Reference

European Window Glossary

Every term you are likely to see on a European window quote, spec sheet, or submittal package - defined in plain English, with a link to the full guide where one exists. Start with a term below, or jump straight to a category.

Price a Window Schedule

Performance and energy

The numbers on a spec sheet that tell you how a window performs against heat, sound, and water - the same figures a plan reviewer or energy code checks first.

U-factor: U-factor is the rate at which a whole window lets heat through, measured in Btu/(h.ft2.F) - lower is better. It is the number US energy code actually regulates, and the one every European system provider publishes for the whole assembly, not just the glass. U-factor by climate zone. Full definition.
Uw / Ug / Uf: Uw, Ug and Uf are the European U-values for the whole window, the glass alone and the frame alone, in W/(m2.K). US code only asks for the whole-window value, so I always convert and quote Uw, never Ug, to avoid an inflated-sounding number that does not match what the plan reviewer expects. Multiply Uw by 0.17611 for the US U-factor. Canadian code reads the whole-window Uw in W/(m2.K) directly. Metric U-value to U-factor converter.
SHGC (Solar Heat Gain Coefficient): SHGC (Solar Heat Gain Coefficient) is the fraction of solar heat that passes through a window, from 0 to 1. Low SHGC glass keeps a sun-facing room cooler in summer; a good glazing package balances SHGC against U-factor and visible light rather than chasing one number. Full definition.
VT (Visible Transmittance): VT (Visible Transmittance) is the share of visible light that passes through the glass, from 0 to 1. Coatings that cut SHGC hardest also tend to cut VT, so a low-SHGC, high-VT glass package costs more and is worth specifying on a north-facing wall of glass where daylight matters.
R-value: R-value is a material's resistance to heat flow and the inverse of U-factor (R = 1/U) - higher is better. It is used in wall and insulation callouts more than window schedules. If a spec calls for R-value instead of U-factor, converting it correctly matters - see the calculator. U-factor to R-value calculator.
Air infiltration rate: Air infiltration rate is how much outside air leaks through a closed window, measured per square foot of window at a test pressure. Tilt and turn hardware's multi-point perimeter lock is why European windows post lower infiltration numbers than a single-latch North American casement.
Water penetration resistance: Water penetration resistance is the wind-driven rain pressure a window is tested to withstand without leaking, expressed in psf. Coastal and high-wind projects specify this directly - it drives which hardware and glazing depth a system provider can offer.
DP rating (Design Pressure): A DP rating (Design Pressure) is the NAFS structural rating for the wind and structural load a window assembly is rated to carry, expressed as a number like DP50. Higher DP means a stronger frame and heavier hardware, which is why a large lift-and-slide opening needs its own rating for its size. Full definition.
CRF (Condensation Resistance Factor): CRF (Condensation Resistance Factor) is a 0-100 score for how well a window resists interior condensation in cold, humid conditions - higher is better. Thermally broken aluminum and multi-chamber uPVC frames score well because the frame itself stays warmer on the interior face.
Acoustic rating (Rw / STC): An acoustic rating is the number of decibels a window cuts from outside noise: Rw is the European lab rating, STC the North American one. They are similar in scale but tested over different frequency ranges, so compare Rw with Rw and STC with STC. Laminated glass and a deeper air gap raise both; it is a glazing choice more than a frame choice.
Psi-install: Psi-install is the extra heat loss at the perimeter where a window meets the wall - a thermal-bridging number used in Passive House and deep-energy-retrofit modeling. It depends more on the installation detail (buck, insulation, tape) than on the window itself.

Window types and operation

How a sash opens - the single biggest thing that separates a European window schedule from a North American one.

Tilt and turn: A tilt and turn window is an inward-opening window with one handle and two modes: turn it 90 degrees and the sash swings inward like a door; turn it 180 and the top tilts inward for ventilation. Tilt-before-turn hardware changes this sequence; ordinary tilt is not a rain, child-safety or intrusion-protection feature. It is the default European window - see the full guide for how it compares to casement and double-hung. European tilt and turn windows.
Tilt-in / tilting window: A tilt-in or tilting window is what most North American drawings call a tilt and turn window - the same inward-opening sash with a tilt position for ventilation and a turn position that opens it like a door, just a different name for the same mechanism.
Casement (European / outswing): A European casement window is a side-hinged sash that opens outward, closer to a North American casement than tilt and turn is, with the screen staying on the interior. Specify it when the design wants an outswing sash but the frame and glazing of a European system. European casement windows.
Hidden sash: A hidden sash window is an operable window whose sash sits behind the outer frame, so from outside it looks identical to a fixed pane next to it. It comes in aluminum and in aluminum-clad wood (Clad Hidden Sash), on tilt and turn or side-hung leaves. Hidden sash windows.
Lift-and-slide door: A lift-and-slide door is a large sliding door whose handle lifts the heavy sash off its seals before it rolls, so one person can move a panel that can weigh several hundred pounds. It is the go-to for wide openings where a swing door will not fit. Lift-and-slide vs multi-slide doors.
Multi-slide door: A multi-slide door is a set of sliding panels that stack to one side or pocket into a wall, opening a wall-width span. Compared against lift-and-slide in the linked guide - the choice is mostly about how much of the wall needs to disappear. Lift-and-slide vs multi-slide doors.
Bifold door: A bifold door is a row of panels hinged together that fold and stack to one side, with a footprint similar to a multi-slide but a different hardware and price point. Bifold door cost.
Pocket door: A pocket door is a sliding or lift-and-slide door whose panels disappear fully into a wall cavity, leaving no visible frame at the open opening. It requires a wider rough opening and more structural coordination than a standard slider.
Pivot door: A pivot door is an entry door that swings on a pivot point set in from the edge rather than on side hinges, so it can carry a much larger, heavier slab than a hinged door of the same size. Pivot doors on luxury US projects.
Egress window: An egress window is a window that meets a building code's minimum clear opening, sill height, and operability for emergency escape from a bedroom. Tilt and turn's turn mode gives a full clear opening that qualifies in most jurisdictions. Tilt and turn windows and US egress code.
Fixed light: A fixed light is a pane of glass in a frame that does not open at all - used to fill a wall of glass around operable units without paying for hardware on every panel.

Materials and profiles

What the frame is made of, and the engineering inside it.

uPVC: uPVC (unplasticized PVC) is a rigid, multi-chamber plastic window profile, steel-reinforced where a sash gets large. It is the best price-to-performance material I ship - not the same product as a North American vinyl window, which uses a simpler, thinner extrusion. Aluminum vs uPVC guide. Full definition.
Multi-chamber profile: A multi-chamber profile is a uPVC frame extruded with several internal air chambers instead of one hollow cavity. More chambers trap more still air, which is most of why a European uPVC frame outperforms a simpler single- or double-chamber profile on U-factor.
Steel reinforcement: Steel reinforcement is a galvanized steel insert run through a uPVC profile's largest chamber so a big sash does not sag or bow. It is standard on tall or wide tilt and turn sashes; the schedule tells the fabricator where it is needed.
Thermally broken aluminum: Thermally broken aluminum is an aluminum frame split into an interior and exterior half joined by an insulating barrier, so the metal cannot conduct heat straight through. Without a thermal break, aluminum is a poor insulator - with one, it competes with uPVC on performance while carrying larger spans. Thermally broken aluminum windows explained. Full definition.
Real steel: Real steel means the window or door frame is made of steel profiles, not aluminum shaped to look like steel. I quote it from drawings. Steel-look aluminum is a separate product and keeps its own name. Real steel windows and doors. Full definition.
Thermally broken steel: Thermally broken steel is a steel frame split into an inside and an outside half joined by insulating bars, so heat cannot conduct straight through the metal. It is the same idea as a thermal break on aluminum, applied to steel. Real steel windows and doors. Full definition.
Janisol: Janisol is the name of the steel profile system line from Jansen, a Swiss system provider, covering thermally broken doors, windows and lift-and-slide doors. Jansen is the system provider whose profiles I specify. Steel systems. Full definition.
Sightline: A sightline is the visible width of a frame, sash or mullion seen from the room, measured across the face. Narrow sightlines let in more glass and light. Steel-look aluminum and real steel are both chosen for slim sightlines, and the exact figure depends on the system and the position in the window.
Polyamide strip: A polyamide strip is a reinforced nylon bar mechanically crimped between the interior and exterior aluminum profiles - one of the two real ways to build a thermal break. It is common on European systems: strong, precise, and reversible in a repair. Thermally broken aluminum windows explained.
Pour-and-debridge: Pour-and-debridge is the other real thermal-break method: a liquid polyurethane resin poured into the profile, cured, then the connecting aluminum web milled away to leave only the insulating resin joining the two halves. It is not obsolete - both methods are current and each system provider has a reason for its choice. Thermally broken aluminum windows explained.
Wood (timber) window: A wood window is a window whose frame and sash are laminated timber, finished with a stain or opaque color. European wood windows are built from layered scantlings to control movement; my timber lines are Timber Classic and Timber Estate, quoted from drawings. European wood windows.
Aluclad: Aluclad (aluminum-clad wood) is a timber window with an extruded aluminum shell clipped to the exterior over a ventilated gap - warm wood inside, a low-maintenance metal face to the weather outside. My clad lines are Clad Flush, Clad Hidden Sash and Clad Passive, quoted from drawings rather than the estimator. Aluminum-clad wood windows.
Wood-alu: Wood-alu is another name for aluclad - a wood window frame with an aluminum exterior cladding. Aluclad vs aluminum vs wood.

Glass and glazing

What is actually in the sash - the part that does most of the performance work.

IGU (Insulated Glazing Unit): An IGU (Insulated Glazing Unit) is the full sealed glass assembly - two or three panes separated by spacers and gas fill, sealed at the edge. "Double glazing" and "triple glazing" both describe an IGU with two or three panes.
Low-E coating: A Low-E coating is a microscopically thin metallic layer on one glass surface that reflects heat back to its source while staying visually clear - it is why modern IGUs perform so much better than plain glass without looking any different. Full definition.
Argon fill: Argon fill is argon gas sealed into the gap between panes instead of plain air. It conducts heat more slowly than air, which is a large part of how an IGU hits its rated U-factor, and it is standard on most European double and triple units. Full definition.
Krypton fill: Krypton fill is a denser insulating gas than argon, used when the gap between panes is too narrow for argon to perform well - typically triple glazing in a slim aluminum sightline. It costs more than argon and is used only where the geometry needs it.
Warm-edge spacer: A warm-edge spacer is the strip separating the panes at the edge of an IGU, made from a low-conductivity material (foam, composite, or thin stainless steel) instead of solid aluminum. It cuts the cold line and condensation risk right at the edge of the glass. Full definition.
Laminated glass: Laminated glass is two panes bonded to an interior plastic interlayer so the assembly holds together when broken - used for security, impact resistance, and acoustic performance rather than thermal performance.
Tempered glass: Tempered glass is glass heat-treated to break into small, blunt pieces instead of sharp shards. It is code-required near doors, low sills, and wet areas - a safety-glazing requirement, not an optional upgrade.
Triple glazing: Triple glazing is a three-pane IGU instead of two. It meaningfully lowers U-factor for a real cost premium - worth it in cold climates and Passive House projects, often unnecessary in mild ones. Triple vs double glazing. Full definition.

Hardware

The mechanism inside the frame that most North American buyers have never seen up close.

Concealed hinges: Concealed hinges are hinges built into the frame and sash rebate rather than visible on the face of the window - the detail that gives European windows their clean, uninterrupted sightlines. Concealed window hardware.
Multipoint lock: A multipoint lock is an espagnolette mechanism that drives locking points around the full perimeter of the sash from a single handle - 4 to 8 points on a typical tilt and turn window, versus one or two latch points on a standard North American casement or double-hung. Full definition.
Tilt-first restrictor: A tilt-first restrictor is a hardware setting that forces the handle into tilt mode before it can reach full turn, so a window cannot be swung open by accident - common on upper floors and near stairwells for child safety.
Handle types: European window handle types differ in function as well as finish: standard turn handles, lockable handles (key-operated, for ground floor security), and tilt-first restrictor handles.
RC2 (hardware security class): RC2 is a European burglary-resistance class for windows and doors, the common baseline for ground-floor openings, achieved with reinforced strike points and mushroom-head cams that resist prying.

Installation

How the window meets the wall - the part that determines whether it performs as tested.

Rough opening: A rough opening is the framed hole a window installs into, sized larger than the window unit to allow shimming and flashing. European window sizes are set in millimeters, so the rough opening has to be planned against the metric-to-imperial conversion, not assumed. European window rough opening sizes. Full definition.
Nailing fin / flange: A nailing fin (nail flange) is a flange around the perimeter of the frame that nails or screws directly to the wall sheathing, matching standard North American new-construction installation. It is an option on selected European systems, not the default - the default is bracket-mounted. European windows with a nailing fin. Full definition.
Bracket mount: A bracket mount is an installation using adjustable metal brackets fixed through the frame into the rough opening, rather than a nailing fin. It is the standard European installation method - it allows precise shimming and works in retrofit openings a nailing fin cannot reach. Installing bracket-mounted aluminum windows.
Installation clip: An installation clip is a smaller fixing clip used in some retrofit and light-commercial installs in place of full brackets - lower cost, less adjustment range.
Sill pan: A sill pan is a pre-formed or site-built pan under the sill that catches any water that gets past the window and directs it back outside, rather than into the wall assembly. It is good practice on any window and mandatory on most inspected jobs.
Frame depth: Frame depth is how deep the window frame is, front to back. Deeper profiles generally mean better thermal and structural performance, and it is a number worth checking against your wall assembly and interior trim detail before ordering.
mm-to-inch conversion: The mm-to-inch conversion is the step that turns a European schedule, engineered and manufactured in millimeters, into inches for the North American drawing set. Every schedule I quote gets converted, but the manufacturing tolerance and the rough opening math both trace back to the metric dimension.

Codes and certification

What a plan reviewer, inspector, or energy code actually asks to see.

NFRC: NFRC (National Fenestration Rating Council) is the US body that certifies and labels U-factor, SHGC, and VT for windows sold in the US. Not every European system carries an NFRC label - NFRC-rated units are available on selected systems, and I flag which projects need one and which can proceed without. For Canadian projects, the accepted test standards and documentation are confirmed with the designer and building official for the actual assembly and compliance path. NFRC and NAFS certified European windows.
NAFS: NAFS (North American Fenestration Standard) is the structural and performance test standard (air, water, structural load) that produces a window's Performance Grade and Design Pressure rating. NFRC and NAFS certified European windows.
NBC climate zones (Canada): NBC climate zones are the climate zones the National Building Code of Canada uses to set energy requirements, based on heating degree-days - from zone 4 on the mildest coast to zone 8 in the far north. A climate zone alone does not establish the required window value. Provinces and territories adopt codes with their own editions and amendments; the designer and building official confirm the applicable compliance path and documentation. Metric U-value to U-factor converter.
CSA A440 / NAFS Canadian supplement: CSA A440 is the Canadian family of window standards: CSA A440S1 is the Canadian supplement to NAFS, adding air, water and wind-load requirements for Canadian climates, and CSA A440.2 covers energy performance - U-value and Energy Rating. It is listed here as reference information; the documentation a Canadian project needs is confirmed per project with your building official.
Energy Rating (ER): Energy Rating (ER) is a Canadian single-number score for a window's net energy performance in a heating climate, combining heat loss, solar heat gain and air leakage - higher is better. Canadian code and ENERGY STAR Canada read either a U-value in W/(m2.K) or an ER, depending on the path and the product; which one your project uses is confirmed with your building official.
IECC climate zones: IECC climate zones are the International Energy Conservation Code's eight US climate zones, each with its own maximum allowed U-factor and, in hot zones, SHGC for windows. They are the single biggest driver of which glazing package a project needs. European windows by climate zone.
Title 24: Title 24 is California's own energy code, stricter and structured differently than the base IECC - it sets its own U-factor and SHGC targets by climate zone and requires its own compliance documentation.
HVHZ (High Velocity Hurricane Zone): HVHZ (High Velocity Hurricane Zone) is the Florida building code zone, most of Miami-Dade and Broward counties, that requires windows tested and approved to a higher wind and impact standard than the rest of the state or country.
PHI / Phius: PHI (Passive House Institute) and Phius (formerly Passive House Institute US) are the two certifying bodies behind Passive House performance targets. A window can meet Passive House performance numbers without being individually PHI-certified; certification is a separate, optional step. Passive House windows.
CE marking: CE marking is the European Union's mandatory conformity marking, confirming a window meets EU manufacturing standards. It says nothing about US code compliance on its own - NFRC/NAFS testing is the separate step that matters for a US permit.
Egress code: Egress code is the building code section (IRC R310 and local amendments) setting minimum clear opening width, height, area, and sill height for bedroom windows used as a fire escape. Tilt and turn windows and US egress code.

Importing

How a window gets from a European factory to a job site in the US or Canada, and what the paperwork means.

DDP (Delivered Duty Paid): DDP (Delivered Duty Paid) is an Incoterm meaning the seller's price already includes freight, insurance, customs clearance, and duty all the way to the job site. Every US estimate I send is DDP - the number you see is the number you pay, with no surprise at the port. Canadian orders ship DAP instead (see below). Importing European windows on DDP terms.
DAP (Delivered at Place): DAP (Delivered at Place) is an Incoterm meaning the seller delivers the goods to a named place - for my Canadian orders, your job site - with freight and transport covered, while import clearance and taxes stay with the buyer as importer of record. On a Canadian DAP order I prepare the CETA origin documents and coordinate the broker, while import clearance, applicable taxes, brokerage and unloading remain buyer responsibilities unless the written quote says otherwise. Tax credits depend on registration, eligible commercial use and records. European windows for Canada.
Importer of record: The importer of record is the party legally responsible for an import - it declares the goods to customs, pays any duty and taxes, and keeps the records. On US orders shipped DDP, clearance and duty are handled on my side; on Canadian orders shipped DAP, the Canadian buyer is the importer of record; an authorized broker acts on the buyer's behalf, and I prepare the origin documents and coordinate the broker.
CETA: CETA (Comprehensive Economic and Trade Agreement) is the trade agreement between the EU and Canada that provides preferential treatment for qualifying originating goods with the required origin documentation. Shipping from Europe alone does not establish eligibility. For aluminum, wood, aluminum-clad wood and uPVC windows and doors made in the EU, I prepare that origin declaration with every Canadian order. European windows for Canada.
CBSA: CBSA (Canada Border Services Agency) is the federal agency that clears imported goods into Canada and collects duty and GST at the border. On a Canadian window order, the importer of record - or the customs broker acting for them - files the entry with CBSA; I coordinate the broker and supply the commercial and origin documents.
GST at import: GST at import is the 5% federal Goods and Services Tax that CBSA collects when goods enter Canada. The importer of record pays it at clearance, and input tax credits depend on GST/HST registration, eligible commercial use and supporting records, so I show it as a separate information line rather than inside the landed price.
Incoterms: Incoterms are the standard international trade terms (DDP, FOB, EXW, and others) that define exactly where the seller's responsibility for freight, insurance, and customs ends and the buyer's begins.
HS code: An HS code (Harmonized System code) classifies a product for customs and determines which duty rate applies. Window assemblies and glass are classified separately, which is part of why duty math is not a single flat percentage.
Duty: Duty is the customs tax applied to imported goods at clearance, calculated against the HS code and the country of origin. The rate depends on frame material and classification - every DDP price already has it built in, so there is nothing extra to plan for on your side.
Container: A container is the 20 ft or 40 ft ocean shipping box a window order travels in, shared or dedicated - the unit that shipping and freight costs are calculated against.
Lead time: Lead time here runs from approved shop drawings to delivery, including production, freight and clearance. Standard uPVC and aluminum planning is 9-16 weeks, confirmed per order. Pre-approval decisions are outside that clock; wood, aluminum-clad wood and unusual configurations need a separate schedule. European window lead times.
Proforma (invoice): A proforma invoice is the formal pre-order document that fixes pricing, quantities, and terms before production starts - the step between an accepted estimate and a confirmed order.
RFQ (Request for Quote): An RFQ (Request for Quote) is a formal request sent with a window schedule and drawings asking for firm pricing - the standard way to move a project from budget estimate to an order-ready number.
Submittal package: A submittal package is the compiled set of drawings, performance data, and certifications a contractor submits to an architect or building department for approval before fabrication - I assemble this for every order that needs one.

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