January 22, 2018

Low E Glass – Low ‘Emissivity’, Energy Efficient Glass

Windows have long represented a major source of unwanted heat gain and heat loss.


Creating Energy Efficient Buildings

“Buildings are the nation’s largest energy consumer” and Secure Glass can help you achieve greater energy efficiency in your building whether it be a new construction or a retro-fit.


Without Low E Glass - Heat Gain

With Low E Glass - Less Heat Gain


Western Australia’s extreme climate requires that for much of the year we waste energy in cooling down our building interiors. In recent years Low E coatings that reject solar heat without darkening the glass have undergone a technological revolution. It is now possible to significantly reduce solar heat gain and improve comfort while providing clear views and daylight.

In winter, the reverse is true. These same old windows represent a major source of unwanted heat loss, discomfort, and condensation problems. By having Secure Glass install Low E Glass throughout your home it is now possible to minimise your energy consumption bills by reducing the heat loss and/or retaining heat gain.

Low E Glass will also minimise condensation, increase your comfort and enhance the value of your home. It will not be long before residential building standards will require Energy Efficient Glass to be installed in all new residential buildings. This is a global trend.


Without Low E Glass - Heat Loss

With Low E Glass - Less Heat Loss

There are two basic types of Low E Glass:

Hard Coat Low E Glass has a pyrolytic coating sprayed onto the glass surface during the float glass process at high temperatures. It also comes in a laminated form (2 sheets of glass with a PVB interlayer) with the hard, durable pyrolytic coating on one side for use in single glazing. The coating is very durable but the glass has the possibility of a slight haze, which can be visible under certain angles, and does not provide the same energy efficiency as Soft Coating.

Soft Coat Low E Glass, also known as Sputter Coat glass, is mostly used in double glazing. The sputtered coating of multiple layers of optically transparent silver sandwiched between layers of metal oxide is applied in a vacuum chamber. This process provides the highest level of performance and a nearly invisible coating.

In terms of residential or commercial glazing the most effective energy saver is Insulated Glass Units (also known as double glazing). And IGU’s that incorporate Soft Coat Low E Glass in their fabrication provide the ultimate in energy saving. Double glazing (or IGU’s) comprises two sheets of glass sealed together but separated by an airspace creating a vacuum. A specially designed aluminium spacer containing drying agents ensures no moisture is present within this area. The sputter coated surfaces of the glass are faced to each other inside the unit, and this application results in a much lower SHGC (Solar Heat Gain Coefficient); a distinct reduction in heat-gain from that of direct solar radiation on clear, uncoated glass. In winter, although it limits the entrance of part of the solar energy, the strength of winter solar energy is only one third of that in summer; besides, the internal thermal retaining performance is not affected.

However, both types of Low E Glass are designed to transmit the maximum possible amount of visible light, absorb and reject the maximum amount of solar infra red energy, and reflect the maximum amount of long wave (room temperature) infra red energy, thus working towards more sustainable, energy efficient buildings.


The following represents a complete range of Energy Efficient Glass available from our manufacturer:

Energy efficiency without compromising your views

A clearly superior Low E glass

EnviroShield Performance™ ITO
Increasing solar control without sacrificing daylight transmission

EnviroShield Performance™ XIR
Incorporating a performance interlayer to further enhance solar control

The world’s first pyrolitic reflective Low E glass

PerformaTech E™
High Performance IGU with Low E

The world’s first self cleaning glass

Solar Control with Low E
High daylight transmission outstanding solar and thermal control

A clearly superior Low E glass

Highly versatile with outstanding performance in warm and cold climates

For colour, excellent solar performance and comfort, this advanced toned glass is a natural

For colour, excellent solar performance and comfort, this advanced toned glass is a natural

For colour, excellent solar performance and comfort, this advanced toned glass is a natural

Maximum energy savings, superior interior comfort

Insulating Glass Units (IGU’s)/Double Glazing:

ThermoTech™ Metal Spacer
Double Glazed Low E Glass with metal spacer and good solar control

ThermoTech™ Thermoplastic Spacer TPS®
Double Glazed Low E Glass with plastic spacer

Glass Progress

So you think glass is just glass?

Well think again.

While you have been staring out your plain old window for the last decade, Glass has been undergoing a technological revolution.

This progress has been driven partly by man’s insatiable desire to ‘improve, and improve again’, but the key driving factor has been the building industry’s acknowledgement and embracing of the need to use better, safer, more durable – and most importantly – more Energy Efficient products in their construction. Yes, the glass industry is going Green – in a big way. And it is ironic, is it not, that glass has always had a slightly green tinge to it when viewed on its edge.

While the building industry throughout the western world has been constantly up-grading and improving Safety Standards, there has been a parallel drive in the Glazing Industry to improve its products safety performance and thermal loss and gain: old-style glass being notoriously bad at preventing heat and cold from passing straight through it – both ways.

Don’t worry ‘help is on the way’! A collaboration of scientists and technicians working on all these above problems over the years have come up with practical solutions. Even the earlier solution to the problem of heat loss and gain, Double Glazing, has been improved out of sight; I was wowed the other day on seeing venetian-style blinds within the glass of a sealed, double glazed unit. Do you realise what this means? You would never have to clean the blinds! Fabulous.

In respect to Safety: The improvements have been primarily in the strengthening of glass; prevention of shattering and breaking into dangerous shards; heat resistance in the face of fire; and the withstanding of high wind loads – ‘hurricane proofing’ in climatically challenged zones, but equally applicable in curtain walled (all glass) high-rise building.

Images sourced from www.viridianglass.com


Images sourced from www.viridianglass.com


In respect to Energy Efficiency: Besides the use of smart, tinted films being laminated into windows the scientists have moved towards thermochromics, a passively responsive technology where the optical properties of the glass change in response to heat (appearing to darken in the sun), and electrochromic glass that requires voltage to similarly create a gradual tint to dark grey. This latter system allows the glass to be controlled by a ‘smart’ building system, or overridden by an actual human.

Clever stuff, all of which has devoured billions of dollars in research and development funds over the years, and all, ultimately, to better our comfort in the buildings in which we spend so much of our time. Maybe we should just get outdoors more!