From time to time, we compile some of the most frequently asked questions from our clients. We have organized those questions into the following categories:
1. Insurance & Tax discounts (read more)
2. Design characteristics (read more)
3. Testing & Permitting (read more)
4. Cost (read more)
5. Energy Efficiency (read more)
6. Miscellaneous (read more)
7. Technical (read more)
Q: What makes window or doors energy efficient?
A: Numerous factors, including how the frame and sashes are engineered and built, type of glass used (single-, double- or triple-pane), weather stripping, type of low-emissivity coating on the glass and the presence of argon or krypton gas.
Q: What is an R-value and how important is it in selecting windows and doors?
A: The U-value is the most important element in evaluating
windows and doors today; however, most are unfamiliar with the concept of R-value (or R-factor). The R-factor of a window or door is the measure of its resistance to the transfer of heat flow. The higher its R-value, the greater it's insulating ability.
Q: What is a U-value?
A: U-value (or U-factor) is the measurement of a window's ability to conduct heat (i.e. the amount of heat transmitted through a window). A window with a lower U-value is better at insulating your home.
Q: What is the Solar Heat Gain Coefficient?
A: The Solar Heat Gain Coefficient (SHGC) represents the amount of heat going into a home. The lower the number, the less heat penetrates the home. Inquire about the SHGC value if your home is primarily air conditioned. Clear glass
hurricane impact-resistant windows or doors feature a SHGC of 0.72; bronze and gray glass hold a 0.55 and 0.56 SHGC value, respectively.
Q: What is “Low-E”? How important is it to have on windows and doors?
A: A recent advancement in glass technology, Low-E stands for low emissivity. It is a microscopic, metallic coating that is applied to glass surfaces. This has the effect of reflect and re-radiates heat energy into or out of a home (varies depending on climate conditions). Utilzing Low- E is an excellent method for increasing windows and door energy efficiency.
Q: What is ENERGY STAR®? How does it concern windows and doors?
A: ENERGY STAR is a U.S. government program that is administered by the Department of Energy and the Environmental Protection Agency (with the cooperation of manufacturers). It is designed to reduce fossil fuel consumption through educating consumers. ENERGY STAR covers a wide range of products.
Windows and doors can bear the
ENERGY STAR only after being tested by an independent laboratory through the NFRC program and meet specific, predetermined U-value ratings. By choosing
ENERGY STAR products, consumers reduce their energy costs and help make the environment cleaner.
Q: What is an ENERGY STAR qualified window or door?
A: ENERGY STAR qualified
windows or doors meet a stringent energy efficiency specification set by the Department of
Energy (DOE) and have been tested and certified by the National Fenestration Rating Council (
NFRC).
NFRC is an independent, third-party certification agency. It assigns specific energy efficiency measures such as U-factor and Solar Heat Gain Coefficient (SHGC) to the
complete window system. The
ENERGY STAR qualifications are based on a maximum U-factor and SHGC for each of four different climate zones. To meet the U-factor and SHGC levels,
ENERGY STAR qualified windows, doors, and skylights can use:
- Two or more glass panes.
- Warm-edge spacers between panes.
- Enhanced framing materials.
- Low-E. These microscopically thin coatings direct heat inside during the winter and outside during the summer.
Please note that
ENERGY STAR qualified windows are not required to feature any of the items listed above. Although
DOE requires window products to meet a certain efficiency standard, it is up to the window manufacturer to accomplish this.
Q: Which window or door brands and models are ENERGY STAR qualified?
A: There are many
ENERGY STAR qualified windows and doors models available; however, qualification is dependent on geographic usage. For this reason,
ENERGY STAR does not maintain or provide a list. In other words, a window or door that is qualified in Florida may not be qualified in Colorado. One must also understand that manufacturers offer different glass packages for brands or models that may or may not cause the product to be
ENERGY STAR qualified. Contact the manufacturer of the product or its authorized dealer to determine if it is
ENERGY STAR qualified. Also be sure and check the U-Factor and SHGC for further confirmation.
Q: What framing material should I select to ensure that the window, door, or skylight product is energy efficient?
A: When selecting energy efficient windows and doors, simply look for the
ENERGY STAR label. Since
ENERGY STAR criteria is based on whole-unit performance, you can select products qualified for your climate zone, as opposed to searching for the most energy efficient materials, components, or technologies\.
Q: What is the NFRC? What must I know about it?
A: NFRC stands for "National Fenestration Rating Council," a program established by the U.S. Department of Energy to help consumers compare window products. Participating
window and door manufacturers must label every unit to its specific thermal performance level, so customers can trust that the products selected meet the requirements for their application. Participation in the
NFRC program is strictly voluntary. Some manufacturers elect not to participate, because doing so requires outside third party inspection and extensive product testing.
Q: Does argon or krypton gas between glass panes matter in regards to energy efficiency?
A: Air must remain as still as possible to insulate properly, because moving air carries energy. Both argon and krypton are heavier than air; therefore, these substances are less prone to convection or thermal movement. Ultimately, heavier-than-air gases offer more insulation. Note that, although argon and krypton are found naturally in the air, both are completely harmless to breathe.
Q: How essential is weather stripping?
A: Weather stripping provides a barrier against air and water in windows and doors; thus, making it very important. Weather stripping is the sole element that makes
windows or doors reasonably air tight. High-quality weather stripping, when properly applied and compressed, substantially improves the insulating performance of
windows and doors.
Q: What are the different kinds of weather stripping and what are their benefits?
A: There are many different types of weather stripping but, in truth, they essentially fall into one of the following categories: woven piles, flaps, and hollow or foam bulbs. What is the best type of weather stripping? This is dependent on the window's style, design and application. Expertly engineered windows and doors designed with weather stripping create the tightest possible seal that sustains over time and heavy use.
Q: Are impact-resistant windows and doors a sufficient provider of Ultra-Violet protection?
A: Ultra-Violet (UV) light beams reside on a portion of the solar spectrum that is not visible to the human eye. UV has the effect of causing fabric to fade over time. When comparing UV readings, you should know that lower ratings denote that more UV is being blocked (e.g. a 0% U-V value translates to 100% blocking). Clear, gray and bronze
impact-resistant windows and doors provide 99% protection (i.e. 1% U-V penetration).
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