Argon: The clear, non-toxic gas that is found between panes of glass in a window to provide insulation.
Center post mullion: The vertical supports in the walls of a sunroom that add additional strength, and are designed to conceal wiring.
Condensation: Water which collects as droplets on a cold surface when humid air is in contact with it, such as a cold window exposed to humid indoor air.
Conduction: The process by which heat is directly transmitted through glass or walls when there is a difference of temperature between indoor and outdoor temperatures.
Convection: The circular motion that happens when warmer air — which has faster moving molecules, making it less dense — rises, while the cooler air or liquid drops down. (Like the saying "hot air rises"). Convection affects heat transfer from the surface of glass to room air, and between two panes of glass.
Extrusion: The process of producing vinyl or aluminum shapes by forcing heated material through shaping dies, then cooling to obtain the final rigid profile. Also, any item made by this process.
Fascia: On the exterior of a sunroom, it's the long piece that covers the joint between the top of the wall and the projecting eaves from the roof.
Four season (or all-season) sunroom: Intended to be used all year-round, through all four seasons. Typically built with double paned glass and an HVAC unit for temperature control.
Frame: The frame provides support to the entire window, holding the other pieces in place.
Gable roof: Two roofing panels supported by a beam in the center, and each panel slopes away from the beam.
Gas fill: A gas other than air, usually argon or krypton, placed between window glazing panes to reduce the U-factor by suppressing conduction and convection.
Glazing: Window glazing helps control the type and amount of sunlight that enters the sunroom. Proper glazing also controls solar heat gain so the sunroom stays at a comfortable temperature.
Header: Tilts to match the pitch of your roof. Sealed to become part of the roof. Enhances strength and the greater thickness supports a larger glass viewing area.
Heat gain: The transfer of heat from outside to inside by means of conduction, convection, and radiation through all surfaces of a house.
Heat loss: The transfer of heat from inside to outside by means of conduction, convection, and radiation through all surfaces of a house.
I-Beams: The strong, load-bearing structures that support the roof of a sunroom.
Infrared: Sometimes called infrared light, it is electromagnetic radiation with wavelengths longer than those of visible light. It is therefore invisible to the human eye, but can still cause fading to upholstery, drapes, and other fabric surfaces.
Insulated glass: Two or more glass windowpanes separated by a vacuum or gas-filled space to reduce heat transfer.
Interlocker: The vertical piece of frame in a sliding glass door which engages with the corresponding frame in an adjacent panel when the door is closed.
Knee panels/Knee walls: The bottom "squares" of a sunroom wall below the windows. Knee panels can be solid and insulated, or made of energy-efficient glass.
Low-emittance (Low-E) glass: Glass that has a coating which helps deflect UV rays, keeping heat out of the house during the summer and keeping heat in the home during the winter.
Meeting rail: The part of a sliding glass door or a sliding window where two panels meet and create a weather barrier.
Screen room: A covered outdoor area surrounded with screens that provides protection from insects. No protection from heat or cold, meant to be used at times of the year when the weather is comfortable.
Studio roof: A single slope roofing panel.
Tempered Glass: A type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. When broken, it crumbles into small pellets instead of sharp shards, greatly reducing the chance of injury.
Three season sunroom: Designed for use from spring through fall, in regions with cold winters. Typically built with single or double paned glass, and not intended to be heated or cooled.
U-Factor: A measurement that makes up a window's energy performance rating. It refers to the conduction of the flow of heat.