Here Is Everything You Need to Know about Window Energy Ratings | Golden Windows

Shopping for new windows and doors is exciting. You get to envision your home in a whole new light – literally! From choosing the material types, colour, grille patterns and panel options, to watching as a professional install your new purchase, the process is exciting and rewarding.

But there's one lingering question you might have: how do you make sense of window energy ratings? Most homeowners agree that energy-efficiency is an integral part of their decision-making process. Still, when it comes time to do research, they are greeted with several unfamiliar terms, numbers and scientific concepts.

How do you make sense of it all? And how, as a homeowner, do you ensure that you are getting an energy efficient product that’s right for your home? One way to tackle the issue would be to contact the window and door experts at Golden Windows. Our knowledgeable customer service representatives and design experts are always ready to help, with clear answers to all your unique questions.

For those who prefer to do their own research, we have put together this resource on window energy ratings. Written with the average homeowner in mind, our goal here is to empower you to make the best decisions possible for your home and family. In this guide, we will discuss the measurements for window energy ratings, the meaning behind that ENERGY STAR® logo you see on products, the reasons for choosing energy efficient windows and doors, and the importance of installation in ensuring efficiency.

Excited to shop for bright new windows and doors, but unsure how to read those energy ratings? Read on to get the help you need.

What Measurements Go into Window Energy Ratings?

It isn’t enough to use materials and processes known to produce energy efficient doors and windows; the products themselves should be subject to tests to certify their efficiency. Here in Canada, we use the Canadian Standards Association (CSA) A440.2 standard or the National Fenestration Rating Council to test the energy performance of windows, doors and skylights.

Windows, doors and skylights are tested according to several values, like U-factor, Visible Transmittance and Solar Heat Gain Coefficient. This section will cover the values used in Canada’s energy performance ratings, trying as best we can to distil the complex science and provide accessible definitions.


The U-Value (sometimes referred to as U-factor) looks at the heat transfer rate from warm to cold areas. You will either see it measured in watts per square metre Kelvin (W/m2K) or British thermal units per hour per square foot Fahrenheit (Btu/h x sq. ft. x °F). You want the number to be low, which indicates that the product has better insulating properties.

Visible Transmittance (VT)

Visible Transmittance, as the name suggests, concerns the amount of light that passes through a material. Measured as a ratio of visible light passing through a product (in this case, a window), Visible Transmittance tells you how much natural light you can expect pouring through your windows. For more natural light, look for a higher VT number.


Solar Heat Gain Coefficient (SHGC)

Where VT measures the sun’s light, Solar Heat Gain Coefficient (SHGC) measures its heat. It is expressed as a ratio indicating the amount of solar radiation, or heat, that is allowed through the window – either directly, or through absorption and subsequent release. There is no universally correct SHGC number, as the optimal number for your home will depend on its outdoor climate, position and shading.

Energy Rating (ER)

It may seem odd that one of the values used in Canada’s energy performance ratings is simply called “energy rating.” The purpose of ER is to bring together, and balance, other values on this list – U-factor, SHGC, and air leakage heat loss. When shopping for the right windows, it is helpful to have a number that coalesces different values. In this case, look for a higher ER value, which indicates better performance.


R-Value measures a product's resistance to heat transfer and can be read as numerically equal to the inverse of U-Factor. While not a part of the energy performance standards, R-Value is often quoted by manufacturers and contractors as a reliable indicator of performance. At Golden Windows, we list it as part of our Thermal Performance Data resource. Look for products with a higher R-Value, which, (like products with a low U-Value,) indicates better window performance.

What is ENERGY STAR® Certification?

The familiar blue-and-white symbol is a beacon for homeowners seeking efficient products. But what is ENERGY STAR® certification, exactly?

Where windows are concerned, products are eligible for ENERGY STAR® based on their U-factor (remember: the lower, the better) or their Energy Rating (the higher, the better). To gain certification, a product must meet the strict technical specifications for energy performance set out by ENERGY STAR®. According to the NRC, energy efficient windows and doors should have low-emissivity coatings (Low-E), insulated sashes and frames, and the option of triple glazing to further insulate heat.

Golden Windows is proud to be an ENERGY STAR® participant, a designation meaning that we are committed to manufacturing ENERGY STAR® certified products designed with the Canadian climate in mind. At Golden Windows, we offer tons of different window styles and door types that not only look fantastic but also help you save energy.

As further encouragement to choose efficient, certified windows, check out the ENERGY STAR® rebates and incentives directory to find out if your window replacement is eligible.

Why Energy Ratings Matter

By adhering to standards laid out by the Canadian Standards Association and gaining ENERGY STAR® certification, a product has demonstrated its efficiency. For windows and doors, that means that the entire functioning unit has been optimized for energy-efficiency and performance.

Simply put, energy ratings matter because energy efficiency matters. Beyond the blue-and-white seal of approval, there are reasons that manufacturers like Golden Windows strive to design, produce and install energy efficient windows and doors. We believe in providing customers not just a brighter today, but a brighter tomorrow as well.

In this section, let us restate the importance of energy ratings by looking at a few of the reasons why we take energy-efficiency seriously.

A Greener Option

Thankfully, environmental issues have gained renewed spotlight in the last few years, not just in the media but also in the purchasing habits of homeowners and homebuyers. People are increasingly looking to make small but significant differences in the way their home operates by choosing energy efficient products and following best practices to reduce their carbon footprint.

It is heartening to see. The purpose of striving for a greener planet has always been partly about creating a more habitable planet today, and partly about bestowing the next generations with a healthy, happy environment. Many of us have fond memories of paddling across the lakes of Algonquin Park or visiting the old-growth forests of BC and hope to preserve those experiences for our children and grandchildren.

Small, personal, incremental changes, like installing new, energy efficient windows and doors, have an accumulating effect and greatly impact our overall footprint-reduction efforts. 


Lower Utility Bills

Windows and doors can potentially contribute to significant energy loss in your home – up to 35%, in fact. With our cold Canadian winters and humid summers, that means you end up paying a lot more for your energy bills.

The NRC estimates that by replacing all your windows with ENERGY STAR® certified windows, you can save an average of 45% on your energy bill, a notable chunk of change that you can put towards the things that matter: family, fun, retirement savings or home improvement. They also estimate that a new, ENERGY STAR® certified door is 25% more energy efficient than its standard alternative.

Suddenly, those energy ratings above take on a real monetary significance. It pays, literally, to research the U-Value, R-Value and ER of your new windows and doors and choose the ones that are right for your home.

To preserve the integrity of your new windows’ operating hardware, and ensure its continued efficiency, check out the handy window operating instructions we’ve detailed on our website.

Striving toward Net-Zero Energy Housing

Net-zero energy (NZE) houses combine the above two benefits: they reduce the impact of housing on the natural environment, and significantly cut down on energy-related costs, both present and future. They take it a step further, though.

An NZE house is designed and built specifically to minimize a household’s energy needs, with the goal being to reach a state of equilibrium between energy produced and energy consumed. This does not mean "living off the grid." An NZE house still uses the energy grid – but it supplies the energy grid when it has a surplus and draws from the grid when household demands exceed the amount of electricity produced onsite.

At Golden Windows, we believe in striving toward NZE housing. Not only does it save money and create a comfortable living space for occupants, but it is also a more harmonious way for housing to exist with its natural environment.

The first step in achieving Net-Zero energy housing is to reduce the home’s energy requirements by using less energy and efficiently operating the home. Windows and doors that are tested according to the values above and qualify for ENERGY STAR® certification are a fantastic first step.

When people talk about NZE, they generally associate it with new homes, but it is also possible to apply the same principles to existing homes. Whether you are building a new home or renovating your existing home, let Golden Windows help make it as energy efficient as possible.

Learn More about Golden Windows Energy Ratings

At Golden Windows, we have performed thousands of physical and thermal simulations of our products. And although the product and options you select may change or affect the thermal performance specifications, you can feel comfortable knowing that you are getting an energy efficient product from us.

We hope the above explanations of values and ENERGY STAR® participation were informative. We encourage those looking for more information to visit the Natural Resources Canada website or, for those in the United States, the National Fenestration Rating Council website. There, you can also find the thermal test results of our products. Of course, if you’d prefer a direct line, you can always contact us at sales@goldenwindows.com for details or clarification.

When It Comes to Efficiency, Installation Matters

The very last thing you want is to choose an energy efficient window or door, going through all the work to ensure that it looks and performs just the way you want it to, only to have it improperly installed.

Improperly installed windows and doors can cause drafts, condensation, and water leakage, rendering even an energy efficient window incapable of doing its proper job. It’s paramount that you choose a trustworthy installer.

Luckily, Golden Windows is an end-to-end service – we design, manufacture and are available to install all our products. When you contact Golden Windows about a window replacement opportunity, you will be put in touch with an Installation Sales Representative who will come to your home at a convenient time for a free onsite measure and discussion.

You will be provided with a quote, and, upon your approval of the quote, connected with a member of our Certified Installer Team, who will perform a final measure. With the details confirmed a second time, we will custom make your product, and the Certified Installer Team will work their magic. With professional oversight every step of the way, you can rest easy knowing that you are receiving an expertly installed ENERGY STAR® certified addition to your home.

Energy Ratings may be difficult to understand at first. The numbers and terminology populating a thermal performance document can seem like they are written in Greek. Hopefully, with the explanations above, you feel more confident in your ability to make the right choice. Not just how to determine energy efficiency, but why energy efficiency is vital, and why choosing the right installer makes all the difference.


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