Teaches Architects About Benefits of High-Performance Fenestration
April 16, 2009
A number of architects tuned in this afternoon to a webinar that
offered insight into the role of glass and fenestration systems
in creating energy-efficient buildings. The webinar on "Energy-Saving
Architectural Solutions for High-Performance Buildings" was
sponsored by the Lawrence Berkeley National Laboratory (LBNL) and
Moderator Jackie O'Brien of Alcoa opened the session by commenting,
"As many of you know, more than one-third of the energy consumed
in the U.S. is consumed by commercial buildings." Although
this may be the case, it's a figure that will need to change - she
pointed out that $50 billion in line items in the recent stimulus
package referenced building construction or renovation, making knowledge
of energy-efficient systems more important than ever.
Steve Selkowitz, program head of the Building Technologies Department
of LBNL, also addressed the "big picture" of energy use
in U.S., explaining that buildings are the biggest user of energy
in the country and growing the fastest, over transportation and
industrial uses. "Over $400 billion each year" is spent
on energy to cool, heat and light buildings, he commented.
Selkowitz also told his audience, made up primarily of architects,
that one of the challenges in designing for high-performance fenestration
is the image glass has as an energy waster. "There are conflicting
views of the role of windows
in the '70s most windows were
single-glazed and the conclusion was - well, the reality was that
they were real energy hogs
If you turn the clock ahead now
30 years, what you often see in the magazines are highly glazed
the reality is likely somewhere in between."
The challenge, he noted is moving toward the more efficient image.
Selkowitz told his audience that there are essentially three paths
available when it comes to specifying the windows. The fist option
is to "just meet the code" with small windows that offer
nothing "special" in terms of shading or daylighting.
As he reminded his listeners, "If you've just met the building
you've designed the worst building you're legally allowed to."
The second option is to use conventional "good solutions"
such as modest-sized windows and skylights. Many of these options
now utilize low-E coatings and double-glazing, as well as options
such as manual interior shading, to maintain a comfortable interior
The third, ideal option is the new opportunity for "transparent
intelligent façades." Selkowitz explained that upon
adding more glazing, a better set of tools is needed for optimization
of the system, including automated shading and dimmable lights.
He also pointed to two challenges. The first is finding ways simply
to become energy-efficient by minimizing winter heat loss and summer
heat gains. The next step, which is growing imminently more probable,
is utilizing the window in the creation of a zero-energy unit. These
systems likely will need operable façade components and should
rely on automation to best cooperate with HVAC systems and other
utilities. Specifically, lowering lighting costs by utilizing daylight
is the biggest opportunity for advancing the use of glass in energy-efficient
buildings, Selkowitz said.
"This is a real opportunity, this is the reason we often have
windows in building. This is a great opportunity but a great challenge,"
he added. "The façade system needs to be designed as
part of an integrated system."
To explain why automation of systems can improve its performance
Selkowitz pointed to a building in California that LBNL had measured
for energy performance. A year after the first set of measurements,
the building was retrofitted with daylight controls. "We learned
we got greater savings in the North, which we didn't understand
at first," he said. "People were using shades in the South
and they don't often open the shades back up." Automatic shading
would therefore help make use of daylighting benefits of glazing
while keeping residents comfortable.
During the second half of the webinar, Eddie Bugg, director of
sustainable solutions of Alcoa's Kawneer Co., focused on practical
applications for achieving efficient buildings such as those Selkowtiz
described. But before running through some of the company's available
products, Bugg talked about the evolution of the LEED rating system
from its previous inception as version 2.2 to the 2009 version,
which he noted would be launched on April 27 and offer more points
and credits. "Most noteworthy today is the doubling of points
and credits for the energy and atmosphere category," he pointed
out. He noted that credits there for "optimizing energy performance"
have moved from 10 to 19, and added that there are a number of ways
in which glass products can help achieve those credits.
Another change he pointed to is that the reference standard in
LEED has been updated from ASHRAE 90.1 2004 to 2007, "which
also raises the bar on being able to design buildings to energy
In addition, credits for on-site renewable energy has increased
from three to seven.
When it comes to choosing products to meet LEED credits and otherwise
improve building efficiency, Bugg noted, "You can't come up
with just one [window] product to use universally on any project
on your drawing boards today."
But as this program stressed, windows shouldn't be overlooked in
the critical role they play in making buildings more efficient.
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