High-Performance Building Envelopes
Tight building envelopes provide occupant comfort and a
The building envelope is made up of many different
components: roof, walls, windows, doors, etc. The building envelope
acts as a thermal barrier, playing an important role in regulating
interior temperatures and determining the amount of energy required
for optimal thermal comfort. Creating a high-performance building
envelope means each piece is designed to minimize the transfer of
thermal energy, which in turn creates an energy-efficient or tight
The design of the building envelope can determine the amount of
lighting, heating or cooling it will need. For James Pastine,
project manager and project designer at Crawford
Architects, Kansas City, Mo., the essential elements of a
high-performance building envelope are the combination of the
building skin and the openings in it. The key is "Getting those two
elements to function together to provide the best environment
possible for the end user of the building," he says.
In addition to good windows and fenestration design, Brian
Court, AIA, partner, and Jim Hanford, AIA, LEED AP BD+C, principal,
at Miller Hull
Partnership, Seattle, say balancing heat loss, solar control,
daylighting and glare is essential. Next is airtightness, since
undesired infiltration affects long-term durability through
moisture control, HVAC sizing, energy efficiency and occupant
A high-performance building envelope should employ sustainable
strategies to provide a healthy and comfortable environment for the
building occupant, adds Ruth Ro, AIA, LEED AP BD+C, associate
principal at New York City-based Dattner Architects. "This means, starting in
the schematic phase, you consider passive strategies that would
affect performance--building orientation, solar exposure, climate.
Then, in design development, you consider material selection, solar
shading and daylighting strategies."
Climate and Location
Where a building is located plays a role in how the building
envelope is designed. In colder climates, the building envelope
reduces the amount of energy needed to heat the building, while in
hotter climates, it can reduce the amount of energy needed for
While understanding the climate is a good starting point,
Pastine says it's important to know how much a building is going to
have to be insulated, and what kind of environment it's going to be
in. "Is it going to be hot and dry? Is it going to be cold and wet?
Is it going to be wintery? Is there going to be huge rains?" he
asks. "Once that is determined specifically, we have to respond to
the very local environment on the site, such as the building's
orientation, adjacent buildings near it, the temperature it's going
to function in, etc."
The climate determines the strategy in designing the building
envelope. "In a mixed climate, we depend on mechanical systems to
provide a comfortable indoor environment most days of the year," Ro
explains. "The goal is to reduce the heating and cooling
While energy efficiency is the primary goal, Court and Hanford
say occupant comfort is just as important. "Access to natural light
and ventilation while controlling for glare are high priorities,"
they add. And, they note, working with the mechanical and
electrical systems to integrate the envelope's performance with
system selection and sizing is also important.
"Solar heat gain and glare control on the east and west façades
can be challenging," explain Court and Hanford. "Often, the best
solutions-such as limiting fenestration on these façades- isn't
always an option. The next best solution is often the most
expensive-automated exterior blinds, for instance."
When it comes to choosing the proper insulation for a
high-performance building envelope, Pastine says he is looking for
something that is going to perform well over time and won't break
down. "It has to have a continuity throughout the entire envelope
of the building," he says. "You don't want any cold or hot spots.
And getting our air barriers and vapor barriers in the correct
location, depending on the climate that we're in."
"Continuous insulation with no interruptions is important in
reducing heating and cooling loads," Ro explains. "Not only is this
good practice, but it is required by code. Insulation with a tested
R-value is meaningless if it is interrupted by metal study every 2
feet." And, she adds, it is important to be mindful of all
instances of thermal bridging. "That metal stud or metal girt will
act as a thermal bridge same as a non-thermally broken aluminum
Ro recommends looking for a higher R-value per inch of material.
For instance, closed cell foam insulation has an R-value of 6.5 per
inch and also acts as an air and moisture barrier. "This type of
insulation has to be tested as part of an assembly to conform to
non-combustible construction requirements," she says. "This is
typically achieved with a thermal barrier like a layer of gypsum
board, metal panel or even a spray-applied coating."
The Right Solution
Research and working together is essential when designing a
high-performance building envelope. "Buildings and building
envelopes have become a significant team effort," Pastine explains.
"We meet with experts on all the different particular products, we
meet with engineers and consultants, as well as contractors
familiar with new construction methods, and we evaluate other
facilities. We compare products and systems for performance, cost
and longevity, and then take all of that research and build a big
knowledge base to choose the right solution for a building. It
helps from a design standpoint, it helps from a cost standpoint,
and it gives us all of the information that we need to be armed
with to recommend the right solution to our client."
And, Pastine says one of the biggest challenges is educating
clients about the right solution. "We have to be full of knowledge
ourselves as designers to be able to come to them with an
appropriate solution, especially if it is something that they have
not gotten before. A lot of clients, contractors and architects are
resistant to doing anything different than what's been done for the
last 20 or 30 years."
To do that, he recommends keeping up with the latest technology,
arming yourself with the right information to be able to prove that
this new way of doing things is the right way of doing things.
"Sometimes they get it, and sometimes they don't," Pastine
explains. "Sometimes they see that it's going to be a bit higher
cost upfront, and so they just want to go back to what they've done
before. They can do it that way, but they're not realizing the full
life cycle costs of the building or that they'll be able to recoup
a lot of their costs by having systems inside the building that can
function very efficiently and minimally. Just because we've
designed the exterior better."
Simplicity is key, Ro says, when designing for energy
efficiency. "Whenever a window is placed in a deep recess or
whenever the material changes, keep in mind that these sections
need to be detailed thoroughly and with constructability in mind,"
she says. "Fortunately, there are so many products that allow for
deviation while maintaining a high performing building
*Image credit: HUB in Downtown Brooklyn,
designed by Dattner Architects and developed by Steiner