How Much Heat Do Old Windows Let In and Why Modern Windows Matter More Than Most Homeowners Realize

When you live in Florida, it doesn’t take long to realize how much your windows affect your comfort—and your electric bill. Most people don’t realize just how much heat older glass pulls into the home. I’ve been doing this a long time, and the difference between old windows and today’s glass technology is night and day.

Why Heat Comes Pouring Through Old Windows

A single pane of glass lets in about 76% of the sun’s heat. That’s why an older Florida home feels warm no matter how low you set the thermostat.

Modern insulated glass—what we call an IG Unit—drops that dramatically. An IG Unit includes:

• Three layers of Low-E (silver, tin, copper, zinc)
• Argon gas between the panes
• Impact-rated interior glass
• A sealed package from a trusted manufacturer like Cardinal

With that setup, heat transfer drops to about 20%, and most homeowners see rooms cool down by eight degrees or more. That’s conservative.

What is Low E Glass Made Of

Low E glass is made from standard float glass that is coated with an ultra thin, transparent layer of metal or metal oxide. This microscopic coating is usually applied during manufacturing and is often made from silver or similar reflective materials. The coating works by reflecting heat while still allowing visible light to pass through, which helps improve energy efficiency. In many windows, the Low E coating is sealed between two panes of glass, protecting it from damage and allowing it to perform consistently over time.

Choosing the Right Frame for Your Home

A lot of homeowners go straight to brand names. But windows aren’t like buying a TV. Frames must match the wall construction of the home.

In our market, that usually means:

• Block homes with stucco need one type of frame
• Vinyl or Hardy siding homes need another
• Wood-frame homes with stucco need a different version entirely

Think of it like matching tires to the road. It’s all about the conditions you’re dealing with.

Florida Is Moving Toward Impact Glass Everywhere

Insurance companies are pulling out of Florida, and the ones staying are pushing for hardened homes. Because of that, most of our region is shifting toward impact-rated products.

Right now:

• All of Pinellas County requires impact
• Most of Hillsborough, Manatee, Sarasota, and Pasco require it

Even when it’s not required, the insurance savings speak for themselves.

What Insurance Will and Won’t Cover

Many people assume their homeowners’ insurance will pay for new windows. That’s not the case.

Insurance doesn’t replace windows, but it does offer annual premium credits when all openings are protected. That can include impact windows or, in some cases, hurricane screens over certain doors.

How to Know When It’s Time to Replace Your Windows

If you’re unsure whether your windows are failing, here’s what to look for:

• Dirt or dust around the frame
• Play or wobble when you slide the glass
• Cold air leaks in during winter
• Cool air leaking out during summer

Aluminum windows in particular loosen over time and start to vibrate, which leads to gaps—and higher power bills.

Why Homeowners Choose Us

The biggest compliment we get is that we’re not a pressure company. We:

• Provide line-by-line budgets
• Show multiple options and price points
• Let homeowners think about everything without pushing them
• Send educational videos so they can do their own research

We believe in informing—not forcing. People make better choices when they feel respected, and that’s exactly how we run our business.