Improved Simulation Tools Help Users Optimize
Tools to evaluate facade design, such as COMFEN, provide a cost-effective
and simplified solution to whole building energy analysis, said Sneh Kumar,
manager of Department of Energy Projects at Traco in Cranberry Township,
Pa., during a recent presentation.
Kumar was one of several speakers during the National Fenestration Rating
Council (NFRC) presentation, "Key Tools for Commercial Window Energy
Performance," at Ecobuild America in December, in Washington, D.C.
"Nonresidential buildings consume 15.5 quadrillion BTU of primary
energy or 16 percent of all energy used in the United States," said
Nils Petermann, project manager of Efficient Windows Collaborative in
Washington, D.C. "Fenestration consumes 32 percent of that primary
energy. On average, only 30 percent of all nonresidential buildings use
Ray McGowan, senior program manager at NFRC, discussed the different NFRC
tools available to determine fenestration energy properties. There are
three kinds of tools, he said: fundamental, intermediate and advanced.
Fundamental tools, such as Therm, Window and CMAST, and intermediate tools,
such as COMFEN and Radiance, are used on fenestration components and systems,
and advanced tools, such as EnergyPlus and DOE-2, are used on buildings
"The Therm and Window tools, used for residential products, have
seen 95 percent manufacturer participation," McGowan said. However,
he noted, "CMAST, used for commercial products, has had almost no
certification and only 85 users in two years."
Kumar elaborated on COMFEN, developed by the Lawrence Berkeley National
Laboratory (LBNL) in Berkeley, Calif. "Fundamental performance indices
of fenestration products-for example, U-value, solar heat gain coefficient
(SHGC), visible transmittance, condensation resistance, air-leakage, etc.-are
good for comparing products, but they do not provide information about
the extent of impact on the building's annual energy, peak loads, daylighting,
or thermal and visual comforts. Building designers need this information
in order to select the most energy-efficient and cost-effective fenestration
solution for their application."
COMFEN has come a long way since its initial versions, Kumar said. "This
tool is being continuously improved by LBNL," he said. "Some
of the impressive features of COMFEN are the daylighting and comfort evaluations
built in COMFEN. It does daylight illuminance calculation to show the
illuminance level in the façade boundary areas for a specific date
and time. It takes into the account the effect of any overhand, fins,
shading or attachments on daylighting, besides energy."
Thermal and visual comfort indices also are calculated for various design
options, Kumar said. The COMFEN library has expanded with predefined façade
component library, such as glazing, frame, wall, shading systems and spandrel.
Industry Stands to Benefit from New DOE Determination
With the Department of Energy's (DOE) determination that the adoption
of ASHRAE 90.1-2010 would reduce energy use by 18.5 percent compared to
the 2007 version of the code, the market for high-performance glazing
and framing systems looks poised to jump up.
In November, DOE officials announced that analysis shows that implementing
the 2010 version of Standard 90.1, Energy Standard for Buildings, Except
Low-Rise Residential Buildings, will save commercial building owners energy,
help them meet sustainability goals and reduce carbon pollution.
"The DOE findings are aligned with the current glass and glazing
industry trends of working towards more high-performance, energy-efficient
products," says Urmilla Jokhu-Sowell, technical director of Glass
Association of North America in Topeka, Kan. "The 2010 version of
ASHRAE 90.1 incorporates the use of high-performance glass and glazing
products and dynamic glazing, and also encourages proper daylighting design."
When DOE issues a final determination, states are expected to review the
new code provisions and update their building code to meet or exceed the
energy efficiency of the new standard within two years.
© Copyright 2012 Key Communications Inc. All rights reserved.
No reproduction of any type without expressed written permission.