A free online tool from architectural glass fabricator Viracon, Owatonna, Minn., can help architects and building owners calculate the energy performance and cost savings of different glazing.

The new Product Selection Tool makes it easy to figure energy costs, peak demand, carbon emissions, daylight, glare and thermal comfort for various geographic regions, building orientations and glass configurations.

It is one of only a few tools that calculate cost savings and carbon emissions per square foot of glass, says the company.

Viracon says using the calculator is more accurate than using only U-factors and solar heat-gain coefficients.

“While these numbers are useful, they don’t relate energy performance to the building’s orientation and climate zone,” says Don McCann, Viracon architectural design manager. “Our new tool puts all these factors into context and gives building owners realistic square-foot-dollar comparisons to help them evaluate which type of glazing will have the highest energy payback.”

Kerry Haglund, a sustainable-design researcher, says, ”This tool is unique in that it is designed to be used early in the process for early decision making. It is the only tool available that allows users to compare and rank different glazing products.”

Haglund worked with fellow researcher John Carmody to develop the Viracon software program. All simulations were done using COMFEN by the staff at the Windows and Daylighting Group at Lawrence Berkeley National Laboratory (LBNL).

“We found that a lot of decisions that can have a significant impact on a building’s overall energy performance are made early in the design process by architects, consultants and building owners without the aid of sophisticated engineering tools,” says Stephen Selkowitz, head of the Building Technologies Department at LBNL. The Viracon Product Selection Tool is easy to understand and operate. It allows users to very quickly compare alternatives and focus on solutions that may be appropriate to their project.”

The tool is at www.viracon.com.