Energy-efficient windows
Glass packages explained in plain words: what U-factor means, when triple pane is worth it, and what to expect on your bills.
- U-factor, standard double pane
- 0.27
- U-factor, triple-pane option
- 0.20
- Triple pane, per window
- $150+
Overview
What makes a window efficient.
Most of what makes a window efficient is the glass, and most of the glass is invisible: a coating thinner than a hair, a gas you can't see, and the spacer that holds the panes apart.
Here is what each part does, what the numbers on the sticker mean, and an honest word about your heating bill.
Cross-section
Five parts, in plain words.
- 1 Low-E coating A see-through metal layer, thinner than a hair, that bounces heat back toward the room in winter and keeps some summer sun out.
- 2 Argon gas A heavy, harmless gas between the panes. It slows heat moving across the gap better than air does.
- 3 Warm-edge spacer The strip that holds the panes apart. Ours is mostly foam and plastic instead of aluminum, so the edge of the glass stays warmer and fogs less.
- 4 Two panes of glass Two layers of glass with a sealed space between. Triple pane adds a third layer and a second gas space.
- 5 Insulated frame Hollow chambers in the frame trap air, so the frame isn't the cold spot once the glass is good.
U-factor
The window's winter coat, as a number.
U-factor is how fast heat leaks through the whole window: glass, edges and frame. Lower is better. It is the most useful number on the sticker in a cold climate.
Typical whole-window values. Your new window's sticker is the number that counts.
-
Single pane 1.05
Cold glass, frost on the inside in January
-
Single pane + storm 0.50
Better, but drafty at the sash
-
1990s double pane, clear 0.48
No coating, air between panes
-
Lakelight double pane 0.27
Low-E coating, argon fill
-
Lakelight triple pane 0.19
Two coatings, three panes
Reading the sticker
Every new window comes with a rating label. Here's what it says.
- U-factor
- How fast heat leaks through the whole window. Lower is better. Think of it as the window's winter coat: 0.27 is a good coat, 1.0 is a T-shirt.
- Solar heat gain (SHGC)
- How much of the sun's heat gets through, from 0 to 1. Higher can help a south room in winter; lower keeps a west room cooler in July.
- Visible light
- How much daylight comes through, from 0 to 1. Coatings and extra panes trim it a little; most people never notice.
- Air leakage
- How much air sneaks through the window itself. Lower is better. Casements and awnings usually score best because they clamp shut.
- Condensation resistance
- How well the window resists fog and frost on the inside glass, from 1 to 100. Higher is better in a Rochester January.
- We leave it on
- The label stays on your new window until you've seen it at the walkthrough. Then it comes off, and the numbers go on your invoice.
Glass options
Glass packages and what they add.
Swipe the table sideways to see every column.
| Package | Typical U-factor | Added per window |
|---|---|---|
| Double pane, Low-E, argonOur standard on every window | 0.27–0.30 | Included |
| Double pane, two Low-E coatings, argonA little better in winter | 0.25–0.27 | $40–$90 |
| Triple pane, Low-E, argon or kryptonBest insulation; heavier sash | 0.17–0.22 | $150–$350 |
| Laminated glassQuieter rooms, harder to break | Same as package | $90–$220 |
U-factors are typical whole-window values for our lines and vary by style and size. The sticker on your new window is the number that counts, and we leave it on until you have seen it.
Full price guide and estimatorYour heating bill
An honest word about savings.
New windows usually lower heating and cooling costs some. Going from single pane makes the biggest difference; going from 20-year-old double pane is mostly about comfort, noise and condensation.
We won't promise a percentage, because it depends on your house, your furnace, your air leaks and your habits. Anyone who quotes you one before seeing your home is guessing.
Rebates and credits
Check what applies when you buy.
Utilities, the state and the federal government have all offered incentives for efficient windows and doors at different times, and the rules change often. We print the product ratings you need on your invoice and point you to current programs.
We never subtract a rebate from your price or count on one to close a sale.
Packages
What each glass package does
- Panes
- Two, with one Low-E coating
- Gas fill
- Argon
- Typical U-factor
- 0.27–0.30
- Feel
- No cold glass, no drafts
- Cost
- Included
- Best for
- Most rooms in most homes
- Panes
- Three, with two Low-E coatings
- Gas fill
- Argon or krypton
- Typical U-factor
- 0.17–0.22
- Feel
- Warmer glass, a bit quieter
- Cost
- $150–$350 more per window
- Best for
- North rooms, bedrooms, big glass
- Panes
- Inner pane is two layers bonded together
- Gas fill
- Argon
- Typical U-factor
- Same as the package it's added to
- Feel
- Noticeably quieter; holds together if broken
- Cost
- $90–$220 more per window
- Best for
- Busy streets, ground-floor security
Straight answers
Is it the right call for your home?
A good fit when
- Single-pane windows, with or without storms
- Rooms where the glass feels cold or fogs up inside
- Bedrooms that never warm up
Think twice when
- Paying for triple pane in every room. Often it only makes sense on the north side and in bedrooms
- Any company that promises a percentage off your bill. Nobody can know that before they've seen your house
Every quote includes
- Low-E, argon-filled double-pane glass in every window
- Warm-edge spacers that cut cold edges and condensation
- Rating stickers left on so you can check the numbers
- The numbers you need for any rebate or credit, on your invoice
Will new windows lower my heating bill?
Usually some, but rarely enough to pay for the windows on their own. If you have single pane now, you'll notice it more. If your windows are newer double pane, the change is mostly comfort. We won't quote you a percentage, because it depends on your house, your furnace and your habits.
Are there rebates or tax credits?
Sometimes. Utilities, the state and the federal government have all offered incentives for efficient windows and doors at different times, and the rules change often. We put the product ratings on your invoice and help you check what applies when you buy. We never count a rebate in your price.
Why does my new window fog on the outside some mornings?
That is actually a sign the glass is working. The outer pane stays cold because heat isn't leaking through, so dew forms on it on cool, damp mornings. It burns off as the sun comes up.
Other products
Free, in writing, no pressure
See the glass before you choose it.
Feel single, double and triple pane in the showroom cold box, or have an installer measure your home and price each room's glass on its own line.
Rather talk? (585) 555-0136, weekdays 8 to 5:30.