The U.S. Department of Energy estimates that the amount of energy lost annually through windows is $35 billion. Furthermore, the DOE states that the average American household spends between $1,500 and $2,000 every year on energy bills and estimates that 45 percent of that amount is spent on heating and cooling. The majority of heat and cold that is lost can be attributed to windows; whether they are old and aged or they are simply woefully unsuccessful models of energy efficiency.
Energy Goes Out The Window
How do windows “lose” energy? According to the National Fenestration Rating Council (NFRC), in winter, poor quality windows that aren’t well insulated create drafts in the home. These inefficient windows create the feeling of a draft due to changing air temperatures: warm air near a cold pane of glass will quickly cool and then fall, creating a cycle of moving air. Moving air generally creates a cooling effect.
In summer, it can be difficult to adequately and efficiently cool a room with poor window quality because the sun is able to directly influence and heat the temperature of the room.
Combatting the problem of energy loss is a major issue for home and business owners, especially in areas that are subject to extreme temperature fluctuations. A growing number of these consumers are searching for ways to improve their energy efficiency.
To help, a series of ratings exists which can help consumers decide which windows are not only the most energy-efficient, but cost-effective as well. These ratings have been adopted by the NFRC and are displayed on all NFRC-approved windows. At the bottom of the post is a sample label with energy and performance ratings. Source: nfrc.org
About Energy Performance Ratings
U-Factor measures how well a product prevents heat from escaping a home or building. These ratings generally fall between 0.15 and 1.20. The lower the number (factor), the better a product is at keeping heat inside. During winter months, U-Factor is a particularly important rating especially in colder climates. In other countries, U-Factor may be displayed in metric units.
Solar Heat Gain Coefficient (SHGC) measures the amount of heat from the sun that is blocked by a window. Expressed as a number between 0 and 1, ratings closer to 0 indicate better blocking of solar heat gain. Blocking solar heat gain is particularly important during the summer cooling season in hot southern climates (www.nfc.org). Windows with a lower (SHGC) can lessen the effect that direct sunlight can have on a window and improve the ability to efficiently keep a room cool during warmer months. In contrast, people in northern climates may prefer a higher solar heat gain during the cold winter months to lessen the cost of heating a home. Overall, windows with lower SHGC ratings will effectively lower cooling bills and reduce frequent temperature fluctuations.
Visible Transmittance (VT) measures the amount of light that is transmitted through a window. Like SHGC, VT is expressed as a number between 0 and 1. The higher the VT, the more daylight is allowed to pass through the window.
Air Leakage measures how much outside air measures how much outside air comes into a home or building through a window. Air leakage rates generally fall between 0.1 and 0.3. The lower the air leakage, the better a product is at keeping air out. Air leakage is an optional rating, and some manufacturers choose to omit it from their labels.
Other important ratings to consider when researching potential windows include condensation resistance, water infiltration, structural performance ratings, acoustical performance ratings, and security performance ratings. Perhaps the most important is the product’s endorsement from the ENERGY STAR program.
ENERGY STAR is a joint program of the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE). Its official mission is to help consumers save money while protecting the environment through energy-efficient products and practices. The EPA and DOE set strict energy-efficiency guidelines for ENERGY STAR qualified products. In 2012 alone, ENERGY STAR helped Americans save more than $27 billion on their utility bills.
To become ENERGY STAR-qualified, windows, doors, skylights and other products must be independently tested and certified by the NFRC and labeled according to ENERGY STAR climate zones. Manufacturers that are certified ENERGY STAR partners tailor the components of their windows to work most efficiently in these specific climate zones. These climate zones take into consideration typical energy usage and costs within their respected geographic locations.
Here is the official ENERGY STAR climate zone map:
Each ENERGY STAR-approved product is recommended for at least one of these zones. The second image shows the most recently-recommended criteria including U-Factor and Solar Heat Gain Coefficient for residential windows.
The HERO Program
To encourage energy-efficient homes, some utility companies offer rebates for home improvements such as installing new windows. Consumers are urged to check with their local utility company to find out about rebates in their area and to ensure that they are purchasing qualifying products.
Government-assisted programs like California’s HERO (Home Energy Renovation Opportunity) provide special financing opportunities to residential home owners as well as commercial property owners. The HERO program offers 100% coverage of the costs associated with purchasing and installing eligible products.
HERO, like many similar programs, offers low-fixed interest rates, flexible rates for most products (sometimes between 5 – 20 years), and the option to have repayments made through your property taxes each year.
Interest paid on the principal balance is also tax deductible.
There are currently over 150,000 products eligible for HERO financing. Windows make up a large portion of the eligible products and other items include doors, water heaters, lighting fixtures, flooring, and much more.
The HERO program ultimately lowers utility bills by lowering energy consumption and reduces harmful carbon emissions.
Play An Active Role
Energy efficiency is quickly becoming a top priority for not only homeowners and business owners but manufacturers as well. Installing new windows is easier than ever before, and with the help of local government-backed programs like HERO, finding ENERGY STAR and NFRC-approved windows and other home improvement items is quite simple and affordable.
Manufacturers are building their windows to not only meet ENERGY STAR and NFRC requirements, but to meet the rising demand of consumers who are actively taking part in energy conservation and purchasing and installing goods like energy efficient windows. Reliable companies guarantee that all of their products are compliant with the highest of standards and are proud to sell products that not only look great, but help to save money as well as the environment. Replacing windows is one of the easiest as well as the most recommended ways to improve energy efficiency.
About The Author:
Martin Whitmore is the President & Founder of US Window & Door. Established in 1987, the company is one of the oldest exclusive window and door replacement companies that serve the Southern California areas of Orange County and San Diego County. Martin has guided US Window & Door to become one of the most reliable and successful companies of its kind.