U-Value vs Solar Heat Gain Coefficient: Which is More Important for Your Windows?

When it comes to choosing the right windows for your home, the conversation usually turns to two key numbers: U-Value and Solar Heat Gain Coefficient (SHGC). But which really matters more?

The truth is – both are important, and the priority depends on where you live. At Centra Install Pros, we’ve worked with thousands of homeowners across BC and Alberta, and with over 40 years of experience, we know all there is to know about windows and exterior doors – and how to choose the right ones for your project. Choosing the wrong combination of these ratings can lead to uncomfortable homes and soaring energy bills.

Let’s break it down.

What’s the Difference Between U-Value and SHGC?

U-Value measures how well a window prevents heat from escaping your home. The lower the U-Value, the better the insulation – meaning your home stays warmer in winter and uses less energy.

Solar Heat Gain Coefficient, on the other hand, measures how much solar heat enters your home through the glass. A lower SHGC means the window is blocking more of the sun’s heat – a key factor in keeping homes cool during warmer months.

Here’s a quick side-by-side:

The image below demonstrates different glass types, with a thermal camera used to show the amount of heat passing through. On the left, we have clear glass with a high SHGC. Further right, we have glasses with different low-emissivity coatings, with the glass on the far right blocking the most heat.

It Depends Where You Live

In Alberta:

With long, cold winters and less intense summer heat, U-Value is the top priority. You want a window that keeps heat inside and boosts your home’s overall insulation performance.

In Kelowna and the Okanagan:

It’s a different story. With hot, sunny summers and plenty of solar exposure, SHGC matters just as much – if not more. A high SHGC window can turn your home into a greenhouse in July – and your A/C will struggle to keep up.

We’ve heard that some window companies are still installing windows with SHGC ratings of 0.50 or higher in sunny regions like Kelowna. That’s far too high, and it’s going to lead to a lot of unhappy homeowners a year or so down the line. It might still meet rebate requirements based on U-Value, but your home will still be sweltering all summer long. That’s not performance – that’s a problem.

Rebates & Loans: Why U-Value Gets All the Attention

Most government rebates and incentive programs – including the Canada Greener Homes Loan, CleanBC, and FortisBC rebates – focus on U-Value as the key qualification metric. That’s because U-Value is easier to standardize and it directly impacts efficiency – a major concern across Canada.

But here’s the catch:

A window with an excellent U-Value but poor SHGC can still make your home uncomfortable for half the year.

You might qualify for rebates and interest-free government loans – only to find your upgraded home is unbearably hot in the summer. At Centra, we believe true energy efficiency means comfort year-round, not just meeting a checkbox on a rebate form. Finding the right balance for your climate is also how homeowners maximize savings on energy bills with new windows.

The Right Window for the Right Climate

Choosing the right window and installer means striking the right balance – and at Centra Install Pros, we design and install windows in-province, specifically engineered for the local climate.

• In Kelowna, we strongly recommend low SHGC glazing to keep solar heat out during the intense summer.
• In Alberta, focus on low U-Values to lock heat in during the winter.
• In Coastal or mixed climates, balance both to provide comfort and performance throughout the seasons.

And we never rely on subcontractors – our trained Employee Owners handle every step of your project to ensure it’s done right. It’s one of the reasons we’re able to offer a better warranty.

The Centra Difference: Rebates + Comfort = Real Value

With Centra Install Pros, you don’t have to choose between performance and rebates. We help you:

• Select the ideal U-Value and SHGC combo for your region
• Qualify for CleanBC, FortisBC, and the Canada Greener Homes Loan
• Access the exclusive Window Efficiency Plan – saving you up to $4,500
• Get windows built in Western Canada, designed for Western Canadian weather
• Back your install with a 30-Year Full Warranty – for both window and installation, no gimmicks, and labour costs covered!

Know the Numbers, Feel the Difference

When you're shopping for new windows, don't just ask: "What’s the U-Value?"

Also ask:

• “What’s the SHGC?”
• “Is this window designed for my climate?”
• “Will this make my home more comfortable – not just more efficient?”

At Centra, we’ve built our reputation on helping homeowners get the best of both worlds: real comfort and real savings.

Western Canada’s Top Choice for Windows & Doors

Have an upcoming window and door project? Reach out to the experts at Centra Windows & Install Pros for a free consultation! If you have any questions regarding this topic or anything else to do with windows, contact a local Centra Employee Owner at 1-888-534-3333 or drop us an email at info@centra.ca. Follow us on Facebook and Instagram to stay up to date, and test your window knowledge on LinkedIn.