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

Hollow Glass

Glass doors and windows are the primary means through which we commune with both the inside and the outside of a building, permitting light to flow into the interior (in daytime) and allowing us expansive views.

They can also be decorative, but the natural indoor and outdoor heat exchange means a great influx of heat in summer and a great outflow of valuable energy, through generated heat, in winter. This, traditionally, has led to wasteful energy consumption through the heating and cooling of buildings.

Insulating glass is the solution, providing energy-saving, environmental protection and comfort (noise reduction), yet still enabling us to commune clearly through our glass.

Insulating Glass, usually referred to as Double Glazed in Australia and New Zealand, also comes under the category of Hollow Glass, though this intriguing name refers also to a much broader category of glass products including bottles, glass spheres or bubbles.

Energy conservation of buildings is arguably a more important topic today and Hollow Glass (the IGU and Double Glazed Unit) continues to play an important role in this field. Over 30% of energy inside buildings flows away through doors and windows. This nagging fact alone ensures that the energy conservation capabilities of doors, windows and glass curtain walls will continue to be an important topic in the glass industry.

Double Glazed units need not be dull: spacing bars, made from fire-resistant macromolecule plastics or colourful aluminium, can be embedded within the hollow glass and can be different in colour and shape.

Low-E insulating glass filled with inert gas: Low-E coatings on glass effectively block heat radiation. Low-E Hollow Glass filled with inert gas can further reduce the direct transmission of heat energy and reduce the thermal transmission coefficient of glass. Hence the ‘Energy Efficiency’ tag I often apply to the product.


Laminated Glass - Double Glazed

In order to achieve different effects, Hollow Glass units can also be combined with coated glass, toughened glass or laminated Switchable Privacy Glass to form various desirable composite products.

Eco Friendly Glass Clad Buildings

The Green Design Award 2011 Winner in the USA

Visually dynamic, or a blot on the landscape? You be the judge. But the clever use of grey Low E glass and blue insulating glass had it being selected as the winner of the above award.

Let us look at it from the inside:
The property showcases 9.5 foot high, floor-to-ceiling glass allowing for 92% natural light and unobstructed mountain views, and also affording sweeping city views for the tenants.

In the words of Ron Izzo, associate principal at architectural firm RNL and project designer on the building:

“. . . We began our studies by looking at the building in the uniform skin of precast and glass. Using a subtractive design process, we created voids and filled them in with the contrasting blue glass. This gave us the right visual balance with the grey glass set in a precast spandrel. Each blue glass module is a repetitive derivative of the smallest module within the building, which on a standard office building is typically five feet. The modules then combine to fill the column bay; this is typically 30 feet from column-to-column and 14 feet from floor-to-floor. The pattern grows or shrinks in multiples of these structural bays, evolving around all four sides and spreading across all elevations. All of the blue glass modules stand off the skin.”

To create pleasant, day-lit interiors without glare or thermal discomfort, the glass fabricator helped create a unique glazing solution: Grey Insulating Glass with a Low E coating is the primary glass. The glass has a visible light transmission of 23% to allow enough light inside without glare or significant solar heat gain. This glass is broken up by large squares of Blue Insulating Glass. The blue glass has a lower light transmission (8%) than the grey, but casts a beautiful contrasting light into the building. The grey glass has a solar heat gain coefficient (SHGC) of 0.23 while the blue has a SHGC of 0.16. This high solar performance was chosen to reduce overall internal energy consumption.

I can appreciate that from the point of view of the persons working inside the building it could have a pleasant ambience, but IMHO, from the outside, it is still a not-particularly-attractive glass box.

Eco Friendly Glass Clad Building (photo by Frank Ooms)