Low iron glass and low-E coatings for ambitious transparent facades
A guide to realising a distinctive low-iron aesthetic with high transparency and visible light transmittance
Choosing the right glass is the centrepiece of an impressive glass façade design concept. Low-E coatings for glass facades are often considered the basis of a glazing specification for this type of installation; however, many architects and designers know that Low-E coatings fail to achieve the beautifully clear aesthetic that inspired the façade design in the first place.
Low-E glass coatings are repeatedly specified due to their solar-control, low-emissivity properties. By using these solar control coatings and low-E coatings your architectural glazing can reduce solar gain, reduce internal cooling costs, and create a comfortable interior environment. It is highly recommended for large façade installations as solar gain will be a prominent challenge without any solar protection.
IQ projects recommend that a solar control glass coating should be considered in the design of large facades even if the glass specification already includes a low-E coating within the insulated glass.
Structural glass facades
Structural glass facades are extremely common for a variety of architectural design applications including storefronts, entrances, atriums, and retail facilities. It’s frequently specified due to its versatility and contemporary aesthetic, however, there are several types of glass specifications to consider achieving the desired aesthetic for each project.
Architects are aware that a standard architectural glazing specification doesn’t use low iron glass, which means that the glass isn’t completely clear. This can be difficult to notice without the standard glass being held against the low iron glass. Standard glass has a green aesthetic to it which becomes more pronounced when it’s viewed at an angle and usually appears darker when the thickness of the glazing is increases and even when Low-E coatings are used.
Responding to architects’ requirements for structural glazing, IQ has developed a new thermally broken structural glazing system called Invisio structural glazing. This unique structural glazing system overcomes the issues of thermal bridging with its unique thermal break. The thermal break installed within an insulated glass unit has been tested for a Uw value of 1.1-1.2 W/m²K. Invisio structural glazing can be manufactured with low iron glass and include a Low-E coating for an impressive glass façade performance.
Low iron glass coatings for structural glass facades
Iron oxide within the glass, leftover from the manufacturing process, gives standard glass its green tinge. There is a solution to this undesirable attribute and that’s low iron glass. With its low iron content, low-iron glass significantly reduces the green aesthetic, making it an ideal solution for facades or minimally framed or frameless glass installations where clarity is required.
Extra clear low iron glass is ideal for when a thick glazing specification is required, as you can layer up many thick units of glass and still achieve clarity, which isn’t possible with standard “clear” glass. It is also recommended to use low iron glass in façade design where you have two differences in the thickness of glass specifications, for example when structural and framed glass are used in close proximity to each other.
Low iron glass is an excellent substrate for low-E coatings, as the heightened clarity is complemented with outstanding energy performance. This combination allows architects to achieve high clarity and high-performance exterior façades, with high VLT (visible light transmittance) and stunning views outdoors.
Commercial building design is often a balancing exercise between performance, aesthetics, budget, and quality. However, improving the standard glazing specification to include both low iron glass and low-E glass coatings doesn’t stretch the budget and is worth the upgrade due to the exceptional clarity and performance offered.
To discuss your project with a member of our team, simply email us at hello@iqprojectsuk.com
Lucy Thompson
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