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RSS-Amman, 18th January 2006الطاقة - لحفظ المناخي التصميم

البيئية - المساهمة الداخلية الرطوبةالحراري للعزل

Energy Conservation Through Thermally Insulated Structures

•Ayoub Abu-Dayyeh*•*Engineer and Doctor of Philosophy

•President of the society of Energy Conservation and Environmental sustainability

•P.O.Box: 830305 Amman 11183 Jordan

•E-mail :_ .E casesociety@yahoo com

•Mobile no.: 00 962 79 5772533

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The purpose of this paper is to explicate its title through investigating the following: 1) How is energy saving possible through thermal insulation and passive design?2) The feasibility of investing in thermal Insulation?3) Is Thermal Comfort and a healthy atmosphere possible inside the dwellings during all seasons! (Insulation and passive design)4) What Environmental Impacts can exist due to thermally insulating buildings?

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0.01

0.02

0.03

0.04

0.05

0.06

0

Density of Thermal Insulating Materials Kg/m3

K-

valu

e (W

/m. C

)

Polyurethane

Rock Wool

10 20 30 40 50 60 70 80 90 100

Expanded Polystyrene

o

Criteria:Cost

AvailabilityRequirements(Architectural,

Codes, etc)Durability

Vapor BarrierGloss

Health hazardsFire hazards

Economical Design

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MaterialDensityK valve W/m2.k

Cost US $/ m3 2005

Concrete23001.75

Lime Stone22001.53

Normal Glass25001.05

Concrete Hollow Blocks12000.77

Plastering15700.53

Polystyrene (expanded)150.04090

Glass Wool640.038150

Polystyrene (expanded)200.036100

Polystyrene (extruded)28-350.035125

Rock Wool50-1000.03590

Polystyrene (expanded)250.034110

Polyurethane (on site)300.026300

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1

1

2

2

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•Design: The Jordanian thermal insulation code published in 2002, specifies a minimum of thermal transmittance value (U -value) of 1.8 W /m2.k for exterior walls (Including exterior openings) and a value of 1 W/m2.k for roofs Wall 1. 30 cm plain concrete and stone cladding (3-5 cm thick) with

2cm cement-sand plastering from the inside, traditional wall.Wall 2 Recently, the construction industry has been using a similar sort of construction

by introducing hollow blocks made of concrete, 10 cm thick, 40 cm in length and 20 cm in height. They are used as a replacement to formwork from the inside, keeping the total thickness of the wall in the range of 30 cm. The section consists of an extra 2 cm of cement-sand plastering from the inside as.

Wall 3 Our recommended economical section 33cm

Wall 3Wall 2Wall 1U = 2.6 W/m2.k U = 2.19 W/m2.k U = 0.76 W/m2.k

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• Definitions of symbols:• K (Thermal Conductivity); R (Thermal Resistance) = d / k ; U (Thermal

Transmittance); e ( Emissivity ) ; d ( Thickness )

• U – value calculations: • U = 1 ÷ R ; R = d ( Thickness ) ÷ K ( Thermal Conductivity )• Ri = 0.13 ; Ro = 0.04m2.k/W• For Wall 1• U1 = 1 ÷ (Ri + Ro + (0.05 ÷ 1.53) + (0.25 ÷ 1.72) + (0.02 ÷ 0.53)• = 1 ÷ 0.383• = 2.6 W/m2.k• For Wall 2• U2 = 1 ÷ (Ri + Ro + (0.05 ÷ 1.53) + (0.15 ÷ 1.75) + (0.10 ÷ 0.77) + (0.02 ÷ 0.53)• = 1 ÷ 0.46• = 2.19 W/m2.k• For Wall 3• U3 = 1 ÷ (Ri + Ro + (0.05 ÷ 1.53) + (0.15 ÷ 1.75) + (0.03 ÷ 0.035) + (0.10 ÷ 0.77)

+(0.02 ÷ 0.53)• = 1 ÷ 1.32 • = 0.76 W/m2.k

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• Energy Saving: If we add exterior opening effects on the over whole U-value of the walls (Doors and Windows), which we assume they constitute 20 % of the total exterior peripheral area, we can then calculate the saving attained in energy and fuel consumption due to thermally insulating the exterior walls only. The calculations follow:

• Assume that the average U-Value for exterior openings U-value (Windows & Doors) = 4 W/m2.k

• The average U-value becomes:-• 0.76 × 0.8 + 4 (0.2) • = 1. 4 < 1.8 • • This is okay for the existing Jordanian thermal Insulation code, but we are

striving to reduce this value by 50% which will still be dramatically higher than the values recommended by many European standards.

• The average U-value for the traditional wall:• 2.6 x 0.8 + 4 x 0.2 • = 2.88 W/m2.k

Percentage saving ( W3-W1) = 2.88-1.4 / 2.88 = 51.3%

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• Fuel Saving: Assuming that the air exchange stays the same before and after applying the new

insulated section, and also assuming that the flat is loosing heat from four directions only.

• Where the roof is occupied by neighbors and heated. The area of the flat is 15 × 10 =150m2. Where U1 & U3 represent Walls 1 & 3

• Q saved = (U1-U3) x A x T (Ti-To)• Where U1=2.88, U3 = 0.76, A= 125m2, T = 20 K (Average temperature change)• The flat in question has a wall surface area of 125 m2.• Q = (2.88 – 1.4) × (125 m2) (20) • = 3700W = 3.7 Kj/second• = 3.7x3600 Kj/ hour• One liter of diesel = 7000 K.calory = 7000x4.2 Kj ( 1calory=4.2 joules)• Saving in diesel/hour = 3.7x3600/7000x4.2• = 0.45 lt./ hour

• If we Assume that Amman needs 1300 Heating Hour Day and 700 cooling hour day, then the total consumption is:

• 0.45x2000 = 900 lt. yearly

• This means nearly 200 US$ Saving on fuel only by thermally insulating walls only, if we add

reduction in maintenance and spare parts and increasing the time life of the electro-mechanical system, this number is easily doubled. Therefore saving is up to 400$ yearly. Remember that if improvement on the thermal properties of the roof is also administered, the savings are far greater. This is a substantial amount of money to most people in Jordan.

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• It must be noted here that air gaps do not have the ability to resist heat more than 0.18 W /m. k, no matter how thick the gap is (provided the gap is bounded by traditional construction materials, such as concrete). Actually the wider the gap is the worse would be its resistance to heat transfer as convection currents become more effective in wasting energy in winter (see figure 3 for details).

• If we calculate U3, for wall 3 once again using an air gap 2cm wide, then the U-value becomes as follows:

• U3 = 1 ÷ (Ri + Ro + (0.05 ÷ 1.53) + (0.15 ÷ 1.75) + (0.03 ÷ 0.035) + (0.10 ÷ 0.77)+ 0.18 ( see figure 3, the value 0.18 is illustrated by arrows) + (0.02/0.53)

• U3 = 1/1.46 • = 0.67 W/m2.k

• It is clear now that not much change has been achieved through adding the effect of the air gap, that is from 0.76 to 0.67W/m2.k. (i.e. 13% improvement )Whatever width the air gap is, no more resistance to heat flow is attained. Actually the opposite happens as the wider the gap becomes the lesser the resistance to heat flow the air gap sustains.

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Cavity with one aluminum surface

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60Cavity thickness (mm)

Th

erm

al

res

ista

nc

e -

R-v

alu

e

(m2.

K /

W)

Cavity uncoated

Cavity

Heat Flow Direction in Winter

Heat Flow Direction in Summer

Cavity with onealuminum surface

Aluminum Foil

BS 6993:PART1-1989

Figure 4

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Comfort Zone

Very Hot Zone

Very Cold Zone

Ave

rag

e T

empe

ratu

re o

f A

mbi

ent

Air

Figure 5 a

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Average surface temperature of internal walls

5 10 15 20 25

10

12

Wall 113

degrees

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Wall 1 (Vertical section-Winter(

16.5 C o

20 Co

0 C

o

Wall 1 - plan- Winter

16.5 Co

20 Co

0 Co

14 o

15 o

16 o16.5 C

o

Wall 1 - plan - Summer

26 Co

50 Co

o32 o

31 .Co

13 o

33.5 Co

33 C

out side inside

6 ) a( 6 ) b( 6 ) c(

o3

2

o3

1 .

Co

o3

3

C14

o15

o

16

oinside

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Table 2

1Breathing and Sweating4 – 7 kg

2Using petrol based fuel in heaters of no exhausts

10 – 15 Kg

3Cooking2 – 6 kg

4Bathing (Twice weekly)1 – 3 kg

5Washing activities1 – 2 kg

6Laundry2 – 4 kg

7Drying clothes4 – 8 kg

8Washing and drying dishes0.5 – 1 kg

9Other activities, plants, .. etc0.5 – 1 kg

Total25 – 47kg

Averages of weight of water vapor produced by a family in Jordan consisting of an average of 5 persons

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Picture 1 - 3

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Plate 1

Plate 1Winter Condition

Window Frame

Outside0 k

Inside20 k

Area of a SharpTemperature

Gradient

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Plate 2

outside

Area of a SharpTemperature Gradient

Area of extremely sharp temperature gradient

Plate 2

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Cold Joints

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See picture 1-2

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Wall 1 (Vertical section-Winter(

16.5 C o

20 Co

0 C

o

Wall 1 - plan- Winter

16.5 Co

20 Co

0 Co

14 o

15 o

16 o16.5 C

o

Wall 1 - plan - Summer

26 Co

50 Co

o32 o

31 .Co

13 o

33.5 Co

33 C

out side inside

6 ) a( 6 ) b( 6 ) c(

o3

2

o3

1 .

Co

o3

3

C14

o15

o

16

oinside

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Wall 113

degrees

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Infra Red Scanning

Reference: S, Baradey, Iproplan , Germany

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Wall 3 (Vertical cross-section)

19.2 C o

20 Co

0 Co

Wall 3 - plan , Winter

20 C o

0 Co

19 C o 19.2 C o

19

C

o1

9.2

C

o

Wall 3 - plan , Summer

18.2 Co

27.2o

28.2 Co

50 Co

Ambient temp. = 26 C

o

8 ) a( 8 ) b( 8 ) c(

27

.2

Co

25

18.2K

Wall 319.2K

Iso-thermal LinesNo 18

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Passive Design• Passive design is that which does

not require mechanical heating or cooling. Homes that are passively designed take advantage of natural energy flows to maintain thermal comfort.

At almost no extra cost:• Significantly improves comfort. • Reduces or eliminates heating and

cooling bills.• Reduces greenhouse gas emissions

from heating, cooling, mechanical ventilation and lighting.

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Shading

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Solar, Shading and ventilation

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Thermal Mass-Trombe wall

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التي • العوامل تلخيص نستطيعبين / جليًا / واضحًا الفًارق تجعل

هو بمًا والحديثة القديمة البيوتآت:-

•. المستعملة- البنًاء مواد نوع•. والسقوف- الجدران سمًاكة•. والسقوف- الجدران لونالمسًاحة،- ( • البنًاء تصميم طبيعة

أسًاليب الطوابق، عدد االرتفًاع،الخًارجية الفتحًات مسًاحة التهوية،

الواقعة المظالت واتجًاههًا، وشكلهًاالخًارجية، فتحًاته وحول البنًاء حول

.( ذلك ونحوعدد- ( • النمطية العًائلة طبيعة

اإلشغًال فترة القًاطنين، السكًانالتدفئة 24خالل وسًائل نوع سًاعة،

وطريقة تشغيلهًا وفترة المستعملةتهويتهًا).

Passive design in Traditional houses

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إلى • المًائل الطبيعي الحجر لون وكذلك والقش، الطين لون إنالالمع البني اللون إلى أو الفًائح األصفر / ،اللون جدا منًاسب

. بًالمنًاشير قصه يتم الذي اليوم، فًالحجر / معًا والشتًاء للصيفبفعل الشتًاء، فصل في يفقد البيًاض، نًاصع اللون أبيض ليصبح

حوالى الحراري التي % 90االبتعًاث الحرارية الطًاقة منالمنزل، تدفئة من والحجًارة يكتسبهًا الوديًان حصى تبتعث فيمًا

نسبة ،/ مثال . 50الطبيعية، مًا % وهذا فقط الحرارية الطًاقة منالعيش في أجدادنًا تمتع التي التقليدية البيوت من بداخلهًا جعل

وبًالتًالي الشتًاء، فصل في / دفئًا أكثر . أمًاكن ومتعة راحة وال أكثرفي كفًاءxة أفضل ستكون البيضًاء الحجًارة أن zظن ي أن ينبغي

الرخًام فقدرة الصيف، الحجر فصل أشعة أو امتصًاص علىتبلغ التقليدية % 53– 44الشمس والحجًارة الزلط فإن بًالمقًابل ،

. 29تمتص التي % األبنية أن يعني وهذا الشمس أشعة من فقط / جوا ألطف كًانت أجدادنًا /، أشًادهًا أيضًا الحًار الصيف فصل في

كًانت . وبًالتًالي فيهًا للسكن ومتعة راحة أكثر

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Beehivesلمًادةا

اللونالتهويةالفتحًاتالظاللالتالصقالالتجًاهالخشونة

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Thermal mass

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Materials, Color and Emissivityهو • األول أسًاسيين، عنصرين على والمًادة اللون تأثير قًاعدة تقوم

االبتعًاثية االمتصًاصية Emissivityمفهوم مفهوم والثًانيAbsorption .هو الالمع غير األسود للون المًاصية معًامل كًان فإذا

الجسم 1 على السًاقطة الضوئية األشعة كًافة أن ذلك يعني ،من قريبة مًاصية ذو الجسم فإن وبًالمقًابل امتصًاصهًا، يتم األسود

. وهذا / تقريبًا بًالكًامل عليه السًاقطة اإلشعًاعًات يعكس الصفرعًالية بًابتعًاثية يتميز الالمع غير األسود الجسم أن / أيضًا يعني

. 1تسًاوي مًائي المعزولة السطوح أن يعني وهذا / بًاإلسفلت ًاأيضًاالشتًاء فصل في كبيرة طًاقة تفقد فقط األسود

• ( بنسبة ( حرارة تفقد تبتعث الخرسًانة % 65وتمتص % 91إنبنسبة • فيبتعث والحجر الرخًام %53 – 44ويمتص % 93أمًابنسبة • تبتعث األبيض اللون % 12وتمتص % 90وطالءxاتبنسبة • فيبتعث الفًاتح األصفر اللون طالء %45ويمتص % 90أمًابنسبة • يبتعث األلومنيوم % 18ويمتص % 30وطالء• ( بنسبة ( تبتعث الزلط الوديًان %29وتمتص % 50وحصىمفيد • األلومنيوم بطالء اإلسفلت دهًان أن أعاله األرقًام من نستنتج

. الوديًان حصى استخدام وكذلك ،xشتًاء / صيفًا

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• Conclusion: • In Jordan, we have proved that using wall 3 solution at

an extra cost of 1000 US $ per 150 m2 flat is immediately refunded from the reduction in boiler capacity, quantity of radiators, diameter of pipes and capacity of pumps.

• The profitable investment in thermal insulation persists and multiplies by time ever since the moment of occupying the building, as less fuel and electricity is spent on heating and cooling, and very little maintenance thereafter is needed. We have proved that a saving of 400 $ per flat per year is achieved, only via heat losses through walls.

• Less fuel consumption, i.e. Sustainable natural resources• A more comfortable environment is also prevailing inside

the house, whence thermal insulation is used. Less cracks and less thermal movement within the insulated zone.

• No condensation is possible and no fungus growth.• And above all less fumes are emitted to the atmosphere.

That means less pollution for the environment.