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June 26, 2017

Why is ETFE used for Atriums?

In past years in the construction industry, glass has been the “go to” material for atriums.  Elegant in appearance and lengthy in endurance, this has caused architects to choose this material over other possibilities.  A plethora of polycarbonates have also been on the market for years, however due to their poor physical properties, poor aesthetic values and bad durability, they have not been the number one choice or gained popularity in the construction industry.

 

However, since Ethylene Tetra Flouro Ethylene (ETFE) has been introduced into the ‘game’, we are seeing a sharp decline in the construction of glass atriums and for many good reasons, including design options, cost reductions and last but not least improved Fire Health & Safety capabilities. New technology means that the skins of the ETFE roofs are now more secure, reliable and easily joined and therefore able to span large areas of space, in a cost effective and elegant way.  

 

The first and perhaps the most obvious asset of EFTE in lieu of glass, is its flexible nature.  Glass is brittle, and generally used as only a flat panel.  ETFE however, is malleable and ductile.  It is possible to stretch and elongate the foil membrane up to 200 – 300% more than its original size before failure.

 

Secondly is size.  The air filled cushions can reach up to a massive 25m x 3.5m and more when designed with slip cables.  This allows for not only minimum joints, but also maximum aesthetic value.  Generally the largest size for a piece of toughened glass is 4m x 2m.  This glass will also have to undergo a number of checks that ETFE will not:  toughening oven restrictions, weight, and handleability.  

 

ETFE is also able to do away with traditional tolerances and movements.  When using glass in an atrium, the architect and designer will need to consider movements at the joints necessitating the use of sealants and gaskets on each side of the glass.  ETFE is clamped at its edges, which means any movement is absorbed into the material itself.  This means that EFTE has significant air filtration benefits over glass.

 

Even a standard Ethylene Tetra Flouro Ethylene foil membrane cushion has a far better U-Value than tripled glazed glass, making a glass atrium a costly investment.  The standard U-Value of an ETFE cushion is 1.95W/m2k, and can be reduced even lower with extra layers that have been treated with low E coatings.  Energy can also be saved due to the transparency of ETFE, which is found to be 95% transparent for visible light and 85% transparent for ultraviolet rays.  This percentage can be played with in a number is differing ways: layers of the cushion can be graphically printed to tamper with the transparency.  This can also be changed by adding additional layers into the cushion.

 

Before we get too deep into the science of why ETFE is becoming the preferred choice to glass for atriums, let’s look at the element that is vital to any build: Price.  EFTE cushions can be installed for approximately HALF the price that of a high-performance glass roof can.  However, ETFE isn’t to be considered a cheap alternative, it’s a highly engineered, specialist quality product, and continues to be more cost effective than glass even after it has been built.  Maintenance costs are also reduced due to the self-cleaning nature of the material.   The smooth and anti-adhesive properties of the foil mean cushions don’t attract dirt.  Nature is your cleaner, easily washing bird droppings away when it rains. The lightweight nature of ETFE also means less supporting structures, meaning more scope for design, less costly steel and concrete supports, and a wider range of potential building plots.

 

 

Ethylene Tetra Flouro Ethylene Foil Fire Safety Features

 

ETFE is also superior to glass in terms of fire risk and repairs.  Should an ETFE cushion become damaged during its life span, that single panel can easily be replaced.  The replacement can be carried out without any internal access being needed – business continues as usual.  In terms of fire risk, ETFE is amazingly self-extinguishing.  In the event of a fire the cushions will ‘self vent’ and shrink away from the fire, allowing the fire and smoke to vent into the atmosphere.  Because the material is shrinking rather than burning, this means that little to no debris will fall in the event of a fire.  Meaning that any persons who may be inside the ETFE building won’t be at risk.  In addition to this, the chemical composition of ETFE does not allow for combustion, which means no unexpected explosions when the fire meets oxygen.   These properties mean that unlike with a glass roof, little risk assessment for a fire needs to be made and eradicates the need for the ventilation precautions.  This aspect alone greatly reduces the cost of fire protection construction within the space beneath, making it a highly cost-efficient solution.

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A little geeky fact; ETFE is so incredible, that its performance has even been missile tested, ETFE has had large and small missiles fired at in, with little fracture or breakage.  It’s better to be safe than sorry..! This is also why the product is being used more and more for the construction of Airports, Train Stations and other important public spaces where unfortunately terrorist attacks are being aimed at.   It is a sad world we live in but this is also another primary reason Ethylene Tetra Flouro Ethylene foil is being used as it can absorb explosive shock ways and prevent large percentages of debris from passing through.

 

It is also being used for hotels in areas of the world prone to Hurricanes for the same reasons as above. We have even seen video footage of palm treed being uprooted and smashed into a hotel, shattering the temporary boarding and glass behind. However, when hitting the ETFE roofing, it was unable to rip through the cushion and instead got jammed within the first layer skin, preventing the tree from entering the building.

 

ETFE Fire Technical Data

 

The technical data also boasts of impressive quality in terms of the material itself; melting points of 260 ºC – 280 ºC, its ability to turn into a gas and its reduction/shrinking abilities when heated. These aspects all point to an improved safety performance when compared to that of glass especially in an atrium setting, this coupled with how cost effective an installation process is required shows it’s various superiorities to classical construction methods.

 

Airsculpt has a rich and varied history in the use of ETFE in atriums.  We look forward to helping realise the true potential of any project that we tackle.  To speak to one of highly qualified team members please call us on 01249 848 649 or email on Info@Airsculpt.com

 

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