Apogee CEO Talks to Glass Expo Midwest Attendees
About Zero Energy and BIPV
March 23, 2010
By 2025just 15 yearscommercial construction is targeted
for zero energy design, as the Department of Energy's Building Technologies
Program has set a strategic goal to create technologies and design
approaches that will lead to marketable zero energy commercial buildings
by that year. A net-zero energy building one with reduced needs
for energy through efficiency gains (60 to 70 percent less than
conventional practice), with the balance of energy needs supplied
by renewable technologies. For some, building integrated photovoltaics
(BIPV) might come to mind first when thinking about products that
will help us achieve zero energy; others, though, disagree.
Russ Huffer, chief executive officer of Apogee Enterprises, spoke
to Glass Expo Midwest 2010 attendees last week in Schaumburg,
Ill., about BIPV and achieving zero energy systems, and to him,
BIPV is still a technology that's ahead of the glazing industry.
He pointed out that Apogee, in fact, "spent millions of dollars
trying to develop solar panels, but [we found] it wasn't right and
that project has been abandoned," he said. Looking toward zero
energy, Huffer stressed the importance of understanding the values
delivered by these systems.
"Why zero energy? Because commercial buildings generate half
of all electricity used. Not only that, they are extremely inefficient,"
Huffer said, explaining that the focus for the glazing industry
will be on zero energy curtainwall and windows.
"Let's simplify the problem. Glass and metal systems transcend,
absorb and reflect energy, so a low-E coating is a mirror to long-wave
energy efficiency. For most systems this can be calculated and measured
very accurately. We know how much energy is coming in on a hot day
and leaving on a cold day," said Huffer. "Solar energy
accounts for most heat gain through our systems to the inside of
the building; air conditioning is the primary cost for most buildings."
He also noted that peak solar energy is about 100 watts per square
foot; on a vertical wall it's about 70 watts per square foot.
Understanding the payback is also critical.
"Also, if you are called to install [panels] on a roof, find
out the life of the roof," advised Huffer. " If the BIPV
payback is 30 years and the roof has to be replaced every 20 years
you are at a loss."
He also noted, "Excess solar energy gain moves us further away
from a zero energy wall. During heating we want to reduce heat loss
through the systems while utilizing heat gain.
"We want the glass to compete for use in zero energy buildings
our designs have to compete aesthetically and designs have
to compete economically. And the real measure of energy performance
is how much is needed to mitigate the heat gain and loss caused
by our systems."
In addition, Huffer said zero energy designs should include the
cost of sustainably designed power systems that will result in zero
energy wall designs.
Looking at mitigating energy systems, he said the added cost of
a vertical installation system within the curtainwall is about $120
per peak watt.
"I recommend keeping them in a green field," he said,
which will provide a greater payback. "A zero energy wall is
impossible to do in a flat wall. In order for it to exist new technologies
will have to capture and concentrate energy. In the end, I think
people will be asking for this, but the technology is still ahead
of the industry. These systems are limited in their payback and
what they can do," he added.
Huffer continued, "All things considered, what we're already
doing, dual-glazed systems, low-E coatings, etc., is better than
BIPV. We're headed in that [BIPV] direction, but we can't get there
with today's technology because the payback is so long," he
said and added, "PV panels lose 1 percent of their output every
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