• Aucun résultat trouvé

Cost of energy conservation measures for new housing

N/A
N/A
Protected

Academic year: 2021

Partager "Cost of energy conservation measures for new housing"

Copied!
25
0
0

Texte intégral

(1)

Publisher’s version / Version de l'éditeur:

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.

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.

Building Research Note, 1981-09

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

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=173a937c-e03f-4d88-ab10-7967681d522a https://publications-cnrc.canada.ca/fra/voir/objet/?id=173a937c-e03f-4d88-ab10-7967681d522a

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.

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.

https://doi.org/10.4224/40000536

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

Cost of energy conservation measures for new housing

Dumont, R. S.; Orr, H. W.

(2)

10171

ISSN

0701-5232

(3)

COST

OF ENERGY

CONSERVATION

MEASURES FOR NEW

HOUSING

by

R.S.

Dumont and H . W . ~ r r *

INTRODUCTION

T h i s report presents n study of t h e costs for the

extra

energy

c o ~ l s c ~ v : ~ t j o t ~ mcasures t h a t nrc now b e i n g uscd on a significant nurnhcs o f low-cncrgy hauscs*'

in

Western Canada, p a r t i c u l a r l y i n the Saskntosn a r e a . As o f 1981, approximately 150 low-energy houses have been

constructed

i n

t h a t part o f Canada.

Far an average-sized, contractor-built, new h o u s e , the extra c o s t s for t h e energy c o ~ ~ s c r v a t i o n measures o v e r and above t h e present n i i l i i m u m s t a n d a r d iIrc i n tltc snngc of $30(10 to $5000, which i n c l u r l c 3 normal p r o f i t f o r thc h u i l d e r . The analysis o f the payback on such an e x t r a investment js complicated by the d i f f e r e n t f u e l prices t h a t

e x i s t .

To simplify matters somewhat, f u e l prices are d i v i d e d i n t o separate c a t e g o r i e s . The three price ranges for s h e consumer i n Saskatoon a r e approximately as follows:

1. p r e s e n t consumer p r i c e for natural gas (about $2.30/1000 cu ft), which is equivalent t o a space heating f u e l c o s t of a h o u t $3.50/GnJ when burned in a ftlrnacc of 65% seasonal e f f i c i e n c y ;

2. present consumer p r i c e for fuel oil (20 $ / L or electricity 13 #/kW-h), which is now equal t o about $8JGJ a s u s e f u l space h e a t i n g ;

3 . present

OPEC

o i l

price

($41 (Can.) per b a r r e l ) ,

which is

equivalent to about $ 1 1 / ~ J as useful space heating.

This range of p r i c e s ( $ 3 . 5 0 , $ 8 and $ll/GJ) obviously affects the cost-

benefit analysis of energy conservation measures for low-energy housing.

*

Both a u t h o r s are members o f the P r a i r i e Regional Station, Saskatoon, DBR/NRC.

**

For purposes

o f t h i s Note, a

low-energy house

i s defined as a

house w i t h moTe t h a n RSI 5 wall insulation, in o r d e r to d i s t i n g u i s h

t h e s e houses from the large number of new houses with

RSI

3.5 wall insulation.

(4)

?icasurcs that a consumer would deem economical when prices a r e $ l l / G J a r e

not

attractive when t h e p r i c e is o n l y $3.50/GJ. The intermediate p r i c e of $8/GJ is u s e d l h e r e f o r the b u l k o f t h e analysis. This is the c o s t f i g u r e that most consumers in Central and Eastern Canada face at this time.

The

economic analysis i s carried

out

using the simple payback p e r i o d method, t o the exclvsian o f a

number of

life-cycle c o s t

techniques such as t h e present worth or internal rate of return anal- yses. The simple payback p e r i o d f o r an energy conservation measure i s d e f i n e d a s t h e initial e x t r a investment d i v i d e d by t h e f i r s t year s a v i n g s in enerEy cost. For a space-heating energy price of $ 8 / G 3 ,

t h e simple payback period f o r t h e encrgy conservation methods discussed in t h i s paper i s between 4 and 25 years f o r housing i n the p r a i r i e region o f Canada.

The g r e a t advantage of the payback period analysis

is

t h a t it

compares two known quantities, the present p r i c e of energy conservation f e a t u r e s

and

the present cost of energy. A second advantage i s t h a t it i s widely understood by b o t h t h e public and t h e engineering

community. One disadvantage is that the increased value embodied in t h e house investment i s n o t accounted for. On balance, however, the simple payback analysis has attractive features which make i t s use acceptable for comparing t h e economic feasibility

of

d i f f e r e n t levels of energy conservation.

An

alternative approach is the p r e s e n t worth analysis,' which uses a discounting t e c h n i q u e to r e l a t e a f u t u r e s t r i n g of payments to t h e i r equivalent value a t t h e present time for comparison with an investment i n t h c p r e s c n t . 'I'fkis a p p r o a c l ~ Ilas becn used to d e t e r m i n e the insulatjnrl requirements i n t h e Canadian ""Measures

for

Energy Conservation in New Buldings 1978."2 A prescnt worth f a c t o r o f 18 was chosen at that t i m e along with a base energy price

of

S3.42JGJ (corresponding to fuel oil at 1 3 . 2 $ J L ) . When burned

in

a furnace of 6 0 % seasonal efficiency, the n e t energy cost i s $ 5 . 7 0 J G J . This present worth factor o f 18 corres- ponds t o a useful lifetime of 30 years (typical mortgage l i f e ) and a

mortgage interest rate 3% h i g h e r t h a n t h e r a t e of annual e s c a l a t i o n in t h e p r i c e of f u e l .

W i t h the p r e s e n t w o r t h f a c t o r so d e f i n e d , the simple payback period can be r e l a t e d t o t h e present w o r t h factor. For a present worth f a c t o r equal t o 1 8 , onc could j u s t i f y conservation measures up to t h e p o i n t where t h e l a s t incremental measure used would have a simple payback of

18 y e a r s . W i t h a higher p r e s c n t worth factor, a longer payback p e r i o d

would be acceptable.

ENERGY

CONSERV.4TION MEASURES

The t h r e e measures used f o r law-energy housiny a r c a s follows: air tightness w j t h coritrollcd ventilation, s u - p e r i n s u l a t j o n , and use of south windows for passi.ve solar gain.

(5)

I . Air T i g h t n e s s w i t h Controlled Ventilation

I n average new housing i n Canada, air exfiltration accounts f o r approximately 25% of t h e t o t a l heat l o s s from a dwelling. Typically, a i r change r a t e s f o r dwellings arc i n the range of 0 . 3 t o 0.5

air

changes p e r hour during the heating season. In houses w i t h combustion equipment such as oil, n a t u r a l gas, o r propane h e a t i n g , about 0 . 2 a i r

changes p e r h o u r a r c r e q u i r e d t a satisfy the combustion and chimney air requirements of t h e combustion equipment [furnace and water h e a t c r ) .

The results from a sample of low-energy houses in Saskatoon show t h a t it is p o s s i b l e to decrease t h e uncontrolled

air

change r a t e

in

a house to approximately 0.05 t o 0 . 1 0 air changes per hour by tightly sealing the house and isolating any combustion equipment if uscd, by means o f a sealed furnace room. The techniques for achieving t h i s low a i r lea- kage a r e described in t h e booklet "Low Energy Passive Solar H o ~ s i n g . " ~

To d a t e , forty I~ouses incorporating t h e s e a i r tightness techniques have

b e e n tested u s i n g a portable fan a p p a r a t u s . The air leakage o f the w e l l sealed houses is approximately 1/3 t h a t of s t a n d a r d housing i n t h e Saskatoon area.

The air-vapour b a r r i e r installation is the crucial operation i n assuring air tightness i n t h e houses. I n s t a n d a r d houses t h e vapour

barrier is u s u a l l y 50 prn p o l y e t h y l e n e and t h e j o i n t s are

n o t

caulked or s e a l e d . In the upgraded case, 150 pm p o l y e t h y l e n e i s u s e d and

t h e j o i n t s a r e c a r e f u l l y sealed u s i n g a non-hardening c a u l k i n g compound The time to install t h e vapour barrier to t h e upgraded standard i s about 6 person-days of l a b o u r . F e r a s t a n d a r d vapour basrier, about 1 person-day of labour is involved. Thus t h e n e t extra l a b o u r charge i s 5 person-days. The c o s t s are presented in T a b l e I .

Cantrolled ventiIntion using an air-to-air I~cat exchanger

Controlled ventilation i s necessary f o r houses

with

upgraded air tightness. Because t h e house i s r e l a t i v e l y t i g h t it i s possible ta u s e an air-to-air heat exchanger. Canadian-made a i r - t o - a i r heat exchangers a r e available a t allout $425 F.O.B. i n Saskatoon. The c o s t of a u n i t i n c l u d i n g the installation charge is presented

in

T a b l e 2 .

Tf a combustion f u r n a c e is uscd in a relatively airtight house, p r o v i s i o r r must I)c made f o r the s u l ~ p l y of combustion a i r and chimney i . Scver;tf a p p r o a c h e s arc p o s s i b l e :

1. u s e of n d i r e c t outside a i r supply to the furnace through s p e c i a l

d u c t i n g ;

2 . u s e o f a s e a l e d furnacc room with a duct t o t h e outside; and

3 . use o f an outside a i r duct t o supply outside a i r t o the huuse; t h e f u r n a c e air i s t a k e n from t h e l ~ o u s e . Normally t h e o u t s i d e a i r duct is connected to t h e return air plenum on the furnace to

(6)

With appro:lches Nos. 1 and 2, n s u p p l y o f outside a i r must be provided f a r t h e occupants of t h e house. T h i s o u t s i d e air can

be

provided at a low energy c o s t if an air-to-air heat exchanges i s used.

With

approach

No.

3 t h e air-to-air heat exchanger i s not

r e q u i r e d .

Care must

be taken, however, to e n s u r e thar s u f f i c i e n t

a i r

flow

is

maintained to p r o v i d e adequate ventilation f o r the occupants.

A number

of

reports have presented cost data on t h e total extra c o s t s for insulation beyond t h e present

minimum

standards. The '%~uilders Guide r o Energy Efficiency i n New ~ o u s i n ~ , ~ ' 4 produced for HUDAC and the Ontario M i n i s t r y of Energy

in

1980, presents cost datn

for walls, bascmcnt walls and c e i l i n g s . These d a t a are presented as t h e incremental c o s t s beyond the m i n i m u m standards. Ilurnont, Besant

and ~ c h o c n a u s p r e s e n t c o s t d a t n for a I n n m2 bungalow w i t h a preserved wond fuutlcl3tion. 'J'hc N:~tion:al llcscarch Cozlncil i n t h e "Commentary o n Mcasurcs for Ericrgy C r ~ n s c r v a t i o n

in

Ncw l l u i l d i n g s 1978,"fi presents cost data developed by a consultant. ~ e d l i n 7 h a s i n i r i a t e d a study of supesinsulation casts, and h i s results were made available f o r t h e costs o f double s t u d w a l l canstruction. A paper by Besant,

Dumont and schoenau8 includes these figures. Enercon Ltd.

of

Regina h a s prepared a comparative cost study9 f o r superinsulated walls.

The c o s t s presented by the various authors are summarized i n Table 5 .

The incremental costs for ceiling insulation are

in

close agreement between t h e five reposts, varying from 85.5 t o 110 #/m2 RSI. The c o s t s for t h e concrete basement wall i n s u l a t i o n a r e also in close agreement -

244

and

249 g/m2 RSI. For t h e preserved wood foundations, t h e two costs vary from 103 to 155 #/m2 RSI. It is believed that t h e h i g h e r

figure i s caused by t h e inclusion o f t h e c o s t o f t h e gypsum s h e e t i n g i n t h e h i g h e r c a s t estimate.

The

major d i f f e r e n c e i n c o s t s f o r t h e

i n s u -

lation of t h e concrete

and

wood basements is due to the presence of studding in the wood basement,

which

g r e a t l y reduces the c o s t of the structure to hold the insulation.

With

t h e concrete basement insulated o n t h e i n s i d e , the cost of t h e structure to hold the insulation i s a

s i g n i f i c a n t c x t r a . For t h e above-grade walls, the c o s t s of the cxtra

r u a E l i n s u l a t i o n a r e i n a range of 0 to 1047 #/m2

RST.

T h i s variation is, ;tr f i r s t glxncc

,

d i f f i c u l t to reconci l c .

A morc clct;i i l c d colnl~irrisorl o f the cost figures produccd by t h c various a u t h o r s f o r wall i n s u l a t i o n a r c presented i n Fig. 1. The c o s t

for t h e b a s i c wall ( e x c l u d i n g s i d i n g and i n t e r i o r gypsum board) is S 1 3 . 4 4

/mZ

fos a standard 38 x 89 mrn wall w i t h fibre~lass b a t t

i n s u l a t i o n . O f t h c seven d i f f e r e n t s e t s o f cost f i g u r e s p r e s e n t e d , some were originally p r e s e n t e d as the extra c o s t for t h e more h i g h l y i n s u l a t e d wall. In o r d e r to p r o v i d e n more consistent basis f o r comparison, t h e total cost f o r t h e w a l l s , rather than the extra cost, i s p l o t t e d i n this figure. The total cost was calculated by adding t h e

extra

c o s t to t h a t of the basic wall which i s $13.44/m*.

(7)

As can b e seen

from

the d a t a t h e r e is a considerable amount of s c a t t e r i n t h e p o i n t s . F o r convenience

sake, t h e

wall i n s u l a t i o n l e v e l s are d i v i d e d i n t o two groups, the s i n g l e stud and the double s t u d designs.

Single

stud designs

For the single stud designs, t h e lower incremental c o s t s a r e

generally based on

the

use of r i g i d i n s u l a t i n g board t o replace the

c o n v e n t i o n a l s h e a t h i n g materials such a s p l ~ w o o d , particle board o r gypsum board. With this approach, the extra wall c o s t i s only t h e cxtra m a t e r i a l cost f o r t h e i n s u l a t i n g board r e l a t i v e to the con- v e n t i o n a l sheathing plus a c o s t for e x t r a wall bracing t o p r o v i d e s u f f i c i e n t r a c k i n g strength. A t t h i s p o i n t t h e o b j e c t i o n can b c

raised, however, t h a t one is no l o n g e r comparing equal walls i n

terms o f quality of construction. T h e argument goes that a wall w i t h plywood or comparable s h e a t h i n g m a t e r i a l i s superior co a wall s h e a t h e d w i t h an insulating board w i t h low d e n s i t y and low tensile strength. The resolution of this argument i s beyond the scope of t h i s paper.

Up t o a n i n s u l a t i n g l e v e l o f a b o u t RSI 3.5 t h e insulating boards may be used w i t h conventional 38 x 89 mm studs. Beyond t h i s wall

insulation level, 38 x 140 m m studs p l u s i n s u l a t i n g board may be used t o a c h i e v e an insulating value of about RSI 5 - 3 . Beyond this insu- lating level, 38 x 190 m s t u d s may b e used, although t h e double stud wall appears to h e more popular f o r these h i g h e r i n s u l a t i o n l e v c l s . The less expensive s i n g l e stud designs have an incremental c o s t slope of about 220 $/m2 RSI, a s shown in Fig. 1.

Double stud d e s i e n s

As shown in F i g . 1, t h e costs for the double stud designs e x h i b i t

a l a r g e amount o f s c a t t e r , with a c o s t

difference

o f about $7/m2

between thc h i g h e r and lower values. It

is t h e

a u t h o r s ~ j u d g m e n t t h a t t h e upper figures r e p r e s e n t a more up to d a t e estimate of t h e incre- m e n t a l c o s t s for the double stud wall d e s i g n s . As can be seen from t h e

graph, a

discontinuity

occurs in the price l e v e l s when t h e insulation l c v c l exceeds RSI 5.3 and a double stud wall design is used. The

m a j o r c o s t incsomcnt is due to the labour and material c o s t of t h e cxtra s t u d w:111, O n c c t h c cloublc wall h a s been c o n s t r u c t e d , however, the i ~ ~ c s c m c n t a l c o s t f o r c o r i s t r u c t i n g tllc tlljcker wall i s a g a i n r e l a t i v e l y

law.

'I'he e x t r a costs f o r t h e wall. included t h e costs for t h e e x t r a f i n i s h i n g materials a t wlndows and doors to accomodate the greater wall

thickness.

Not included in t h e figures, however, a r e s h e extra

c o s t s f o r the roof

and

siding to accomodate t h e extra wall thickness. Also n o t included ( w i t h the exception of the H e d l i n flgures7) is any charge f o r the cxtra foundation o r lost space in the dwelling. The e x t r a s i d i n f i r e q u i r e d because of the increased wall rhickness, and the

(8)

cxtra r o o f area required ta m a i n t a i n the same r o o f overhang, a r e n

minor e x t r a c o s t . These additional c o s t s a r e approximately as follows for a bungalow:

s i d i n g c o s t

Roof cost

of additional floor area (Masonite s i d i n g ) of additional f l o o r area

(Asphalt s h i n g l e s )

With the wall thickness increased

from

t h e srandard 8 9 mm s t u d t o

300 mm, the extra cost for t h e s i d i n g and roof f o r a 12

m

x 8.5

m

bungalow would be 41 x

[i"~O~,8n]

x $20.50 = $ 1 7 f this wore

c o n v e r t e d to an additlon'al chargk a g a i n s t tlze insulation, the cost for t h e wall area would b c equivalent t o 37 g/m2 RSI. As can b e seen from Table 3 , these extra costs a r e relatively small (<30%)

for

even t h e most inexpensive cost f i g u r e s presented,

The e x t r a cost f o r the space r e q u i r e d for the t h i c k e r wall i s a n o t h e r f a c t o r that should be considered. A t one extreme, one could claim that t h e ~ e i s

a

c o s t o f about $500/m2 of lost f l o o r space, as

t h i s

is

t h e average cost of f i n i s h e d space

in

an average house. With a t h i c k e r wall u s i n g & m 2 o f space, for example, there would b e an e x t r a c h a r g e of $4000. A t t h e o t h e r extreme, t h e r e is t h e argument t h a t t h e lost space has na v a l u e whatsoever. The approach

i s

taken that ground space outside the house is used, not f l o o r space, f o r t h e extra w a l l thickness, and t h a t the c o s t of that space for an average lot is o f t h e o r d e r

of

$30/m2 or l e s s . Provided the house

i s

designed p r o p e r l y , no extra foundation is needed for the t h i c k e r wall, as the extra insulation i s cantilevered outside t h e foundation. The t w o options a r e shown

in

F i g . 2.

Thc second option of c a n t i l e v e r i n g t h e extra wall insulation appears t o b e t h e bctzer

of

t h e t w o strategies and thus the extra

c o s t s f o r the wall space should bc only a relatively minor charge on the extra i n s u l a t i o n f o r t h e w a l l s .

Beyond an i n s u l a t i n g value

of

about RSI 5 , t h e use

of

a double s t u d w a l l h a s advantages o v e r the s i n g l e s t u d designs. A particular advantage of t h e double stud d e s i g n i s that it allows the placement of t h e vapour barrier on t h e outside o f the inner stud

wall.

With this technique, t h c electric wires may be placed

on

the warm s i d e o f the vapour b a r r i e r , t h u s a l l o w i n g the vapour barrier to remain f r e e

of penetrations. A shcmatic of" a double stud

wall

is shown in F i g . 3 - To d a t e , about t e n of t h e s e lrouses u s i n g double stud walls have been c o ~ ~ s t r u c t e d i n tllc Saskatcson area, w i t h sevcral more

in

(9)

British Columbia, Alberta, Manitoba, O n t a r i o , and p a r t s of Saskatchewan. The material and labour

c o s t s

f o r a double stud wall are higher than t h o s e f o r a m i n i m u m standard wall.

One contractor'' now

specializing

in this

double wall cons- truction estimates t h a t h i s t o t a l incremental c o s t s are equal t o the extra materials plus $5.50 m2 of wall surface. The total cast f o r a wall with

RSI

6 . 3 is presented in T a b l e 4 .

Another advantage o f t h e double wall construction

is

that very large amounts of insulation can h e

added

with

such

a design.

The

o n l y extra c o s r s a r e f o r t h e insulation, the t o p and bottom p l a t e s , d r y w a l l r e t u r n s and t h e

e x t r a

roof and s i d i n g once the doublc wall is built. Several h o u s e s using RST 10.6 walls have been constructed using the doublc wall design shown. Y e t another advantage of the

double wall i s that t h e c o s t o f t h e conventional vapour barrier is reduced because no plastic pans or wall vapour barrier at the conventional location are required.

In summary, the incremental c o s t s for t h e insulation are as follows: ceiling

-

1 1 0

$/m2;

basement walls [concrete) - 247 $/m2; basement walls (preserved wood) - 155

elm2.

Because t h e above grade walls have a discontinuous incremental cost, the w a l l costs a r e presented i n Table 5 f o r a number of discrete incremental steps. The additional costs for the e x t r a roof and s i d i n g t o accomodate the greater wall thickness axe

included.

One argument f o r increasing t h e insulation levels

in

housing is that a t v e r y high l e v e l s of insulation it becomes p o s s i b l e to reduce the size and complexity of t h e h e a t i n g system considerably. A

conventional forced air furnace and duct system can be replaced with either a smaller furnace or electric baseboard heater, resulting

in

savings of up to $1000 on t h e initial c a p i t a l cost of t h e heating s y s t e m . Assuming t h a t an average house h a s a surface area of 300 m2

and

t h a t t h e average increase in R value due to the superinsulation i s RSI 5, the c o s t s a v i n g due t o t h e sarnller heating system could

be

2

$ 1 0 0 q . x 100 #/dollar

,

67 ,,$

RSI

300 rn2 x 5 mzmoC/W

These il l u s t s n t i v c f i g t ~ r e s i n d i c a t e t h a t t h e lltrueTQcas o f extra insulazion c a n bc r ~ d u c c d owing t o COST reductions in t h e ovcr-

a l l system.

3 . Uneraded South Windows

The solar heating e f f e c t of s o u t h windows can he substantial in most populated p a r t s of Canada. Table 6 presents data from a report by ~asakatll on the

net

h e a t gain f o r windows facing the cardinal

(10)

p o i n t s . Results are p r e s e n t e d f o r Swift Current, Saskatchewan, which h a s a climate much l i k e Saskatoon.

N o t e t h a t f o r a double g l a z e d window, t h e net heat gain i s

+549 MJ/m2 f o r a s o u t h orientation

and

-899 W/m2 f o r a north orientation. A

wall

insulated t o a l e v e l

of

RSI 3.5 would have a n c t heat l o s s of 103 ~ ~ / m 2 - y r for a south exposure. Thus the n e t h e a t g a i n for'a double glazed south window relative t o

a

wall with RSI 3.5 i s 5 4 9 - (-103) = +652 ~ ~ / r n Z . y r .

If

t r i p l e g l a z i n g i s used, the n e t h e a t g a i n increases to 1008 M J / ~ ~ yr c ~ m p a r e d t o a w a l l

with

RSI

3.5. F u r t h e r improvements may be made

by

using q u a d r u p l e g l a z i n g or d u a l glazing with n i g h t i n s u l a t i o n . In a

t y p i c a l house tllc window area is about 10 to 1 5 % of t h e f l o o r

a r e a abovc grade. Thus a standard bungalow would have about 13 m 2 of window. I f 80% o f e h i s area (10 m2) were on t h e south facade and t r i p l e g l a z i n g were used, alrout 10 G J per h e a t i n g season would b e gaincd on an avcrngc house in Saskatoon, using this analysis.

The u s e f u l passive gain

from

south

windows

will be reduced for

a v e r y highly insulated house, however, because of t h e reduced period o f t h e

year

f o r which purchased heat is r e q u i r e d . Thus the useful h e a t

gain

would be

reduced

to well below 1800 ~ ~ / r n 2 -

y r .

It could b e as low as 600 b~Jm2.yr.

The extra c o s t s associated w i t h placing t h e major areas o f g l a z i n g an the s o u t h s i d e o f t h e house are g e n e r a l l y very small, p r o v i d e d that t h e o r i e n t a t i o n of the Lot i s suitable. The c o s t s f o r upgrading the windows t o triple g l a z i n g rather than double g l a z i n g will vary in t h e range o f 20 to 50% extra depending on t h e window s t y l e .

The approximate simple payback period on t h e upgrading may be determined by u s i n g t h e p r e v i o u s l y mentioned figures. The calcula-

tion is presented

i n

Table 7 for a s o u t h window in Saskatoon. Altllough the payback period for t h e triple glazing o p t i o n i s rela- t i v e l y long, t h e increased comfort and r e d u c e d condensation problems would serve to reduce the t o t a l c o s t to t h e owner.

In the case of e a s t o r wcst f a c i n g windows, t h e energy savings jn the Saskatoon a r e a for t r i p l e glazing over d o u b l e glazing amount

t o 4 2 5 ~1,~/rn"?~r.

WIG

~ a y h a c k period is reduced to 10 years. CASE STUDY - RESIIIENCE LOCATED IN SASKATOON

As w i t h most investmcnts i n energy c o n s e r v a t i o n , t h e phenomenon of d i m i n i s h i n g r e t u r n s is p r c s c n t . T h m s t h e c o s t to save the first

III (;.I u year in a l~ousc E~catjng b i l l by reducing t h e heat requirement From 1SO to 1413 G J i s v e r y much l e s s than t h e c o s t to save 1 0 G J a year by reducing t h a t same house from 20 G J / y r t o X O GJ/yr.

To

(11)

o f a reference house located in Saskatoon, Saskatchewan is p r e s e n t e d . The reference house i s built to the current (1980) minimum e n e r g y conservation standards f o r this location. The insulation, vapour barrier,

and glazing

s t a n d a r d s a r e presented i n

Table

8 .

A number of d i f f e r e n t sequences might be followed in up- grading t h e thermal behaviour of the house. The f i r s t and likely most cost-effective alternative, A,

is

to maximize t h e u s e f u l passive g a i n , upgrade the vapour barrier and a i r t i g h t - n e s s , increase t h e insulation levels, install an exhaust air heat recuperator, u s e t r i p l e g l a z i n g and again increase t h e insu-

l a t i o n l e v e l s . A l t e r n a t i v e B simply involves an increase i n insulation.

As t h e house is at t h e design stage o n l y , it is possible to reorient the b u i l d i n g to maximize the passive solar gain. (With

a n actual housc, this may not be possible because o f obstruction from a d j a c e n t b u i l d i n g s or o t h e r structures.)

Using t h e computer program HSLD,12 a program for calculating residential h e a t l o s s ,

and MSUNPR,

1 2 a program f o r calculating t h e month-by-month behaviour of a house having substantial

internal gain and passive solar gain, it was possible t o estimate t h e annual h e a t s a v i n g s from t h e various measures

in

both alter- n a t i v e s A and B .

For the standard house the annual space h e a t i n g energy con- sumption is equal to 98.7 G J . (With a combustion furnace of 0.6

efficiency, t h e energy c o n t e n t

o f

t h e

f u e l

would

be

165 G J . ]

The

annual loads f o r the house u s i n g upgrading alternative A

are

presented i n T a b l e 9 . As can be seen from t h e Table, t h e passive gain increase is t h e most c o s t effective of all the measures,

r e q u i r i n g o n l y a site orientation change at no extra charge provided t h e l o t is s u i t a b l y oriented. The next most cost e f f e c t i v e measure i s t o increase t h e basement wall insulation t o RSI 2 . 2 f u l l height, w i t 1 1 a payback period

of

4 . 1 yr. By upgrading the air-vapour

barrier to r c d u c e t h e a i r change to 0 . 2 / h , the payback period is calcttlated to I,c 4 . 2 yr, Increasing the insulation lcvcls as

shown in ~ t c p 4 , TabIc 9 results in payback pcriads ranging t o

14 years.

The installation of the air-to-air h e a t exchanger (step 5)

reduces t h e annual space h e a t i n g load to 28.9 GJ/yr, and has a payback of 1 0 . 9 yr. Triple glazing ( s t e p 63 has a payback of 13.5 y r . Furtl~cr i n c r e a s i n g t h e insulation as i n step 7, demons- t r a t e s payback periods ranging to 26 yr.

The cumulative t o r a l c o s t of the seven upgrading measures would equal $5021; w i t h that investment, the annual space heating load is

(12)

reduced

from

99 t o 14 GJ/yr. If upgrading steps 6 and 7 are

eliminated, thc cumulative t o t a l cost o f the upgrading measures is $3016; as a "package" f o r a new house the measures would reduce the annual space h e a t i n g load from 99 t o 29 GJ/yr.

The payback periods

for

Alternative B , t h a t of increasing t h e i ~ l s u l a t i o n l e v e l s o n l y , are presented in Table 10. The f i r s t increase i n t h e insulation levels h a s a payback p e r i o d of about X yr, t h e second increase a payback period o f 13 yr, and t h e t h i r d an increase o f about 21 yr. The t o t a l e x t r a c o s t for the t h r e e measures is $3450, and the annual space heating load i s reduced

from 99 to 45 C J / y r . From an observation of alternatives A and B, it can be s e e n that t h e inclusion of passive gain, air tightness,

and an a i r - t o - a i r h e a t exchanger can produce a more energy c o n s e r v i n g house t h a n can superinsulation alone.

A presentation

has

been made of the

extra

c o s t s f o r new housing of a number o f measures designed to reduce space heating c o s t s . The measures used to reduce t h e energy consumption i n new houses may be categorized as follows: (1) a i r t i g h t n e s s w i t h controlled

ventilation; ( 2 ) s u p e r i n s u l a t i o n ; ( 3 ) u s e of the south windows for passive solar gain.

The

approximate c o s t s f o r these measures 011

a new house in Saskatoon, and the simple payback p e r i o d based on a space heating energy price of $8/GJ are a s follows:

Simple Payback Period yr. 1 . Air t i g h t n e s s

Irtlproved vapour barrier $500 Air-to-air heat exchange^ $565

2. Superinsulation

C e i l i n g insulation increased from:

RSL 4 . 9 to RSI 6

US1 6 to RSI 7 RSI 7 to RSL 8

IS1 8 t e RSI 9 Wall insulation increased frm:

RSI 2 . 2 to RST 3 . 5 4 . 2 RSI 3.5 to RSE 4 . 9 13.5 RSI 4 . 9 t o RSZ 6 . 3

(including benefit of increase

i n a i r tightness) 18.1

Basemct~t wall insulation increased from :

RSI 1 . 4 ( 6 0 0 m below grade)

to RSI 2 . 2 full h e i g h t 4 . 1 R S I 2.2 t o RSI 3 . 5 9.0

R S I 3.5 to R S I 4.9 21.9

Basement floor insulation increased from:

RSI 0 to RSI 0.88 6 . 1

AS1 0.88 t o RSI 1.7b 1 5 . 7

3 . Reorientation of w i n d o w s to south $0 Use aF t r i p l e ~ l a z i n f i $507

(13)

In o t h e r parts of Canada with d i f f e r e n t fuel

prices,

climates

and

construction costs, t h e analysis will be somewhat d i f f e r e a t . However, t h e numerical results presented i n t h i s paper are likely to be applicable i n most

parts

of

the Canadian prairie. Such an a n a l y s i s should logically be extended to the o t h e r major cltmatic zones

in

Canada.

REFERENCES

ASHRAE Handbook and Product Directory, 198 0 Systems, New Y o r k , 1980 Chapter 45.

' ~ e a s u r e s for Energy Conservation in New Buildings 1 9 7 8 . National Research Council of Canada, Associate Committee en the N a t i o n a l

Building Code, Ottawa, 1978.

(NRCC

16574)

3

Low Energy Passive Solar Housing. U n i v e r s i t y of Saskatchewan, Dept.

of Mechanical Engineering, Saskatoon, Saskatchewan, 1979. 4

B ~ i i l d e r s Guide to Energy Effi.cjcncy i n New Housing. Housing and

l l r b a n L)evelo])mcnt Association of Canada and O n t a r i o M i n i s t r y

of Energy, 1 9 8 0 . A v a i l a b l e from H U M C National Office, 15 Toronto St., Toronto, O n t a r i o .

' h m o n t , R.S., Besant,

R.W.

and Sehoenau, G.J. Recently Constructed PassSve Solar Buildings i n Saskatoon. P r o c . , Conf., Solar Energy Society of Canada I n c . , Charlottetown, P E I , August 1979.

G~ommentary on Measures f o r Energy Conservation

in

New Buildings. National Research Council o f Canada, Associate C m i t t e e on the National Building Code, O t t a w a , 1978. [NRCC 16945)

7 i ~ e d l i n , C. P., Narional Research Council of Canada, Division of

Building Research, Saskatoon, Saskatchewan, private communication. 8

Bcsant

,

It.

W. , I)mont, R. S

.

and Schoenau, C . J

.

Tlle Saskatchewan Conservation Ilouse - A year of Pcrfarmance Data. Proc., Conf., S o l a r Encrgg Society e f Canada I n c . , Charlottetown, P E I , A u g u s t

1079.

9

Lange, L . , Enercon B u i l d i n g C o r p o r a t i o n , Regina, p r i v a t e communication. 1°~ibson, R.

,

Custom Solar B u i l d e r s , Saskatoon

,

Saskatchewan, private

(14)

"Elarakat, S.A. Solar Heat Gains Through Windows in Canada. National Research Council of Canada, Division of Building Research, NRCC

18674, October 1980.

1 2

Dumont, R.S.

and

Harnlin, T. A Simple Computer Program f o r Estimating the Space Heating Requirement o f Residences. To be published.

(15)

TABLE 1

COSI' CO~IFARISON 1"CaR STANlIhRF) AN11 UPGRADED

VAPOUR

BARRIER

Standard

Vapour Barrier Upgraded Vapour Barrier

50

urn

polyethylene

-

300 m2 at 1 2 . 8

$/m2

1,ahour charge

- 1 person-day at $75/d

Upgraded vapour barrier

Less: standard vapour barrier

Extra

cost for upgraded vapour barrier

150 pm polyethylene

- 300 m 2 at 3fl

#/m2

$ 90.00

Acoustic31 sc;llant caulking coml~ound

24 tubes a t $.'t/tul>a 7" t1)II

J.abour charge

-

6 person-days at $75/d 450.00 $612.00

TABLE

2

COST

FOR AIR-TO-AIR HEAT

EXCHANGER

Cost o f a i r - t o - a i r heat exchanger

C o s t of dehumidistat controller

C o s t of d e f r o s t control timer I n s t a l lation cost

(16)

TABLE 3

BEYOND

THE 1979

MINIMUM STANDARDS

Basement

Walls

Concrete Preserved

Walls Ceiling Wall Wood

6 Commentary 37 9 104 x i c ~ g l c stuil 3 90 85 double stud h m o n t and Besant 143 110

Schoenau5 single stud

Durnont and Besant 196 8 5

~choenau5 double s t u d Builders ~ u i d e ~ O to 1047 104 single stud Ensrcon 9 237 s i n g l e stud 344 double s t u d

Note: The figures presented a r e t h e extra c o s t s for increasing the insulation resistance of 1

m2

of surface by I u n i t o f thermal resistance. The wide variation in costs is explained in the text,

(17)

TABLE 4

NI:'F EX'TRA IIOST FOR

INSULATION

FOR

DOUBLE- STIIU

WALL

CONSTIEUCTION

Basic wall

38

x

89

mm

s t u d s at 600

mm

on c e n t r e w i t h 131 ywood s h e a t h i n g

Double s t u d wall

I n n e r w:1L1 - identical t o basic wall w i t h addit ionaL 1Stl Vrn polyethylene

O u t c r wall - s i n g l e stud d e s i g n with no s t r u c t u r a l headers; t o t a l wall t h i c k - ness 267

mm

Extra materials cost per square metre o f wall I n s u l a t i o n - fibreglass batt

-

RSI 4 . 2 3

Outer studs and p l a t e s 2 . 0 0

Vapour b a r r i e r - 150

urn

n.30

Plywood t o p and bottom plates (including interior walls)

Drywall returns 0.50

Total extra

material

c o s t 7.20

Extra labour c o s t A-5 -50

T o t a l cost $12.70

--

7

(18)

TABLE 5

WALL

COSTS

FOR

INCREASING INSULATION

LEVELS

Wall Design

Wall

Thermal

Wall Cost* per

Resistance, Unit Area,

rn2

*oc/w

$/m*

I . Basic wall 38 x 89 mm s i n g l e stud with g l a s s f i b r e b a t t s 2 . 38 x 8 9 m m s i n g l e stud with g l a s s f i b r e b a t t s and RSI

1 . 4 insulating foam sheathing 3.5 16.02

3 . 38 x 140 m m single s t u d w i t h g l a s s f i b r e b a t t s and RST

1 . 8 i n s u l a t i n g foam s h e a t h i n g 4 .!I 20.54 4. 38 x 89 mm double s t u d with

lass

f i b r e b a t t s ; total insulation

t h i c k n e s s = 267 m m 6 . 3 2 8 . 3 5 5. 38 x 89 m d o u b l e s t u d with g l a s s

fll-lre batts; total insulation

thickness = 450 rnm 1 0 . 6

*13xcluding c o s t of i n t e r j o r gypsum board and exterior f i n i s h , hut i n c l u d i n g costs f o r extra f i n i s h i n g work and extra roof and s i d i n g

(19)

TABLE 6

Single

pane

Double pane Triple pane

NET

SOLAR HEAT GAIN

DURING HEATING SEASON

FOR SWIFT

CURRENT, SASKATCHEWAN

( ~ ~ / r n z

.yr)

South East

TABLE

7

PAYBACK ANALYSTS FOR TRIPLE

GLAZING

IN

SASKATOON

- SOUTI3

WINDOW

North -2457

Double g l a z e d south window (basic wall)

Triple glazed south window

N et h e a t g a i n by going from double to

triple g l a z i n g

N e t Solar Gain, cost, $/m2 ~ ~ / r n 2 .

y r

(inc 1. frame)

Energy saving p e r square metre assuming energy

c o s t

of

$8/GJ $ 2 . 84/m2

-

yr

(20)

TABLE 8

IZEFERENCE HOUSE DESIGN

llousc Type Ceiling Walls Windows - s o u t h -east -west - 110rth Doors Basement w a l l s -above grade -helow g r a d e F l o o r Vapour barrier Tnternal h e a t gains Wall exterior surface

absorptivity Roof exterior s u r f a c e absorptivity E x t e r i o r surfaccs film h e a r transfer coefficient Tns i d e tcn~pcraturcs - m : l i n f l o o r - bnscment Annual i ~ t i x i l i a r y space h e a t i n g e n e r g y r e q u i r e m e n t

Bungalow with R111 bnsemer~t Area, R Value, m 2

--

m 2

-

QC/IV 96 4.9 61.8 2.2 SO

urn,

n o t caulked 708

W

from electricity 179 W from h o t water I l n n u a l space h e a t i n g c o s t w i t h energy at $8/GJ (equivalent to electricity at 2.S8

$/kW-h,

or fuel o i l at 20

&/I,

w i t h a f u r n a c e w i t h a seasonal efficiency of O . h 5 % ) $789

-

" l i x c l t ~ r l i ~ ~ ~ : ~ l - o u n J o f f c c t : l ~ n ~ r s c vnIrrmc = 4 I l m"; : ~ i r C ~ I : B J I ~ C r;1tp = [ ) . * i / l ~

(21)

k W QJ M E: r m

a

.=

-

2

h W .rl 0 +.' m o P) v x al N 1 - A -0 d 1 1 0 0 V 1 - e cr O--. I - a s4 -4 u C m m n U C +zvJ 4 t d P k +I Y - - I w e n C H

(22)

3 . n h * d 4 N I D N L O O = ~ O I

4 r - m

. .

~

. * . .

m - e r o a r - r r - . *

-h & n dl- e m d m o n m m

(23)

FIGURE

1

4 4

I

I

I 1 I I I

4 4

BUILDERS GUIDE

4 0 0 HEDLlN EXCL. F W N D A T I O N COSTIT 7

HEDLlN (1NCL. F O U N D A T I O N COST)

COSTS OF WOOD FRAME WALL AS A FUNCTION OF TI4ERMAL RESISTANCE

3 6

3 2

THIS STUDY

- V DUMONT, BESANT. SCHQENAU~

-

A ENERCON' -

-

-

-

- A & - - I

-

0 i

-

SINGLE STUD

1

(24)

.

.

W A L L B U I L T I N W A R D

. - -

NOTE

W A L L B U I L T O U T W A l R D

TWO

POSSIBLE OPTIONS

FOR LOCATION

OF

EXTRA WALL

INSULATION

(25)

Z reated cardboard

insulation stop ,

acoustlcai ssabnt

7.5 rnm (5/16 in) plywood 150 pm (6 mr!) wpbur b a r n

39 X &rnm (2 I X 3 in) stud 400 mm (16 in) O.C.

5 3 8

x

89 mm (2

x

4 in) stud 40 mrn (16 in) 0 . C

s h e a t h i n g a r

building paper and siding- RSI 4.9 (R28) minimum

7.5 mrn (5/16 in) plywood - 38 X89rnrn (2 X 4 i t 1 1 4

1 1 ~

400 mrn (16 in)

O.C.

RSI 2.1 (~12)* RSI 3.5 IR20)- 1/2 in rigid fibreglass- drainage layer

toe nail to concrete floor

FIGURE 3

WALL SECTION - CONCRETE WALL

AND FOOTING FOUNDATION

Références

Documents relatifs

(2013) Length-weight relationship and seasonal effects of the Summer Monsoon on condition factor of Terapon jarbua (Forsskål, 1775) from the wider Gulf of Aden including

Identification and detection of a novel point mutation in the Chitin Synthase gene of Culex pipiens associated with diflubenzuron resistance...

These depend on which actor controls the trait (the vector or the parasite) and, when there is manipulation, whether it is realised via infected hosts (to attract vectors) or

Brennan TP, Woods JO, Sedaghat AR, Siliciano JD, Siliciano RF, Wilke CO: Analysis of human immunodeficiency virus type 1 viremia and provirus in resting CD4+ T cells reveals a

The newly employed reactive magnetron co-sputtering technique has allowed us to enhance the absorption coefficient from the MLs owing to the high density of Si-ncs achieved and/or the

Market and communication schemes have taken a noticeable place in temples and some of them can be regarded as types of “mega-temples.” 2 This article describes the

Altogether, these results indicate that expression of the endogenous DRP1 protein is important for maintaining normal mitochondrial morphology in NHEK and that loss of this

sour rot symptoms in the field and in the laboratory (n = 5 bunches), ‘Post-harvest mild rot’ indicates fruit that were collected without rot symptoms but showed mild rot in