How Many Panes of Glass is Enough for Replacement Windows in San Diego?

Not too long ago, there was basically one option when it came to windows for your home—single-pane windows. Now, you can get a single pane, double pane, and even triple and quadruple pane windows for your San Diego home. But do you really need three or more panes of glass for maximum energy efficiency? Well, that question is a bit more complicated than it seems on the surface.

Read on, and we’ll try to take some of the confusion out of shopping for energy-efficient windows in San Diego.

Single Pane Windows for San Diego Homes

If you have an older home with original windows, they are most likely a single pane, with either an aluminum or a wood frame.

triple-pane-window-installationAnd while they may be in good shape, they probably don’t do a very good job of keeping the interior of your home comfortable in extreme weather.

If you replace them with newer single-pane windows, you will see some improvement because of improved window frame technology, but the panes themselves will continue to allow cold air in during the winter, and heat in the summer. This can be improved, however, with the addition of a low-E coating or tint on the glass.

If you’re on a budget, but want increased energy efficiency in your home, you may want to consider weatherproofing your current single pane windows rather than replacing them with new single-pane windows. This can get you by as you save up for more energy-efficient double or triple-pane windows.

Double Pane Windows for San Diego Homes

Double pane windows contain two panes of glass. The space between the two panes of glass is filled with air or a gas, such as argon or krypton, for greater energy efficiency. Higher quality double-pane windows may also have a warm edge spacer to keep the panes spaced at the correct distance from each other, while also insulating the pane edges and reducing the amount of heat that is transferred through the window. In general, a double-pane window will insulate about two times better than a single-pane window.

Triple Pane Windows for San Diego Homes

Triple pane windows can further increase the energy efficiency of replacement windows. By adding a third pane of glass and an additional layer of air or gas between the panes, triple pane windows are great insulators. However, there are instances where certain higher-quality double pane windows can outperform some triple-pane windows when it comes to energy efficiency, so don’t just assume that triple pane windows are the best choice. Look carefully at the energy performance numbers.

There are also quadruple pane windows on the market, but the difference in performance between triple and quadruple pane windows is usually negligible, and probably not worth the higher cost.

U Factor and SHGC Ratings Explained

Most windows on the market will be labeled with energy performance ratings.

Insulated-triple-glazing-cross-sectionYou can also ask a San Diego replacement window company for those numbers for each of the products they sell.

One of the most important factors to look at when shopping for replacement windows in San Diego is the Solar Heat Gain Coefficient (SHGC).

This measures the ability of a window to keep solar heat out.

SHGC is expressed as a number between 0 and 1, with a lower number being better.

You will also see a U factor number when you are researching replacement windows. This number tells you how much heat is lost through the window. In general, most windows will have a U factor rating between 1.3 and .2, with a lower number being better.

Since the San Diego area doesn’t experience extremely cold temperatures, the U factor rating is less important than the window’s SHGC number, but should still be taken into consideration.

What About ENERGY STAR Windows?

ENERGY STAR windows are those that are manufactured by an ENERGY STAR partner company, of which there are more than 300, including all of the major replacement window brands sold in San Diego. ENERGY STAR windows are inspected and certified by the independent National Fenestration Rating Council (NFRC) as having ratings that meet the energy efficiency guidelines set up by the Environmental Protection Agency (EPA).

ENERGY STAR criteria for windows vary by location, but in San Diego, replacement windows must have a U Factor of .30 or less and an SHGC rating of .25 or less. Most programs offering rebates for energy-efficient upgrades require that you install ENERGY STAR window products in order to qualify for the rebate.

Comparing Apples to Apples

When you are looking at the energy performance ratings of the various replacement windows you are researching, make sure you are looking at windows of the same size to make your comparison. U factor and SHGC ratings can vary based on the ratio of glass to framing material, so the performance ratings can be different even among windows within the same product line. So, if you are looking at the energy specifications for a 3’x5’ replacement window from Anlin, make sure you are comparing it to 3’x5’ windows from other window manufacturers.