JBeD
Journal of Building Enclosure Design
An official publication of the National Institute of Building Sciences
Building Enclosure Technology and Environment Council (BETEC)
National Institute of Building Sciences: An Authoritative Source of Innovative Solutions for the Built Environment
Winter 2013
Thermal Bridging:
It Can Be Done
Better
Contents
JBED
Feature:
Heat Transfer
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15
11
Numerical Modeling
Perspectives: SteelFramed Wall Analysis
Thermal Bridging:
Ignorance is not Bliss
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18
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Thermal Bridging: The
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Journal of Building Enclosure Design
An official publication of the National Institute of Building Sciences
Building Enclosure Technology and Environment Council (BETEC)
National Institute of Building Sciences: An Authoritative Source of Innovative Solutions for the Built Environment
Winter 2013
Messages:
Message from Institute
07
09
President Henry L. Green
Message from BETEC
Chairman Wagdy Anis
Industry Updates:
27
32
Thermal Bridging:
It Can Be Done
Better
BEC Corner
Buyer’s Guide
On the cover: The Centre
for Interactive Research on
Sustainability (CIRS), located at
the University of British
Columbia, is one of the
greenest buildings on earth…
and provides a great example
of thermal bridging done right.
Winter 2013 5
Message from the National Institute of Building Sciences
Henry L. Green, Hon. AIA
It has been a busy summer and
fall. Since my last column, I had the opportunity to meet with members of Greater
Detroit’s Building Envelope Council (BECGD). Not only was it good to be back in
Michigan, it was good to meet with members of the Detroit BEC, whom I worked
with for so many years while serving as
Director of Michigan’s Construction Codes
Program.
While at the BEC-GD September
Meeting, I was privileged to present
discussions along with Fiona Aldous, Dr.
Theresa Weston and Chris Mathis. The
event included some 200-plus members
of BEC-GD and a number of vendors who
displayed their services. I focused my
discussion on the role that the National
Institute of Building Sciences, the Building
Enclosure Technology and Environment
Council (BETEC) and local BECs share in
developing sound, scientific discussion on
envelope protection and the integration
of measures that yield high performing
resilient buildings and communities. I
want to thank the members and officers of
BEC-GD for their gracious hospitality and
a willingness to become a part of a nationwide effort to improve the building process
and the built environment.
I also wanted to follow up on the
discussion I began in the Summer issue of
the Journal of Building Enclosure Design
(JBED) regarding the code proposals being
advanced in the International Codes to
address the use of foam plastics in exterior
wall systems and vertical and lateral fire
propagation.
Our proposal to address the use of foam
plastics in exterior wall systems was not
accepted but we were able to initiate a good
dialogue. While the Institute was unable
to get this included in the next edition
of the codes, we will try again at the next
opportunity to make the necessary revisions
to allow for the use of foam plastics in
exterior wall assemblies, to create a system
that provides for both fire safety and thermal
resistance in building envelopes.
The good news is that the revision to
the vertical and lateral fire propagation
section of the code was accepted. It allows
for the use of combustible water resistant
barriers without the need for a fire test
under National Fire Protection Association
(NFPA) 285 in certain instances.
Leading up to this, a meeting was
convened to discuss the proposed revisions
with all of the parties of interest. I want to
thank all of the participants in this effort
who worked to find a common resolution
to this issue.
Unfortunately, our effort to revise the
code provisions of Section 2603.5 was
not successful. This proposed change
would have reformatted the section for
foam plastics and modified it to allow
for fireblocking as an alternative to
testing. To overcome the committee
recommendation for disapproval, a 2/3
majority of the voting members was
required to hear the public comment to
include our revisions. The attempt to
overturn was not successful. However,
I believe this discussion provides the
basis for ongoing discussions and we
can revisit this issue over the next year
to resubmit the revision for the next
round of code hearings. Unfortunately,
that is not until 2016. I would challenge
the BETEC to take up this discussion
and formulate a plan of support for a
resubmission.
I would also like to encourage you to
attend Building Innovation 2013, which
is the Institute’s Conference & Expo. It is
scheduled for January 7-11, 2013, at the
Washington Marriott at Metro Center in
Washington, D.C. This is also where BETEC’
Symposium, Fenestration: A World of
Change, will be held. This event will include
leading experts in building enclosure
research, design and practice who will unite
to tackle the latest issues. The council, which
is celebrating its 30th year, will present the
most current data available on fenestration
performance and technology.
I look forward to seeing you there.
Henry L. Green, Hon. AIA
President
National Institute of Building Sciences
Winter 2013 7
Message from the Building Enclosure Technology and Environment Council
Life may become more complex as we reach
out to deal with this type of “low-hanging fruit”
from an energy conservation and better building
perspective, but we need to bite the bullet. Taking
the lead from our earlier efforts with water-resistant
barriers, we should develop code proposals to
address this issue in the next code cycle.
Wagdy Anis, FAIA, LEED-AP
Welcome to the 2013 Winter edition
of the Journal of Building Enclosure Design
(JBED). This edition is dedicated to thermal
bridges in buildings, which are building
components made of conductive building materials, such as aluminum, steel and
concrete. These materials bridge across the
continuous thermal insulation barrier in
building enclosures. Thermal bridges can
have a considerable negative impact on energy efficiency, which you’ll read about in
the articles in this edition.
The United States is facing a nationwide
problem, yet there are no current code requirements to define, quantify, regulate
or control thermal bridges in buildings. In
addition to the energy impact of thermal
bridges, there are potential health and durability concerns associated with moisture
accumulation and condensation. There are
human comfort problems associated with
cold surfaces indoors. There are also aesthetic concerns associated with the disfigurement of façades because of the growth
of microorganisms and the accumulation
of dust and soot associated with Brownian
motion, due to temperature differentials indoors. This can only be described as a “bad
deal” for the many good aspects of building
enclosure design. Why do we let this continue, when energy independence and security require reducing the energy consumption
of buildings?
Interestingly, Oak Ridge National Laboratory, one of the research laboratories of
the U.S. Department of Energy, commissioned a study published in 1989, entitled,
Catalog of Thermal Bridges in Commercial
and Multi Family Residential Construction.
It identified and quantified many of the
common thermal bridges that are still being designed today, in addition to the many
more that the ingenuity of the design and
construction community has devised since
then. Yet, the sustainability codes, the International Green Construction Code (IgCC)
and ASHRAE 189.1, as well asLeadership in
Energy and Environmental Design® (LEED),
or the New Buildings Institute’s Core Performance® have still to address this issue.
ASHRAE recently commissioned a research project, Thermal Performance of
Building Envelope Details for Mid- and
High-Rise Buildings (1365-RP), which studied common thermal bridges in buildings,
quantified their energy impact and proposed approaches to simplifying the types
of thermal bridges. I believe we need to
do some more work to identify acceptable
strategies that minimize thermal bridges resulting from fastening cladding onto buildings through continuous insulation layers.
We then need to identify and quantify the
three types of bridges described in 1365-RP
and legislate maximum allowable amounts
of such details in buildings.
There are solutions available today for
thermally breaking major structural components that protrude beyond the insulation.
What remains is the multitude of enclosure
components that are non-primary structures, such as cladding, trim, cornice and
parapet attachments, solar shading devices, as well as steel mechanical equipment
dunnage on roofs (for example, why are we
not using fiberglass structural sections?)
and aesthetic visual screens of mechanical
equipment. Fall protection tie-backs can
also be another challenge.
This subject is complicated. I believe
that codes in the United States try to simplify the requirements so that designers
can more easily comply with codes and
building officials can more easily control
what’s going on. England dealt with this
problem head-on in its building requirements, which require calculations for thermal bridges. I believe the United States
needs to do the same. Life may become
more complex as we reach out to deal with
this type of “low-hanging fruit” from an
energy conservation and better building
perspective, but we need to bite the bullet.
Taking the lead from our earlier efforts with
water-resistant barriers, we should develop
code proposals to address this issue in the
next code cycle.
On another note, please pencil April 18
and 19, 2013, into your calendars and make
sure to attend the Air Infiltration and Ventilation Centre’s (AIVC) conference, which is
sponsored by the Building Enclosure Technology and Environment Council (BETEC).
It will be held in the Washington, D.C.,
area. The conference is being organized by
the Belgian-based International Network
for Information on Ventilation and Energy
Performance, for the Air Infiltration and
Ventilation Centre, and includes a track developed by BETEC that specifically focuses
on the United States. (Since air tightness of
buildings is now a code requirement.)
Another major event is the Seattle Northwest Regional Building Enclosure Conference, entitled, Zen and the Art of Building
Enclosure Design, which will be held at the
Seattle Art Museum on May 21, 2013. It is
being organized by the Portland and Seattle
Building Enclosure Councils. BETEC will be
holding its Board meeting the day preceding
this event.
I hope to see you at these events!
Wagdy Anis, FAIA, LEED-AP
Chairman, BETEC
PrincipalWiss, Janney, Elstner Associates, Inc.
Winter 2013 9
Feature
Heat Transfer Numerical Modeling
Perspectives: Steel-Framed Wall Analysis
By Axy Pagán-Vázquez and Jeff Allen
In recent years, the building
industry has established priorities to
move towards the construction of highly
energy-efficient buildings, including the
prevention or mitigation of thermal bridges. In the past, when building energy efficient wasn’t such an issue, thermal bridge
problems were considered to be insignificant or negligible, given that the rest of the
losses through a building envelope were
dominated by the lack of insulation implementations, infiltration, etc.
Today, as the industry improves the
thermal barrier in those areas of the building denominated as “clear wall”—those
parts which are free from doors, windows
or any other protrusion mainly for structural purposes—the thermal bridge effects
tend to be more noticeable. Now that there
is a more pressing need to determine how
influential the thermal bridge effects can
be at various building connection details,
the computational modeling approach has
been shown to be an attractive method. It
can achieve reliable results that can’t be determined by physical measurements, such
as temperatures inside a composite wall
structure or within a building foundation.
Among other sources, the Assessment
and Improvement of the EPBD Impact
(ASIEPI) project has compiled a number
of software programs relating to modeling
thermal bridges. The project is designed
to give an overview of the status and progress of the many European Union energy
initiatives. Stemming from this work, this
article independently evaluates a thermal bridge scenario using two software
programs that have different levels of
capabilities.
The selected software programs comply
with Standard ISO 10211: Thermal bridges
in building construction—Heat flows and
surface temperatures—Detailed calculations. This standard defines requirements
for 2D and 3D numerical heat transfer software used to determine the heat transfer
effects associated with thermal bridges. According to ISO 10211, the thermal bridging
modeling software should be able to replicate the calculated heat flow and temperatures for a standard set of thermal bridge
scenarios.
The first selected software, COMSOL
Multiphysics Finite Element Analysis
(FEA) Simulation software, was chosen
for its extensible methods for defining the
model geometry and its amenability to
non-linear material properties. The second software, HEAT3, Finite Difference
Method (FDM)-based software, was selected for its concise capability to handle
rapid 3D steady state and transient simulations. It also includes a materials library
with more than 200 common building
materials. TABLE 1 compares some of the
features of both software programs.
ANALYSIS
ASHRAE RP-1365 Thermal Performance of Building Envelope Details for
Mid- and High-Rise Buildings references
two separate works; the first one conducted by Desjarlais and McGowan (Comparison of experimental methods to evaluate
thermal bridges in wall systems, 1997) and
the second one by Brown and Stephenson
(Guarded hot box measurements of the dynamic heat transmission characteristics of
seven wall specimen-part II, 1993). These
studies were performed in the Building
Technologies Research and Integration
Center, a division of Oak Ridge National
Laboratory (ORNL). In summary, the
test procedure, known as Hotbox Testing, consists of placing a large building
Table 1: HEAT3 and COMSOL Multiphysics feature comparison
Non-linear material property
Software Name Relative Price 3-D Modeling?
modeling?
section (in this case, an 8 ft. by 8 ft. wall)
inside a calibrated apparatus that, in turn,
measures heat transfer based on heat and
temperature inputs. Wind flow inside the
apparatus can also be controlled by the
tester. For the present analysis, RP-1365
referenced steady state and transient data
were selected. This data was used to determine the analyzed specimen R-value. This
has been used as a baseline to compare
the HEAT3 and COMSOL models. A wall
section schematic is shown in Figure 1.
The HEAT3 and COMSOL models
share several common simplifications
with respect to the physical specimens.
The vertical steel studs and horizontal rails
were assumed to be a single, continuous
component, eliminating the “rail flange
over vertical stud flange” configuration.
No screws or any other joint component
were included in either model. The rest of
the dimensions were modeled exactly as
stated in the references.
Also, the steady state and transient
model’s mesh was manually refined on
Figure 1. Steel-framed wall tested at ORNL
and modeled on HEAT3 and COMSOL.
Dimension units given in millimeters. Not
shown to scale.
Thermo-fluid
modeling?
Transient
Simulation?
COMSOL
High
Y
Y
Y
Y
HEAT3
Low
Y
N
N
Y
Winter 2013 11
Figure 2. COMSOL Multiphysics (left) and HEAT3 (right) steady
state temperature contour profiles (both scales in °C). Section
viewed from the interior side of the building.
both software programs. Note that HEAT3
considers surface film co-efficients referenced in the 2009 ASHRAE Handbook
- Fundamentals (34 W/m2-K for the cold/
exterior side and 8.3 W/m2-K hot/interior
side of the modeled wall. These co-efficients were not considered in the COMSOL models. The steel studs were modeled
in COMSOL as “highly conductive layers”.
This user-selected option, in principle,
assumes no temperature gradients along
steel stud thickness direction. Figure 2
12 Journal of Building Enclosure Design
Figure 3. Measured and computed wall heat flux during a 24hour period (COMSOL, HEAT3 and Hotbox test results).
shows the temperature contour profiles
for COMSOL and HEAT3. The steel framing reveals its low temperature in relation
with the rest of the wall, as indicated by
the vertical orange stripes. The high thermal conductivity of the studs causes a
much higher heat flux through them than
through the insulation, leading to a much
lower surface temperature.
Comparing the steady state results
from the Hotbox experiment, as well as
each of the two simulations, resulted in
the following R-values: 1.39 m² ∙ K/W
(Hotbox), 1.41 m² ∙ K/W (HEAT3) and 1.49
m² ∙ K/W (COMSOL). Both HEAT3’s and
COMSOL’s R-value relative error stayed
under 10 percent. The result deviations
are caused, in part, by the exclusion of the
contact resistance effects between material surfaces, as well as the exclusion of
joint connectors, such as bolts, etc. RP1365 model validation analysis concludes
that contact resistance, such as steel-tosteel interfaces and insulation interfaces,
can have significant impacts on the overall wall thermal resistance, particularly
on steel stud assemblies without exterior
insulation. McGowan and Desjarlais’s
(1995) work demonstrates the relevant
contact resistance impact on steel stud
assemblies.
For the transient analysis, the total heat
transfer was evaluated for a period of 24
hours. A fixed temperature value was set
at the inner wall surface, while a time-dependent temperature was assigned to the
outer wall surface.
One notable difference between the
COMSOL and HEAT3 transient models
was the chosen time step and the selected initial temperature conditions. A
time step of one second and one hour
were selected for COMSOL and HEAT3,
respectively. An homogeneous temperature value of 32.9⁰F (0.5⁰C) was assumed for the entire wall system in the
COMSOL model, while a non-homogeneous field was assumed on the HEAT3
model. Previous to the HEAT3 transient
analysis, a quasi-steady state simulation
was performed to determine the temperature field representative of the initial temperature conditions. As a result,
a location-dependent temperature field
was obtained and included in the model. The transient simulation results were
compared with RP-1365 transient testing
data, based on Hotbox testing performed
by Brown and Stephenson (1993). These
results are shown in Figure 3. Note that
all the mentioned possible factors influencing the steady results discrepancy
also have influence over the transient
simulations.
Even though COMSOL and HEAT3
solve the same partial differential
equation (heat diffusion equation), as
mentioned, they implement different
numerical techniques to solve it. Emerly
and Mortazavi (1982) conclude that FDM
heat balance appears to be best for problems in which continuity of the heat flux
is important, whereas FEM is best suited,
among other scenarios, in the examples
with concentrated heat sources. Also, the
exclusion of the surface film co-efficients
on the COMSOL model causes a subestimation of the simulated total heat
transferred, consequently inducing an
over-estimated equivalent wall thermal
resistance.
CONCLUSIONS
The software programs’ results were
specific for the selected scenario. Understanding that thermal bridging problems
are developed in building sections having
similar geometrical and composition patterns, the use of HEAT3, at least for this
particular simulation, appears to be a practical tool, considering its cost and similarity
to the Hotbox results. Additional building
envelope models, however, should be considered in order to determine if the two
software programs consistently match experimental results, or if the results were
unique for this particular scenario. n
Axy Pagán-Vázquez is a mechanical
engineer at the U.S. Army Corps Engineer
Research and Development Center (ERDC),
Construction Engineering Research Laboratory (CERL). He has been involved with
heat transfer modeling of building envelope
sections as part of the laboratory’s research
in prevention and mitigation of thermal
bridges in buildings. He’s currently pursuing graduate studies focusing on numerical modeling aspects for fluid and solid
mechanics.
Jeff Allen is a research mechanical engineer at ERDC’s Information Technology
Laboratory. He holds advanced degrees
in mechanical and aerospace engineering as well as an undergraduate degree in
mathematics. His interests include highperformance computational modeling of
multiphysics and multi-scale systems.
References
1. Assessment and Improvement of the
EPBD Impact (2010), An Effective
Handling of Thermal Bridges in the
EPBD Context-Final Report.
2. Morrison Hershfield (2011), Thermal
Performance of Building Envelope
Details for Mid- and High-Rise Buildings (RP-1365).
3.International Standard Organization (2007), ISO 10211:2007 Thermal
bridges in building construction—
Heat flows and surface temperatures—Detailed calculations.
4. Brown W. C. and Stephenson D. G.
(1993). Guarded hot box measurements of the dynamic heat transmission characteristics of seven wall
specimens-part II. ASHRAE Transactions 99, 643-660.
5.Desjarlais and McGowan. (1997).
Comparison of Experimental and Analytical Methods to Evaluate Thermal
Bridges in Wall Systems. 3rd ASTM
Symposium on Insulation Materials: Testing and Applications: 3rd Vol.
ASTM STP 1320.
6. 2005 ASHRAE Fundamentals Handbook Table 5, Chapter 3.
7.InfraMation 2006 Proceedings ITC
115 A 2006-05-22.
8.Emerly and Mortazavi. (1982). A
Comparison of the finite difference
and finite element methods for the
heat transfer calculations.
Winter 2013 13
Feature
Thermal Bridging:
Ignorance is not Bliss
By Mark Lawton and Neil Norris
Across North AMERICA, the industry
is facing more stringent thermal requirements in building codes, and designers are
responding by increasing the amount of
insulation in walls, all in an attempt to increase energy efficiency in buildings. But
how effective are these changes on building energy use when the impacts of 3D heat
flow in transition building components (for
example, exposed concrete slabs, window
flashings and un-insulated parapets), are
ignored? What if the building components
that are neglected have a much greater impact on energy than first realized? And how
will that affect the decisions that are currently made regarding the building envelope?
Thermal bridging cannot be completely avoided since many of these transition components, such as shelf angles
and canopy penetrations, are required for
structural purposes. The building industry
has long struggled with how to deal with
analyzing these components from a thermal perspective. The current thought process is: “If these structural members have
to be there, they are small compared to the
total wall area AND the energy impacts
are difficult to calculate, so they can be
ignored and focus can be put elsewhere.”
This has resulted in codes and standards
increasing the thermal resistance requirements of walls and windows (lowering
maximum wall U-values), while largely
neglecting heat flow between transitional
components.
More often than not, this increase in
thermal requirements is interpreted as:
“More insulation in the walls means proportionally better energy-efficiency in the
building.” The reality is, the industry is doing things wrong and as a result, bad decisions are being made. Simply adding more
insulation to the walls will not necessarily
decrease the energy use of your building if
most of the heat flow bypasses the insulation through poor details anyway. This will
leave you with diminishing returns as you
add more insulation.
As an analogy, the building envelope
can be thought of as a leaky water bucket
with several holes. You may keep trying to
plug one spot (for example, stuffing more
insulation into the walls) but the hole
right beside it is still leaking. If you want
to achieve real energy savings AND minimize costs, you should consider the impact
of these thermal bridges from transitional
components in our analysis (Figure 1
and Figure 2).
Recent studies, such as ASHRAE 1365RP Thermal Performance of Building
Envelope Details for Mid- and High-rise
Buildings, have shown that thermal bridges
in transitional components can be significant contributors to heat flow through the
envelope and cannot be ignored. The results show that lateral heat flow from studs
or other bridging elements in the wall assembly connect to the bridging elements
of the transition components. This creates
3D heat flow paths that allow heat to bypass the insulation of “high R-value” walls
through the transition components, negating the benefits of having more insulation
in the walls.
Having common details, like exposed
slabs and metal flashings around windows, can more than double the expected
heat flow. By ignoring these components,
the unaccounted for heat flow is passed
on as extra heating and cooling costs,
oversizing of mechanical equipment and
impacts on condensation and thermal
comfort that are not fully realized. Let’s
also not forget about the cost of adding
more insulation.
Fortunately, there are sensible ways
to account for the effects of these thermal
bridges. The method of linear transmittance, as outlined in ASHRAE 1365-RP,
has been around for a while but not widely
used in North America. Now, with relevant
data to support the method, there is an opportunity to integrate this approach to improve current practices.
Essentially, this method allows transitional details to be characterized by the
amount of extra heat flow they add to the
wall assembly. For example, the linear
transmittance of a slab edge is the added
amount of heat flow from the slab per linear foot of the slab across the building.
This approach also works for point transmittances, like steel canopy penetrations.
Figure 1. Brick veneer assembly with flush
slab.
Figure 2. Thermal profile showing heat flow
bypassing the insulation through the slab.
Winter 2013 15
Table 1: Summary of Floor Slab Linear Transmittances
Floor Slab Detail
Exterior Insulated
Z-Girt Framing at
Concrete Slab
Insulated Metal
Panel at Structural
Steel Framed Floor
Exterior Insulated
Z-Girt Framing at
Structural Steel
Framed Floor
Thermally Broken
Concrete Slab
Extension
Insulated Metal
Panel at Structural
Steel Framed Floor
Pre-Cast Concrete
with Steel Anchors
at Concrete Slab
Stand-off Shelf
Angle Attached to
Concrete Slab with
Continuous Metal
Flashing
Standard Shelf
Angle Attached to
Concrete Slab with
Continuous Metal
Flashing
Un-insulated
Concrete Slab
Extension
Un-insulated
Concrete Slab with
Exterior Slab Face
Flush with Brick
Wall Assembly
Linear Transmittance
Btu/hr∙ft OF
(W/m K)
Category
Exterior Insulated Steel
Stud Wall
0.02 to 0.06
(0.03 to 0.11)
Efficient
Horizontal Insulated
Metal Panel System
0.02 (0.03)
Efficient
Exterior Insulated and
Interior Insulated Cavity
Steel Stud Wall
0.07 to 0.18
(0.12 to 0.31)
Efficient to
Average
0.12 (0.2)
Efficient
0.19 (0.32)
Average
Sandwich Panel with no
Interior Insulation
0.12 (0.21)
Efficient
Precast Concrete Panel
with “Continuous”
Interior Insulation
between Panel and
Drywall Framing
0.22 (0.38)
Average
Precast Concrete Panel
with Interior Insulation
Interrupted by Steel Stud
Framing
0.29 (0.50)
Poor
Exterior Insulated
Brick Veneer Wall with
Concrete Block Back-up
0.19 (0.33)
Average
Exterior Insulated Brick
Veneer Wall with Steel
Stud Back-up and Cavity
Insulation
0.18 (0.31)
Average
Exterior Insulated Brick
Veneer Wall with Steel
Stud Back-up and Cavity
Insulation
0.26 (0.45)
Poor
0.29 (0.51)
Poor
0.34 (0.59)
Poor
0.43 (0.75)
Poor
Interior Insulated
Concrete Mass Wall
0.47 (0.81)
Poor
Exterior Insulated
Brick Veneer Wall with
Concrete Block Back-up
0.36 (0.62)
Poor
Exterior Insulated
Brick Veneer Wall with
Concrete Block Back-up
Vertical Insulated Metal
Panel System with Metal
Stacked Joint
Exterior Insulated
Brick Veneer Wall with
Concrete Block Back-up
Exterior Insulated
Brick Veneer Wall with
Concrete Block Back-up
Exterior Insulated Steel
Stud Wall
16 Journal of Building Enclosure Design
This allows details to be categorized from
poor to efficient in terms of the additional
heat flow they produce (examples for floor
slabs are shown in Table 1).
By characterizing the heat flow through
transitional details in this manner, designers can more accurately make informed
decisions when designing energy-efficient building envelopes. For example,
the heat flow through a poor-performing
detail, like an exposed concrete slab edge,
could account for over 40 percent of the
heat flow through the building envelope.
This amount alone is surprising when
you consider that it is typically ignored in
calculations.
In comparison, a thermally efficient
detail, such as an insulated slab edge,
could contribute less than 10 percent. Insulating the slab edge could be much more
cost-effective than trying to add more insulation to a wall assembly. By addressing
transition components along with wall
and window assemblies, a designer can
more accurately evaluate what the best
way is to improve overall U-values.
In order to change current practice for
dealing with thermal bridging in transition components, communication between all members of the design team
is essential. Increasing the accuracy of
the U-values of walls will affect other aspects of the building design. Previously,
heating, ventilation and air conditioning
(HVAC) equipment had to be oversized
with a significant safety factor because
thermal bridging was difficult to quantify.
Now, with the inclusion of an easy way
to determine this heat flow, HVAC load
calculations can be evaluated with more
confidence.
Moving forward, understanding and
integrating these thermal performance
methods into practice is required by all
parties involved in the building industry.
For the architect, this is identifying efficient details over poor details in design.
For the HVAC engineer, this is understanding the impact of accurate wall Uvalues on load calculations. For the energy
modeler, this is using overall U-values that
include thermal bridging in whole building energy simulations, as well as recognizing the sensitivity of wall U-values on
simulated energy use. Most importantly,
for governing bodies and standards associations, this is acknowledging thermal
Thermal Bridging on CIRS
The Centre for Interactive Research on Sustainability (CIRS), located at the University of British Columbia, is a good example of thermal bridging done right.
In fact, in order to achieve a high level of energy efficiency with the building envelope, thermal bridging
was minimized during the design of this building.
The main structure is wood frame, using glulam
beams and some concrete sections. The cladding is
connected to the structure using intermittent clips, which significantly reduced the thermal bridging compared to continuous girts.
This also allows the exterior insulation to be run more continuously, especially over slab edges and rim joists. The roof insulation is
run outboard of the structure with few penetrations. Additionally, the curtain wall was also aligned with the plane of the exterior
insulation to minimize heat loss at curtainwall transitions.
bridging and providing incentives for better practice.
These governing bodies set the framework for industry to find the most efficient
solutions. If thermal bridges in transition
components are not recognized by the
codes and standards, then there will not
be a level playing field for designers. Accounting for heat flow through these transition components will make the building
appear to be worse off than if they were
just ignored. In reality, if the transition
components are recognized and addressed, the building will have a much
better thermal resistance. This creates a
bizarre situation where you are rewarded
for being less accurate. If there are no consequences for bad practice, or no recognition of good practice, then there is no
incentive to improve on what is currently
being done.
If there are real gains of improving
overall building U-values to be made, then
the governing bodies and standards associations will have to include accounting for
thermal bridging in transition components
in their compliance paths.
As architectural designs become more
complex and demands for energy-efficiency increase, it will be up to industry
to ensure that current practice sufficiently
reflects reality. All members of the design
team must be aware of these issues to ensure thermal bridging is recognized when
it does make a difference. Otherwise, as
energy costs rise, the industry will find out
pretty quickly that ignorance is not bliss. n
Mark Lawton, B.A.Sc., P.Eng. and Neil
Norris, MASc., are with Morrison Hershfield, Ltd., based out of Vancouver, British
Columbia.
Winter 2013 17
The Truth is
Out There:
Feature
Efficiency and Iconic
Architecture Can Co-Exist
By Joseph Lstiburek, PhD, P.Eng., ASHRAE Fellow
4 and Figure 5. These are available right
here in the good ‘ole US of A. They’re also
apparently available in Serbia (Figure 6)
and pretty much anywhere folks want them.
Triple-glazed gas-filled curtain walls have
been around for a while. The thermal breaks
have also been around for a while; mostly in
Europe and in Canada.
The Aqua Building is not an exception.
Most buildings are like this; thermal bridges
galore. It is a big deal. The good news is folks
are beginning to get it (ASHRAE 90.1) and
great work is being done on the research
side.1 The bad news is that although we know
this stuff, it is not getting used. It seems to me
that folks are just not serious about energy.
This is an architectural problem. This is an
Figure 1. Extended finned-surface, made
of concrete.
Figure 2. An infra-red of the Aqua Tower.
architectural detailing problem. This is an
architectural detailing problem that involves
structural engineering. To deal with this is
going to require collaboration between architects and structural engineers. Serious
collaboration.
Too often, structural decisions are made
in isolation from the energy impacts. It is not
that the structural engineer does not care. It’s
just that no one asks—but it’s time to ask. It’s
time to get great things from your structural
engineer.
Balconies are a big deal and everyone
knows that. But relieving angles can be an
even bigger deal. They go completely around
a building and sometimes occur at every
floor. Balconies rarely do, previous exception
noted. The good news is that we know how
to deal with relieving angles. The bad news is
that we often do not. Sound familiar?
The best way to deal with relieving angles is to hang them off of the building with
a “stand-off” (Figure 7) and then spread
them out every second or third floor. This
Dave Robley and Michael Stuart, Fluke Corp.
It is a beautiful building. Quite
stunning actually. It is an embodiment of
everything that is right and wrong with architecture. An orgy of glass and concrete. It is a
thermodynamic obscenity while it takes your
breath away. An 82 story heat-exchanger in
the heart of Chicago (Figure 1, Figure 2
and Figure 3).
Could it have been constructed differently without the thermal bridges and without
changing the appearance? Sure. It could have
been an example of efficiency, not just iconic
architecture. And that would have been a
beautiful thing. And it could have been done
with off the shelf stuff, no less. How about a
true R-5 curtain wall between thermally broken cantilevered slabs? Check out Figure
18 Journal of Building Enclosure Design
Figure 3. An infra-red of an Aqua Tower
balcony.
allows your insulation to run past the angle.
Presto, continuous insulation (Figure 8).
The stand-offs can be welded to plates cast
into slabs or welded to structural steel supports (Figure 9). Amazing as it seems to
civilians and other mere mortals, the architect obsesses over the location of the relieving angle. It can’t be just anywhere. It has to
look good wherever it is. Sometimes it has to
line up over the heads of windows for reasons
that escape me, a mere mortal, so we have to
ask the structural engineer to be clever (Figure 10). See, all you have to do is ask.
What if I do not like brick? Great, no relieving angles. How do I do panels? And, how do
I do panels “conservatively” if I don’t buy into
all that other stuff you have talked about? Ok,
ok, ok. Check out Figure 11. Although the
structural design required for thin stainless
angles and long galvanized L-rails is simple,
engineers normally are designing for loads of
thousands of pounds (kips) and the hundred
pound loads involved here are unfamiliar
and sometimes scary.
We also have to deal with the thermal
bridges associated with windows. For reasons that are unclear to me, where windows
are concerned, we don’t call it a thermal
bridge, we call it “flanking” losses. Flanking
losses are losses around the window often
through the buck or through the structure
components the wall is installed in. The bottom line is that you need to line up the thermal control layer in the window unit (a.k.a.
“thermal break”) with the continuous insulation you are now required to install on the
exterior of the wall. That often means pushing your window outboard and hanging it in
mid-air, sort of. Gotta talk to the structural
engineer again. Magic will happen again. Figure 12 has everything, including
relieving angles on stand-offs and bumped
out windows. Nice. I wonder if there are any
Leadership in Energy and Environmental
Design® (LEED) points for this? Yeah, probably not.
The best thing to do is to take your structural engineer out to lunch and discuss
relieving angles, window attachment and
balcony thermal breaks.
Enjoy a nice moment with your engineer…
n
Joseph Lstiburek, PhD, P.Eng., ASHRAE
Fellow, is principal of Building Science
Corporation.
Unless otherwise noted, all photos/images provided by ©buildingscience.com.
The rest of the images are located on the
next page.
Beodom, Inc., Belgrade, Serbia
Figure 6. The product shown here, which is being used on a
building in Serbia, prevents thermal bridges on balconies.
Schoeck Canada, Inc.
Figure 4. Section at balcony glazing interface. Take a highperformance curtainwall and couple it with a high-density
expanded polystyrene thermal break and some basic slab water
control and you have a beautiful thing.
Figure 5. Pre-manufactured thermal break. High-density graphiteenhanced expanded polystyrene. Note the reinforcing rods
penetrating the foam are stainless steel, not carbon steel. Stainless
steel has less than half the thermal conductivity of carbon steel.
Figure 7. Relieving angles. Hang them off of the building with a
“stand-off.” This allows your insulation to run past the angle.
Winter 2013 19
More images relating to this article are available
at www.buildingscience.com/documents/insights/
bsi062-thermal-bridges-redux
Figure 8. Continuous insulation. If you are serious about energy,
this becomes standard practice.
Figure 11. Clip and rail minimum thermal bridging to support
metal panels, fiber cement panels and composite panels.
Figure 9. Stand-off. This can be welded to plates cast into slabs or
welded to structural.
Figure 12. A little bit of everything…relieving angles on stand-offs
and bumped-out windows.
Figure 10. Relieving angle line up. Notice how the relieving angle
lines up with the top of the window.
20 Journal of Building Enclosure Design
FOOTNOTE
1. ASHRAE Report No. 5085243.01, Thermal Performance of
Building Envelope Details for Mid- and High-Rise Buildings
(1365-RP), addresses thermal bridges. The report was done
July 2011, for Technical Committee 4.4, Building Materials
and Building Envelope Performance. www.morrisonhershfield.com/.../MH_1365RP_Final_%20small.pdf.
SAVE THE DATE!
The twelfth international conference on Thermal
Performance of the Exterior Envelopes of Whole Buildings,
sponsored by BETEC, ASHRAE and organized by the Oak Ridge
National Laboratory (ORNL), will be held on December 1-5,
2013 at the Sheraton Sand Key Resort in Clearwater Beach,
Florida. This conference will be presented in two concurrent
tracks:
Principles - Devoted to Research; and Practices - Focusing on Practical Applications and Case Studies. Specific
topic workshops will be presented before and/or after the conference.
Inaugurated in 1979, the “Buildings Conference” takes place every three years allowing time to develop new
research and technology applications and to document the findings. Attendance is international and draws heavily
on the advanced technical knowledge of all our global experts.
The “Buildings Conference” presents a great opportunity for product manufacturers, research groups, technical
advisors, builders, designers and other consultants to discuss their work achievements, interest and awareness of
buildings issues, and provide solutions to some of our major building problems.
This is also a great opportunity to create a presence at the conference by becoming a sponsor. For additional
information on sponsorship, please contact Andre Desjarlais at desjarlaisa@ornl.gov or phone (865-574-0022).
Winter 2013 21
SAVE THE DATE
January 6-10,
2014
Washington, D.C.
Be there in 2014 as the National Institute
of Building Sciences focuses on Advancing
Life-Cycle Performance during this second
annual conference and expo. The Institute
will present informative programming
from all of its councils, committees and
projects and feature the following:
• ThebuildingSMARTalliance™
Symposium
• FEDCon® – The Market Outlook on
Federal Construction
• TheBuildingEnclosureTechnology
andEnvironmentCouncil(BETEC)
Symposium
• TheMultihazardMitigationCouncil
(MMC)Symposium
• SustainableBuildingsIndustryCouncil
(SBIC)Symposium
• Innovativetechnologydemonstrations,
includingCOBie,SPieandother
information exchanges
Andmuchmore!
Sponsorship Opportunities Available
Witness the Institute’s impact on the
industry, interact with industry experts and
innovators, gain a wealth of information
througheducationalprograms,earnCEUs,
share your expertise and experiences and
participate in advancements toward a
betterbuiltenvironment.
Sign up to receive updates and more
information at:
www.nibs.org/conference14
National Institute of Building Sciences: An Authoritative Source of Innovative Solutions for the Built Environment
Feature
Thermal Bridging: The Final Frontier
of High-Performance Buildings
By Matt Capone, Assoc. AIA
Minimizing our use of energy and natural resources
are vital components of the global strategy to protect our environment and mitigate climate change. Buildings and the construction
sector represent a large portion of total global energy and resource
consumption. The United States has responded to this awareness
with a tightening of building energy and performance standards.
ASHRAE 90.1 has significantly reduced the energy that can be consumed by a building.
One significant aspect of energy loss from a building is conductive
heat transfer through the building envelope. There are common improvement strategies to minimize conductive heat loss that include
reducing the window-to-wall ratio, using high-performance window
systems and improving façade insulation. These assemblies are largely responsible for the overall thermal performance of an exterior wall.
The focus has turned to a long-overlooked aspect of the design—
thermal loss through structural components. Traditionally, not a lot
of attention has been paid to the various thermal bridges that are integral to these larger envelope assemblies because they were thought
to represent a relatively small percentage of the overall energy loss.
As we improve the thermal performance of our overall wall systems,
however, the heat loss through thermal bridges becomes a much
greater percentage of energy loss and, thus, more important to consider and control.
These overlooked thermal bridges are a concerning topic. Off-theshelf, manufactured structural thermal breaks (MSTBs) have already
proven to be an attractive solution through their performance, not to
mention the material and system testing being completed by the system manufacturers. These products are now considered standard
building practice in Europe and are available in the United States market now too.
conductive materials that results in high levels of heat loss. As a consequence, in cold climates, low internal surface temperatures occur
during the winter that may create conditions for condensation and
mold growth.
In the case of uninsulated balcony slab connections, the interaction of the physical geometry (“cooling fin effect” of the balcony slab)
and the material properties (thermal conductivity of a reinforced concrete slab) can result in significant heat loss, meaning that the uninsulated balcony connection is one of the most critical thermal bridges
in the building envelope (Figure 1). Buildings that contain uninsulated balcony connections have significant incentives for adoption of
thermal break technology to improve thermal comfort, energy efficiency and indoor air quality.
Generally speaking, there are many different structural elements
and/or building components that penetrate the building envelope
and may form thermal bridges. This includes balconies, canopies,
slab edges, parapets or corbels. These components are common architectural features or essential structural elements in residential
buildings, as well as in commercial buildings, such as hotels, schools,
museums and gymnasiums.
Depending on the assembly design and climate zone, these structural penetrations through the building’s thermal layer are providing
a direct path for energy loss and premature structural damage due to
condensation. Another possible effect of thermal bridges includes an
uncomfortable living environment, due to differentiating temperatures within one space. During the wintertime in a cold climate, the
center core temperature of the room needs to be increased to make
the edges and corners bearable. While some may think that radiant
flooring can combat thermal bridging, the result is an increase in energy use to constantly heat a lost cause.
Identifying Structural Thermal Bridges
Thermal bridges are localized elements or assemblies that penetrate insulated portions of the building envelope with thermally
An Approach to Reduce Thermal Bridges
The more efficient a building is designed to perform, the more impact thermal bridges have, as the thermal path will follow the easiest
route with the least thermal resistance—structural thermal bridges.
Figure 1. This thermograph photograph shows that if thermal
bridges at balconies are not addressed, the balconies act as
“cooling fins”, conducting the heat off the building and cooling the
rooms adjacent to the balconies.
Figure 2. An illustration of balcony connections with structural
thermal breaks.
Winter 2013 23
Windows are often seen as the largest thermal bridge in buildings because the thermal performance is often quite low compared
to the surrounding walls (for example, an R-2 metal frame window
within R-20 insulation). However, exposed slab edges and balconies
can have almost as large of an influence, having effective R-values
around R-1.
These weak links in the building envelope reduce the efforts of insulation and air barriers. The design team should be aware of the thermal calculations of the design to ensure the entire building envelope
meets the project’s expectations for efficiency.
To reduce structural thermal bridges, the engineer should also be
involved early in the design process. Architects deserve the freedom to
explore their design and working with the structural engineer earlier allows time to find solutions to enhance or follow the design input. This
collaboration between the architect and engineer is essential to energy-efficient designs, especially when dealing with structural thermal
breaks.
Solutions to Structural Thermal Bridges
Structural thermal breaks (Figure 2) reduce the heat flow, while
also conserving structural integrity. At uninsulated balconies, for example, the reinforced concrete at the connection is replaced with an
insulating material, while continuous reinforcement bars are used
to transfer loads (moment and shear). In some instances, these reinforcement bars may be replaced by stainless steel where they penetrate the insulating material, as it is much less thermally conductive
than conventional reinforcing steel. The use of stainless steel not only
reduces thermal conductivity but also guarantees longevity of the
24 Journal of Building Enclosure Design
structural components in the gap where no concrete protects them,
through its inherent corrosion resistance.
Other materials are also used in some proprietary systems, with
the aim of reducing thermal conductivity, such as concrete modules
to transfer compression instead of stainless steel.
The combination of all these aspects means that structural thermal breaks can average an equivalent thermal conductivity of k =
0.19 W/mK (0.110 btu/h ft K) to connect a standard balcony with a
cantilevered length of 2 m, instead of k = 2.2 W/mK (1.27 btu/h ft K)
for reinforced concrete at an untreated balcony connection. This reduces the thermal conductivity at the connection by up to 90 percent
and can also elevate the surface temperature in the living area up to
a maximum of 63.7°F (17.6°C), depending on the nature of the structure. (Figure 3).
The improvement in thermal performance by using MSTBs may
benefit the application of green building programs, such as Leadership in Energy and Environmental Design® (LEED), by contributing
to the reduction in overall building energy use. Typically, a range of
MSTBs are available from the manufacturer, depending on the load
requirements and deflection criteria, so that the optimal solution between structural and thermal performance can be found.
Integration in Building Design
in the United States
To ensure that the requirements of a project are met, an integrated
design process between the project architect, engineer, relevant specialty consultants, construction team and manufacturer’s technical
staff is recommended. For example, an appropriate design solution
Figure 3. The diagrams illustrate the influence of an effective insulation
product in a concrete construction. The heat can freely flow out via a
non-insulated balcony slab but by using the product, heat loss will be
reduced and the inside surface temperature will be increased.
for a high-rise residential building with cantilevered concrete balconies will vary based on regional construction practices and cladding
assemblies (brick veneer, architectural pre-cast concrete, exterior insulation and finish system, painted concrete, etc.) (Figure 4).
Therefore, the project architect will be required to determine and
illustrate the location/placement of the thermal breaks, taking into
account considerations from the integrated design team. This will
include the code consultant to comply with code requirements for
fire resistance/protection specific to the project details; the building
envelope consultant to maintain continuity of the critical barriers (air,
moisture, vapor and thermal); and the structural engineer in order to
avoid interference with the structural attachment of other elements
(glazing, framing, etc.).
Additionally, the structural engineer should also take into account:
slab rotation at the slab extension, primarily due to the elongation
of the unbonded bars in the MSTB; expansion joints in the exterior
structure, due to thermal elongation of the exterior element; and
lap reinforcement to ensure the transmission of the loads into the
slab. The manufacturer’s technical staff may also offer support with
those previously noted, based on project experience and research/
testing completed by individual manufacturers. Some manufacturers provide recommendations for these considerations in their technical manuals, based on structural calculations for ensuring code
compliance.
To summarize, the following key points should be discussed
among the design team prior to the project architect illustrating the
integration of structural thermal breaks in design drawings:
• Desired thermal performance;
• Structural demand versus capacity of the MSTB;
• Minimum clearance required for structural attachment of other
elements;
• Fire protection requirements at selected details;
• Continuity of the building envelope critical barriers;
• Waterproofing transition and connection details; and
• Installation procedure and construction sequencing.
Figure 4. An illustration of a sample detail at a typical balcony with a
brick wall, for reference purposes. There are several solutions possible
and the shown detail should create an idea of how to integrate thermal
breaks in current construction methods. The shown waterstop should
solve the issue that the concrete curb is not integral with the slab.
Conclusion
As energy efficiency requirements in the United States building
construction market continue to become more stringent, greater
emphasis and attention is likely to be required at thermal bridge locations in design. In addition to the energy use benefits of thermal
breaks, there are also other benefits, such as reduced risk of condensation and mold occurrence and improved user thermal comfort.
Manufactured structural thermal breaks provide an attractive option
because the system testing has already been completed to facilitate
ease of adoption in design and construction.
The integration and installation of MSTBs has various considerations that require collaboration among the project stakeholders
to ensure that the project requirements are met. This is no different from any quality construction project. Adoption of this building
technology is growing and providing a knowledge base specific to
the United States construction market. Owners and developers can
also facilitate project specific adoption of this technology by utilizing design professionals and preferred product suppliers already
experienced with the integration of MSTBs in building construction
in the United States.
n
Matthew Capone, Assoc. AIA, is the United States Sales Manager for Schöck USA, Inc. Capone is an architectural designer with
a wealth of experience in design-build projects and implementing
energy-efficient strategies. His project experience extends from initial design development to construction practice. With a drive to create a lasting positive impact on our communities and environment,
Capone applies techniques and industry insight to bring realization
to the table. He is both proficient in building information modeling
(BIM) and in energy-efficient strategies, such as Passive House. Capone holds a B.Arch. from Roger Williams University.
Winter 2013 25
Industry Updates
BEC Corner
National
By Fiona Aldous, WJE; Building Enclosure
Council (BEC)-National Co-Chair
The BEC-National Executive Committee
is comprised of six members, including Cochairs Dave Altenhofen and Fiona Aldous;
Past-Chair Rob Kistler; AIA Liaison David
Herron; and Secretaries Whitney Okon and
Brian Stroik. In January 2013, Altenhofen will
transition to the role of past-chair, Aldous will
take on the position of chair and a new vice
chair and secretary will be selected.
BEC-National is responsible for organizing, assisting, supporting and promoting the
individual BECs in their local efforts; addressing issues at a national level that are common
to some or all of the BECs [such as recent
code hearings regarding the use of plastic insulation and compliance with National Fire
Protection Association (NFPA) 285]; the promotion and encouragement of discussion,
training, education, technology transfer, exchange of information about local issues and
cases, relevant weather conditions, and all
matters concerning building enclosures and
the related science; and dissemination of best
practice knowledge to all concerned with the
building enclosure.
BEC-National has assisted in the development of the recently-formed BEC-Cleveland and is currently coordinating with an
additional three cities interested in joining
the growing list of BEC chapters around the
country. We look forward to 2013 as an exciting year for BECs.
Austin
By Keith A. Simon, AIA, LEED-AP, Associate
III, WJE; BEC-Austin Chair
BEC-Austin programming for 2012 consisted of Daylighting Fundamentals, by Keith
Simon, WJE, in January; a Spray-Foam Roundtable in February; Vapor & The Building Envelope Basics, by Jen Doyle, Engineered Exteriors,
in March; Sustainable Green Roofs for Texas, by
Bruce Dvorak, Texas A&M, in April; Commercial Roofing Fundamentals, by Dennis Wilson,
C-CAP, in May; Advanced Roofing Seminar, by
Edis Oliver, WJE, in June; Building Enclosure
Fundamentals, by Matt Carlton, WJE, also in
June; a High-Performance Detailing Symposium,
by Brian Roeder, PSP and Will Wood, McKinney/York, in July; Thermal Imaging & Building
Diagnostics, by James Kolarik, Entest, in August;
a Construction Litigation Roundtable in September; Sealants 101, by Ben Rogers, Tremco,
in October; and Integrated Enclosure Design, by
Justin Wilson, Building Performance Solutions,
in November. In December, we were excited to
host our first full-day seminar, Adventures in
Building Science, with Joe Lstiburek, Building
Science Corporation.
Another new initiative for BEC-Austin in
2012 was the formation of the International
Energy Conservation Code (IECC) task force,
led by Jeff Acton, WJE & Scott Magic, Michael
Hsu Office of Architecture. We provided comments and recommendations on the enclosure items in the 2012 Energy Code for the
city of Austin through open forums with the
Austin-AIA.
In 2013, Terese Ferguson, DFP, will be the
primary BEC-Austin chair; Keith Simon, WJE,
will remain as co-chair; and John Posenecker,
Chamberlin, will also join as co-chair.
Boston
By Jonathan Baron, AIA, LEED-AP, Associate,
Shepley Bulfinch; Boston-BEC Co-Chair
The Boston-BEC continues to meet
monthly (except for August and December) at the Boston Society of Architects’ new
headquarters in downtown Boston. Recent
presentations have included How to Avoid
Wall Flashing Leaks, by BEC-Boston members Matthew Carlton and Derek McCowan,
Simpson Gumpertz & Heger; Durability
Analysis for Building Envelopes by Achilles
Karagiozis, Owens Corning; and A Comparison of Original and Replacement Windows,
by BEC-Boston member Jarod Galvin, Frank
Shirley Architects. We typically have 30 attendees at our meetings and there is always
spirited discussion with the presenters.
In addition to presentations, BEC-Boston
held a detailed workshop in October, at which
five groups analyzed details and presented
findings to the larger group. Each team traced
thermal barriers, air barriers, vapor retarders and drainage planes and described incongruities and potential improvements.
While we usually host great discussions, this
exercise led to exceptional involvement from
all members present.
Founding chairperson Richard Keleher,
after serving as co-chair since the founding
of the first BEC in 1996, has stepped down.
Maria Mulligan, past co-chair, has accepted
the position again and will lead with current
Co-Chair Jonathan Baron. We thank Richard
for his 16 years leading the BEC and establishing the template for BEC chapters around the
country.
Visit us at www.bec-boston.org.
Chicago
By Kevin A. Kalata, RA, SE, Associate
Principal, WJE; BEC-Chicago Co-Chair
BEC-Chicago’s membership continues
to grow. In 2012 alone, we have added more
than 60 new members, raising our total
membership to over 180. Our success can
be attributed to the quality of our monthly
presentations. BEC-Chicago is committed to
providing high-level technical presentations
related to current topics affecting the design
and construction of enclosure systems. Recent presentation topics have covered solar
reflectivity, by Curtainwall Design Consulting; high-performance façade technologies,
by Goettsch Partners; vacuum-insulated
panels, by Larry Carbary, Dow Corning; and
stone façades, by Chuck Muehlbauer, Marble
Institute of America.
Our website (www.bec-chicago.org) was
revamped and re-launched earlier this year.
It is based on an interactive platform that allows users to create and update their profiles
and access contact information for other
members, as well as view and post upcoming
events. The site also serves as a resource for
building enclosure documents and links.
In 2013, BEC-Chicago is looking to build
upon this platform to provide additional
features, including a technical forum where
BEC members can post and/or reply to inquiries, automated RSVPs for our monthly
meetings and web-based elections. Funding
has been provided by our generous sponsors and we would like to thank them for
their continued support: Corinthian-level—
BAMR; BASF; CertainTeed; Grace; Henry;
Raths, Raths & Johnson; Sto; USG; and WJE.
Winter 2013 27
Doric-level—Dow Corning and Powers
Fasteners.
For more information: ecassin@wje.com,
skflock@rrj.com or kkalata@wje.com.
Cleveland
By Nate Gamber, PE, WJE, and Ed Taylor,
Technical Assurance, Inc.; BEC-Cleveland
Co-Chairs
Since our formation last spring, BECCleveland has been met with enthusiasm
and support from AIA-Cleveland and the local building community. Following a charter
sponsor drive that was conducted throughout
the summer, BEC-Cleveland kicked off our
inaugural technical presentation on October
17, 2012. We were thrilled and gratified with
the support provided to BEC-Cleveland by all
of our charter sponsors and we doubled our
initial goals heading into the charter sponsor
drive. Nearly 150 professionals attended our
kick-off meeting, which featured a presentation by keynote speaker Dr. Joseph Lstiburek,
Principal of Building Science Corporation.
Dr. Lstiburek charmed the audience and gave
an insightful, educational and entertaining
presentation on building science topics, sustainability and how these issues specifically
relate to the climatic conditions of Northeast
Ohio. Several architecture students from Kent
State University were in attendance as well.
On December 5, 2012, Terry Brennan,
chair of the Air Barrier Association of America’s Whole Building Test Committee, provided an overview of air barriers. Topics covered
included performance requirements of air
barrier materials, assemblies and systems,
common design and installation issues, code
requirements and market forces driving energy-efficient buildings. Future presentations
are anticipated to cover NFPA 285 and building enclosure commissioning topics.
On behalf of BEC-Cleveland, we’d like
to thank AIA-Cleveland and our leadership
board for all their hard work in starting our
chapter and coordinating our first technical
presentations. We’d also like to thank and
recognize our charter sponsors. Without their
generous support we would not be able to
provide these programs:
• Platinum: Johns Manville (REPSofOHIO); DuPont Tyvek (Parksite); Dow
Corning; Tremco; VIP Restoration; and
WJE.
• Gold: Firestone Building Products (Advanced Building Products); Derbigum;
Prosoco; and Technical Assurance, Inc.
28 Journal of Building Enclosure Design
• Silver: Siplast (Icopal); SikaSmart (ChilCo
Diversified); Mid State Restoration, Inc.;
ECO Commissions; Integrated Engineering Consultants, Inc.; and Chas. E. Phipps
Co.
• Annual: Properties magazine.
Visit us at www.bec-cleveland.org.
Colorado
By Linda McGowan, PE, AIA, Building
Consultants & Engineers, Inc.; BEC-Colorado
Past Chair
In its eighth year, BEC-Colorado (BECCO) continues to maintain a strong presence,
with monthly programs preceded by a brief
business meeting averaging 43 attendees
who have backgrounds in architecture, engineering and construction. BEC-CO is grateful
to JE Dunn for the use of their Denver conference room.
In 2012, BEC-CO program topics included: January, Designing with Spray Foam Insulation; February, Ensuring Compliance of
Fenestration with Today’s Energy Codes and
Green Standards; March, Electronically Tintable Glass: A Project Showcase; Apri, Polyiso:
The High-Performance Choice for Continuous Insulation; May, Precast Concrete “Sandwich” Wall Panels; June, Building Envelope
Construction Defects; July, Skin and Bones:
Breaking Structural Façade Design Down to
Its Essence; August, Attaching Exterior Veneers
Over Continuous Insulation; September,
Annual Fall Seminar, Why Buildings Matter - Sustainability Challenges and Building
Science Lessons; October, Annual planning
meeting; November, Building Envelope Commissioning; and December, Air/Water Barrier
Detailing.
At our annual fall seminar, Chris Mathis
entertained a crowd of more than 110 attendees, with a focus on building energy consumption during construction and over the
potential 100-year life of a building. He also
provided a thought-provoking analysis of the
myriad of factors associated with building design and construction.
The success of the BEC-CO’s annual fall
seminar is due in large part to the support of
our sponsors: Colorado Prestresser’s Association; HDR Architecture; SBSA, Inc.; American
Hydrotech; BASF; BMC & Anderson Windows; Building Consultants & Engineers.;
CAD-1; Carlisle Coatings & Waterproofing;
CENTRIA Architectural Systems; CosellaDorken Products; Dow Building Solutions;
Georgia-Pacific; Group 14 Engineering; Nagel
& Associates, RW Specialties; VaproShield
by Elliott Associates; W.R. Grace; and CWA
Architecture.
BEC-CO leadership consisted of Chair
Chip Weincek, AIA, LEED-AP; Programs Director David Milliken, AIA; and Secretary Will
Babbington, AIA, PE, LEED-AP. As of October
2012, new positions are: Chair David Milliken; Programs Director Will Babbington; Secretary Alastair Huber, AIA; Communications
Coordinator John Price; and Sponsorship
Coordinator Jim Holt. BEC-CO is thankful for
the support of the AIA-Colorado and the tremendous efforts of Jenna Cather.
For 2013, BEC-CO will continue to explore
diverse program topics including the seventh
annual BEC-CO Fall seminar in September
2013. BEC-CO plans to support the AIA-BEC
and BETEC by funding the Chair to represent
BEC-CO at a national BEC conference.
Dallas
By Dudley McFarquhar, PhD, PE,
McFarquhar Group, Inc.; Dallas-BEC Chair
We are excited to report that the 2012
lectures series, Dynamic Dallas: Innovative Building Enclosure Design, was a success and sparked growth to our chapter.
Our monthly series began with the Perot
Museum of Nature and Science, with a talk
by the design team of Morphosis (CA) and
continued to lively events on the building
enclosures of the Winspear Opera House
(McFarquhar Group Inc and Seele, Inc.);
the retractable roof of the Cowboys Stadium (HKS and K Post); and the innovative
tubing cladding system of the Wyly Theatre
(McCarthy). Before our summer break, we
held a highly-attended meeting on the new
International Building Code (IBC) 2012 requirements for NFPA 285 testing (Carlisle).
Stepping back into the groove after our
summer hiatus, September’s gathering was
done Texas style with a barbeque meet and
greet and open discussion on trends, challenges and recent experiences regarding
building enclosures. We have had regular
meeting attendances averaging 40 people
with 75 maximum to date.
In October, we focused on how software
is integrated to assist in helping design a
better performing building. Representatives
from WJE and Corgan Associates presented
Dynamic Design Tools Used with Buildings &
the Building Enclosure: WUFI and BIM. We
closed out the year with a coda to our Dynamic Dallas series and a presentation on
the Dallas Audubon Center with BRW. They
discussed their design concept for the first
LEED-certified Dallas Park and Recreation
Department project.
We are thrilled looking to 2013, with a
presentation in the works focusing on the
adoption of the International Green Construction Code (IgCC) in Dallas. To learn more,
contact me at dudmcjr@gmail.com or follow
us on LinkedIn: Building Enclosure Council
– Dallas.
Greater Detroit
By Brian J. Tognetti, RA, CCCA; BEC-Greater
Detroit Program Committee
In 2012, BEC-Greater Detroit (BEC-GD)
again offered multiple engaging technical
seminars. Annually, we provide six regularly-scheduled, one-hour presentations on
cutting-edge building science, focusing on
guidance for building owners, facility managers, design professionals, construction
managers, contractors, material suppliers/
fabricators and other interested parties. We
averaged nearly 60 attendees per hourly program, and when considering the October
Annual Symposium, with over 200 registered
participants, the BEC-GD has provided continuing education with an overall contact
hour-to-date tally exceeding 5,000 hours!
On October 16, 2012, the BEC-GD hosted its 4th Annual Symposium in Livonia,
Michigan. The attendees benefitted from a
distinguished panel of nationally recognized
experts in the field of building enclosures.
This year’s symposium, Trends in Building
Enclosure Performance, was presented by
Henry Green, President of the National Institute of Building Sciences; Fiona Aldous, Associate Principal with WJE; Dr. Theresa Weston,
Research Fellow with DuPont Building Innovations; and Christopher Mathis, President of
MC2 Mathis Consulting Company. As with
our past symposiums, the cost to attend was
less than $10 per credit hour, an exceptional
value considering the technical topics and
networking opportunity.
The BEC-GD also took the opportunity
at the symposium to present a plaque to the
outgoing chairman, Steve Robbins, thanking him for his commitment, dedication and
leadership to BEC-GD.
For additional information, please contact any of our board members by visiting the
AIA-Detroit website (www.aiadetroit.com)
and clicking on the “committee” link to the
BEC Building Enclosure Council Committee.
For specific program information, contact
Andrew Dunlap (313-442-8186 or andrew.
dunlap@smithgroup.com). For program
sponsorship opportunities, contact Dan
Zechmeister (248-663-0415 or dan@mimonline.org).
Minnesota
By Judd Peterson, AIA, Chair, BEC-Minnesota
Following is a synopsis of what happened
in 2012. BEC-Minnesota participants Al Gerhke and Dick Quandt presented a two-part
session about Rockwool acoustic and fire
safing insulation. Then Craig Wetmore, York
Manufacturing, made a visit to explain York’s
decision to discontinue their fiberglass-clad
copper flashings in lieu of an elastomericcoated copper flashing.
James Reed, Thermocromex, came to explain the versatile, limestone-based, exterior
finish coating. And for the high-tech, futureis-now people, we had Paul Wisniewski, Dow
Corning, come to talk about Dow Corning’s
new vacuum-insulated panels. These are the
panel materials that have extraordinary R-values of 25 to 30 per inch! We also participated
in a Dow webinar about NFPA 285 and spray
foam assemblies.
Winter 2013 29
Tim Eian and his associates, Peter Yackel
and Jay Weiderholt, invited us to participate
in further discussions about passive house
energy-efficient construction. We joined
them for a discussion about the design and
construction on the MinnePHit House, which
was a significant retrofit effort.
Retrofitting for energy efficiency has become urgent and, in response, Minnesota
Senator Al Franken has developed the Back
to Work Minnesota: A Retrofit Jobs Initiative.
Senator Franken participates as co-chair of
the National Institute of Building Sciences
Senate Caucus on High Performance Buildings and he and his staff are currently working with Institute president, Henry Green, to
develop this retrofit program. Working with the BETEC Board Committee on Education Curriculum for Building Commissioning Certification, our BEC
participants have volunteered with various
Minnesota state colleges and universities,
primarily including Inver Hills Community
College, in developing curriculum with the
Institute for this Commissioning Certification
through the alliance between the Institute
and ASTM.
To this end, Senator Franken’s staff, including Lisbeth Kaufman and Katherine
Blauvelt, worked with Deanna Christensen
and Beverly Hauschild of AIA-Minnesota,
Rick Carter of LHB, and with BEC-Minnesota
to present an update on the status of the initiative, the BECx curriculum and the retrofit
initiative at the AIA-Minnesota Annual Convention in November. contact list. Attendance at monthly meetings averages about 50. The meetings are
free and held at AIA-Philadelphia’s Center
For Architecture over lunch and include a
one-hour technical presentation focused
on building enclosures and related building
performance issues.
BEC-Philly is excited to host a roundtable discussion with the German Federal Ministry of Economic and Technology
and the German American Chamber of
Commerce, Inc. The topic, Integrating
High-Performance Products into a WholeBuilding Design, will be moderated by
David Altenhofen, The Façade Group. The
morning session will explore issues related to incorporating high-performance
attributes into projects and to share the
different experiences between Philadelphians and Germans as they create energy-efficient buildings. The round table
will explore ideas for the evaluation of
products and materials in a holistic fashion that makes their performance a crucial
value-added part of the whole building.
We wish to thank the Architectural Glass
Institute for their generosity in support of
this event.
We were fortunate to have the opportunity to host Herb Yudenfriend this summer
and wish to thank him for making a presentation regarding security glazing. We especially
thank Valerie Block, DuPont, for her extremely interesting and impromptu presentation
on laminated glass. We are most grateful for
Valerie’s knowledge and support!
Philadelphia
By Cheryl Smith, AIA, LEED-AP, Cope Linder
Architects and Joe DeAngelis, AIA, LEED-AP,
TBS Services; BEC-Philly Co-Chairs
BEC-Philly membership continues
to grow; we now have almost 300 on our
Research Triangle
By Rita Ray, Senior Associate, WJE; BEC-RT
Chair
Since our founding in May 2011, the Research Triangle (BEC-RT) continues to have
regular involvement from local industry
30 Journal of Building Enclosure Design
representatives and our membership has
grown to over 200. The BEC-RT board used
their “free time” over the 2012 summer
monthly meeting break to develop and publish the new group website, which can be
found at www.bec-researchtriangle.org. It
is organized to provide visitors with general
information about us, upcoming BEC-RT
events, sponsorship, relevant educational references and upcoming national events that
are of interest to our members.
Through the course of 2012, the chapter
hosted regular monthly meetings with presentations by J. Patrick Rand, NC State University, Comparison of Masonry and Other
Cladding Materials in Terms of Embodied
Energy and Carbon Dioxide “Costs”; Mike
Gainey, Azon USA Inc., Optimizing Performance in Commercial Fenestration; Keith
Boyer, Centria, Navigating High-Performance
Wall Systems Using Insulated Metal Panels
and Integrated Windows; Bill Warren, Southern Energy Management, Energy-Efficient
Commercial Buildings Through Air Barrier
Consulting and Testing; Larry Harmon, Air
Barrier Solutions, LLC, Finding Air Leakage
in Small and Mixed Use Commercial Building
Enclosures; Brian Cordak, Koster American,
Solutions for Floor Moisture Control; Scott
LaPorte, BBH Design, Moisture Migration:
Hygrothermal Analysis of Complicated Wall
Sections; Kevin Day, Freelon Group, Documentation of Complex Building Enclosures;
and Andrea Wagner, Dow Corning Corp.,
Sealants in Air Barrier Systems. BEC-RT also
hosted a full-day roofing seminar in May,
with technical presentations by design and
manufacturer experts.
Many thanks again to our chapter’s founding sponsors: Baker, BBH Design, Centria
Architectural Systems, CFE Roofing, Curtis
Construction Co., Custom Brick and Supply
Company, Dow & Knight Wall Systems, The
Freelon Group, Hydrotech, Lend Lease,
Perkins+Will, VMZinc and WJE. Thanks also
to our 2012 monthly and event sponsors:
Carlisle Coatings & Waterproofing, Custom
Window Company, Centria Architectural
Systems, Grace Construction Products, Fibertite, Permier Building Products, Sika/Sarnafil,
Tremco, Inc., Koster Waterproofing Systems,
David Allen Company/Supercap LLC, Custom Brick and Supply Company, and Dow
Corning Corp.
For more information contact me at rray@
wje.com or contact Vice-Chair James Esquivel at james@jae-arch.com.
San Antonio
By Erik Murray, AIA, Senior Associate, WJE;
BEC-San Antonio Chair
BEC-San Antonio is wrapping up its first
year and all in all, it went very well. In our
kickoff meeting we asked the audience to
rate various aspects of the building enclosure based on importance, as it relates to
their respective lines of work. We had an
overwhelming response for air barrier and
related flashings in the cavity wall, along
with building envelope commissioning.
Our first presentation used case studies to
cover multiple aspects of the building envelope, which allowed us to segue into more
specific topics. The previously-mentioned
presentations included an in-depth look
into through-wall flashings and air barrier
testing.
Our plan for 2013 is to offer bi-monthly
educational presentations that will focus
on roofing, thermal dynamics, vapor barriers and historic preservations of existing
façades, to name a few. We are very excited
about growing the BEC in our community
and are looking for help from individuals
who have a passion for educating our industry in all facets of the building enclosure.
If you are interested, you can reach us at either of the following social websites. To help
us grow, please Like us on Facebook at www.
facebook.com/BECSanAntonio and join
our Linkedin page at www.linkedin.com/
groups?gid=4639297.
Seattle
By Roxanne Navrides, Seattle Housing
Authority; SEABEC Chair
Seattle Building Enclosure Council (SEABEC) membership continues to grow—we
are in our eighth year with 125 current members! We are always seeking new avenues to
reach students, architects, suppliers, contractors, building owners and property managers
who are not familiar with our organization.
We moved our meetings to South Seattle
Community College, near the trades section
of the school, to reach out to the students and
centralize our meetings.
Our September kick-off meeting was The
Passive House. Meeting information is available at www.seabec.org. Upcoming meetings
this fall include Optimizing Performance in
Commercial Fenestration, Indoor Air Quality
and a plant tour of Walters and Wolfe Curtain
Wall Manufacturing. Our December holiday
party once again raised funds for Habitat for
Humanity.
We are currently planning an all-day
symposium for May 21, 2013, at the Seattle
Art Museum, in conjunction with the British Columbia-BEC and Portland-BEC, for a
northwest/international event. The theme
is Zen and the Art of Building Enclosure Design. We have details on our website and
SEABEC extends an invitation to our BEC
colleagues nationwide to join us for this
educational event (plus, it’s the best time to
see the city).
SEABEC is pleased that the National
Institute of Building Sciences has opted to
hold the BEC chairs meeting and the BETEC
board meetings in Seattle the day prior to the
symposium. Numerous new apartment and
mixed-use projects have started and more
activity is reported by design firms here in
Puget Sound. Amazon, among other companies, continues to expand and occupy
more space. After the real estate melt-down
of years past, Seattle is experiencing exciting
growth, including the possibility of a new
sports arena near the two that host the Mariners and the Seahawks. Please send us a basketball team!
n
Winter 2013 31
Buyer’s Guide
Air and Vapor Barriers
Hohmann & Barnard, Inc....................24, 30
BASF Wall Systems....................................10
Associations
Air Barrier Association of America............26
RCI, Inc.....................................................33
Below Grade Water and Containment
Barrier
Polyguard.....................................................4
Building Science and Restoration
Consultants
Read Jones Christofferson.........................32
Building Sheathing Manufacturers
Georgia-Pacific Gypsum............................14
Consulting, Commissioning,
Engineering, Testing, Certification
and Inspections
Architectural Testing............................. OBC
Fasteners
Leland Industries, Inc................................12
Fenestration and Thermal Barriers
Azon USA, Inc...........................................31
Industrial Glass Supplier
PPG Industries..................................34, IBC
Masonry Anchoring Systems
Hohmann & Barnard, Inc....................24, 30
Masonry and BIM Modeling
Endicott........................................................3
Masonry Products
Hohmann & Barnard, Inc....................24, 30
Mineral Wool Insulation
Roxul, Inc.....................................................8
Pre-Engineered Steel Building
Manufacturing
Varco Pruden Buildings..............................29
Roofing
Duro-Last Roofing, Inc..............................17
Structural Engineering, Design and
Consultants
WJE............................................................13
Water Intrusion Test Equipment and
Training
The RM Group, LLC.................................32
Water Proofing/Air Barriers
MFM Building Products Corporation.........6
Sto Corp..................................................IFC
32 Journal of Building Enclosure Design
Winter 2013 33