DualPurpose  
A New Façade  
Technology  
Combines  
Energy  
Performance,  
Aesthetics  
and  
Transparency  
by Ellen Rogers  
Let’s start with a few things  
to think about:  
Architects love  
1
.
transparency.  
Active façade  
2.components can  
be optimized for energy  
consumption and cost.  
Integrated, intelligent  
3.control systems are  
making building envelopes  
smarter every day.  
Located in Sydney, Australia, the 200 George Street project incorporates  
CCF  
2
15,300 square feet of the mfree-S constructed with timber blinds  
from Accoya, vertical timber shading elements and three layers of  
performance glazing.  
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USGlass, Metal & Glazing | February 2017  
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The JTI Building in Geneva-Sécheron,  
Switzerland, was designed by SOM  
and features nearly 200,000 square  
CCF  
feet of Permasteelisa’s mfree-S  
.
The project complies with the global  
Minergie Standard and exceeds  
the exacting Swiss National Code  
efficiency goals by 20 percent.  
See For Yourself  
See For Yourself  
Currently, there aren’t any projects in va-Sécheron, Switzerland, is a nine-floor Group, manufactured 1,280 CCF units,  
the U.S. that incorproate the mfree-S sys- office building featuring a steel structure 900 of which are standard units.  
tem, but there are a number of examples andahighlytransparentglassfaçadecon-  
Another project completed is 200  
around the world. The first, according to structed with nearly 200,000 square feet George Street in Sydney, Australia. De-  
Permasteelisa, is the LEO Building in of the CCF system. Each façade unit has a signed by architects Francis-Jones More-  
Frankfurt,Germany,whichwascompleted 2.8-meter-widefabricsunscreenblindand hen Thorp, the tower’s 215,300 square  
in 2014. More recently, projects were built isdividedbyadiagonalmullionsothatthe feet of the mfree-S CCF incorporate auto-  
in 2016 in both Switzerland and Australia. outer glazing is fixed at different angles, mated timber blinds from Accoya, as well  
Designed by U.S. architectural firm according to information from Permas- as vertical timber shading elements and  
SOM, the JTI Building located in Gene- teelisa. Gartner, part of the Permasteelisa three layers of performance glazing.  
Given these considerations, glazing sealed. Solar shading is also integrated two there is a shading device,” says  
has a big part to play. While dynamic within the cavity. Originally developed Franceschet. “In a standard DSF  
glass is one option, glazing itself doesn’t in 2008, the system has been used in a there’s a flow of ventilation between  
have to be active to achieve the desired number of projects around the world, the skins. The problem we’ve seen is  
performance results. Passive glass will but has not yet entered the U.S. market. that … there is a maintenance issue  
continue to have a place in façades. The  
“We’ve done a lot of work and research from the owner’s perspective, as they  
key, however, will be incorporating it in this evolution of double skin façades have to maintain two surfaces. [Plus]  
with other dynamic elements for the our intention is to now bring it to the the cavity between the two needs to  
highest performance.  
U.S,”says Alberto Franceschet,executive be cleaned so the interior typically  
Interest in automated shading de- vice president of business development must be operable. We heard these  
vices, for example, has grown as a solar and sales - North America for Permas- issues [and thought] … if we closed  
control option. Double skin façades teelisa North America Corp., which has the cavity, what will happen? How  
(
glazing technique. A recent develop-  
DSF) are another high-performance U.S. headquarters in Windsor, Conn.  
can we avoid having to maintain the  
cavities one to two times a year?”  
The result is a system designed so  
What’s the difference in a traditional that dust and condensation contam-  
ment from the Italian Permasteelisa Great Expectations  
Group incorporates both automated  
shading within the cavity of a DSF DSF and this new evolution? Less ination are not permitted inside the  
for a holistic design and performance maintenance for one.  
cavity, creating a moisture- and dust-  
“The principle is the same— free system. This is achieved by creat-  
CCF  
solution. The company’s mfree-S  
closed cavity façade (CCF) system is two façades, typically one is dou- ing a slight over-pressure between the  
a DSF where the cavity between the ble glazed (interior) and one single  
inner and the outer skin is completely glazed (exterior) and between the  
continued on page 40  
www.usglassmag.com  
February 2017 | USGlass, Metal & Glazing  
39  
DualPurpose  
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  
design phases.”  
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  
40  
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