Living in the Scottsdale area means your windows face extreme conditions: blistering summer heat, intense UV exposure, and big temperature swings between day and night. That’s why choosing the right window material isn’t just about looks—it’s about performance.
In this article, we’re comparing two of the most popular window materials—aluminum and fiberglass—to help you decide which one is the better investment for your Arizona home.
In summary, we’ve found that most clients who choose aluminum windows are not very happy with them long-term. There are a few untidy build-quality issues they don’t care for, and draftiness is always an issue, due to how the frame is chambered. And since fiberglass windows can be as little as 15% more than aluminum, depending on the brand you chose? It’s definitely worth considering. Even with all available upgrades on an aluminum, thermally broken window, you’ll get more energy-efficiency from a fiberglass window.
We’re big fans of Milgard Ultra Series and Pella Impervia fiberglass windows.
But client feedback aside, let’s explore some key differences between aluminum and fiberglass.
Quick Arizona Climate Comparison: Fiberglass Wins
Aluminum conducts heat and can warm up your interiors, even when thermally broken. However, fiberglass remains stable, cool to the touch and resists warping—no matter how hot it gets outside.
This area is where fiberglass really pulls ahead. Aluminum is the weaker performer, even with thermal breaks to improve energy efficiency. Fiberglass provides excellent insulation, reducing strain on your A/C and helping lower energy bills. Its low conductivity, tight seals and long-lasting performance make it the most energy-efficient of the three—and a great investment for homeowners who want to keep cooling costs under control.
Aluminum can fade, oxidize or pit over time, especially in exposed areas with prolonged UV exposure. Fiberglass resists corrosion, doesn’t rot, and can easily last 30+ years with minimal upkeep. It resists fading and holds its finish extremely well, even in direct sunlight.
Both are very low maintenance, with the same glass and track cleaning that all windows require. When it comes to the frame, aluminum requires occasional cleaning and touch-ups, especially if scratched or dented. Fiberglass frames require almost no maintenance—just rinse and wipe down occasionally.
Aluminum is perfect for ultra-modern homes with large, unobstructed views. Its clean, minimalist profile can be very appealing. Fiberglass is more versatile: it can be painted to match trim or mimic the look of wood, offering more flexibility for both modern and traditional homes.
Aluminum can be more budget-friendly upfront. Fiberglass costs more, but it pays off long-term with better energy savings, a longer lifespan, and more strength and durability.
Aluminum Windows: Sleek but Not So Insulated
Aluminum windows are loved for their slim frames and modern appearance. They’re lightweight, strong, and relatively affordable. Many builders and architects favor them for contemporary designs and large glass expanses.
But when it comes to thermal performance, aluminum has its drawbacks—especially in hot climates like ours.
Pros of Aluminum Windows:
- Clean, modern aesthetic
- Allows for larger glass areas and narrower frames
- Maximizes available window sill on the interior
- Lightweight and strong, ideal for very large windows (and doors)
- Typically less expensive upfront
- Black-on-black now comes standard
- Budget friendly (less than fiberglass or composite, but more than vinyl)
Cons of Aluminum Windows:
- Some operational styles can be difficult to open/close
- Allows significant dust and noise to enter the home
- Least energy-efficient choice of frame material
- Conducts heat into the home, even when thermally-broken
- Often experiences condensation in the cooler months
- Prone to drafts due to the frame’s outdated channel design
- Two-tone options not available from all manufacturers
- Some styles of operation are not EnergyStar 7.0 compliant
Aluminum windows are known for their strength and sleek, modern design. They typically have a thinner profile, with maximum glass viewing area to let in natural light. They’re also not as deep, in terms of overall depth—a boon for those who like to set plants or décor on the window sill inside their home.
But aluminum is a highly conductive metal, which means it transfers heat quickly. It’s not ideal for scorching hot summers in the Sonoran Desert, even when it’s a thermally broken product.
Making matters worse, it’s the one product our customers are most likely to be unhappy with after the purchase.
Aluminum windows have not gone through a redesign in decades, and the design is problematic. These windows drain through weep holes cut into the tracks, which create a suction effect when the air is warm inside and cool outside. That cold air is sucked into the home through the funnel this creates. Some manufacturers try to address this problem by adding valve flaps over the weep holes, but these commonly get stuck open, leading to the same funnel effect. It’s an energy-efficiency problem that creates drafts. Overall, aluminum windows leak more than any other frame material, including where seams overlap, where mohair touches, and in other areas. They’re just prone to it.
Aluminum windows can also look untidy. They have visibly butted corner seams, often with metal shavings embedded in the sealant during manufacturing, which many homeowners do not like the appearance of.
If you’re tempted to overlook these issues because you love the slim look of aluminum windows, we understand. Sometimes you just want the look you want, right?
On the good news side, both aluminum and fiberglass windows are fairly equal when it comes to how they expand and contract with weather and humidity changes. They’re pretty stable.
Fiberglass Windows: The Most Energy Efficient Option Available Today
Fiberglass windows are made from glass fibers and resin, creating a material that’s incredibly strong, stable and energy efficient. Unlike aluminum, or even aluminum-clad wood, fiberglass doesn’t expand and contract much with temperature swings—a major plus in Arizona’s climate.
This stability helps fiberglass maintain a very tight seal, which keeps air leakage to a minimum. It’s also the longest lasting frame material, with unmatched durability.
And with a price that can be as little as 15-30% more than aluminum? The money saved with your utility bills and extended lifespan will more than make up that difference over time.
Because of these factors, and its top energy efficiency rating, the Pella Impervia and Milgard Ultra Series of fiberglass windows are our top product choices in the Arizona market.
Pros:
- Exceptional insulation and energy performance
- Performs exceptionally well in extreme heat and sun
- Long-lasting with minimal maintenance
- Will not warp, rot, or corrode
- Clean tongue-in-grove corner seams
- Paintable and available in a wider variety of colors/finishes (including a wood-like texture, or a two-toned interior/exterior look)
Cons:
- More expensive
- Thicker frame profile
- Less impact-resistant, it can splinter or crack
DunRite’s Recommendation
Either aluminum or fiberglass can be a great choice—along with aluminum-clad wood, which we haven’t compared today—but in the intense heat of Scottsdale, fiberglass windows win our recommendation for homeowners who value energy efficiency, long-term durability and minimal maintenance. And it’s something homeowners never regret over time, which can happen with aluminum windows.
At DunRite Windows & Doors, we offer premium fiberglass brands like Milgard Ultra and Pella Impervia, expertly installed to protect your home and enhance your comfort year-round. We appreciate their superior energy efficiency, long lifespan, and proven performance in the Arizona desert.
Let’s Find the Right Window for Your Home
Every home is different—and so is every homeowner’s style and budget. If you’re not sure which window material is best for your needs, schedule a free in-home consultation with one of our product experts. We’ll help you compare options and find the right fit.
Schedule a free, no-pressure, no-obligation consultation. Whether we come to your home or meet at the Phoenix showroom, our window experts would be happy to walk you through options that best fit your home, style and budget.
DunRite: Helping thousands of Phoenix homeowners keep their cool. Literally. 🤣🤣🤣
