Building Envelope, Beyond Aesthetics

The functionality of windows, walls and doors need not be sacrificed for a grand facade.

By Angelo Arzano, AIA and Donald Marmen, AIA
From the February 2018 Issue

For many people, the term “modern commercial architecture” brings to mind grand structures veiled in steel, glass, and concrete. And while gleaming curtain walls and sweeping composite shells can garner attention, it’s often the finer detail—the function over the aesthetics—that makes a building facade work for its occupants.

building envelope facade
(Photo: HOK)

For facility management professionals, this is vitally important. A building with a stunning street presence is great, but beauty, as they say, is only skin deep. A building envelope should not sacrifice its performance—and need not with current design technologies. When it comes to a building’s exterior, there are three key aspects that will factor into its long-term operation: maintenance, energy conservation, and comfort. How a facade responds to those three factors will ultimately determine whether its architecture transcends simple aesthetics and provides truly exceptional design.

Minimizing Maintenance

Every building, whether a modest 1,200 square foot home or a large corporate headquarters, requires steady maintenance to prolong its state of originality and intended performance. Yet maintenance can be costly, leading building owners of all stripes to seek solutions that require the least amount of upkeep.

As architects, one of the first things we want to help clients define is the true life expectancy of a building. Armed with that knowledge, we can begin to develop a facade design that minimizes maintenance costs over the entire scope of the building’s life. This is especially important for buildings designed to have an intended use over numerous decades (even centuries) as the long-term maintenance savings for these projects can be substantial.

building envelope facade
A gasket between two windows is often a preferred
sealant method, rather than higher maintenance caulking.
(Photo: HOK)

One simple technique for minimizing exterior maintenance is to use gaskets or flashings for exterior fittings and connections instead of sealants that harden over time and must be replaced. To ensure longevity of a sealant joint, strict guidelines must be followed from the manufacturer. These guidelines require stringent QAQC and replacement will become necessary if guidelines are not properly adhered.

Using gaskets eliminates this concern. Durable, corrosive-resistant materials—while initially costlier than other products—can also provide significant maintenance savings in areas where the exterior of a building is prone for abuse, such as along walkways and near loading docks.

At Centene Corporation’s new headquarters in St. Louis, MO, for example, black granite envelops the building anywhere it meets a sidewalk. In other projects, we use corrosive-resistant materials, such as stainless steel, to fortify and prolong exterior quality. These design techniques lead to facades that retain their original beauty while enduring the daily battle with external forces and reducing long-term operating costs.

Energy Conservation

Building and energy codes can vary greatly from state to state and from one municipality to the next. Yet even in jurisdictions with relatively lax codes, we encourage our clients to build to the highest possible levels of energy conservation and sustainability. Why? Because many of today’s green buildings can be constructed for around the same price point as conventional buildings while providing significant financial benefits over the long term. According to Dodge Data & Analytics’ latest “SmartMarket Report”, green buildings are 14% less costly to operate and have a net value 7% higher than conventional buildings of similar comparison.

Key design techniques for improving the performance of building facades include incorporating thermal breaks (to mitigate conductive heat loss), utilizing continuous air barriers to minimize air infiltration, and ensuring the continuity of vapor barriers and insulation throughout the building envelope. Our facade team applies these principles to every building envelope (whether or not required by code) to maximize the energy performance of each building. By doing so, the burden on mechanical systems (such as heating and cooling) can be reduced while ensuring the comfort of building occupants.

Sometimes the goals of comfort optimization can be in direct conflict with the goals of energy conservation. A glass curtain wall, for example, may provide natural lighting and outside views yet also introduce excessive glare and heat loss that diminishes occupant comfort. It is our charge as architects to consider all the impacts of design and provide solutions that in addition to providing long-term aesthetics offers lasting performance.

Optimizing Comfort

While occupant comfort and building performance can, as mentioned, be at odds, they can also work in harmony, particularly when conceptualized early in the planning process.

Take windows, for example. It’s known that daylighting and views to the outdoors positively impact the well-being of building occupants. Yet windows also have traditionally been major sources of heat loss and transfer. Fortunately, recent advancements in window design (such as triple glazing) have made it possible to use more glass with less impact on energy efficiency.

As examples, the facades for the expansions of Barnes-Jewish Hospital and St. Louis Children’s Hospital in St. Louis (the Washington University Medical Campus Renewal) were designed with the input of mechanical engineers and hospital representatives to determine the best way to optimize comfort for patients and visitors. With the visitor area located along a glass exterior wall, a solution was needed to ensure visitor comfort while maintaining pleasurable patient views. A consistent triple-pane glazing proved vital to regulate temperature and air movement in the space. Simultaneously, this approach eliminated the need for perimeter heat, resulting in significant savings in mechanical systems.

Another technique, fritted glass (created with small ceramic particles either built into or adhered to the outside of the glass) was used to provide a decorative, yet functional, solution to shading (see photo on page 32). Together, these glass shading techniques ensure that occupant needs are at the forefront of design for the Washington University Medical Campus Renewal.

Every project presents new and dynamic sets of challenges from climate and building codes to owner requirements and contractor and consulting limitations. Yet building owners and facility executives can benefit early on in a project with a holistic approach to design. This is especially true when it comes to a building’s exterior. Great facades must do more than just catch the eye. They must also enhance the resiliency, efficiency, and enjoyment of a building for years to come.

building envelope facadeArzano is the technical principal in the St. Louis office of HOK, a global design, architecture, engineering, and planning firm. With more than 25 years of experience, he manages the project delivery process for HOK’s clients in the 17-state North Central Region.

building envelope facadeMarmen is a senior facade specialist in HOK’s New York office with more than 23 years of experience in building envelope design and technology.

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  1. Great article showcasing the balance of design and lifetime performance in building envelopes. Even durable surfaces like granite, anodized aluminum, and stainless steel need periodic maintenance to ensure their long-term operation and aesthetics.

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