The Two Labels on a New Florida Window, and What They Mean
One sticker tells you what the window does about heat and light. The other tells you what it does about wind. Between them you can judge a quote without taking anyone's word for it.
A new window arrives with stickers on the glass, and most people peel them off without reading them. That is a small mistake, because between them those labels answer every performance question a quote can be vague about.
There are two of them and they cover completely different things.
The NFRC label: heat and light
The National Fenestration Rating Council label carries the energy numbers, tested to a common method so that products from different manufacturers can be compared honestly. Three of them matter.
U-factor is how fast heat conducts through the whole assembly. Lower is better insulated. It is the headline number in a cold climate and the secondary one here.
Solar heat gain coefficient, SHGC, is the share of the sun’s energy hitting the glass that ends up as heat in the room, on a 0 to 1 scale. Lower means cooler, and in a climate that spends most of the year cooling this is the number that does the work: the sun through the glass matters more than conduction through the frame.
Visible transmittance, VT, is the share of visible light that gets through. This is the one nobody checks and then regrets. Push SHGC very low and VT tends to follow, and a bright room becomes a gloomy one. The skill in choosing glass is getting SHGC down while keeping VT high enough that the room still reads as daylit.
The glass guide covers how those numbers interact in more detail. The short version: in Deltona, read SHGC first, U-factor second, and check VT before you commit.
The approval information: wind
The second set of information is structural and it has nothing to do with your power bill.
Design pressure is the wind load the assembly is rated to hold, positive pushing in and negative pulling out, and it follows every Florida window no matter how far inland it is. It rates the frame, the anchors, the glass and the hardware together as a system, which is why the number describes an installation rather than a product on a shelf.
Impact rating, if present, means the assembly passed a large missile impact test followed by thousands of pressure cycles on the damaged unit. It passes by keeping the opening sealed, not by keeping the glass unbroken. Deltona sits more than fifteen miles inland, well outside the coastal strip, so for most addresses here it is a choice rather than a foregone conclusion. The comparison guide works through whether to make it.
The product approval number, an FL number, or a Miami-Dade Notice of Acceptance, identifies the exact product and the conditions it was approved under: the sizes, the pressures it holds, whether it is impact rated and the installation method that was tested. If a quote cannot tell you what the window carries, that is a fair thing to ask about.
Why these get confused
Because a salesperson quotes them in one breath. “Low-E impact glass, high performance, hurricane rated” is four ideas in six words, and two of them are energy claims while two are structural claims. They come from different tests and appear on different labels.
A quote that separates them cleanly is usually a quote from somebody who does this properly. A quote that will not tell you the SHGC or the design pressure is a quote that is asking you to trust an adjective.
Do this before the labels come off
Photograph them. All of them, on every window, before the crew takes them off at handover.
The information is not recoverable afterward without going back to the manufacturer with an order number, and you will want it twice: once when your insurer wants evidence of what is installed, and again when a buyer’s agent asks the same question years later.
It takes two minutes and it is the highest-return two minutes of the whole project.
Getting windows priced in Deltona or nearby?
Call (386) 742-5619 or use the quote form, and a free written price comes back from a local contractor.