THE BUYER’S SIDE OF THE CATALOG
How to Choose Replacement Windows for Your Home
A replacement window is a specification, not a name. These are the parts of that specification that change what arrives at your house, roughly in the order they change what it costs.
- No obligation
- We sell no windows
- Sources named where a fact has one
Take the specification with you
Two quotes described in the same words can be two different products. Knowing which lines to ask for is what separates them.
How the project runs →
Six things that separate one replacement window from another
In roughly the order in which they move the number at the bottom of a quote.
Frame material
It sets the maintenance you take on, how slim the frame can be for a given opening, and how the frame itself handles heat. It is also the first thing you will be told, and the least specific.
Glazing package
How many panes, which coating sits on which surface, what fills the cavity and what the spacer at the edge is made of. Two windows with identical frames can behave very differently here.
Certified performance numbers
Ratings are certified for a product with a glass package, not for a brand. A figure quoted for the range rather than for your configuration is not an answer to the question.
Hardware and operation
Balances, locks, hinges and rollers are the parts that get touched every day and the parts that most often fail in use. Ask what they are and whether they can be replaced on their own.
How it is sized
A unit made to fit inside the frame you already have is a different product from one made for the rough opening behind it, even from the same line.
Warranty terms
What is covered, by whom, for how long, whether it moves with the house, and what voids it. Four of those five are usually left to you to ask about.
One product line is usually sold with more than one glass package, more than one frame reinforcement and more than one hardware set, and the certified numbers change with each combination. So the useful question is never which window is good. It is what, exactly, has been quoted for each of your openings.
How a specification is built
Four decisions, in the order they constrain each other. Taken out of order, an earlier one has to be made again.
Settle the opening
Insert into the frame you have, or full-frame back to the rough opening. Everything below is chosen inside that decision.
Choose how it opens
The operating type decides which sash moves, how much of the opening ventilates and what the window does to the room. It also constrains what sizes are available to you.
Fix the glass
Pane count, coating, cavity fill and edge spacer. This is the part of the specification a photograph cannot show and a lower price most often comes out of.
Pin the paperwork
Frame reinforcement, hardware, screens, the certified ratings for that configuration, and both warranties with their exclusions attached.
Frame materials, described by the certification program
Neutral descriptions rather than a sales case, taken from the ENERGY STAR product criteria.
Vinyl
ENERGY STAR describes vinyl frames as low maintenance with good thermal insulation. Sections may be hollow or filled with foam insulation, and wide vinyl sills may be reinforced with metal or wood.
Fiberglass
ENERGY STAR describes fiberglass frames as strong, durable, low maintenance and good insulators, and notes that they can be either hollow or filled with foam insulation.
Aluminum
ENERGY STAR describes aluminum frames as durable, low maintenance and recyclable, and notes that the frame design typically includes thermal breaks to reduce conductive heat loss through the metal.
Wood
ENERGY STAR describes wood frames as strong and good insulators, generally favored in historical neighborhoods, and notes that the exterior surfaces of many wood windows are clad with aluminum or vinyl to reduce maintenance.
Composite
ENERGY STAR describes composite frames as made of various materials blended together in manufacturing, producing frames it characterizes as durable, low maintenance and well insulated.
Combination
ENERGY STAR describes combination frames as using different materials separately through the frame and the sash — for example a vinyl exterior with a wood interior — to suit each face to its job.
One fact does more than any of those descriptions to keep a material argument in proportion: ENERGY STAR certifies windows across all of those framing types and requires no specific technology to do it. A frame material is a set of trade-offs about maintenance, strength, sightline and cost — not a shortcut to performance. Where each one is genuinely strong and genuinely weak is on vinyl, fiberglass and wood.
Frame descriptions and the no-required-technology statement read on 22 August 2026 from the ENERGY STAR key product criteria for residential windows, doors and skylights. The wording above is a summary of that page, not a claim of our own, and we have tested nothing.
What a catalog shows, and what a quote has to state
Eight lines. A quote that carries them can be priced by a second company without asking you anything.
| Line | What the catalog shows | What your quote has to state |
|---|---|---|
| The unit | A product name, a photograph and a price. | The product line and model quoted for each opening, not a brand and not a category. |
| The glass | A phrase such as energy-efficient glass, with no components named. | Panes, coating and which surface it sits on, cavity fill, and the spacer at the edge. |
| The ratings | A figure attached to the product line, or to the strongest configuration the manufacturer sells. | The certified U-factor and solar heat gain coefficient for that unit with that glass. |
| The scope | Nothing. A catalog sells a unit, not an installation. | Insert or full-frame, stated per opening rather than once for the whole house. |
| The frame | The material, in one word. | Frame material and, where it applies, what the frame or the sill is reinforced with. |
| The fittings | A hardware finish, usually chosen from a small set of photographs. | Hardware, finish and screens, and whether screens are in the price or an addition. |
| The old units | Not addressed at all. | Who removes the old units from the opening, and who disposes of them. |
| The warranties | A headline length, usually the longest one available on any component. | Both warranties in writing, with their lengths, their exclusions and their transfer terms. |
A company that configures windows for a living can produce all eight. Ask for them in writing: the quote is the only artifact that survives the conversation.
What the label on the glass actually reports
Five measures, certified per product, and one sequence worth knowing.
The National Fenestration Rating Council certifies five energy performance measures for residential fenestration: U-factor, solar heat gain coefficient, visible transmittance, air leakage and condensation index. Certified products are listed in the NFRC Certified Product Directory and carry the label showing those ratings. The sequence matters too — NFRC states that a product must be NFRC-certified before it can be enrolled for ENERGY STAR certification, and that NFRC is the official certification body for ENERGY STAR windows through its FenStar program. A performance claim with no certified numbers behind it has skipped the only step that would have made it checkable.
What the measures mean, and which thresholds apply where you live, is on energy-efficient windows; how a sealed glass unit is built and what happens when one fails is on double-pane replacement; and how each operating type behaves is on window types.
The five certified measures, the certified product directory and the NFRC-before-ENERGY STAR sequence were read on 22 August 2026 from the NFRC residential certification page.
When one quote comes in far below another
A price gap is information about scope before it is information about value. These are the four places it usually lives.
Where a lower number usually comes from
- It is an insert where the other quote is full-frame, which is a different amount of construction.
- The glazing package is thinner — fewer panes, a different coating, or a different spacer at the edge.
- Removal, disposal, trim, screens or making good have been left out of the number.
- The certified ratings quoted belong to the product line rather than to the unit being sold to you.
Where a higher number usually goes
- The frames are coming out, so the sill and the framing behind the trim are exposed and made good.
- The glass is specified for the climate the house is in rather than for the catalog photograph.
- The frame is reinforced where the size of the opening asks for it.
- The scope includes the parts of the job that are invisible once the trim goes back on.
Reconcile all of those before you treat a gap as a discount. When the specifications match and a difference remains, that difference is real. Market figures, quoted from named publishers with the dates they were read, are on the cost guide, and the permit question inside a scope is decided locally and covered on window installation.
Questions to ask a contractor about the product
Six questions about the unit being sold to you rather than about the company selling it.
- Which model and glass package is quoted for each opening, by name and in writing?
- Which certified ratings belong to that exact combination rather than to the product line?
- What is the frame reinforced with, and at which openings?
- Which hardware components can be replaced without replacing the whole sash?
- Are the screens in this price, and are they in this price for every opening?
- Who issues each of the two warranties, and what does each one exclude?
Browse by state
All locations →Which companies quote your house depends on your ZIP code, not on the state it sits in.
Common questions
Specify first, then compare
A quote that names the unit, the glass and the scope can be checked. One that names a brand cannot.