Helpful Information Care & Maintenance   
    
Please refer to our Care & Maintenance brochure for information to keep your windows and patio doors operating at peak performance.

Condensation Information

Why does condensation occur?
Condensation (water vapor or moisture in the air) is a sign of excess humidity inside the home. Condensation occurs when moist air comes in contact with the colder surface, such as a window or mirror. Although the surface of a window may be the first place you notice condensation forming, the window is not the problem. Windows, in this case, merely provide a visible sign that excess humidity or moisture is present in the house.
Warm air holds more moisture than cool air. When that warm, moist air comes in contact with a cooler surface, the moisture suspended in the warm air transfers to the cooler surface as condensation.

What causes moisture inside the home?
Indoor moisture in the air is caused by a variety of factors. Common household activities such as cooking, showering, using the washing machine or dishwasher and other activities that use hot water all add moisture to the air.
Newer homes are often more subject to condensation because they are constructed with better weather tight materials than older homes. Weather stripping, improved insulation, vapor barriers and modern construction techniques are designed to reduce air leakage. But at the same time, these materials and techniques can also seal moisture inside the home. In newer, more weather tight homes, it is important to be aware of humidity levels and to provide adequate ventilation to reduce humidity levels.

Energy Efficiency

Making Your Home More Energy Efficient
Atrium understands your desire for easy-care, energy-efficient products. That’s why most Atrium products can be specified to meet Energy Star® criteria in all climate regions.

Energy Star® windows
The Department of Energy (DOE) and the Environmental Protection Agency (EPA) have developed the Energy Star designation for products meeting certain energy performance criteria. Most Atrium windows and patio doors available in your market area can be specified to meet Energy Star criteria for your climate zone.
Please refer to the Energy Star website to access complete program information. Energy Star is a registered trademark of the U.S. Department of Energy. www.energystar.gov

Return to Top

Frequently Asked Questions
What is a U-factor?
The U-factor is a measure of heat flow or conductivity through a material, the reciprocal of R-value. Although R-values are used as for measures of the resistance to heat flow for individual building materials, U-factor is always used to measure the conductive energy of building enclosures.

What is a Design Pressure Rating?
Design pressure, or also referred to as DP, expresses a numerical value that defines the structural wind loading requirements (in pounds per square foot) for a building and the components and cladding of a building. For windows and patio doors, the higher the DP rating indicates better performance under wind load (eg: a DP-50 window is structurally more sound than a window rated DP-35). Coastal regions often require higher DP ratings by code to anticipate higher wind velocities that can be encountered in proximity to the coast line.

What is meant by “Solar Heat Gain Coefficient” (or, sometimes expressed as “SHGC”)?
The number to know when selecting windows and patio doors – it measures how much of the sun’s heat is transmitted through these fixtures, expressed in a number from zero to one. A window that has a SHGC of .30 will allow 30 percent of the sun’s heat to pass through. Whether you want a higher or lower number will depend on your goal. Especially in the South, you will be primarily interested in a window or patio door with a low SHGC that will help to block solar heat gain inside your home, thus reducing cooling loads in hot weather.  Northern climates often look for higher SHGC performance to harness passive solar warmth on cold, sunny winter days.

What is insulated glass?
Insulated glass consists of two pieces of glass hermetically sealed to a spacer. This creates a sealed, insulated air space between the two pieces of glass, resulting in better thermal insulation performance. Insulated glass also helps reduce condensation while keeping the heat in during the winter, and heat out during the summer.

What is low-E glass?
Low-E stands for low-emissivity glass – this is a nearly invisible coating on the glass surface that are microscopically thin metallic oxide layers primarily to reduce the U-factor by suppressing radiative heat flow. The principal mechanism of heat transfer in multilayer glazing is thermal radiation from a warm pane of glass to a cooler pane. Coating a glass surface with a low-emittance material and facing that coating into the gap between the glass layers blocks a significant amount of this radiant heat transfer, thus lowering the total heat flow through the window. Low-E coatings are nearly transparent to visible light. Our primary glass supplier, Cardinal Glass, offers informative details on their website: www.cardinalcorp.com

What is argon gas? How does it work?
Added inside an insulated glass unit air space, argon gas is an invisible, insulating gas with lower thermal conductivity than atmospheric air. During the manufacturing process, the atmospheric air is displaced when argon gas is pumped into the glass unit airspace. When combined with Low-E glass the Low-E glass helps reflect heat away, while the argon gas helps reduce thermal transfer to enhance the glass unit insulating performance.

What is a good source for window installation information?
We recommend that you refer to the American Society of Testing and Materials (ASTM) guide entitled:  ASTM E 2112 “Standard Practice for Installation of Exterior Windows, Doors and Skylights” for comprehensive installation guidance and best practices: www.astm.org

For coastal region installation consideration, you can also refer to the American Architectural Manufacturers Association (AAMA) guide 100-07: www.aamanet.org

How should I evaluate the energy performance of a window or patio door?
Look for the National Fenestration Ratings Council (NFRC) label on the window or patio door. This label shows the U-Value, Solar Heat Gain Coefficient, and Visible Light Transmittance values. All values are backed by independent lab test reports on file with every window and door manufacturer.

Who is the NFRC?
The National Fenestration Rating Council (NFRC) is a non-profit, public/private organization created by the window, door and skylight industry. It is comprised of manufacturers, suppliers, builders, architects and designers, specifiers, code officials, utilities and government agencies. NFRC has established a voluntary national energy performance rating and labeling system for windows, doors and skylights. For more information, visit their website: www.nfrc.org

What is the Energy Star® program?
Energy Star is a voluntary partnership among the U.S. Department of Energy, the U.S. Environmental Protection Agency, product manufacturers, local utilities, and retailers. Partners help promote efficient products by labeling with the Energy Star logo and educating consumers about the benefits of energy efficiency. By choosing Energy Star-labeled products, you’ll help to keep your utility bills lower, and help the environment at the same time. For more information, visit their website:  www.energystar.gov    (Energy Star® is a registered trademark of the U.S. Department of Energy).

What about window condensation?
Condensation is a direct result of interior humidity and the difference between indoor and outdoor air temperature. If you keep the humidity in your house low, then the likelihood of experiencing condensation is also low. However, the efficiency of your window will also impact the temperature and humidity level at which condensation occurs. Energy efficient windows will help reduce condensation. Here’s why – high performance windows with low U-factors result in inside glass surface temperatures much closer to the room air temperature. Windows with non-metal frames and more thermally-efficient spacers in the dual-pane glass units are also less likely to have condensation on the frame or at the edge of the glass.  Also, realize that in certain conditions (such as humid mornings after a clear night sky), some highly insulative windows may have dew on their outside surface. These windows are such good insulators, that dew is condensing there just like it does on an insulated wall.

Can you provide me with an independent, informative website where I can learn more about energy efficient windows?
For extensive information, backed with details provided by the U.S. Department of Energy, refer to: www.efficientwindows.org

Return to Top

Glossary
A

Air Chambers
Small honeycomb spaces within the sash and frame extrusions that help to insulate and strengthen the window.
 
Argon Gas
 A gas that is heavier than air – it can be used to fill the airspace of an insulated glass unit. Argon is a safe, colorless, odorless, tasteless, non-toxic gas, which is six times denser than air. Argon increases the insulating value of an insulated glass unit as well as helps improve sound insulation qualities.
 
Awning Window
 A window that is hinged at the top horizontal edge, and cranks open or shut from the bottom.

B

Balance
The system in the side jambs of a single or double-hung window that helps open and support the weight of the sash, and helps hold the sash in place while in an open position.

Bay Window
A bay window is generally made up of three windows. The side or flanker units project out from the building at 30, 45, or 90 degree angles. The center is parallel with the building wall and is made up of one or more joined windows. All of the units can be stationary, operating, or any combination of the two. Typically the center section is stationary, while the side units are operating for ventilation.

Beveled Exterior
An extension of the vinyl frame that adds an aesthetically pleasing dimension to the exterior of the
window.

Bow Window
A series of three or more adjoining window units, commonly five in number, each connected at 10-20
degree angles to form a circular arch appearance.
  
Brick Mould
Exterior casing trim around a window or door. Brick mould covers the gap between the frame and masonry opening. In some cases, siding is installed up to the edge of the brick mould.
  
Buck Size
The exact (net) window size, not including the nail fin.

C

Casement Window
A window unit in which the single sash that opens outward to the left or right, projecting off the plane of the wall. The sash unit is hinged on one side and is operated by a crank mechanism.
  
Casing
Inside casing is a flat, decorative moulding that covers the inside edge of the jambs and the rough openings between the window unit and the wall. Outside casing (or brickmould), serves the same purpose.
  
Caulking
A compound for filing joints to prevent air and water leakage. Caulking is used where air and water leakage and/or movement may occur.
  
Circle Top
A generic term referring to any of a variety of window units having a curved top frame member, and are often used over another window or over a door opening.
  
Condensation
The formation of water vapor from the air on any cold surface, whose temperature is below the dew point.
  
Cottage Window
A double hung or single hung window with a larger proportioned bottom sash, as compared to the top sash.

D

Design Pressure
The pressure a product is designed to withstand. This value is a measure of a product’s capacity to withstand the forces of wind loading, in both positive and negative directions, while it is closed and locked.
  
Dew Point
The temperature at which condensation occurs.

Divided Lite
A window opening divided into smaller sections by a grid system on the interior or exterior of the glass, between the glass panes, or any combination of these three.
  
Double Glazing
Two panes of glass separated by a sealed air space, forming a glass panel that increases energy efficiency and provides other performance benefits such as improved outside noise reduction.
  
Double Hung Window
A window unit that contains two vertically-sliding operable sashes, which move vertically in the frame.
  
Drip Cap
A molding designed to divert water from the top of a window unit so that water moves beyond the outside of the frame.   

E

Egress Window
A window opening large enough, as defined by local building codes, for exit or entry in case of an emergency. Typically required in bedrooms where no other means of exterior escape exists.
  
ENERGY STAR®
A government-backed program helping businesses and individuals protect the environment through the use of energy efficient products. ENERGY STAR® qualifying products, such as windows and doors, mean these items use less energy, save money and help protect the environment. Energy Star is a registered trademark of the U.S. Department of Energy.
  
 Extrusion
 A particular cross-sectional shape produced by forcing material through a die.
 
F

Fenestration
An industry term of Latin origin that refers to the broader category of windows, doors and skylights.
  
Fixed
A window that is non-venting or non-operable, such as a picture window.
  
Flashing
A metal or plastic strip attached to the outside of the head or side jambs of windows and doors to provide a weather barrier, resisting leakage between the window or door frame and the wall.

Frame
The combination of head, jambs, and sill to form a precise opening in which a window sash or door panel fits.
  
Fusion Welded
Refers to vinyl frames and sash attached together at corner joints, using a heat source to create a fused, weather tight corner joinery.

G

Garden Window
A window that projects out from an exterior wall, often used as a greenhouse window for house plants. It has a slanted glass roof that allows heat and light from the sun to enter.
  
Geometric Window
Specialty windows of various shapes including: rectangles, triangles, trapezoids, octagons, pentagons, half-rounds, quarter rounds, full rounds sectors and ellipses.
  
Glazing
The process of sealing glass to a sash or frame for a weather tight seal.
  
Glazing Bead
A removable decorative trim around the glass perimeter, covering the gap between glass and frame.
  
Grille
A decorative grid on the interior or exterior surface of the glass, or, more commonly found between sealed between glass panes in an insulated glass unit, or in any combination of these locations that divides a window opening into smaller openings to create simulated divided lite or true divided lite. Grilles may or may not be removable.   

H

Head
The main horizontal member forming the top of the window or door frame.
  
Hopper Window
The sash is hinged at the bottom so that the window opens into the house. Primarily used in basement applications.
  
Horizontal Sliding Window
One or more sash that slide horizontally past each other. One or more sash may be fixed (inoperable), or each sash may operate to open and close.

Infiltration
Air that is able to flow through cracks and other spaces around a window or door, and also at the meeting rail within a window unit.
  
Insulated Glass (IG)
A combination of two or more panes of glass with an hermetically sealed air space between the glass panes. This space may or may not be filled with an inert gas, such as argon gas.

J

J-Channel
“J” configuration designed into window frame exterior shape for the primary purpose of receiving siding to self-trim around a window perimeter.
  
Jalousie
A series of rectangular, horizontal overlapping glass slats held together by metal end-frames attached to a side-jamb mechanical unit that simultaneously opens or closes the slats in unison.
  
Jamb
The main vertical members forming the sides of a window or door frame.  

L

Lift Rail Handle
Handle or grip installed on the sash of a window to make it easier to raise or lower the sash.
  
Lite
A unit of flat glass; one glass panel expressed as a “lite”.
  
Low-E (Emissivity) Glass
Glass treated with a thin transparent coating of metallic oxide (generally silver). Allows natural light and short-wave heat energy to freely penetrate glass during the winter, while reflecting long-wave heat energy back outside during the summer months. Helps keep your home cool in the summer and warm in the winter. It greatly reduces ultraviolet light to enter the home, minimizing fading exposure to carpet and furnishings.

M

Meeting Rail
The joinery point where horizontal or vertical sections of the top and bottom sash meet when the window is closed. On sliders, the meeting rail is vertical. On single and double hung windows, the meeting rail is horizontal.
  
Moulding
Strips of wood usually shaped to a curved profile, used to accent and emphasize the ornamentation of a structure and to conceal surface or angle joints.
 
Mulled Unit
Two or more window units structurally joined together.
  
Mullion
A metal or vinyl extrusion used to structurally join two or more windows.

Muntin
The pieces of decorative grid that help divide a window opening into smaller sections. Also called a grille or a grid.
  
Muntin Bar
See:  muntin.

N

Nailing Fin
Used to secure the window into a rough opening.

O

Obscure/Translucent Glass
A frosted or textured glass that transmits light, but obscures the view.

Oriel Window
A double hung or single hung window with a larger proportioned top sash, as compared to the bottom sash.

P

Pane
A framed sheet of glass within a window or door frame.
  
Panel
Usually refers to the separate panel or panels in a door frame. A panel may be operable or stationary (fixed).
  
Picture Window
A fixed window that contains no operable sash.
  
Pitch
The pitch of a roof is the degree of the inclination upward from horizontal or flat. It may be expressed in degrees, or as the ratio of the number of inches it rises in each 12 inches of horizontal span:  a 4/12 pitch means the roof rises four inches for every running foot of horizontal span.

Q

Quad
A group of windows mulled in combination of fours.

R

R-Value
Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value. It is the inverse of the U-Value (R=1/U).
  
Rail
The horizontal top and bottom members of a window sash or door panel.

Replacement Window
A window designed to replace and  fit into an existing window opening once the old window is removed.
  
Rough Opening
The framed opening in a wall into which a window or door unit is to be installed.

S

Sash
A single assembly of stiles and rails made into a frame, designed to hold the glass in a window, which is then set into a main frame. A sash may be operable or inoperable.
  
Sash Balance
A system of cords, and/or springs that assist in raising a sash, while keeping the sash in any placed position by counter-balancing the weight of the sash.
 
Sash Lock
Generally, a cam-action or other latch-type lock applied to the sashes of a sliding window to both pull the sashes tightly together and to seal the sash tightly to the frame, both for security and to create a weather tight seal.
  
Sash Stop
An extrusion molding piece, generally about 2” long that covers the joint between window sash and the jamb, stopping the operable sash at its maximum opening.
  
Shims
Wood, plastic or composite wedges used to secure the window or door unit in the rough or masonry opening in a square, level and plumb position both during and after installation.
  
Sidelight
Tall, narrow, fixed or operating sash on either or both sides of a door to light an entryway or vestibule.
  
Sill
The main horizontal member forming the bottom frame portion of a window or door.
  
Simulated Divided Light (SDL)
A method of constructing windows in which muntins are affixed to the inside and outside of a panel of insulating glass to simulate the look of true divided light panes.
  
Single Glazing
Use of a single pane of glass in a window. Not as energy-efficient as insulated glass.
  
Single Hung Window
Window with a fixed top sash and a vertically operating bottom sash.
  
Slider Window
Window that slides horizontally to the left or right.
  
Sliding Patio Door
A patio door in which a vent panel moves horizontally on a sill track system past a fixed or operable panel.
  
Solar Heat Gain Coefficient (SHGC)
A measure of how effective a window or door is at keeping out solar heat. It is calculated by taking the amount of solar heat that enters a room through a window or door, divided by the amount that is actually contacting the exterior of the unit. The lower the value, the better the unit keeps out solar heat.
  
Sound Transmission Class (STC) Rating
Measures the amount of noise reduction that can be achieved with a given product.  The higher the number, the better the product is at suppressing sound transmission.

Stile
The vertical member of a window sash or frame, or of a door panel.

T

Tempered Glass
A glass panel that is heated and subsequently rapidly cooled in its manufacturing process, creating a product that can withstand abnormal force or pressure on its surface, and which does not break into sharp pieces (also known as ‘safety glass’); code requires tempered glass in all doors (including patio doors), and in windows that are located near doors, bathtubs, or showers.
  
Thermal Break
An element of low conductance placed between elements of higher conductance to reduce the flow of heat (or cold).  In thermal break window frames, a non-metallic polyurethane material separates the transmission of cold between the frame’s exterior and the frame’s interior.
  
Tilt Window
A window designed in such a way that the sashes tilt inward for easy cleaning of the outside glass surface.
  
Transom
A small window placed over the top of a door or window, primarily for additional light and aesthetic value.
  
Triple
A group of windows mulled (joined) in combination of threes.
  
Twin
A group of windows mulled (joined) in combinations of twos.

U

U-Value (U-Factor)
A calculation expressing the rate of heat transfer through a window or door. The lower the U-value, the better the insulating properties of the window or door.

W

Weatherstrip
Various shaped metal, vinyl, plastic or fiber strips that fit tightly against the window or door frame to resist air and water infiltration through gaps and cracks.
  
Weep Hole
A small hole (or holes) found along the bottom sill frame edge of a window or door unit that allows any trapped water to escape to the exterior.
  
Wind Load
Force extended on a surface by moving air.

Return to Top