ASHRAE, ANSI, the U.S. Green Building Council and the Illuminating Engineering Society recently released the 2014 version of the green building standard. The new version, Standard 189.1-2014, “Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings,” includes some implications regarding glass and fenestration.

“One change was in how they set the prescriptive envelope requirements, including windows,” says Tom Culp of Birch Point Consulting. “Rather than develop the traditional tables of criteria for each zone and each product type, ASHRAE 189.1 now just sets its requirements as a set percentage better than ASHRAE 90.1.”

In the new standard, the U-factor is set for 10 percent lower than the ASHRAE 90.1 value in all zones, which Culp says will encourage more efficient products–including higher performance framing, warm-edge spacers, argon gas fill, and fourth-surface low-E coatings–but without requiring triple glazing.

For solar heat gain coefficient (SHGC), the standard considers how SHGC ties into building orientation and daylighting, so SHGC is required to be 10 percent lower only on the west and east sides of the building, and no lower than 0.25.

Another alteration to the standard was the addition of Environmental Product Declarations (EPD) in the material requirements section, similar to LEED and the new International Green Construction Code’s inclusion of EPDs. Culp says that as the standard is adopted, manufacturers and the glass and fenestration industry will start to see more requests for EPDs on their products.

The new standard also strengthened its requirements for onsite renewable energy, which often comes in the form of rooftop solar panels or building-integrated photovoltaics—which ties to the glass and glazing industry.

“An onsite-renewable system that provides between six to 10 kBtu per square-foot of roof area is required, unless the building does not receive a minimum amount of solar incidence due to shading, building location, etc.,” says Culp. “In that case, they still have to purchase renewable energy credits, which still can include photovoltaics on other buildings, or off-site solar farms.”

Additionally, one of the biggest aspects of the standard is what didn’t change–the window-to-wall ratio reduction that was proposed.

“As reported last January, the proposal that would have reduced the glazing area allowed under the prescriptive path by 25 percent was defeated,” says Culp. “This was a huge issue, and the entire industry joined together along with daylighting and other building science experts to show how the proposal was actually counter to high performance building design, daylighting, and occupant well-being. The committee agreed, and withdrew the proposal.”

2 Comments

  1. Nice and very informative …need more on Green Building for Hot climate

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