Low E Glass Window Ratings

The coating is then applied to the glass ribbon while it.

Low e glass window ratings.

The white national fenestration rating council label. Have nfrc ratings that meet strict energy efficiency guidelines set by the us environmental protection. Many of the windows from this manufacturer are energy star qualified across the entire country regardless of climate. The lower the u factor rating the more energy efficient the glass.

So in the winter months if you have low e glass in your home much of the warmth heat given off by the furnace and all the objects which the furnace has heated is bounced back into the room. The ratings for glass are a bit more complicated than ones we are used to for insulation qualities. Such glazing would emit only 4 of the energy possible at its temperature and thus reflect 96 of the incident long wave infrared radiation. Choosing a window with a spectrally selective low e coating allows as much natural light to enter as possible.

For windows skylights and glass doors a u factor may refer to just the glass or glazing alone. With insulation we expect the higher r value to be a better insulator than one with a low. By comparison low e glass coatings can have an emittance as low as 0 04. This may sound like a low insulating value but even the finest energy efficient windows today carry u values hovering in the 22 through 30 ranges.

Nfrc u factor ratings however represent the entire window performance including frame and spacer material. Which should i choose. This means doors can provide more insulation than a window or skylight can. In other words if there is a heat source inside your house or outside the glass bounces the heat from that object back away from the glass.

This glass works by reflecting heat back to its source. The 2 most important window and door labels. Low e low e2 low e3 windows. The ratio between the window s visible light transmittance and its solar gain coefficient rating.

This means you should look for windows with a vt rating as close to 1 as possible. Window manufacturers product information may not list emittance ratings. It s usually expressed in units of btu hr ft2 of. But even doors with lots of glass like a sliding patio door have lower glass to frame ratios than windows or skylights.

Examples of windows with good low e ratings. Here s what all those scientific terms and numbers about energy savings mean. U factor is the rate at which a window door or skylight conducts non solar heat flow. Low maintenance well insulated windows.

Okay so low e glass obviously is a special glass that has a low rate of emission. This is a fairly normal industry standard that has been around a good many years. Thus correlating to r values of 4 55 through 3 33. Low e glass allows visible light to pass through it but blocks heat generating ultraviolet light requiring less artificial heating or cooling to keep a room at the desired temperature.

Types of low e coatings. The two labels you should look for. With the high cost of replacement windows and doors it s wise to know exactly what you re getting for your money. Light to solar gain.

Infinity from marvin is one brand that emphasizes energy efficiency.