etfe icames 2015 final

7/26/2019 Etfe Icames 2015 Final

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ICAMES 2015

TWENTY-FIRST INTERNATIONAL

CULTURAL AND

ACADEMIC MEETING OF

ENGINEERING STUDENTS

BOAZNVERSTY,

ISTANBUL, TURKEY ENGINEERING SOCIETY

May 02-09, 2015

GHEORGHE ASACHITECHNICAL UNIVERSITY OF IAI, ROMANIA,

FACULTY OF CIVIL ENGINEERING AND BUILDING SERVICES

ETFE a sustainable alternative

to traditional glass

TEAM MEMBERS:

Marius-Cristian BRESCU-IFTIMIE

Mihaela-tefaniaMILU

Rita-Cristina PITA

TEAM ADVISORS:

Senior Lecturer PhD. Ioana OLTEANU

Senior Lecturer PhD.Ionu-Ovidiu TOMA

[email protected]@ce.tuiasi.ro

[email protected]

[email protected]

[email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


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ICAMES 2015

ETFE a sustainable alternative

to traditional glass

Project abstract:Ethylene Tetrafluoroethylene (ETFE) a stable, durable andeasy to join polymer has been developed due to intensive research in building

materials technology focused on sustainability and it can be used in civil engineeringespecially as a sustainable alternative to traditional glass in double skin faades

and roofs of buildings. The advantages of ETFE in comparison to glass are thereduced specific weight and embodied energy, the self-cleaning property and the

high corrosion resistance. This project refers to a comparison study regarding theadvantages of using ETFE in civil engineering, focusing on the reduction of the

amount of material of the load bearing structure due to the fact that ETFE is 100times lighter than glass.

Keywords: sustainability, light-weight, double envelope, low embodied

energy, self-cleaning material, adaptable, natural ventilation, high corrosion

resistance;

1.Introduction

The greenhouse effect is a natural phenomenon of maintaining the temperature ofthe Earths surface. Through thisprocess part of the solar radiations are retained inthe Earths atmosphere as a result of the presence of greenhouse gasses such as watervapor, carbon dioxide, methane, nitrous oxide, ozone and chlorofluorocarbons. Inthe past decades the concentrations of the greenhouse gasses have increased and

according to The World Business Council for Sustainable Development, the buildingsector is accountable for 40% of the world energy use, thus the resulting carbon

emissions are in substantial amounts.

The lowering of energy consumption in new or already existing buildings has gained

a lot of attention in the past few years and notions such as passive building or zeroenergy building have been introduced in civil engineering vocabulary. One of the

solutions that is implemented in order to improve thebuildings energy performanceis the double-skin faade concept.

A double-skin faade consists of two skins placed in such a way that the air flows in

the intermediate cavity. The main advantages of a double-skin faade are: natural

ventilation, thermal and acoustic insulation [1]. Even though the most common


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ICAMES 2015

material choice for this concept is glass, the following report shows why Ethylene

Tetrafluoroethylene is a viable sustainable alternative.

2.Material description

2.1.

History

ETFE is a relatively new material in the building industry. It was developed by Dr.

Plunkett, Fig. 1, in 1938and it is one of the 7 fluoropolymer generated from the

invention of PTFE (poly tetrafluoroethylene), also known as Teflon. ETFEsdistinctive property of the other six polymers is the capability of being extruded. The

first commercialized film was named Tefzel,[2].

Fig.1: Dr. Roy Plunkett[12] Fig. 2: Raw ETFE granules [13]

2.2.

Manufacturing process

Unlike many synthetic plastics, ETFE does not derive from petrochemical

substances. The raw material is called chlorodifluoromethane and the MontrealTreaty on ozone depleting substances includes it in the 2nd class of substances,

meaning that it does not contribute to global warming. The raw material is turned

into tetrafluoroethylene at 125 Celsius degrees. The TFE is then polymerized withethylene and ETFE results (25% ethylene and 75% TFE), Fig.3. After this process

it results a powder which is turned into granules, Fig.2, by heating at 265-285

degrees. The granules can be turned into rods, sheets and films. In building industry,ETFE films are used especially for cladding. The films can also be transparent,

translucent, printed or colored, [2].


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ICAMES 2015

Fig. 3: Industrial synthesis of ETFE [3]

2.3. Benefits of ETFE

2.3.1.

Light transmission and solar control

Across the visible and ultraviolet ranges, ETFE film is very transparent, allowingapproximately 95% and 85% transmission. [4]When light is not needed, ETFE film can be treated in a number of ways to

manipulate its transparency and radiation transmission characteristics. Adding extralayers of ETFE foil to a cushion also allows light transmission and solar gain to be

controlled. Multi-layer cushions can be constructed to incorporate movable layersand intelligent printing, Fig. 4. In these type of cushions, the top and middle layers

are printed in a corresponding pattern which when pressed together cover 100% ofthe surface with fritting. The middle layer is programmed to rise and fall (using air

pressure) to increase and decrease the percentage of printed area and thereforecontrol solar gain, Fig. 5.[4][5]

Fig.4: Printed ETFE foils [8]
http://www.birdair.com/sites/default/files/Negative%20Diffused%20Printing.jpg


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ICAMES 2015

Fig. 5: ETFE performance in case of intelligent printing [19]

2.3.2.

Weight and plasticity

ETFE foil is extremely light weight in comparison with glass, almost 100 times

lighter. This property results in a reduced structural framework, hence considerablyless dead load on the supporting structure [5].Moreover, steel structure can be

combined or replaced by timber, like in the case of Nice Stadium, France, Fig. 6,

where the modules consist of one row of timber crosses connected by steel

tetrahedrons to a steel tube [1],[6].

This material is able to stretch up to three times its original length without losing its

elasticity [11]. Even though the breaking point is up to 600% the films are stillstructurally resistant [8]. Due to its high resistance and elasticity, ETFE is considered

a great solution for places where earthquakes may occur. Unlike glass, which will

shatter in such scenarios, ETFE will deflect or break, but it wont cause severedamage [4].

Fig. 6: Structural model of Nice Stadium in France [6]


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ICAMES 2015

2.3.3.Durability and cost effectiveness

ETFE does not degrade or change any of its properties under exposure toenvironmental pollution, UV light, harsh chemicals or extreme temperature

variations. For the first time it was used in construction in 1982 when a fluorinated

ethylene propylene film on the roof of Burgers Zoo Hall in Arnhem, Netherlands,Fig.7, failed and had to be replaced. The structure is still in service and the materialshows no signs of degradation. The estimated life expectancy of foils is more than

50 years [7].

The installation cost of ETFE can be approximately reduced to half the price of

conventional high performance glass [4]. Moreover, due to the lightweight nature of

the material supporting systems and foundations can be designed more efficiently.

By providing ample natural daylight, the indoor lighting demand and the energycosts are reduced [8].

Fig. 7: ETFE roofing at Burger Zoo in Arnhem, Netherlands [20]

2.3.4.Environmental impact

The embodied energy for ETFE is 315 MJ/m while for glass is 371.21 MJ/m. Thereal difference though is made by the lessening of the frame and supporting system

dimensions, not to mention that replacing steel with timber is also a viable choice

[1]. The nature of the product improves the buildings properties of insulation anddaylighting, therefore it contributes to the low energy aspect of the building. Flexiblephotovoltaic cells can be integrated with either a single layered or cushioned system

to meet performance requirements, [8]. This has been tried at a carport roof inMunich, Fig. 8, and provides an average of 1,000 kWh/kwp electrical energy per

year, [18].


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ICAMES 2015

Being 100% recyclable, wastes from the manufacturing process and even old ETFE

elements can be remolded into new products. The recycling is aided by the absenceof additives in the manufacturing process and the only thing that is required for

recycling is the melting of the material. An old or damaged piece of ETFE foil can

be simply removed from the structure, heated to melting temperature with new ETFEgranules, Fig. 9, and extruded to create more films. This is a great contribution to

the stainability current [2]

One of the most attractive attribute of ETFE is the self-cleaning property, especiallywhen considering the costs of cleaning a large greenhouse. Being derived from

Teflon it is anti-adhesive so occasional rainfall is enough to clean it. Even though

the foil can be penetrated by sharp objects, it has considerable tear propagation

resistance [2].

ETFE film has a very unique behavior in the presence of fire. It is classified as self-

extinguishing because instead of melting and dripping it shrinks away, thus allowingsmoke and fire to be vented to the exterior [4].

Fig. 8: ETFE roof with integrated photovoltaic cells [18] Fig.9: Melted ETFE waste before extrusion [13]

3.Case study

3.1. Structure description

The numerical simulations are made on a structure which is an office building,

Fig.10. The envisioned structure has 10 floors with a height of 34 m and is a framestructure having almost 80% of its exterior surface as double ventilated faade.

Given the fact that the glazed surface is large, it is suitable for us to point out easilythe difference between the classic glass and ETFE material.

The materials used for this structure are steel for columns, being used an H400X509profile and for the slab it is used reinforced concrete of 15 cm thickness. For the

faade we chose layers of glass and ETFE, 15mm thick.


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ICAMES 2015

Fig. 10: Real building Fig.11: Structural model of the building

3.2. Numerical Simulations

3.2.1.Strength simulation

The aim of this simulation is to compare the self-weight and the strength of the

building by using glass and ETFE membrane alternating them into a double skin

faade. For this we had used the SAP2000 computer software which provides an

interactive environment in which the user can study the stresses in the structuralelements, the deformations of the building and also design and check the building

elements, Fig. 11.

For this type of simulation we chose 3 cases of double skin faade, the first case

being the one when there are used two layers of classic glass, the second case is forglass and ETFE layers and the last case is when both layers are made of ETFE

membrane.

Making the analyses for each case we had obtained the following results shown in

Table 1. As a general observation, we can see a reduction of the mass for the entirebuilding - a reduction of 1.86% is obtained when only one layer is made of glass and

another made of ETFE membrane and a reduction of 3.71% when both layers are

made of ETFE.

The load on the column is minimum in case of two layers of ETFE, which willinfluence the design process of the columns, leading to a significant reduction of

material.


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Another conclusion can be made considering the period of vibration, which is lower

for the 3rdcase. This can be explained by the fact that the stiffness introduced on thestructure for the ETFE material is lowest, meaning that the overall behavior of the

assembly (cladding and structural system) is closer to the flexible behavior of the

frame structural system.

Mass (tones) T(s) Nmax(kN) Sigma max

Glass5978,35

2,779567 3570,57 55,10138889

Glass + ETFE 5867,32 2,755688 3481,15 53,72145062

ETFE 5756,3 2,731626 3391,73 52,34151235

Table 1. Results from SAP200

3.2.2.Thermal conductivity simulation

In the past years the construction field has focused on reducing the use of energy anddeveloping more efficient materials. For this, the materials behaviors in differentenvironments and climate condition should be evaluated.We tested 3 types of windows in 2 different conditions by means of Saint-Gobain

Isover SCE program. This program calculates thermic efficiency of a building or acouple of materials components of a structure in different cases of climate and

environments and the results are very accurate. If some specific characteristics ofthe materials are known (density, thermic conductivity, etc.), this program gives

results in form of charts where we can see which the temperature in each point ofthe element.

Regular type of window between heated and unheated spaces (glass-air-glass)

External temperature: -150 C External temperature: 350C

Internal temperature: 200C Internal temperature: 200C

Te= -10.010 C Te=32.860C

Ti=15.010 C Ti=22.140 C


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ICAMES 2015

Special type of window between heated and unheated spaces (glass-argon-

glass)



Te= -11.190

C Te=33.370

CTi= 16.190C Ti=21.630 C

Special window with ETFE membrane between heated and unheated spaces

(ETFE-air-glass)



Te=-13.520 C Te=34.360 C

Ti=18.520C Ti=20.640 C

These diagrams represent the temperature evolution in the structure between 2environments, one heated and one unheated. As shown, the special window with

ETFE membrane has the best results and keeps an optimal temperature on the

internal face of the window. These results confirm that the special type of window

is a better choice than the classical solution.


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ICAMES 2015

15.01 16.1918.52

-10.01 -11.19 -13.52

-20

-15

-10

-5

0

5

10

15

20

25

Low temperature outside

Ti Te

All results obtained in Saint-Gobain Isover can be represented in a simple form as

a comparison between extreme values of temperature, Fig. 12 and 13.

Fig. 12: Extreme values of temperature in cold environment

Fig. 13: Extreme values of temperature in warm environment

These two charts show us the difference between temperature of the exterior face of

the element and the temperature of the inside face. The classical solution of window

has a high heat transfer and a lot of energy is lost. This loss can be reduced byintroducing an inert gas, argon in our case, between the two layers of glass, but the

best solution is a window with ETFE membrane.

When the special window with ETFE membrane is used,better results are obtained

and the heat transfer between the two environments is reduced. This fact leads to a

32.86 33.3734.36

22.14 21.63 20.64

0

5

10

15

20

25

30

35

40

High temperature outside

Te Ti


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ICAMES 2015

saving of the energy consumed to maintain an optimal temperature indoor and the

buildings become greener by using this material for large glazing surfaces.

4.Success international projects which use ETFE solution

4.1. Eden ProjectEden Project, Fig.14(a), is located in Cornwall, United Kingdom and consists of two

biomes. The Mediterranean Biome, Fig.14(b), is 135 m long, 65 m wide and 35 mhigh and it houses a warm temperate environment. The Tropical Biome, is 240 m

long, 110 m wide and 55 m high and it houses a rainforest environment. ETFE wasthe best choice for this project because of several factors:

the clay pit soil has a limited load bearing capacity so a lightweight structure

was necessary;

the original aim was to recreate the 2 climates in a natural way, with the

appropriate height and area;

the achieving of the best light transmission and thermal capacity for the

greenhouses;

the foil has a great geometry and size flexibility.

The cushions for this project consist of three layers of ETFE foil and they are

supported by aluminum frames, supported by steel trusses, Fig.14 (c) [2].

(a) (b) (c)

Fig.14: Eden Project [21]

4.2. Allianz Arena

Allianz Arena is located in Munich, Germany and is shared by FC Bayern and TSV

1860. The Stadium is made of double layer ETFE cushions and it combines white

translucent and transparent foils. The faade is composed of printed foil cushions

that are illuminated with red lights, Fig.15 (a), for Bayern games, with blue lights,

Fig.15 (b), for 1860, white, Fig.15 (c) and 15 (d), for Germany National team and

different colors on regular days.


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2.816 cushions of 2 m by 4.25 m were used for the entire structure. What is really

interesting is the fact that the same cushion shape occurs at most twice in the entire

structure. This would have been really difficult to achieve with traditional glazing

but the elasticity of the ETFE made it easy to accomplish [2].

(a) (b) (c) (d)

Fig.15: Allianz ArenaProject [15, 16, 17]

4.3. Shenzhen Water Park

Shenzen Water Park, Fig. 16, is located in East Huaqiao China and has the shape of

a water droplet. The reasons for which ETFE was selected are its durability,

lightweight, insulation properties and cost effectiveness. Even though the structureis in southern China, the facility needed to be heated during winter months. Because

the structure has a really complex shape, the three layered cushions have severalhundred different geometrically shapes. In the cushions is incorporated LED lighting

which gives the ETFE a dramatic effect [18].

Fig.16: Shenzen Water Park [18]


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References:

1. Koukaroudis Panagiotis-Properties and design guidelines for double-skin faades in

Sweeden,Master Thesis at Chalmers University Of Technology, January 2014

2. Leslie A. Robinson-Structural Opportunities of ETFE(ethylene tetra fluoro ethylene),S.B.,

Civil Engineering Massachusetts Institute of Technology, June 20043. Mihai Grecu-Poly(ethylene-co-tetrafluoroethylene)-based permanent motorway roofs

equipped with night lighting sources and thin film solar cells, Acta Technica Napocensis:

Civil Engineering & Architecture Vol. 54 No. 2 (2011

4. Stephen Tanno- ETFE Foil Cushions As An Alternative To Glass For Atriums AndRooflights Buro Happold Faade Engineering 41-43 Praed Street, London, W2 1NR

5. Amy Wilson-ETFE: The New Fabric Roof, January 2009, www.rci-online.org

6. Adrien Escoffer, Adelyne Albrecht, Franois Consigny- Nice stadium: Design of a flat

single layer ETFE roof,

7.

Linda Charbonneau, Maria Anna Polak, Alexander Penlidis- Mechanical properties ofETFE foils: Testing and modelling, 2014 Construction and Building Materials 60(2014)63-72

8. http://www.birdair.com/tensile-architecture/membrane/etfe

9. http://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-

1386711.html

10.http://www.environmentalleader.com

11.http://www.designingbuildings.co.uk/wiki/ETFE

12.http://www.businesspundit.com/10-accidental-discoveries-that-generated-great-wealth/

13.http://jp1042754017.fm.alibaba.com

14.http://www.infoplease.com/ipa/A0004686.html

15.

https://sstamu.wordpress.com/

16.http://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottma

ning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpg

17.https://www.allianzglobalbenefits.com/news/news_overview.html

18.http://www.makmax.com.au/projects

19.http://rerdm.hyperbody.nl/index.php/project13:Performance

20.http://www.fotodesignandreasbraun.de/index.php?g=13

21.http://www.edenproject.com/
http://www.birdair.com/tensile-architecture/membrane/etfehttp://www.birdair.com/tensile-architecture/membrane/etfehttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.environmentalleader.com/2009/04/27/building-sector-needs-to-reduce-energy-use-60-by-2050/http://www.environmentalleader.com/2009/04/27/building-sector-needs-to-reduce-energy-use-60-by-2050/http://www.designingbuildings.co.uk/wiki/ETFEhttp://www.designingbuildings.co.uk/wiki/ETFEhttp://www.businesspundit.com/10-accidental-discoveries-that-generated-great-wealth/http://www.businesspundit.com/10-accidental-discoveries-that-generated-great-wealth/http://jp1042754017.fm.alibaba.com/product/156405485-0/recycled_ETFE_lumps.htmlhttp://jp1042754017.fm.alibaba.com/product/156405485-0/recycled_ETFE_lumps.htmlhttp://www.infoplease.com/ipa/A0004686.htmlhttp://www.infoplease.com/ipa/A0004686.htmlhttp://www.infoplease.com/ipa/A0004686.htmlhttps://sstamu.wordpress.com/https://sstamu.wordpress.com/https://sstamu.wordpress.com/http://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttps://www.allianzglobalbenefits.com/news/news_overview.htmlhttps://www.allianzglobalbenefits.com/news/news_overview.htmlhttps://www.allianzglobalbenefits.com/news/news_overview.htmlhttp://www.makmax.com.au/projectshttp://www.makmax.com.au/projectshttp://rerdm.hyperbody.nl/index.php/project13:Performancehttp://rerdm.hyperbody.nl/index.php/project13:Performancehttp://rerdm.hyperbody.nl/index.php/project13:Performancehttp://www.fotodesignandreasbraun.de/index.php?g=13http://www.fotodesignandreasbraun.de/index.php?g=13http://www.fotodesignandreasbraun.de/index.php?g=13http://www.edenproject.com/http://www.edenproject.com/http://www.edenproject.com/http://www.edenproject.com/http://www.fotodesignandreasbraun.de/index.php?g=13http://rerdm.hyperbody.nl/index.php/project13:Performancehttp://www.makmax.com.au/projectshttps://www.allianzglobalbenefits.com/news/news_overview.htmlhttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttp://commons.wikimedia.org/wiki/File:Allianz_Arena_in_Rot_rot_506022125_Frottmaning_Abendhimmel_lock_221_und_113_Polizeifahrzeuge_(1500472142).jpghttps://sstamu.wordpress.com/http://www.infoplease.com/ipa/A0004686.htmlhttp://jp1042754017.fm.alibaba.com/product/156405485-0/recycled_ETFE_lumps.htmlhttp://www.businesspundit.com/10-accidental-discoveries-that-generated-great-wealth/http://www.designingbuildings.co.uk/wiki/ETFEhttp://www.environmentalleader.com/2009/04/27/building-sector-needs-to-reduce-energy-use-60-by-2050/http://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.archiexpo.com/prod/vector-foiltec/texlon-etfe-roof-system-68767-1386711.htmlhttp://www.birdair.com/tensile-architecture/membrane/etfe

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