So many factors affect the energy performance of a window that it’s impossible to simply label the products good, better, and best. The direction of the sun, the amount of light you need in a room, and other considerations should all be factored in when choosing new windows.
The ideal for energy efficient replacement windows is typically a gas-filled, double-pane glass with a tightly sealed vinyl frame — installed by a professional so you get the anticipated efficiency. Let’s explore what all the ratings and specs mean, and if you have any questions about choosing new windows, let us know!
Energy Ratings: U-Factor and SHGC
Windows have their own rating systems that help you compare different products. Similar to the “R-value” of home insulation, energy efficient replacement windows can be graded by a “U-factor” and “SHGC.”
- U-factor tells you how much heat is let through by the glass. For energy savings, you want to keep out the temperatures from the outdoors and keep in your cooled or heated air. Thus, a low U-factor is best in all seasons.
- SHGC stands for solar heat gain coefficient, which is a fancy way of saying how much solar radiation passes through the glass. Ever notice a room heating up from sunlight even though it’s cold outside? A low SHGC means that excess heat gets blocked.
Boost Savings & Comfort: Sealed Gas Fills and Low-E Coatings
These are the other two big factors in choosing energy efficient replacement windows. For better performance over time, your double pane glass needs to a strong vacuum seal. This allows for minimal air leakage and maintains the gas fill between the panes.
Low-E coatings block out even more harmful rays, preventing summertime heat-up and UV damage to your furniture. In winter, interior low-E coatings also help keep your home’s heating inside.
Windows that Block Heat without Blocking Light
You want more than just energy savings. Fortunately, today’s energy efficient replacement windows can let natural light flow through without all the sun’s heat coming in.
Some windows have an LSG rating (light-to-solar gain) so you can judge how well the window provides natural light. A high LSG means you have energy efficient replacement windows that maximize light.
Another rating you might see is VT — visible transmittance — which uses a scale of 0 to 1 where a higher number means more light.
Style & Function: Which Energy Efficient Replacement Windows Are Right for You?
Prioritizing energy efficiency does not mean you are very limited in your choice of new windows. Whether your home is Victorian, stucco, Spanish Revival, or midcentury, your new windows can look the way you want while still hitting all the marks for eco-friendly performance!
And for the mild Bay Area weather, we also recommend considering windows that you are comfortable opening and closing — ventilation is often the biggest energy saver. Ask about casement windows (with a crank to open them slightly) to allow a breeze and also close as tightly as possible.
Installing Energy Efficient Replacement Windows
Finally, windows perform their best when installed properly. You could buy the most expensive windows at the store, but a sub-par installation could lead to terrible air leakage.
Talk to us your local experts about the best energy efficient replacement windows for our area and ask about professional installation for the best results.