BUILDING ENERGY - Fall 2017 - 38

FEATURE: RETHINKING EFFICIENCY IN WALL SYSTEMS

HIGH PERFORMANCE
WALLS
BY CHRIS HAMM

PEER REVIEWED BY
JORDAN GOLDMAN

FIGURE 1: SHELF ANGLES
REQUIRED FOR BRICK
FA ADES PRESENT A
SIGNIFICANT REDUCTION
IN EXTERIOR INSULATION
EFFICIENCY. CREATING
A THERMAL BREAK
BETWEEN THE STEEL AND
STRUCTURE CAN MITIGATE
THIS EFFECT SLIGHTLY.
PHOTO CREDIT: STEVEN
WINTER ASSOCIATES.

A

s the design of high performance building
envelopes continues to evolve, so must the
process of evaluation. Throughout the
past few decades and with the growth
of the Passive House standard in the
United States, designers are increasingly being
forced to create finely tuned shells for their projects
that somehow balance cost, ease of construction
and increased thermal performance. Not long ago,
the wall assembly for a project would have been
relatively standard, but a "high performance"
wall worthy of a Passive House plaque demands
attention from several disciplines often before
design development. What has changed in the
fundamental thinking about wall construction that
has created such an obsession? The answer has to
do with a shift in the perception of what makes a
building assembly "efficient."
The definition of efficient is "functioning in the
best possible manner with the least waste of time
and effort." With regard to typical construction
in the U.S., a wall assembly has historically been
considered efficient if it fulfills the structural
requirements of the building and creates a sufficient
barrier from the elements while being as cheap

1
38 * BUILDINGENERGY VOL. 36 NO. 2 | FALL 2017

and easy to construct as possible. Additional
requirements are inevitably introduced to disrupt
this basic equation, but regardless of the project
the original criteria always remain. Luckily, stricter
building codes have served as the catalyst to push
construction toward a new definition of efficiency
where thermal energy is as important as time and
material cost.
The primary function of a wall has always been
structural. Therefore the majority of a wall's
thickness has historically been filled by - you
guessed it - structure. Instead of building solid
structural walls, lightweight but strong materials
act as framing members to cover a greater area at
reduced cost while leaving void spaces for which
we have found many functions. For instance, filling
these convenient spaces with lower density material
has become the obvious solution to an otherwise
unobstructed flow of sound and heat. As the
benefits of such an acoustical and thermal barrier
were realized, building codes began to require a
certain amount of insulation efficiency. When the
concept of super-insulation became popular in the
'70s, it eventually became clear that this formula
of using the structural cavity as the insulation
layer was no longer sufficient. Increasing the wall
depth to accommodate more insulation also meant
beefing up the structure unnecessarily - negatively
affecting the cost efficiency of the assembly. Today,
in the world of high performance construction in
colder climates, it is basically required that some
amount of the insulation layer be separated from
the structural layer, increasing the efficiency of
both components.
Moving insulation out of the structural cavity to
the exterior poses a new design hurdle: what will
attach the fa ade to the structure while spanning
the gap required for insulation? Many systems exist
today to do that and more, varying based on the
fa ade type and backup structure. In addition to
supporting the fa ade, such systems often must
hold the insulation in place and leave an air space
for ventilation.
So what systems are we talking about? Panelized
and lightweight fa ade materials have the widest
array of high performance attachment systems
available. For instance, a clip and rail system reduces
insulation penetrations while forming a grid to hold
insulation, supports a fa ade and creates an air gap.
In addition, a simpler approach is to use continuous
girts, almost like a lightweight stud cavity, to hold
insulation and support the fa ade. Not surprisingly,



BUILDING ENERGY - Fall 2017

Table of Contents for the Digital Edition of BUILDING ENERGY - Fall 2017

From the Executive Director: A strategic plan for emerging professionals.
From the Board Chair: Taking flight into new territory.
What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
Better Steam Heat: Generating steam system upgrades in New York City.
Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
Index to Advertisers
BUILDING ENERGY - Fall 2017 - Intro
BUILDING ENERGY - Fall 2017 - cover1
BUILDING ENERGY - Fall 2017 - cover2
BUILDING ENERGY - Fall 2017 - 3
BUILDING ENERGY - Fall 2017 - 4
BUILDING ENERGY - Fall 2017 - 5
BUILDING ENERGY - Fall 2017 - From the Executive Director: A strategic plan for emerging professionals.
BUILDING ENERGY - Fall 2017 - 7
BUILDING ENERGY - Fall 2017 - From the Board Chair: Taking flight into new territory.
BUILDING ENERGY - Fall 2017 - 9
BUILDING ENERGY - Fall 2017 - What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
BUILDING ENERGY - Fall 2017 - 11
BUILDING ENERGY - Fall 2017 - 12
BUILDING ENERGY - Fall 2017 - 13
BUILDING ENERGY - Fall 2017 - 14
BUILDING ENERGY - Fall 2017 - 15
BUILDING ENERGY - Fall 2017 - Better Steam Heat: Generating steam system upgrades in New York City.
BUILDING ENERGY - Fall 2017 - 17
BUILDING ENERGY - Fall 2017 - 18
BUILDING ENERGY - Fall 2017 - 19
BUILDING ENERGY - Fall 2017 - INSERT1
BUILDING ENERGY - Fall 2017 - INSERT2
BUILDING ENERGY - Fall 2017 - Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
BUILDING ENERGY - Fall 2017 - 21
BUILDING ENERGY - Fall 2017 - 22
BUILDING ENERGY - Fall 2017 - 23
BUILDING ENERGY - Fall 2017 - Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
BUILDING ENERGY - Fall 2017 - 25
BUILDING ENERGY - Fall 2017 - 26
BUILDING ENERGY - Fall 2017 - 27
BUILDING ENERGY - Fall 2017 - 28
BUILDING ENERGY - Fall 2017 - 29
BUILDING ENERGY - Fall 2017 - Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
BUILDING ENERGY - Fall 2017 - 31
BUILDING ENERGY - Fall 2017 - 32
BUILDING ENERGY - Fall 2017 - 33
BUILDING ENERGY - Fall 2017 - Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BUILDING ENERGY - Fall 2017 - 35
BUILDING ENERGY - Fall 2017 - BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
BUILDING ENERGY - Fall 2017 - 37
BUILDING ENERGY - Fall 2017 - High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
BUILDING ENERGY - Fall 2017 - 39
BUILDING ENERGY - Fall 2017 - 40
BUILDING ENERGY - Fall 2017 - 41
BUILDING ENERGY - Fall 2017 - SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
BUILDING ENERGY - Fall 2017 - 43
BUILDING ENERGY - Fall 2017 - 44
BUILDING ENERGY - Fall 2017 - 45
BUILDING ENERGY - Fall 2017 - 46
BUILDING ENERGY - Fall 2017 - 47
BUILDING ENERGY - Fall 2017 - NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
BUILDING ENERGY - Fall 2017 - 49
BUILDING ENERGY - Fall 2017 - 50
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BUILDING ENERGY - Fall 2017 - INSERT4
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BUILDING ENERGY - Fall 2017 - 75
BUILDING ENERGY - Fall 2017 - 76
BUILDING ENERGY - Fall 2017 - Index to Advertisers
BUILDING ENERGY - Fall 2017 - 78
BUILDING ENERGY - Fall 2017 - cover3
BUILDING ENERGY - Fall 2017 - cover4
BUILDING ENERGY - Fall 2017 - outsert1
BUILDING ENERGY - Fall 2017 - outsert2
BUILDING ENERGY - Fall 2017 - outsert3
BUILDING ENERGY - Fall 2017 - outsert4
BUILDING ENERGY - Fall 2017 - outsert5
BUILDING ENERGY - Fall 2017 - outsert6
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