continued from page 39
exterior single glass and interior IGU is built speciﬁcally to respond to its in- even with the best triple silver coatings
using dry and clean air.
cident radiation. “This system allows you need active control—so the pure
The pressure in the cavity is calcu- the designer to create adaptive eleva- IGU route can add electrochromics or
lated so either interior or exterior pres- tions that respond to cloud coverage, traditionally an active shading system
sure is always lower in absolute value,” weather, shadows, etc. to optimize per- (e.g. blinds or roller shades).”
says Franceschet.“This prevents a neg- formance of the building through the
He continues, “If added inside the
glass, the thermal comfort and cooling
While aesthetics and energy perfor- load control is challenging. If added to
ative pressure differential that keeps programming of the blinds,” he says.
dust and moisture from ﬂowing into
the cavity.” There is no regular access mance are important, so is occupant the exterior,cost,maintenance,operation
into the cavity, though it is possible on comfort. Both Franceschet and Cox with wind and snow etc. provide some
an emergency basis.
The unitized system is constructed most potential for use in owner-occu- tions placed the active shading between
within the company’s factory environ- pied buildings. the glazing—a double envelope—with
ment, “pressurized from the moment “In an owner-occupied building, active air ﬂow to the outside in summer
agree that this type of system has the challenges. The next generation of solu-
we complete assembly,” he says.“These there is a desire to retain workers and to reject the collected heat, and a supply
façades combine the positive [energy make sure they’re comfortable in the of- of warmed air in winter to the building
performance] of a DSF, but with an ﬁce space,so often these clients are more interior.” He says while these systems
integrated shading system [installed] willing to spend more on a building skin have been used over the last 10-20 years,
entirely in our facility. This is not typi- to ensure user comfort,”says Cox.
they do require cleaning and mainte-
cal in the U.S. This is done early in the
He explains the shading system is in- DSF projects come to the U.S., with or-
Franceschet adds that over the past nance and are susceptible to condensa-
seven to eight years they’ve seen more tion under some ﬂow conditions.
“The new closed cavity concept places
tegrated into the building management ganizations that own their buildings the active shading in the cavity as with
system to enhance performance from a being most receptive. “And from an double envelope, but the cavity is kept
solar heat gain perspective.
owner’s perspective, [these projects] clean under positive pressure with a
are a larger investment, but the pay- central, sealed dry air supply system to
Beneﬁts and Usage
back [is greater] …”
all windows,”says Selkowitz.“The active
shading in the glazing system will heat
up,but if the shading and glass coatings
As far as the system’s energy perfor-
mance, the U-values are similar to those Viewpoints
of a triple-glazed unit. “And you have
Steven Selkowitz, with the Building are selected and placed properly, the
extremely better solar heat gain coefﬁ- Technology and Urban Systems Divi- system is engineered to deliver good
cient (SHGC) performance,” Franceschet sion at the Lawrence Berkeley National energy performance and comfort.”
says. “This is not a ﬁxed value because Laboratory, has spoken at a number of
He adds, though, that such a system
it’s something you create with the use of industry events, including GlassCon has its own cost and maintenance chal-
solar shading.” For example, on cloudy Global in 2016, about the advantages of lenges,“which have been demonstrated
days it’s not necessary to use the shading. active façades.
to be acceptable for the ﬁrst generation
Alex Cox, business development “This new ‘closed cavity façade’ is in of buildings using the system … These
manager - West Coast with Permasteel- some ways a logical extension of the require design, construction, commis-
isa, adds, “In some northern climates, growing architectural interest in having sioning and operations that go beyond
SHGC is a more appropriate predictor highly transparent, large-area glazed the norm for a conventional curtain-
of overall building energy use than façades with excellent thermal and vi- wall, but they are solvable with the will,
U-value. The mFreeS system works sual comfort, and with low energy and interest and investment.”
well in these situations to moderate carbon impacts,” says Selkowitz. “The
Selkowitz adds “We are hopeful that
solar heat gain and create a building continued client and occupant desire for new solutions like the CCF will add
envelope that is both highly transpar- large glazed areas with views and day- interest and motivation to continue to
ent and energy efﬁcient.”
Another beneﬁt is increased acousti- management of solar gain and daylight goals for advanced façades.” n
cal performance. by either dynamic shading or smart
This is a very high improvement glass … We have seen several gen-
light can only be achieved with active address new, aggressive performance
because we are adding the deep cavity erations of solutions—starting
in the glass creating a sound-dampen- with low-E, gas-ﬁlled, low conduc-
E l l e n R o g e r s is the
editor of USGlass magazine.
Follow her on Twitter @
USGlass and like USGlass on
Facebook to receive updates.
ing effect,” says Franceschet.
tance IGUs (double and triple) with
Cox points out that architects are more sophisticated spectrally selec-
also interested in designing buildings tive, low-E coatings—maximizing
so that each façade and each elevation daylight vs. total solar gain. But
USGlass, Metal & Glazing | February 2017