The Definitive Guide to Making Your Windows More Energy Efficient

First-time homeowners have plenty to enjoy about their investment. Whether it’s the freedom to make upgrades to your home at will or simply settling into the realization that you may never have to move again, the benefits of home ownership are clear and well-established. But that first year of occupancy is also a test bed for the rest of your time in the house. You’ll have a full year to experience each season’s impact on your home’s energy bills and discover the smaller details that weren’t covered on that open house tour, making the second year of home ownership the ideal time to begin planning improvements and exploring ways to save money in year two.

Your home’s first line of defense against the forces of the outside world is not, in fact, the exterior doors. More generated energy will escape your windows than in any other element of your home, accounting for thousands of lost BTUs per hour.

Homeowners have several options to improve your windows and boost your home’s overall energy efficiency at the same time, though each strategy has its strengths and weaknesses – and associated costs. 

Get a Home Energy Audit

home energy audit

We can’t stress this enough – until you understand the strengths and weaknesses in your home’s energy efficiency portfolio, you’ll never be able to adequately correct its deficiencies. While making improvements and upgrades like installing a new furnace or putting in new windows may feel like its the right thing to do, the savings may not become clear for a much longer time if these older features are still operating well.

A home energy audit is a great way to get a better grasp on your home’s energy efficiency capabilities and shortcomings. A professional audit is an intensive, on-site inspection of your home’s energy features that will leave you with a report on the quality and efficacy of your home’s energy plans. While DIY and online resources are available and much more affordable than an in-person assessment, the results won’t be quite as reliable as a professional home energy audit, which can help you on several fronts.

First, you’ll have a clearer picture of the requirements necessary for a complete energy efficiency remodel, as the audit will provide details about each function in your home and its current status. More importantly, however, your audit may be used as a basis for approval of a home improvement loan. If you’re serious about making energy-friendly upgrades to your home and plan to use a loan to finance the project, investigate the various options from lenders before you schedule an audit, as some loans have specific requirements for home energy audits.

Repairing Existing Windows

old windows

Before you set about ordering new window panes for the entire house, it’s important to give equal consideration to each window. Many homeowners will consider the aesthetic discrepancy in being selective with what windows to replace and which to repair, ignoring perfectly good windows (or those requiring only minimal repairs) to return to proper function. If you’re unsure which windows are still suitable for use, this chart is a great resource to analyze and compare your options.

Why Keep My Old Windows?

In older, historic homes, replacing the original windows with energy efficient, modern panes can not only compromise the aesthetic value of your home, but may violate standards for those living in National Register Historic Districts or Conservation Districts.

Furthermore, the costs associated with bringing existing glass up to current energy efficiency standards is far less than the costs of complete window replacement. When combined with other weatherization techniques, repairing original windows can result in significant energy savings. Portland, Oregon’s Irvington Community Association has a wonderful guide to repairing and restoring old windows to near-new performance. 

Replacing Windows

new windows

Homeowners get very excitable when it comes to replacement windows. The appeal of marketing speech and statistics about increased savings make even decade-old windows sound old and decrepit by comparison, but experts say replacing windows isn’t always the way forward to achieving improved energy efficiency and seeing a return on your energy costs. A home energy audit (as described above) can provide insight into the potential energy saved and the period by which you can expect to be paid back for the costs of replacement windows on your energy bills. Otherwise, repairing damaged glass, seals, frames, or applying weather stripping are almost always the preferred option.

If you do opt for partial or complete window replacement around your home, you’ll need to do your research carefully before selecting a particular brand and model for your home, region, and climate.

Understanding Energy Efficiency Labels

Energy efficiency labels on new windows contain information from Energy Star and the National Fenestration Rating Council or simply the NFRC on its own (no Energy Star-rated windows come without another rating from the NFRC). If you see both, you know you’re on the right track.

Depending on the location and climate of your area, your Energy Star ratings may be very different than in other areas. In the northern section of the United States, windows must suit heating requirements for homes in colder climates before they can earn Energy Star ratings, whereas windows designed for the south should meet specific cooling requirements.

Each window seeking Energy Star status undergoes independent testing, certification, and verification by the NFRC, which tests the following criteria:

  • U-Factor: Measures the rate by which heat is transferred to a window and the degree to which a window will insulate. U-factors range from 0.25-1.25, with the lower number signifying better performance in preventing heat from escaping or entering the home.
  • Solar Heat Gain Coefficient: Measures the amount of solar energy transferred through a window and how well a window blocks heat gain. The value ranges from 0-1 and the lower the number on the window, the less solar heat is allowed.
  • Air Leakage: Measures the rate by which air passes through the joints in the window using cubic feet of air per square foot per minute. A rating below 0.30 is considered optimal for reducing air leakage.
  • Visible Transmittance: Measures the amount of light a window lets in ranging from 0.20-0.80. The greater the number, the more natural light is allowed.
  • Condensation Resistance: Measures the window’s performance in resisting water, condensation, and moisture from 0-100. The greater the value, the more resistance the window has against condensation.

Cellular Shades

cellular shades

A stylish and effective upgrade to existing glass, adding cellular (or honeycomb) shades to your home is a great way to improve energy efficiency, keeping your home warmer during the winter and cooler in the summer months. Cellular shades slow the transfer of visible light, UV radiation, air flow, and radiant heat gain and loss.

Small pockets of air in the material of the shades themselves act as thermal buffers between your home and the forces exerted on your windows. Some reports state that the R-value of your windows can be doubled simply by adding a cellular shade.

Plantation-Style Shutters


Physical window shutters remain among the most effective ways to limit visible light transference and insulate windows against unnecessary heat loss or gain – the problem comes with an all-or-nothing approach that leaves some homeowners in the dark.

By diffusing light, the adjustable vanes within the shutters will reduce brightness indoors without completely sacrificing the view of your outdoor areas. When closed, shutters block the maximum amount of light possible and ensure complete privacy. Artificial or synthetic materials tend to perform better than wooden shutters, which are more likely to warp and show signs of wear.

Drapes and Curtains



Most drapes are considered primarily as interior decor statements, but the functional aspect of fabric drapes and curtains can save a ton of generated energy.

Drapes with blackout or thermal lining are particularly effective at shutting out cold air, but as with shades and shutters, they aren’t as effective when they’re open. When used in conjunction with other forms of window coverings, like cellular shades or wooden blinds, you can let sunlight in during daylight hours and shut out cold air at night. Depending on the type of fabric and thickness of the lining, drapes can improve R-values by 3-5.

DIY Projects



A little elbow grease and problem-solving can go a long way to improving the energy efficiency of your windows and doors. Adding storm windows or panels, insulation panels, insulating curtains, thermal panels, and even window quilts can drastically improve the energy efficiency of your home.

For a detailed guide of nearly every creative, functional DIY project to improve your window’s energy efficiency, visit Build It Solar.

Window Film


Even if your windows are brand-new, energy efficient, and Energy Star rated, you’re not doing all you can to save money on your energy bills. With a layer of protective solar control window film, you’ll experience a dramatic improvement in the consistency in room temperature, reduction of glare, and decrease in your energy costs.

Simply by adding an airtight layer of window film to your glass creates a protective seal, further limiting the amount of air allowed to pass through your windows and preventing shattering in the event of a break-in or natural disaster. Different types of window film perform better than others, but solar control films have been proven to reduce heat loss by as much as 30%.

Different Styles of Window Film 

  • Low-E Window Film: Provides greater insulation value on par with a second pane of glass. Provides high visible light transmission without noticeably changing appearance. Protects furnishings from harmful UV rays and therefore fading.
  • Solar Control Window Film: Reduces cooling costs by up to 30% and blocks up to 99% of UV rays. Keeps consistent temperatures between rooms and improves visibility indoors by reducing glare.
  • Safety and Security Window Film: Thicker than most window films, safety and security films offer varying degrees of protection against broken glass, forced entry, impact, and severe weather. Not typically rated for hurricane-force winds and debris impact.
  • Decorative Window Film: Decorate options for interiors and exterior signage or branding. Frosted films improve privacy and reduce the “fishbowl effect.” Ideal for interior office spaces, bathrooms, and street-level homes or offices.

For more information on improving your home’s energy efficiency, contact Brower Tinting and Graphics today.


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