In an effort to keep its Energy Star label relevant, the Department of Energy is tightening Energy Star criteria for windows, doors, and skylights. Beginning in January 2010, these products will need to meet more stringent standards for the rate of heat loss (U-factor) and solar heat gain (solar heat-gain coefficient, or SHGC) to qualify for an Energy Star rating. For example, the maximum U-factor for qualifying windows in the northern climate zone has been lowered from 0.35 to 0.30 (see chart, below). In the southern zone, the extensive current SHGC trade-off menu for windows with different U-factors has been simplified to a one-size-fits-all maximum value of 0.27.
The Department of Energy has simplified the qualification standards for Energy Star windows across its four climate zones. Choices in the northern zone would allow building designers to balance slightly larger U-factors against increased solar heat gain, though it is not clear whether windows with the higher SHGC values will be widely available. New standards for skylights and glazed doors can be found at energystar.gov.
While Energy Star was originally intended to provide above-code guidance for choosing windows and doors, more than 28 states now have energy codes that meet or exceed its existing standards. “Energy Star barely beats the code in many states,” says Richard Karney, the program’s products manager. The new standards are designed to be more stringent than the 2009 version of the International Energy Conservation Code (IECC), the model energy code that states seeking a share of $3.4 billion in energy assistance grants under the federal stimulus package are required to adopt.
Indeed, the overhaul is meant to realign Energy Star criteria with the stimulus package’s tax credit requirements for energy-efficient windows, says Karney. But the Obama administration’s plan actually jettisons Energy Star’s four climate zones and climate-specific standards and instead requires that all windows in all zones have both a U-factor and an SHGC of 0.30 or less to qualify for the 30 percent Section 25C IRS credit. Calling the “30/30” standard “arbitrary,” Window and Door Manufacturers Association president John Stoiber says his organization is lobbying Congress to amend the law to reference the newly released Energy Star standards.
Most manufacturers will be able to meet the new requirements by offering different glass packages with inert gas fills and low-E coatings, according to the DOE. Meanwhile a more robust multiyear study and overhaul of Energy Star standards is also in the works, which the DOE expects to roll out in three or four years. Industry experts believe that those standards will require extensive product re-engineering and predict wider use of triple glazing, especially in northern climates. — Andrew Wormer
Filed under: Green Building, Products | Tagged: Energy Star, Window
