1

1-D adjustable

Any window covering that can adjust in one way, such as up-down, open closed.

Go to top

2

2-D adjustable

Any window covering that can be adjusted in two ways, either top-down & bottom-up for a shade or up-down/open-closed for a louvered blind.

Go to top

A

absorptance

The portion of radiant energy that is absorbed by a material (radiant energy can be absorbed, transmitted, or reflected).

adjustable slats

Refers to any louvered or slatted window covering in which the slats or louvers can be adjuisted or angled to allow different levels of  indirect lighting, privacy, and weather protection. The couterpart to fixed slats.

Synonyms: adjustable slat

air infiltration

Air leaking into a building (can account for 25 – 40% of total cooling/heating energy in a home).

air tightness

How well a window covering resists air infiltration with lower infiltration representing greater energy efficiency and comfort.

Synonyms: airtightness Airtightness

applied film

Most commonly, flexible plastic sheet applied directly and permanently to glass to improve the window’s optical and/or thermal performance. Often called applied film to distinguish it from seasonal film (which is applied to window trim, not the window glass). Many variations exist for additional desired performance including: glare reduction, privacy, security,and winter thermal performance.

Synonyms: surface film surface-applied film window film surface-applied window film applied films Surface film

apron

Interior window trim at bottom of the window, sometime also called a “skirt” (see Window Parts diagram in Overview).

articulate

Term referring to window coverings that have a pivoting action, such as a blind, and generally referring to louvered window coverings.

automated operation

Control and adjustment of window covering settings by sensors, timers, or programming. Motorization is a key element of automation but motorization alone requires active user involvment in setting the window covering.

Synonyms: automation

awning

An exterior shading window covering, either fixed or retractable.

Synonyms: awnings

Go to top

B

blind

Most commonly, louvered window covering with stacked vanes that can be both tilted and raised/lowered.

Synonyms: blinds

bottom rail

Horizontal part of the window sash at the sill (see Window Parts diagram in Overview).

bottom-up

Most often interior adjustable window coverings that operate or adjust by raising the covering from the bottom up.

Btu

Abbreviation for British Thermal Unit, about the heat content of a stick match.

Go to top

C

casement

Window type hinged on the side, most commonly swinging out.

Synonyms: casements

casing

window trim (covers space between framed opening and window unit).

Synonyms: casings

cellular shade

Most commonly, window covering made of pleated fabric that is “honeycombed” and can be raised and lowered. Their adjustability adds elements balancing view, privacy, glare control, and daylighting. Also called insulated cellular shade.

 

Synonyms: cellular shades insulated cellular shade insulated cellular shades

check rail

The sash frame parts of a hung window where the two sashes meet; also called the meeting rail (see Window Parts diagram in Overview).

clear rigid polymer

Transparent sheet material used most often in interior window panels in place of glass.

Synonyms: acrylic rigid plastic plastic

clerestory

Any windows high on a wall designed to daylight most or all of a room.

condensation resistance

How well a window, or combined window and covering, resists liquid water accumulating by condensation on the innermost surface of the prime window (as represented by an NFRC number resulting from a standardized test for this property).

conduction

Heat moving through solids, always from warmer to colder materials (the three ways that heat moves are conduction, convection, and radiation).

convection

Heat moving in fluids (liquids and gases); hot air rises/cold air falls and energy can be lost or gained through convective loops (the three ways that heat moves are conduction, convection, and radiation).

curtain

Interior fabric window covering hanging from a rod, often paired in a window and hanging in loose folds; similar to and often including drapes.

Go to top

D

dark color

Any color on the visible spectrum other than white or very dark shades of all colors that absorb most of the sun’s heat energy.

daylighting control

How well a window covering manages daylight while accomodating other functions, such as view, privacy, solar heat gain.

decorative

Opaque or translucent films that depict scenes or other images and obscure any direct view and provide privacy.

dewpoint

Temperature at which the moisture in air condenses into a liquid.

divided light

Window glass separated by small frames within the sash (see Window Parts diagram in Overview).

DIY installation

Degree of skill, length of time, and tools required to install a window covering yourself.

double pane

Window unit with two panes of glass sealed into a glazing unit; gas between the panes is trapped (also called an insulated glazing unit – IGU).

Double Pane Clear

Double Pane Clear provides strong thermal performance: good resistance to heat loss, high solar heat gain, and high visual transmittance.

Double Pane with Low-e

Double Pane with Low-e glass provides high resistance to heat loss and can be tuned for solar gain but with some loss of visual transmittance.

double-hung window

Rectangular window with top and bottom sashes that slide up and down within the window frame.

double-tracked

For storm windows and window panels, three panels—two glass and one insect screen—with the top panel being fixed in place and the lower glass panel and insect screen operating in tracks in the frame.

drape

Interior fabric window covering most commonly hung from a rod; typically differs from a curtain by hanging well below the bottom of the window it covers.

Synonyms: drapes

Drapes and curtains

Drapes and curtains are primarily used as decorative elements. Their adjustability combines some level of solar and glare control with privacy. Insulating versions improve wintertime comfort.

Synonyms: Drape/Curtain

durability – service life

How long a window covering typically lasts, with a warranty serving as a proxy for this attribute.

Synonyms: Durability - Service Life Durability - service life Durability - Service life

Go to top

E

Efficient Windows Collaborative (EWC)

Sister organization providing fair, rational, and comprehensive information on window performance and window selection.

egress

Emergency exit.

electrochromic

Glass that changes from clear to darkened (and back) based on electrical current (versus thermochromic or photochromic).

emissivity

How readily the surface of a material gives off heat by radiation. Many common building materials have “high” emissivity (around 0.9 out of 1.0 being a perfect emitter), while materials or objects with metallic coatings or surfaces have “low” emissivity (around 0.15 or less).

Ext. louvered shutter

Exterior louvered shutters protect existing windows from weather and improve security and privacy. Certain types also provide excellent solar heat gain control.

Synonyms: exterior louvered shutter Exterior louvered shutter Exterior louvered shutters Ext. louvered shutters

Ext. roller shade

Exterior roller shades cover and protect existing windows from weather and provide solar heat gain control. Their adjustability adds elements of view, privacy, and glare control but can reduce existing window protection.

Synonyms: Exterior roller shade Exterior roller shades Ext. roller shades

Ext. solar screen

Exterior solar screens provide good solar heat gain control while reasonably maintaining view.

Synonyms: Exterior solar screen Exterior solar screens Ext. solar screens

Exterior storm

Exterior window panel (tracked/operable or fixed/inoperable) covering and protecting existing windows from weather, improving energy performance (including air-tightness), while maintaining view. Low-e coatings in cold climates and low solar gain coatings in hot climates increase their energy performance.

Synonyms: Exterior storms storm window storm windows

Go to top

F

face mount

Any window covering installed on to the face of window trim (versus inset mount).

fenestration

Windows and doors or their placement in buildings.

fixed

Window, any glass panel, or awning that is not operable (can’t be opened).

Fixed awning

Fixed awnings provide good solar heat gain and glare control while reasonably maintaining view.

Synonyms: Fixed awnings

fixed slats

Refers to any louvered or slatted window covering in which the slats or louvers are set at a fixed angle, generally an angle that allows indirect lighting and some privacy, but no adjustment. The couterpart to adjustable slats.

Synonyms: fixed slat

Go to top

G

gas fill

Argon, xenon, or krypton gas sealed between the panes of insulated glazing units (IGU). These gases are used because they exhibit less convective heat transfer than air.

glare control

How well a window covering shields from direct, bright, harsh light—light that obscures occupant view of items such as TV and monitor screens.

grilles

Surface-mounted plastic cosmetic grids simulating the muntins in true divided lite windows.

Go to top

H

high solar gain low-e

There are generally two types of low-e coatings that improve energy performance, with the high solar gain (HSG) coatings designed for colder climates. Although currrently these coatings are applied mainly to glass, they can be applied to clear plastic polymer panels as well.

Synonyms: high solar gain low-e polymer

horizontal slats

Refers to any louvered or slatted window covering with vanes or slats parallel to the floor, or horizontally-oriented, operating up and down.

HSG

High Solar Gain

hung window

Any window with sash(es) that move up and down and that resist gravity/make adjustment easier by being “balanced” or “hung” using counterweights or springs.

Go to top

I

infrared (IR)

Invisible heat wave energy (far red) often used as shorthand for an infrared camera, which produces images that represent surface patterns of temperatures of objects.

inset mount

Any window covering installed between the jambs of the prime window (versus face mount).

Installation

Getting the window covering or attachment in place. Installation can be either do-it-yourself or professionally done, with some coverings and attachments better suited to one or the other.

insulated glass unit (IGU)

Window unit with two panes of glass sealed into a glazing unit; gas between the panes is trapped (also called double-glazing).

insulating

Referring to window coverings specifically designed to reduce heat loss and gain (generally with insulating materials and greater air tightness).

insulation

How well a window covering resists heat loss/gain, usually measured with R-value.

Int. louvered shutter

Interior louvered shutters provide solar heat gain control. Their adjustability adds elements of view, privacy, glare control, and daylighting.

Synonyms: Interior louvered shutter Interior louvered shutters Int. louvered shutters

Int. roller shade

Interior roller shades provide solar heat gain control. Their adjustability adds elements of view, privacy, and glare control. Shades are available in a wide range of fabric, affecting many aspects of roller shade performance.

Synonyms: Interior roller shade Interior roller shades Int. roller shades

Int. solar screen

Interior solar screens provide solar heat gain control while reasonably maintaining view. Roller versions add all the advantages of adjustability.

Synonyms: Interior solar screen Interior solar screens Int. solar screens

Interior panel

Interior Panels primarily reduce winter heat loss and improve air-tightness while maintaining view. Low-e coatings further improve their insulation properties.

Synonyms: Interior panels

Go to top

J

jamb

Parts of window frame facing into the window opening, at sides and top (see Window Parts diagram in Overview).

Go to top

L

light color

Any color on the visible spectrum other than black or very dark shades of all colors that reflects most of the sun’s heat energy.

Louvered blinds

Louvered blinds provide solar heat gain control. Their adjustability adds elements balancing view, privacy, glare control, and daylighting.

Synonyms: Louvered blind

louvered shutter

Exterior or interior hinged window covering most commonly with louvers fixed providing shade and privacy with some daylighting.

Synonyms: louvered shutters

low solar gain low-e

There are generally two types of low-e coatings that improve energy performance, with the low solar gain (LSG) coatings designed for warmer climates. Although currrently these coatings are applied mainly to glass, they can be applied to clear plastic polymer panels as well.

low-e

Nearly invisible metallic coating on inside surface of double-pane glass, storm windows, and interior window panels that improves the energy efficiency of the window and the thermal comfort of occupants.

Go to top

M

manual operation

Operation by hand (versus motorized operation).

meeting rail

The sash frame parts of a hung window where the two sashes meet; also called the check rail (see Window Parts diagram in Overview).

motorization

Mechanical adjustment of the covering. User does not have to adjust by hand but the setting is accomplished by user/occupant.

mullion

Most commonly, the location or structural/finish detail where two window separate window units are joined or “ganged.”

multi-cell

Cellular shades with more than one cell in cross section.

muntin

The window part that divides panes or lites within a window sash (see Window Parts diagram in Overview).

Go to top

N

NFRC

National Fenestration Rating Council, which leads the window industry in evaluating window performance based on standardized testing and reporting.

noise control

How well a window covering keeps outside noise from being heard inside.

non-insulating

Referring to window attachments designed primarily for security and storm protection (exterior) or privacy (interior), which lack insulating materials and are not particularly airtight.

non-roller

Referring to window attachments not rolled around a spindle and typically affixed to the primary window with magnetic strips, snaps or other fastener.

Go to top

O

opaque

Material that does not directly transmit light (versus transparent or translucent).

open weave

Referring to the degree of openness in the fabric of solar screens, shades and awnings, open weave lets more light and air (ventilation) through than closed weave fabrics.

openness factor

In reference to solar shades or screens, the % visible light that gets through the window covering.

Operable

Any window covering or attachment that can be adjusted or set in different operating positions.

Go to top

P

pane

sheet of glass in a window (see Window Parts diagram in Overview).

parting stop

A strip of solid material that holds another part of the window or window covering in place; also called a parting bead (see Window Parts diagram in Overview).

photochromic

Glass or glazing that changes from clear to dark based on sunlight levels (versus electrochromic or thermochromic).

Pleated Shade

Pleated shades provide solar heat gain control. Their adjustability adds elements that balance view, glare control, and daylighting.

Synonyms: Pleated Shades pleated shade pleated shades

prime window

This is the existing window to which window coverings are added to improve overall performance.

Synonyms: prime windows

prime window protection

How well an exterior window covering protects the prime window from the weather and traumatic damage.

privacy

How well a window covering obscures view into a building, either during the day or night, or both.

pro installation

Installation by someone you pay, often with greater skill, and sometimes certified specifically for the type of installation.

Go to top

R

R-value

Insulating value of any component of an outside wall. Window coverings can increase R-value of a window (R-1) to R-2 to R-5 (R-value is the reciprocal of U-value).

radiation

Heat moving through empty space by energy wave (the three ways that heat moves are conduction, convection, and radiation).

rail

horizontal element of the sash frame (see Window Parts diagram in Overview).

reflectance

The portion of radiant energy that is reflected by a material (radiant energy can be absorbed, transmitted, or reflected).

RESFEN

Computer modeling program used to estimate the energy performance of windows and window coverings in homes.

Retractable awning

Retractable awnings provide good solar heat gain and glare control while maintaining view. Their adjustability improves qualities such as privacy and glare control.

Synonyms: Retractable awnings retractable awning retractable awnings

roller

Refers to any adjustable window attachment or covering that winds or stores around a pin-hung cylinder or roller.

Roller shutters

Roller shutters protect existing windows from weather, including severe weather, and improve security and privacy. They also provide excellent solar heat gain control. Insulated versions substantially improve resistance to heat loss in cold climates.

Synonyms: Roller shutter roller shutter roller shutters

Roman shade

Roman shades provide solar heat gain control and limited insulation. Depending on fabric type, they can also provide good sound absorption. Their adjustability adds elements that balance privacy, view, glare control, and daylighting.

Synonyms: Roman shades roman shade roman shades

roof window

Any window mounted on a roof rather than in a wall; same as skylight.

Go to top

S

sash

The glass and its frame in any window, not including the window frame in which the sash is installed (see Window Parts diagram Overview).

seasonal film

A temporary, clear, plastic sheet fastened or adhered to interior window trim to improve the airtightness of drafty prime windows (in contrast to window film).

Synonyms: clear flexible polymer

security

Referring to window attachments that improve the security of the primary window.

semi-opaque

Material that transmits some light and energy but no view.

shade

Most commonly an adjustable, fabric, window covering on a roller.

Synonyms: shades

sheer

Term meaning translucent fabric and applied to any of the following—blinds, curtains, drapes, shades—but most commonly referring to horizontal shades that are creased or stack in folds.

Sheer shade

Sheer shades provide solar heat gain control. Their adjustability adds elements that balance view, glare control, and daylighting.

Synonyms: Sheer shade sheer shade sheer shades

side track

Any slotted or notched window covering that rides in a track on the vertical sides, increasing separation of the interior from light, sound, temperature to the exterior of the window covering.

Synonyms: side tracks

sill

The bottom horizontal element of the window frame, often sloped outward for drainage (see Window Parts diagram in Overview).

single hung

Any window or window covering with two sashes or glass panels and only the bottom of the two operable.

Single Pane Clear

Single Pane Clear, commonly found on older homes, provides the weakest thermal performance but highest visual transmittance.

Synonyms: clear glass

single-cell

Cellular shades with one cell in cross section.

solar heat control

How well a window covering blocks the sun’s heat or infrared energy.

solar heat gain

Term used to describe how much of the sun’s energy makes it past the window/window covering. High solar gain means much of the sun’s energy makes it past; low solar gain means little of it does.

solar screen (shade screen)

Course-woven fiberglassor polyester-based screen designed to block sun/maintain view (interior and exterior; fixed frames and roller)

Synonyms: solar screen solar screens solar shade

solar spectrum

Full range of radiant energy from the sun, mainly: ultra-violet (UV), visible, infra-red (IR).

sound absorption

How well an interior window covering deadens inside sounds.

Synonyms: Sound Absorption Sound absoprtion

spectrally selective

low-e coatings and tints on windows and clear window coverings that favor keeping heat in or keeping it out.

stile

vertical member of the sash frame (see Window Parts diagram Overview).

stool

Shelf-like interior, bottom-of-the-window trim sometimes incorrectly called the sill (see Window Parts diagram Overview).

summer comfort

A quality combining a window covering’s insulation, air tightness and most importantly solar heat control; a measure of how comfortable it is to locate close to a window in summer.

Go to top

T

thermal break

Any part of a window covering that is designed to overcome a thermal bridge in the prime window.

thermal bridge

Any part of a window or window covering made of materials that readily conduct heat and therefore represent a weak point in the assembly’s thermal performance.

thermochromic

Glass that changes from clear to dark based on temperature (versus electrochromic or photochromic).

tight weave

Referring to the degree of openness in the fabric of solar screens, shades and awnings; tight weave lets less light and air (ventilation) through than open weave fabrics.

tinted

Referring to applied films when they are darkened to reduce direct sunlight and glare. Tints are available as either low or high solar gain.

Synonyms: tint low solar gain tint high solar gain tint

top-down

Most often interior window coverings that operate or adjust from the top down. Usually top-down adjustment is in addition to bottom-up adjustability.

top-down/bottom-up

Interior window coverings that can be adjusted by raising the bottom and/or lowering the top of the window covering.

translucent

Material that obscures clear vision but lets significant visible light through (versus opaque—no light transmitted—or transparent (all in nearly all visible light transmitted).

transmittance

The portion of radiant energy that is transmitted by a material (radiant energy can be absorbed, transmitted, or reflected).

transparent

Material that lets all or nearly all visible light through; clear vision (versus opaque or translucent).

triple pane

Three panes of glass with two sealed gas spaces.

Synonyms: triple glazing

triple-tracked

For storm windows and window panels this is three panels—two glass and one insect screen—that operate (up and down) inside tracks in the frame.

Go to top

U

U-factor (U-value)

The reciprocal for R-value, a measure of how readily heat transfers through a material or component. This is also one of the three performance properties reported on a window’s NFRC rating.

ultraviolet

Wavelengths of energy too short to be visible but with enough energy to degrade materials, particularly finishes, fabrics, and carpets.

Go to top

V

ventilation

A measure of how a window covering allows outside air/breezes through an open primary window.

Synonyms: Ventilation

vertical slats

Refers to any louvered or slatted window covering with vanes or slats perpendicular to the floor, or vertictally-oriented, operating side to side.

Synonyms: vertical slat

view

How well a window covering gives visual access to the outdoors, with different window coverings using different approaches to maintaining view while performing other functions: awning, solar screens, louvered blinds.

visible light

In the solar spectrum, light energy we can see: red through violet (the solar spectrum is primarily made up of UV, visible, and IR).

visible transmittance (VT)

A performance property of glass/windows that is measure by standardized testing and reported in NFRC window ratings.

Go to top

W

weep (weephole)

A small space intentionally designed into the bottom rail of any exterior window covering to allow condensate to drain and not accumulate.

window attachment/covering/treatment

Each of these three terms is used differently but all mean any component added to the prime window to improve its performance.

window panel

A tracked-operable or fixed-inoperable glass window installed on the interior to supplement the performance of the prime window.

Synonyms: window panels

window quilt

Multi-layered fabric window covering—either adjustable on a roller or fastened in place with snaps or magnetic tape—used primarily in cold climates to improve thermal performance.

Synonyms: window quilts Window quilt Window quilts

window retrofit

Any change to an existing window including window replacement, window repair, and the addition of window coverings.

Synonyms: window retrofits

winter comfort

A quality combining a window covering’s insulation and air tightness; a measure of how comfortable it is to locate close to a window in winter.

Go to top