Week 14
ETFE (Ethylene Tetrafluoroethylene)
BURAK ÇELİK
ADA412 Contemporary Problems in Urban Sustainability Bilkent University Department of Architecture 06.05.2018
What is ETFE? ETFE is a fluorine based plastic, and could be described as a tough high strength version of PTFE. It has excellent chemical, electrical and high energy radiation resistance and a relatively high melting temperature. ETFE is also thermoplastic and can be injection moulded into very thin components or hot compression molded into stock shapes such as Rod, Tube or Sheet.
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Key features:
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Excellent chemical resistance
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Chemical inertness
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Outstanding weathering resistance
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Excellent heat resistance
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Excellent electrical insulative properties
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Low coefficient of friction
Super Lightweight The ETFE film incorporates materials that give it an impressive lightness. The advantage of this in construction is you will require less structural steel to support the ETFE film hence resulting into a much lighter, but strong structures. In addition this ETFE roofing puts less stress loading on the building, meaning structural steel works can be lessened as the main building can usual act as support. This flexibility and lightweight nature explains why ETFE membrane roofs are the future since they give greater design freedom and capabilities.
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Durable and Self-Cleaning Whether it is exposed to chemical, thermal, or physical destructive elements; ETFE is structurally resistant, and can perfectly withstand the shock. Research shows that the ETFE film has the ability to retain its strength for more than 35 years whilst at the same time retaining its transparency and self-cleaning properties.
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Excellent Insulation Performance ETFE can either be used in a single, double or triple layer model, with each option giving it outstanding insulation properties. During the colder seasons, structures built with ETFE retain heat whilst in summer months the same structures keep off heat from entering into the indoor space below. Depending upon which Thermal Value is required, the ETFE roof design can be manipulated to achieve as little as 0.1W/m2k U-values for a roof. This is practically impossible for glazed roofing.
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Solar Control An ETFE installation although transparent and excellent in light transmission, can be manipulated using a variety of techniques, so as to give it tremendous solar control features. Among the techniques used to achieve this include performance printing also referred to as fritting, tinting, surface treatments, radiation and the addition of extra layers of EFTE foil so as to minimize light transmission and control solar gain. This makes ETFE foil one of the most thermally controllable tensile fabrics on the market.
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Eco-Friendliness Unlike other artificial materials, ETFE is a 100 percent recyclable polymer. When it has served its term, it can be removed and recycled back into beneficial ETFE products such as tubing, castings or wires. Being a lightweight fabric, ETFE requires less fabrication and transports costs and this reduces its carbon footprint.
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Natural Day Light Most of us believe that pure glass is 100% clear and provides us with almost perfect natural light transmission. Well you would be in the majority if you thought so; actually glass can block out as much as 38% of natural day light. This means glazed roofs can require artificial lighting during daylight hours. A single layer of ETFE membrane fabric can actually allow up to 92% of natural day light to penetrate to the room below, increasing internal lighting for the buildings occupants.
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Application An example of its use is as pneumatic panels to cover the outside of the football stadium Allianz Arena or the Beijing National Aquatics Centre (a.k.a. the Water Cube of the 2008 Olympics) – the world's largest structure made of ETFE film (laminate). The panels of the Eden Project are also made from ETFE, and the Tropical Islands have a 20,000 m² window made from this translucent material.
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Advantages
Transmits more light, which can be regulated for local climates by applying patterns during the manufacturing process. Insulates better Costs 24% to 70% less to install Only 1% the weight of glass
Disadvantages
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ETFE transmits more sound than glass, and can be too noisy for some places. Usually applied in several layers that must be inflated and require steady air pressure. Working with ETFE is too complex for small scale projects.
Case Studies 1.The Forsyth Barr Stadium, New Zealand The design team spent months researching the perfect material to use for the stadium’s unique roof, and finally agreed upon Ethylene Tetrafluoroethylene, or ETFE. The space industry plastic blocks UV rays, while allowing sunlight through for the stadium to be mostly naturally lit. The ETFE also provides life-giving sunlight for the natural turf growing below, enabling the natural photosynthesis process to take place without being effected by the harsh elements of the weather.
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2.Allianz Arena, Germany One of the points when designing a football stadium like the Allianz-Arena is its impact on natural turf. Sunlight is essential for the growth of natural turf in any football stadium. Because Munich in Germany is located at a high latitude, the sun slants through the arena. Because of this, ingenuity was needed so that the walls and roof would not block natural light. A material that could protect spectators from the elements, but still allow the easy penetration of sunlight to natural turf, was sought, and AGC's "ETFE Film" solved the difficult problem.
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References: https://www.slideshare.net/AMITANAND75/ethylene-tetrafluoroethylene https://inhabitat.com/new-zealand-opens-first-enclosed-uv-blocking-turfstadium/ https://airsculpt.com/latest-news/why-etfe-membrane-roofs-are-the-future/