t f r o m t h e c h a n g e i n w a l l s u r f a c e t e m p e r a t u r e d u e t o t h e i n c i d e n t s o l a r r a d i a t i o n o n p a r t o f t h e w a l l . No c o r r e l a - t i o n f o r s u c h v a r i a t i o n s e x i s t s a t t h i s t i m e . S i n c e t h e r e s p o n s e f a c t o r s f o r s o l a r g a i n a r e n o r m a l i z e d , t h a t i s , a l l t h e g a i n i s a s s u m e d t o s t a y i n t h e building, t h e e x c e s s h e a t l o s s d u e t o r i s e i n w a l l t e m p e r a t u r e i s n o t t a k e n i n t o a c c o u n t i n t h e c o m p u t e r c a l c u l a t i o n s . H o w e v e r , t h i s c a n b e a c c o u n t e d f o r u s i n g t h e "F" f a c t o r d e s c r i b e d i n t h e ASHRAE H a n d b o o k - - I 9 7 7 F u n d a m e n t a l s V o l u m e , c h a p t e r 2 5 , p a g e 2 3 . T h e u s e f u l s o l a r g a i n i n t o t h e b u i l d i n g c a n b e r e d u c e d h y a f a c t o r l e s s t h a n 1 . 0 t o a c c o u n t f o r t h e s e e x t r a l o s s e s . F o r w e l l - i n s u l a t e d h o u s e s , s u c h a s t h o s e b e i n g b u i l t i n C a n a d a , t h e e x c e s s h e a t l o s s w i l l b e i n s i g n i f i c a n t a n d t h e e r r o r d u e t o t h e i r o m i s s i o n i s much l e s s t h a n o t h e r e r r o r s a s s o c i a t e d w i t h s i m p l e c a l c u l a t i v e m e t h o d s , f o r e x a m p l e , d u e t o u n c e r t a i n t y i n s o l a r r a d i a t i o n m e a s u r e m e n t s o r s h o r t w a v e r a d i a t i o n r e f l e c t e d b a c k t h r o u g h t h e w i n d o w .

T h i s paper, w h i l e 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 form by t h e D i v i s i o n of B u i l d i n g R e s e a r c h , remains t h e c o p y r i g h t of t h e o r i g i n a l p u b l i s h e r . It s h o u l d n o t b e reproduced i n whole o r i n p a r t w i t h o u t t h e p e r m i s s i o n of t h e p u b l i s h e r . A l i s t of a l l 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 D i v i s i o n 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 , D i v i s i o n of B u i l d i n g R e s e a r c h , N a t i o n a l R e s e a r c h C o u n c i l o f C a n a d a , O t t a w a , O n t a r i o , KIA 0R6.