Choosing New Windows

Mar 10, 2010 | Energy Efficiency

Snapshot | Savings | How to choose | Incentives | Take action!

Snapshot

An older window in San Francisco: metal frame, sagging weatherstripping and single pane glass.

Photo: WattzOn

Windows can be a weak spot in your home's defense against outside temperatures. Windows let out the heat in the winter, and allow too much heat gain in the summer. Plus, they can leak a substantial amount of air through drafts in the window frame and installation. Replacing some or all of your windows can improve comfort and save energy.

For the best energy savings and comfort improvements, start with the windows on the South and West of your home, and those in the rooms where you spend the most time.

Windows are now an advanced technology with several benchmarks for energy efficiency. Look for double-pane windows that meet the ENERGY STAR criteria for your area. (See below for more information.)

Find a recommended installer. Installation quality is key to window performance.

Savings

Stand next to a window on a cold day, and you can feel the heat loss: There's a pocket of cool air next to an older window. Or stand next to a window on a hot day, and you'll feel the pocket of hot air. It's no surprise that heat loss and heat gain from windows adds 10% to 25% to our energy bills for heating and cooling.

Replacing windows will improve comfort and lower energy bills. Don't look for a quick financial return, however.

Location matters. Windows on the south and west sides of your home face the sun on those long summer afternoons, so if summer comfort is the problem, replace these windows first. If winter comfort is the main problem, start with your windows in the rooms where you spend the most time in addition to those on the south and west sides.

Federal tax incentives are available, see below. Be sure to choose windows that meet the tax criteria; not all ENERGY STAR products qualify.

How to choose With windows, it is all about the details. The graphic below shows the 5 areas where windows are rated by the ENERGY STAR program.

Source: ENERGY STAR

The ENERGY STAR program specifies minimum technical criteria a window must meet by climate zone. In the Bay Area, cities and towns along the coast, including San Francisco, are part of the North-Central climate zone. Cities and towns around the bay and further inland are part of the South-Central climate zone.

The minimum window performance standard to be ENERGY STAR qualified in these 2 zones are:

Region U-Factor SGHC North-Central less than 0.32 less than 0.40 South-Central less than 0.35 less than 0.30

The U-factor measures the insulating quality of the window, and a lower number is better. SGHC stands for Solar Heat Gain Coefficient, and it measures how much of the sun's heat passes through the glass. Again, a lower number is better. Another criteria for window performance is "low-E," which refers to a rating on how much heat the window reflects back inside. (There are no ENERGY STAR benchmarks for low-E, but standard low-E windows have U-factors between 0.30 and 0.40, and SGHC of 0.55 or less.)

Choosing new windows can be a bit daunting. As with many energy-efficient products, installation quality is a key determinant of energy savings. Call WattzOn to get a recommendation for a reliable product and installer.

Incentives

None of the Bay Area utilities offer rebates for windows at this time. Federal tax credits are available.

Take action!

Install double-pane windows

Want to talk over your options? Still have questions or concerns? Want to find a quality contractor?

Speak with a WattzOn Green Home Expert for free. 1-800-314-5997

We are your free, independent, qualified, green home energy experts. We don't sell windows, furnaces or insulation or anything else for that matter. What we do provide is informed, expert and unbiased guidance on your best and most-effective opportunities to save energy, save money and make your home more green. We can recommend products, but we don't get paid by manufacturers. We can also connect you to our network of qualified and verified local green home energy auditors and green home contractors who do great work. Keywords: windows, double pane windows, double-pane windows, energy efficient windows, replacing windows, replacement windows, new windows, energy efficient windows, energy-efficient windows, low-e windows, triple pane windows, how to choose new windows, window contractors, low-e glass, window rebates, window tax credit