Gone are the days when a homeowner's interest in windows was limited to whether they could find stylish window treatments. Today, energy-conscious homeowners want to minimize the costs of heating and cooling their homes, and selecting the right windows is a crucial step. So how far should you go when choosing energy-efficient windows? The key is knowing what window upgrades will give you the biggest bang for your buck without delivering a blow to your bottom line.
There are four factors to consider when choosing energy efficient windows: frame, glass, design and installation.
Most people know a wood frame is less prone to heat and cold transfer than an aluminum one, since metals conduct temperature much more easily than wood. But that doesn't mean wood is always the best choice for a utility-bill-friendly window. There are a variety of materials available for window frames, and each has positive and negative aspects. It's up to you to decide what's best for your style and your budget.
While the material each window is constructed from is important, the reality is most recent window-related buzzwords are all about what's inside the frame. But what do all these upgrades mean for homeowners?
John Lala, president of Rycorp Construction in Virginia Beach, Va., is familiar with the gamut of efficient window options. He's built houses in all price ranges, from bare-bones-basic structures to million-dollar-plus projects with very eco-conscious clients. And after seeing everything out there and talking to lots of homebuyers, he says he ends up using windows with the same basic energy-efficiency features in most of his projects.
"A double-paned window with Low-E glass, with a vacuum-sealed argon fill — that's what people ask for," he says. "It's an extra $40 or so per window for me to add these features, and they really do make a difference in a home's utility bills." John says he's found that doing anything more, like using triple-paned glass or denser gases with greater insulative properties, "just adds cost and gives diminishing returns in efficiency."
So what exactly are you getting when you choose a window with the aforementioned options? "Low-E, argon-filled, double-paned windows provide significantly more insulation than a single-pane window," explains Kendra Weinisch, a residential energy efficiency consultant in San Jose, Calif. "These windows protect the inside of the house from the sun's heat and UV rays in the summer, and they prevent heat from escaping during winter. From the standpoint of energy efficiency and value, these types of windows make a lot of sense."
Kendra adds that while triple-paned windows may be notably more efficient in especially harsh winter climates, they can also reduce the window's visibility and light transmittance.
You shouldn't have to look much further than a window's glass to find out what the unit's efficiency features are. All windows in the voluntary Energy Star program will have a sticker on them with ratings from the National Fenestration Rating Council (NFRC). To qualify for Energy Star status, window manufacturers have to meet standards on these two main metrics:
For both U-Value and SHGC, the lower the number, the better the window should perform.
Some window designs are inherently more efficient than others. The most common types:
Finally, don't overlook the importance of proper installation. Even the most expensive window unit won't perform effectively if it's not installed correctly. Jim says to be wary of any contractor who relies too heavily on expanding foams or sealants to get a window to fit well — these materials aren't waterproof and can lead to problems down the road. Pre-installation waterproofing, often completed long before windows are installed, is the best option, he says.
Flashing and proper caulking may be the cheapest parts of window installation, but if they're not done with an eye to detail, the ensuing water leaks will cause a barrage of problems that could have been easily prevented.