What makes windows and doors energy efficient and why that benefits your home and your wallet.
Good news! Advancements in today's window and door technologies dramatically improves energy effieciency. That translates to more comfortable home temperatures with lower energy costs and federal tax credit on qualifying products.
EXOVATIONS door and window materials allow you to choose the look and degree of energy efficiency you want without sacrificing function or aesthetic. They're beautiful, durable, functional and, yes, energy efficient.
There are many benefits of replacing your home’s windows and doors with new energy efficient units.
The best way to ensure energy efficiency is to look for ENERGY STAR certified windows and doors. At EXOVATIONS, we use windows and doors that meet ENERGY STAR guidelines. Energy Star qualified windows and doors are manufactured by a certified Energy Star partner, and are independently tested by the National Fenestration Rating Council (NFRC). The NFRC label is needed for verification of energy code compliance, and must appear on all products that are part of the Energy Star program. The Department of Energy (DOE) does not require any specific technologies or materials to be used on Energy Star-rated products, although many product features are common in most qualified window and door products.
Window manufacturers have developed many new technologies to improve energy efficiency. These components are evaluated to determine a window’s energy efficiency rating:
Framing - Energy Star certified windows may be made of fiberglass, vinyl, wood (and clad-wood), aluminum or a composite material. Because each material performs differently, construction will vary to optimize the window’s performance. The goal is always to reduce heat transfer and improve insulation capability.
Glass - The technical term for the glass portion of a window is “insulated glazing unit”, or IGU. More commonly, you will hear windows described as doubled-paned (or double-glazed) or triple-paned (or triple-glazed). The purpose of a double- or triple-pane design is to reduce heat transfer through the glass surface.
Gas Fills - There is a sealed gap between the glass panes of double- and triple-paned windows. It may be filled with air, an inert gas such as argon or krypton, or even vacuum-sealed.
Spacers - The spacers that keep the glass panes apart are rated based on the conductivity of the material they are made from. They can be made from metal, non-metal or a combination, but they must create a leak-free gas seal.
Low-E Coating - A low-e coating is a nearly invisible layer of metal applied to one side of a window pane. Its purpose is to minimize bi-directional heat transfer through the glass. In warm climates, it is important to keep outside heat from penetrating through the glass; in colder months, when you are paying to heat the inside of your home, it prevents heat from escaping through the glass to the outside. In a double-paned window, there will be one layer of low-e coating; in a triple-glazed window, both of the two interior panes may have a low-e coating.
The characteristics of an energy efficient door include:
Multiple Glass Panes – Similar to window construction, double- or triple-paned insulating glass in a door can reduce bi-directional heat flow.
Fit and Weatherstripping – Energy-efficient doors must create a tight seal to prevent air leaks. Some new door frames are built with a magnetic strip that creates a tighter seal around the edges.
Improved Core Materials – Some of the most energy-efficient and well-insulated doors available are made of fiberglass, clad wood, and insulated steel.
In evaluating windows and doors, the DOE and NFRC will establish the product’s U-factor, solar heat gain coefficient (SHGC), visible transmittance (VT), air leakage, and condensation resistance. So what do these different ratings mean?
The U-factor is a measure of heat transfer; the lower the U-factor, the better a product is a preventing heat from escaping a home. This is important in cold months when you are paying to heat the interior of your home.
SHGC is a measure of how well a product blocks heat from the sun. Here in Atlanta, you want a low SHGC rating to keep your home cooler in hot months.
VT measures how much light comes through a window. This can be an important factor in reducing the need for artificial lighting in a home.
Air leakage is an optional rating that may not appear on all NFRC labels. It refers to how much outside air comes through a product into a home, and typically range between 0.1 and 0.3. The lower the rating, the better.
Condensation resistance is also an optional rating, and may not appear on all manufacturer NFRC labels. It measures how well a product resists the build up of condensation.