Selecting the right windows is critical when building a sunroom.
The usability of a sunroom often hinges on the glass type used. While standard glass glazing permits heat and sunlight to enter, advanced glass glazing features multiple coatings to block some heat and UV rays, enhancing your comfort. Coatings vary with the different climates and regions of the US; in Oklahoma's heat, glass with a lowers the "solar heat gain coefficient" is preferred for cooling efficiency. Invisible double or triple silver coatings reflect sunlight, and argon gas between panes boosts window performance in the sunrooms. Those coatings might have a little bit of a greenish tint to the windows glass but makes a huge difference between using the area and not using it on a hot summers' day.
Just a few different glass manufacturers supply all the flat glass for the industry's window makers. These manufacturers provide various glazing options for windows, which window companies then cut and assemble to size and specifications. All windows installed below 30 inches and sliding glass doors must be tempered glass. The window glazing is pivotal in a sunroom's construction, affecting whether the room is too hot or comfortable. With a plethora of construction materials for sunrooms, the design options are extensive. Glass solarium kits, designed for specific uses, may be susceptible to regional hail. More glass means more heat, even with high-performance windows. Insulation in the roof, walls, and windows is crucial, as it can determine the space's usability.
For sunroom construction, window performance is key. The National Fenestration Rating Council (NFRC) offers a voluntary program that evaluates
Heat Gain and Loss - Windows, doors, skylights can gain and lose heat through: Direct conduction through the glass or glazing, frame, and/or door. The radiation of heat into a room (typically from the sun) and out of a house from room-temperature objects, such as people, furniture, and interior walls or the Air leakage through and around them. These properties can be measured and rated according to the following energy performance characteristics:
U-factor is the rate at which a window, door, or skylight conducts non-solar heat flow. It's usually expressed in units of Btu/hr-ft2-oF. For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone. NFRC U-factor ratings, however, represent the entire window performance, including frame and spacer material. The lower the U-factor, the more energy-efficient the window, door, or skylight.
Solar heat gain coefficient (SHGC)
is the fraction of solar radiation admitted through a window, door, or skylight -- either transmitted directly and/or absorbed, and subsequently released as heat inside a home. The lower the SHGC, the less solar heat it transmits and the greater its shading ability. A product with a high SHGC rating is more effective at collecting solar heat during the winter. A product with a low SHGC rating is more effective at reducing cooling loads during the summer by blocking heat gain from the sun. Your home’s climate, orientation, and external shading will determine the optimal SHGC for a particular window, door, or skylight. For more information about SHGC and windows, see passive solar window design.
Air leakage
is the rate of air movement around a window, door, or skylight in the presence of a specific pressure difference across it. It's expressed in units of cubic feet per minute per square foot of frame area (cfm/ft2). A product with a low air leakage rating is tighter than one with a high air leakage rating. Note that air leakage also depends on proper installation of a window, which is assumed in all ratings.