Window Replacement Blog

How Energy-Efficient Windows Prevent Heat Loss During Cooler Weather

Depending on the materials used, the lifespan of the average home window currently in place in the United States is anywhere from 15 to 20 years. While high-quality and well-maintained windows can function reasonably well past the upper end of that spectrum, most homeowners begin noticing more and more frequent issues as the years go by. While weathered windows in disrepair are certainly unattractive, a more pressing concern is the loss in energy efficiency that comes with aging windows. 

While it is impossible to completely stop heat loss from windows during cold weather, installing energy-efficient replacement windows is one of the most important steps you can take to reduce your energy consumption – and lower your energy bills. To help you understand this primary benefit of quality replacement windows, we’ve compiled this brief guide to energy-efficient windows and the problems they can solve.

Windows Are a Chief Source of Energy Loss

If your home has aging windows, you may have noticed what seem to be minor issues with the way they’re fitted, sealed, and closed. Poorly fitting windows can provide tiny cracks between the window and the exterior of your home, gaps in the sealant along the outer edges of the frame or sash, or spaces between the frame and sash once closed. While these gaps may seem small when considered individually, multiply them by the number of windows in your home and you’ll soon see how serious the energy losses caused by poorly fitting windows really are.

In fact, the Department of Energy rates windows and doors as the two largest sources of energy loss in your home – even when they’re functioning at an average level. Add in poorly fitting windows – which allow warm air to seep out and cold weather to seep in during cold months – and it’s clear why your HVAC system has begun to work much harder. Eventually, this strain on your system can necessitate additional repairs and cause your energy bills to rise.

How Do Functioning Windows Lose Heat?

Even if there are no existing issues with your window frames or sashes, or cracks in your glass, many older windows were manufactured during a time when far less attention was paid to energy efficiency. In addition, some newer, low-end windows come without essential energy-saving components. These windows can still lose a significant amount of heat to the exterior and keep your energy bills high.

As mentioned, no windows are completely airtight, and even newer, energy-efficient replacement windows will still lose heat to the outdoors – that’s just science. However, if you have older or low-quality windows, chances are, your energy bills are significantly higher than they need to be. In fact, the US Department of Energy states that as much as 30% of your home’s heat may be lost to the outdoors.

Energy Efficient Window Components

To improve energy savings – and thus keeping your home comfortable, reducing your energy consumption, and lowering your energy bills – quality replacement windows utilize a number of different components. Components include: 

  • Argon or Krypton gas. These naturally occurring, invisible gases are known as inert or noble gases, most of which are extremely stable. Energy-efficient windows include two panes of glass or more and utilize one or both of these gases to fill the space between them. These gases are denser than naturally occurring air, which is a mixture of Oxygen, Carbon Dioxide, and a number of other gases, and thus have more tightly packed molecules per square inch. This “heavier” air insulates the window and prevents heat energy from escaping your home.
  • Low-e glass. Specialized glass, known as low-emissivity or low-e glass, includes a very thin coating usually applied to the interior pane of glass. The layer provides additional protection against heat loss and can actually reduce loss by as much as 30%. Fortunately, as low-e technology improves, this coating has become thinner than the width of a human hair and is virtually invisible on the window itself.
  • Weatherstripping. A key area many poorly constructed windows lose heat is between the moving components of the windows. Energy-efficient windows include quality weatherstripping to prevent unnecessary heat loss. This component can be made of metal, vinyl, felt, or foam, depending on the window’s construction.
  • Insulation and Caulking. While not a component of the window itself, quality insulation and caulking are applied by your replacement window installation company. Both help to seal the area between the stationary components of your windows and the surrounding portions of your home’s exterior. When applied under ideal conditions, caulking prevents cold outside air from entering your home through the window frame.

How Can You Tell If Your Replacement Windows Are Energy-Efficient?

When you’re purchasing a set of new, energy-efficient replacement windows, you’ll want to make sure they are rated as such by the Department of Energy. Look for these two rating factors when choosing energy-efficient replacement windows for your home: 

  1. U-Factor. This ratings system describes how well the windows in question perform while preventing heat loss to the exterior during the cooler months. Values range from .14 to 1.20; a lower U-factor number indicates less heat lost to the outdoors, while a higher U-factor number means you’ll release heat easily during the winter. Look for windows with a low U-factor rating for superior energy efficiency.
  2. Solar Heat Gain Coefficient. This ratings system measures how well your windows block incoming heat generated by sunlight. Values range from 0 to 1, with the higher end indicating a window that allows heat entry. Whether you want a high or low solar heat gain coefficient depends on the climate in your region since a high number can allow in too much heat during the summer months. However, if you live in an area with cold winters, you’ll want to allow in some heat to help your home heat with natural light.

Quick Energy Savings Tips

Once you’ve made the decision to invest in energy-efficient replacement windows for your home, it’s important to schedule a replacement as soon as possible to optimize your energy usage and lower your bills. Until replacement day, utilize these tips to help improve energy efficiency: 

  • Replace caulking and weatherstripping. If you have a problem window with large draft entry points, reinforce caulking and weatherstripping elements to slow heat loss. 
  • Utilize window coverings. Keeping curtains and blinds open on cold days and closed in the evenings can allow natural sunlight to warm your home and prevent heat loss in the evening. 

Most other ways to improve energy efficiency – including installing exterior awnings and purchasing storm window panels – can be cost-prohibitive and time-consuming. In most cases, replacement windows are a much better investment. Speak with a local contractor today and take the first steps towards a more energy-efficient home. 

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