What triple glazing does — roughly half the heat loss of a double, a warm inside surface, no January condensation — and what it does not do, what it weighs, which frames take it, and when a good double is the smarter buy.
Short version. A triple-pane window has three lites of glass and two sealed air spaces instead of one. It roughly halves the heat loss through the glass compared with a good double-pane unit, keeps the inside surface warmer so it does not sweat in January, and quietly raises the whole comfort of a room next to a big window. It costs more, weighs half again as much, and needs a frame deep enough to hold it — which is why it is a European-system product first. It does not, on its own, make a room quieter. Here is when it is worth it in New York and when a good double is the smarter buy.
Three lites of glass on two spacers, sealed into one insulated unit usually 1-1/4 to 1-3/4 inches thick, with low-E coatings on two of the inner surfaces and argon (sometimes krypton) in both spaces. Each extra sealed cavity is another barrier to heat, and the second low-E coating reflects room heat back a second time. The result is a centre-of-glass U-value around 0.15–0.18 against 0.24–0.26 for a double unit with one low-E and argon — a 30–40% cut in heat loss through the glass, and with a good frame a whole-window figure in the low 0.20s. Our triple IGU page covers the unit itself; this page is about the window.
| Double-pane (low-E, argon) | Triple-pane (two low-E, argon) | |
|---|---|---|
| Centre-of-glass U-value | 0.24–0.26 | 0.15–0.18 |
| Whole-window U-value, good frame | About 0.28–0.30 | About 0.20–0.24 |
| Unit thickness | 1″ (1/4 + 1/2 + 1/4) | 1-1/2″ to 1-3/4″ |
| Glass weight, 1/4″ lites | 6.5 lb per sq ft | 9.75 lb per sq ft |
| Inside glass surface on a 20°F night | Cool; condensation possible at the edges in a humid apartment | Noticeably warmer; condensation rare |
| Solar heat gain | Higher | Lower — good on a south or west facade, less free heat on a north one |
| Noise | Baseline | Little better; a laminated lite does far more (see below) |
| Cost of the glass unit | Baseline | Roughly 20–35% more for the unit; more if the frame has to change |
| NYC energy code | Meets it | Exceeds it; required only for Passive House-type targets |
Big glass in a cold room. A floor-to-ceiling window wall, a terrace door wall, a north-facing bedroom — anywhere the glass is a large share of the wall, triple takes the cold spot out of the room and lets the radiator or heat pump downstream be smaller.
Passive House and low-energy houses. Certified projects and most new custom houses that chase a tight envelope specify triple as a matter of course; the systems built for it — Reynaers MasterLine 10, Cortizo COR 80, Alutech and Aluplast uPVC at their deeper depths — take 1-3/4″ units in a frame designed for them.
Buildings with a Local Law 97 number to hit. Where a co-op is replacing every window anyway and the 2030 limit is the driver, the extra cost of triple is small against the penalty and it buys the largest reduction the glass can give. See Local Law 97 and your windows.
Condensation complaints. Humid apartments with radiators under the window sweat on double glazing in January; a triple with a warm-edge spacer usually stops it.
Most Brooklyn and Queens houses replacing 1980s aluminium or original wood windows get 80–90% of the thermal benefit from a well-installed double with low-E and argon, because the old window was the problem and the frame and the seal are where the money goes first. Where the existing frames are being kept and only the glass is changing, a triple usually will not fit the pocket at all. Where the frame is a slim steel-look system for a landmark facade, the depth is not there for a triple either, and the answer is the best double the system takes. And where the complaint is noise, triple is the wrong purchase: three equal lites resonate together, and a double with one laminated lite is quieter, lighter and cheaper — the soundproof windows page explains why. Our laminated vs triple comparison has the numbers.
A triple is half again as heavy as a double of the same size — 9.75 lb per square foot against 6.5 with 1/4″ lites, so a 4 × 8 ft tilt-and-turn sash carries 312 lb of glass before the frame. That decides three things: the frame depth (70 mm and up on European systems, which is why most American residential aluminium and vinyl lines stop at a 1″ unit), the hardware (heavy-duty hinge sets rated 170–200 kg on the big sashes, or a fixed lite where an operable would be too heavy), and the handling on site. The glass weight calculator gives the figure for any size and make-up.
European aluminium: Reynaers MasterLine 8 HI+ and MasterLine 10, Cortizo COR 70 Industrial and COR 80, Alutech; European uPVC: Aluplast at its deeper profile depths; and selected wood-clad lines from Marvin and Pella that offer triple in specific series. We fabricate the aluminium systems ourselves, order the rest to survey, and glaze with two low-E coatings, argon and a warm-edge spacer as the standard triple make-up. Where a project wants triple plus noise control, the unit is built with one laminated lite; where it wants triple in a narrow frame, krypton in thinner spaces is the fallback.
The glass unit costs roughly 20–35% more than the equivalent double; the frame and installation cost the same unless the system has to change to a deeper one to hold it. On a whole-house or whole-building replacement that is typically a 10–15% premium on the window package. We quote both in the proposal so the comparison is on the table, with the U-values and weights next to the prices. Window replacement in Brooklyn describes how the job runs.
Yes where the glass is large, the room is cold, the house is chasing a low-energy target, or a co-op is replacing every window under Local Law 97. For a typical house replacing old windows, a good low-E double gives most of the benefit at lower cost and weight.
Centre-of-glass U-value about 0.15–0.18 versus 0.24–0.26: roughly 30–40% less heat loss through the glass, and a warmer inside surface that resists condensation. Whole-window figures depend on the frame.
Only a little. Three equal lites can resonate together; a double with one laminated lite is quieter. For noise, see our soundproof windows page.
The glass unit is roughly 20–35% more than a double; on a whole-house package it is typically a 10–15% premium, more if the frame system has to change to a deeper one.
Usually not: a triple unit is 1-1/2 to 1-3/4 inches thick and most existing frames hold a 1-inch unit. It is a full-window replacement in a system built for the depth.
Deeper European systems: Reynaers MasterLine 8 HI+ and MasterLine 10, Cortizo COR 70/80, Alutech, Aluplast uPVC, plus selected Marvin and Pella series.
No; a low-E double meets the code. Triple is a choice for comfort, large glass, Passive House targets and Local Law 97 reductions.
Triple Insulated Glass Units Insulated Glass Units Low-E Glass Soundproof Windows Laminated vs Triple for Soundproofing Local Law 97 and Your Windows Glass Weight Calculator Reynaers Systems Compared
About this page. Written by Alex GC Inc. d/b/a Alex Glass Construction and reviewed before publication by Aleksandr Chernovolenko, Managing Partner, with our design and estimating lead and a field foreman. Our foremen hold the NYC DOB Site Safety Training supervisor card and our crews the 40-hour worker card; we are certified to fabricate, install and service Alutech and Everest aluminum systems. Facts are drawn from our own projects, manufacturer test data and the applicable codes; where we are giving an opinion, we say so. Last reviewed September 2026. Credentials
Send the window sizes and which way the rooms face. We will quote double and triple side by side, with the U-values and weights next to the prices.
