Green Industry Articles

Energy Efficiency - A Window Crash Course

If some concepts, like U-factor and SHGC, are fuzzy, you're trying to explain the long-term benefits of energy efficient windows, or you need to get up to speed on the latest developments in window technology, spend an hour listening to GRC's July 2011 Webinar.

Nils Petermann and Neal Humphrey, both of the Alliance to Save Energy (ASE), offered a bit of a crash course on efficient windows and delivered useful insight that you can use to help clients who are weighing window decisions.

Consumer Concerns

The ASE's consortium, the Efficient Windows Collaborative (EWC), comprises manufacturers, home performance contractors, research organizations and others focused on promoting high-efficiency windows in both the residential and commercial sectors.

Petermann and Humphrey outlined the main benefits of efficient windows. For one, in the average U.S. home, windows contribute to about 25 percent of heating energy use and about 35 percent of cooling energy use. By tapping current, cost-effective technologies, about half of that
energy use can be saved.

The two also shared some EWC research on consumers' main concerns about windows. You're likely to encounter some of the same issues among your clients. They include:

• Which windows are good for saving energy?
• Questions about specific window options, such as triple pane and passive solar.
• Availability of incentives, tax credits, and so forth, for new windows.
• Options for increasing efficiency without doing a full window replacement.

Reading Labels 101

The Webinar can help you address some of the above concerns, and the one-hour event also offers:

• A refresher on the components-- number of panes, low-E coatings, spacer type, gas fills, frame material and construction--of an efficient window.
• An outline of what to look for in windows, how to compare products, and the rating systems that are in place.
• Some guidance on the labels that the National Fenestration Rating Council (NFRC) has developed at Such labels, according to Petermann, give you a way to make apples-to-apples comparisons among windows.
• The basics of what's on window labels, including U-factor, solar heat gain coefficient (SHGC), visible light transmittance (VT), air leakage (AL), and condensation resistance (CR) ratings and what they mean.
• A strategy for assessing whether windows are efficient when no labels are available.


Added Value

Beyond reading labels correctly, Petermann also noted the importance of climate and a building's design and orientation, which are two things that can be controlled best in new construction.

For example, windows' performance can be enhanced by considering window area and shading. And specifying efficient windows has a ripple effect. For one, it can lower heating and cooling demand and that allows homeowners to consider installing smaller HVAC equipment.

Money Matters

Of course, how to finance such improvements remains a primary focus among homeowners. Humphrey outlined some of the tax credits that are still available for energy efficient improvements to existing homes.

For example, there's a Federal tax credit (up to $500) for energy efficiency improvements in existing homes, and Energy Star windows qualify for 10 percent of the purchase price, up to $200.

There also are always local utility and state rebates and loans to consider. For a list of window incentive programs in 41 states, click here.

Compelling Dollar Figures

But are your clients skeptical about the long-term costs savings associated with energy efficient windows?

One slide in the presentation provides a compelling snapshot of just how much savings are possible by choosing Energy Star-qualified windows over single- or double-pane clear glass windows.


Potential savings are charted by region. In New England, consumers could potentially save $293 in annual energy costs, whereas those in California could see savings of $75.

Source: Green REsource Council Newsletter, July 2011