Guide to Glass Codes
Volunteer to save energy
Gearing up for commercial standards, feds bring
energy-efficient fenestration to the fore with technology and tools
Backed by the U.S. Department of Energy, the nonprofit National Fenestration Rating Council in Silver
Spring, MD, has become a major force in setting energy standards for residential windows. In 2001, NFRC
officials and volunteer leaders began discussing the extension of those standards to commercial windows and
curtain walls, discussions that continue to this day (see story, p. 28).
“It appears that NFRC leaders fully intend to have a commercial component with energy standards not
unlike those on the residential side. These voluntary standards will be like others in the commercial realm, and
we know from experience that they tend to eventually creep into more formal codes. At the same time, commer-
cial windows are more complicated than residential ones, so at this early stage, DOE funds research to develop the
measurement tools and products that will help manufacturers build energy-efficient windows,” says John Car-
mody, director of the Center for Sustainable Building Research at the University of Minnesota in Minneapolis.
By Valerie Block
s ince its creation in 1977 under President Jimmy
Carter, the U.S. Department of Energy has found
numerous ways to partner with the nation’s glass
industry. During the last five years, DOE has con-
centrated on developing software and design tools
that support the widespread use of low-emissivity
glass and operation of the National Fenestration
Rating Council in Silver Spring, MD, a nonprofit,
public-private organization that provides consistent
ratings for windows, doors and skylights.
cient products, DOE officials have laid the ground-
work for realizing two challenging goals: zero net-
energy use in homes by 2020 and zero net-energy
use in buildings by 2025.
To achieve these goals, DOE officials have
adopted an aggressive multiyear plan that empha-
sizes new product development. In this area,
dynamic glazing that can adjust to daily and seasonal
solar conditions and market-viable super-insulating
glass appear to hold the most promise.
Through support of energy standards, develop-
ment of software tools and sponsorship of market- The Merion Station, PA, author provides consulting services to
ing programs to attract consumers to energy-effi- trade associations and companies.
With the support of the U.S. Department of Energy, a book titled Window Systems for High-Performance Buildings is
now available from W.W. Norton & Co. and can be ordered at www.wwnorton.com. Authors John Carmody, Stephen
Selkowitz, Eleanor Lee, Dariush Arasteh and Todd Willmert, discuss the basics of glazing selection and provide useful
information and performance data on the energy efficiency, interior environment, technical and life-cycle-cost consider-
ations related to fenestration in commercial buildings.
The book is part of a set of tools and information for decision-makers aimed at improving the energy efficiency of
windows in commercial buildings.
In addition to the book, an interactive Internet site, www.commercialwindows.umn.edu, enables designers to make
trade-offs and comparisons for window options. Presentation material for the education of architects, engineers and
students is also on the site.
Funding—Always an Issue
In fiscal 2002, Congress appropriated
$6.5 million for the U.S. Department of
Energy’s windows research and develop-
ment. In 2003, this funding was cut to $5
million. DOE makes a request for funds and
Congress responds with an appropriation.
Thus, funding is an ongoing issue that may
influence DOE activity.
Once these new and more complex products are
available, DOE officials recognize the need for soft-
ware programs that can simulate and rate their per-
formance in buildings. Partnerships with the
national laboratories and other private companies
drive the research and development.
Marc LaFrance, DOE’s windows and building-
envelope research and development manager, con-
firms that these activities are already underway. Sci-
entists at the national laboratories are conducting
comprehensive research and looking for fundamen-
tal breakthroughs; industry leaders and other stake-
holders partner with DOE on shorter term product
LaFrance describes one project currently under-
way with Sage Electrochromics Inc., a Faribault,
MN, company with the goal of developing and
commercializing electrochromic glazing for the win-
dow industry. With DOE’s support, prototype
products developed by Sage have gone through sev-
eral years of durability testing for high temperature
and stability in ultraviolet light at the National
Renewable Energy Laboratory in Golden, CO.
According to Mike Myser, Sage vice president of One of three office suites set up at Lawrence Berkeley National Laboratory to test
sales and marketing, “The industry has spent mil- electrochromic products developed by Sage Electrochromics. The lites vary in color
lions of dollars on the development of elec- to illustrate the ability to control light.
trochromic products, but the primary drawback has
always been durability. Sage’s thin-film, inorganic, modes of operation—manual, automatic, and semi-
lithium-based technology is the first to pass NREL’s automatic—will be considered. Because these win-
rigorous durability testing.” dows have the ability to control light and heat with-
Sage’s NREL success has led to engineering field out losing view through the glass, Myser expects the
studies on Sage products at the Lawrence Berkeley inhabitants’ reactions to be positive.
National Laboratory in Berkeley, CA. Co-funded by
the California Energy Commission, the field studies Partners
will examine energy performance of these dynamic DOE has also partnered with Los Alamos National
windows and measure energy savings and perform- Laboratories on development of electro-tinted glaz-
ance under peak loads. ing, a dynamic glazing comprised of two pieces of
LBNL scientist Eleanor Lee notes that the glaz- glass and a thin air space filled with a liquid salt solu-
ing systems will be hooked up to dimmable electric tion.
lights to control daylight and solar heat gain in the According to Anthony Burrell, a technical staff
spaces. member at the New Mexico research facility, this
In addition, three office suites utilizing the prod- electrochromic product does not react with sunlight
ucts have been constructed at the laboratory to eval- and is stable over a wide temperature range. The salt
uate human factors, such as how people work in solution, an ionic liquid, is chemically benign and
these spaces and respond to dynamic glazing. Three will not evaporate. Because of DOE’s partnership,
Guide to Glass Codes
simulate complex glazing products such as fritted
Researchers seek a method to simulate glass, blinds in glazing, prismatic glass and optically
To rate the products that come out of DOE
complex glazing products research, new, more complex software programs
will be needed to simulate performance so that
the Los Alamos lab has constructed and tested pro- products can be included in voluntary industry
totypes for durability. rating programs such as the one administered by
Software Tools This work is underway at Lawrence Berkeley
DOE officials still have plans to maintain software National Laboratory and at the Center for Energy
tools that were developed in conjunction with Efficiency and Renewable Energy at the University
Lawrence Berkeley National Laboratory. These soft- of Massachusetts in Amherst, MA.
ware programs include: According to Charlie Curcija, a mechanical and
• Resfen, a personal-computer program for cal- industrial engineering faculty member at the Uni-
culating heating and cooling energy use of windows versity of Massachusetts, the goals for the 6.0 version
in residential buildings of the Window software include: addition of shad-
• Window, to analyze window thermal and opti- ing devices and other types of window attachments,
cal performance European standards algorithms, and treatment of
• Therm, to analyze two-dimensional heat trans- optically complex glazing.
fer through building products The goals for the 6.0 version of Therm are: addi-
• Optics5, to analyze the optical properties of tion of axi-symmetrical (3D circular geometries)
glazing systems. modeling and more accurate solar heat-gain calcula-
The programs are free and can be downloaded at tions for frame and edge-of-glass sections, an
http://windows.lbl.gov/software/default.htm. improved condensation-resistance model, and an
While occasional updates are required on exist- improved and expanded library of convective
ing software, DOE’s researchers seek a method to boundary conditions. g