The Lowdown on Low-E Glass: What Is It and How Does It Work?

Ever wondered how energy-efficient glass windows actually work? For example, how is it possible that a few panes of glass can actually block out furniture-fading rays, keep your home warm in winter but cool in summer, and let in bright sunshine to help light your home during the day?

In large part, the answer is Low-E glass. Find out how an ultra-thin coating on the glass surface gives your windows near-magical properties that keep your home comfortable year-round and helps save money on energy bills.  

The Science Behind the Sorcery: Shining a Light on Low-E glass

To understand how Low-E (low-emissivity) window glassworks, it helps to understand different types of light within the solar energy spectrum. Ultraviolet (UV) light is responsible for fading items inside your home, such as furniture, flooring, or wall coverings. Visible light is the ‘natural’ light we want to maximize to keep indoor spaces bright without flipping a lightswitch. Infrared (IR) light is the radiant heat energy from the sun that can help reduce the amount of work your furnace needs to do to heat your home in the winter. 

Different Low-E coatings deliver different benefits. Some will minimize UV radiation (furniture-fading) light transmitted through glass without compromising the amount of visible light that passes through. Others, such as passive Low-E coatings, will help reduce heat transfer (and heat loss) inside your home to reduce the overall cost of home heating bills in the winter months.

What do we mean by low E coating? 

Low e materials can describe multiple materials including windows. Low e coating is an extremely thin and essentially invisible metal oxide layer that is placed directly on the surface of one or more of the panes of glass in these efficient windows. 

The main difference between Low-E and clear types of glass is that clear glass doesn’t have the added energy-efficient benefits or insulating properties that these glass units provide. Low-E energy efficient windows, or low emissivity windows, work by reflecting heat rather than absorbing and transmitting heat, whereby reducing the emissivity of the surface. 

Check out our handy window performance guide to see how double-paned Low-E glass measures up against double-paned clear glass in terms of R-value, solar heat gain coefficient, UV transmission and visible light transmission. 

Low-E Glazing Options: How to Choose the Best Low-E Glass for Your Home

There are several different types of Low-E glass available — from hard-coat Low-E coatings that transmit some infrared light to help heat your home, to soft-coat Low-E glass (sometimes called solar control Low-E coatings) which provides excellent UV protection and helps reduce heating and cooling costs by reflecting warm or cool air back into your home rather than allowing it to leak outside. 

The big benefit of solar control Low E  it allows less of the sun’s heat from entering the home to begin with, thus keeping the home cooler in summer.  Choosing the best high-performance window glazing option will depend on the specific solar- and energy-control needs of your home based on climate and geographic location. The latest generation of low-E coatings are designed to reflect solar radiation and reduce the total solar heat gain coefficient (SHGC) while providing high levels of daylight transmission. 

Gienow offers a wide variety of Low-E glazing options that work perfectly for Canadian climates and suit any budget. A few of our most popular glazing options include:

  • Eco Gain 180 High Solar Gain Glass – This Low-E glass is well-suited for the extreme temperatures our northern climate is famous for. It allows solar/infrared energy to pass through and reflects heat back into the room, reducing the home heating needs during the day. 
  • Eco Shield 270 Solar Control Glass – A great option for variable climates, this Low-E glass can reduce solar heat gain by 50% or more compared to ordinary glass. 
  • Eco Max Shield 366 Ultimate Performance Glass – With three layers of silver, this ‘spectrally-selective’ glass provides the highest level of comfort, energy savings, and fade protection. 

In addition to Low-E glazing, coloured tints or obscuring textures provide privacy, glare control, and extra energy savings, all while allowing natural light to shine through and adding decorative interest to your home. 

Learn more about Gienow’s full selection of Low-E Glazing Options or request a free estimate.