Tag Archives: facade

Sustainability in the Desert: Medical education facility showcases copper design

All photos courtesy Timmerman Photography

All photos courtesy Timmerman Photography

by H. Wayne Seale, AIA, NCARB

The design of the Health Sciences Education Building (HSEB) at the University of Arizona College of Medicine–Phoenix is inspired by the iconic canyon formations found throughout the state. Made using predominately recycled copper, the medical education building’s façade blends in naturally with its southwestern landscape, resembling the stratified earth layers and majestic canyons for which Arizona is known.1

Using nearly 6000 copper panels that were fissured, formed, bent, pressed, and perforated, along with more than 10,000 copper components, this massive 24,898-m2 (268,000 sf) facility consists of:

  • six stories of administration and faculty offices;
  • lecture halls;
  • learning studios;
  • flexible classrooms;
  • clinical suites;
  • gross anatomy facilities;
  • laboratories; and
  • conference rooms.

Medical education facility required

Students at both the University of Arizona and Northern University Arizona will have access to the HSEB to support various programs, including the colleges of medicine, pharmacy, nursing, and allied health. The facility will serve as a training ground for 1200 medical professionals annually.

Located within a 12-ha (30-acre) biomedical campus in downtown Phoenix, the building is owned by the Arizona Board of Regents on city-owned land. With a critical physician shortage both in the state and nationwide, there was a growing need to create a medical teaching facility for healthcare professionals to not only learn, but to conduct research as well. Due to economic conditions, the HSEB project faced enormous challenges overcome by using innovative technologies and domestically sourced materials highlighting the sustainable architectural design, elements, and impact.

The Health Science Education Building (HSEB) has a complex copper façade exterior that blends nicely into the Arizona landscape.

The Health Science Education Building (HSEB) has a complex copper façade exterior that blends nicely into the Arizona landscape.

Several design partners contributed to the project’s overall success, including two architectural firms—CO Architects and Ayers Saint Gross—and two contractors, a joint venture of DPR Construction and Sundt Construction Inc.

Online green learning

The selection and development of a building’s site can support the health of its surrounding community and identifies the positive outcomes of using the integrated design process. Maximizing the integrated design process was essential to the building’s success. It meant assembling a team of experts, including designers, construction managers, and exterior envelope contractors, who understood the project’s goals. The sustainability goals, and resulting performance criteria, were defined early during the schematic design phase. The approach also proved essential in solving the complex configuration of the exterior copper panels.

The integrated design approach affected the cost of the HSEB building. It was only through early collaboration between the design, design-assist, and construction teams that the complex, custom copper panel cladding was realized within the project budget. This would not have occurred in a traditional design-bid-build delivery method.

Leadership in Energy and Environmental Design (LEED) Materials and Resources (MR) and Indoor Environmental Quality (EQ) categories for which the contractor had a primary responsibility during construction. These credits include:

  • MR 2, Construction Waste Management;
  • MR 4, Recycled Content;
  • MR 5, Regional Materials;
  • EQ 3.1, Construction IAQ Management Plan–During Construction;
  • EQ 3.2, Construction IAQ Management Plan–Before Occupancy;
  • EQ 4.1, Low-emitting Materials–Adhesives and Sealants;
  • EQ 4.2, Low-emitting Materials–Paints and Coatings;
  • EQ 4.3, Low-emitting Materials–Flooring Systems;
  • EQ 4.4, Low-emitting Materials–Composite Wood and Agrifiber Product;
  • EQ 5, Indoor Chemical and Pollutant Source Control;
  • EQ 6.1, Controllability of Systems–Lighting;
  • EQ 6.2, Controllability of Systems–Thermal Comfort;
  • EQ 7.1, Thermal Comfort–Design; and
  • EQ 7.2, Thermal Comfort–Verification.

The roles and responsibilities of various construction team members for the project are related to Energy and Atmosphere (EA) Credit 3, Enhanced Commissioning. This credit entails additional commissioning activities beyond those required in the prerequisite, including the creation of a systems manual for the operating staff and a building operation review 10 months after substantial completion.

For HSEB, occupants are protected from the desert heat from May through the end of September by an overhead tensile fabric shade structure.

For HSEB, occupants are protected from the desert heat from May through the end of September by an overhead tensile fabric shade structure.

Some of the project’s internal and external conditions affect ventilation. EQ Credit 2, Increased Ventilation, requires the building have ventilation rates 30 percent beyond those required by American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 62.1, Standards for Ventilation and Indoor Air Quality. This is a strategy that can be more easily achieved in the southwest where it is temperate and dry most of the year. Humidity factor is more intense in places like Houston and Miami. However, the HSEB project as a whole did not attempt EQ 2, but the gross anatomy labs do have high air exchanges.

As with most lab applications, dedicated outside air is used. However, HSEB differs from many of its counterparts in the way air is distributed—being brought in above the table, and out below, but energy consumption use was minimized by having the ventilation turned off when it is not in use.

Desert designs

The desert can be relentless and harsh, and the building needed to adapt to its ecosystem. The design for the HSEB was shaped by the Arizona climate with the goal of reducing energy consumption. The building was oriented in east-west wings connected by a north-south axis so it would be shaded from direct sunlight during the summer months.

Windows were eliminated in the east and west wings; instead, deep glazed incisions were made to allow light to flow into the building from the north and south where they could be controlled. Shading devices of numerous geometrical shapes were also installed in varying elevations protecting the glazing on the building so the direct solar radiation hitting it in the summer was minimized, yet the sun’s rays could still be absorbed in the winter to provide some heat load for the building. This contributes to the overall energy savings for the building by reducing the heating and cooling costs.

Shading and daylighting strategies

A geometric shading study, conducted by the project team during schematic design, led to four main design recommendations:

1. Orient the wings in an east-west direction to most effectively control solar gain on the building’s façades.
2. Use self-shading to control solar gain by shaping the façade in three directions, which would entail:

  • curving the floor plates along the east-west axis, reducing the amount of sun on the east, half of the south façade in the morning and the west half of the south façade in the afternoon; and
  • sloping the vertical façade so the upper floors projected beyond the lower floors.

3. Provide shading devices on all elevations to prevent introduction of direct sun into openings from May through the end of September. South façades could be nearly completely shaded with horizontal devices of various geometries. East and west façades should be as opaque as possible, but if exposed, protected from low and high angle sun by honeycomb or screened structures. North façades receive low-angle summer sun and should be protected by closely spaced shallow vertical fins.
4. The courtyard would require protection from overhead.

The design team adapted the design to these principles. Rather than a smooth curve, the north and south wings were bent into a ‘bowtie’ shape, which achieves roughly the same performance while allowing rectilinear layouts of programmed spaces. Programmatic constraints would not allow the sloping of the vertical wall face, so the sunshade design parameters were modified to compensate.

Next, the team considered the program, daylighting, and views to implement the recommendations for shading and fenestration for each façade. In order to rapidly test various options, climate engineering consultant, Transsolar, developed a simplified approach where an individual model was created for each of the five major space types identified in the building program: offices, classrooms, clinical spaces, gross anatomy laboratories, and circulation. Each space was modeled as an individual, typically sized room within the building with three interior walls, and one exterior wall with 60 percent glazed area. Various combinations of ventilation systems, thermal comfort controls, fenestration, and shading devices were modeled. The thermal simulation of these ‘shoebox models’ was performed using energy modeling software.

Daylighting Optimization

The next design study looked at the effect of daylighting on the design of the façade and composition of the elevations, with the important goal of projecting as much daylight deep into the floor plate as possible. While this first appeared counterintuitive for Phoenix, it was justified by the reduction of electrical lighting loads, and maximizing connections to the outdoors for the building occupants. The team configured shading devices to prevent direct sun from falling on glass from May to September. By using the shading devices as light shelves to reflect indirect light into the building, they also reduced glare. A program was used to show sun penetration and generate sun angle studies to help configure the devices.

A close up of the complex copper-clad exterior of the Health Science Education Building.

A close up of the complex copper-clad exterior of the Health Science Education Building.

Finally, an exterior wall section profile was developed for each of the major space types, configured for orientation, ceiling height, room depth, and room activity. These optimized profiles were then applied to the elevations.

The design for HSEB draws inspiration from Arizona’s mountains and canyons; it responds to the desert climate, characterized by intense sunlight and extreme temperatures. For insight and inspiration, the architects turned to early human settlement in the Sonora Desert, where Native Americans traditionally sought shelter deep within slot canyons naturally created by wind and water erosion. These self-shaded majestic spaces maintain temperatures 8 to 14 C (15 to 25 F) cooler than the ambient temperatures outside.

Taking design elements from the mountainous environment, a canyon-like feature was carved through the north and south wings—which are bent in a bowtie shape—to create an outdoor space within the building. Occupants are protected from the desert heat by an overhead tensile fabric shade structure, the thermal mass of the concrete block cladding, and tempered relief air that is directed through the courtyard rather than exhausted from the air-conditioning system.

A big part of the project was integrating the multitude of copper elements into the overall building design. Numerous innovative construction management and project-delivery programs were developed to exhibit the team’s commitment to lean construction and quality, significantly reducing costly rework and waste.

Construction advances included:

  • prefabrication and assembly of the complex exterior copper skin panels on the ground, which were then hoisted into place—improving productivity by 20 percent, by reducing installation time, and eliminating the need for expensive changes;
  • building information modeling (BIM) for virtual 3D mockups, allowing all trades full access to the model to develop and coordinate the design of the panels, reduce errors and improve real-time coordination in the field, as well as enable clear review with the owners;
  • laser scanning providing a detailed, cast-in-place concrete as-built model, which, when superimposed over the virtual model, allowed the team to resolve issues in a virtual environment before fabrication and installation, thus eliminating rework; and
  • software-capable wirelessly networked tablet computers to create a real-time visual rolling completion list system, dramatically reducing time spent resolving quality issues.

Employing copper

The copper wall cladding used for this building is atypical from industry standard flat-panel installations. To meet the design intent, panels had custom shapes with custom folds—some perforated, others not—and the wall assembly was fully engineered for this extreme desert environment. The material is sustainable and changes over time, supporting the aesthetic and functional intent of buildings. Due to its durability, malleability, and high ductility, copper can be formed and stretched into complex and intricate surfaces without breaking.

The Health Science Education Building is clad with copper panels.

The Health Science Education Building is clad with copper panels.

While the copper will likely remain a brownish hue in this arid environment, its color will begin to change and become variegated over time, seemingly appearing to connect more to the surrounding mountains. The copper cladding for the HSEB is made up of 99-percent recycled material from copper mills. With a recycling rate higher than other engineering metals, the material used for the HSEB panels most likely served as a computer part, plumbing fixture, or wiring system several years ago.

Copper is recycled at different rates depending on the final use. For example, electrical wiring only comes from cathode copper and cannot use recycled material. On the other hand, architectural copper typically has anywhere between 75 and 100 percent recycled material. Mills will typically employ their scrap material first, if enough scrap is unavailable, cathode (i.e. material that has been produced through the mining process) will be used. Also, if an architect is submitting a project for LEED certification, he or she can specify the recycled content of their material. If 90 percent recycled material is requested, the mills will run 90 percent recycled copper.

The copper-clad exterior of the HSEB glistens in the evening glow.

The copper-clad exterior of the HSEB glistens in the evening glow.

Kovach Building Enclosures engineered, fabricated, and installed the nearly 2500 custom copper panels for the exterior of the building. Through an interactive, collaborative process in which architects used BIM to generate 3D models of panels, Kovach then fabricated into a series of full-size panel mockups, the team was able to create the appearance of a naturally occurring random pattern, while using only 26 panel types, arranged in multiple combinations.

The panel size and depth balanced visual and performance goals with cost-saving strategies, such as keeping overall panel size to domestically available copper. This project features multiple exterior finishes, including the approximately 113,398 kg (250,000 lb) of copper—most of which is recycled.

In addition to its aesthetic appeal, the extensive copper-cladding provides the HSEB with a skin most suitable for the hot, dry desert climate. With Phoenix temperatures reaching as high as 46 C (115 F), copper is an attractive alternative to steel due to its ability to quickly reject heat. The building’s copper-clad exterior serves as a shield protecting its interior from direct solar exposure.

Adapting rainscreen technology, the building’s design team took a system typically used in the northwest and created a way to use copper cladding as a sunscreen to keep excessive heat out of the HSEB. A fully integrated system consisting of copper panels, a 50.8-mm (2-in.) air space, rigid insulation, and a waterproofing membrane work together to absorb the radiant heat, and allow it to vent out through the building’s top.

Completed in August 2012, the HSEB project targeted Leadership in Energy and Environmental Design (LEED) Silver certification for new construction. Allowing optimal natural light in interior spaces while mitigating heat gain using building siting and advanced materials, the copper exterior meets the objective for thermal performance and durability, while creating an architectural expression unique to the building’s location. At the same time, the use of highly recycled copper honors and respects the state’s abundance of this natural resource.

The HSEB was oriented in east-west wings connected by a north-south axis so it would be shaded from direct sunlight during the summer months.

The HSEB was oriented in east-west wings connected by a north-south axis so it would be shaded from direct sunlight during the summer months.

Conclusion

The HSEB project was integral in boosting the economy through the creation of jobs, both during the construction phase and after the medical facility opened. Approximately 250 design, engineering, and construction jobs, as well as 33 permanent research positions, were created. The overall project is estimated to have an initial economic impact of $27 million. Studies produced by the owner and contractor have indicated the average return on investment of such projects is seven times the initial cost. Approximately 83 percent of metal, wood, cardboard, gypsum, and inert materials were also diverted from the landfill during construction.

The HSEB was recognized with a North American Copper in Architecture Award (NACIA) by the copper industry this year. It was one of 14 projects to be honored for its architectural design, detail, and craftsmanship.

Notes

1 A two-part video documentary produced by the Copper Development Association (CDA), in conjunction with design professional online resource, GreenCE, showcases the materials and craftsmanship of the HSEB project, as well as the philosophy and strategy behind the facility’s sustainable design and construction. Both CDA hour-long videos are registered with the U.S. Green Building Council (USGBC) for continuing education credits and with the American Institute of Architects (AIA). The resource can be accessed at www.greence.com. (back to top)

H. Wayne Seale, AIA, NCARB, is a project manager for the Copper Development Association (CDA) specializing in architectural and plumbing applications. He is an architect registered in New York State and holds a Master of Architecture degree from Virginia Tech along with a BA in Business Management from Minot State University. Seale has been employed by CDA for more than 16 years where he serves as a technical resource in the application of copper and copper alloys on and in buildings and he teaches architects how to design, detail, and specify copper systems. Seale can be reached by e-mail at wayne.seale@copperalliance.us.

Predicting Façade Failures

Author-photo-KJB1_smHORIZONS
Kimball J. Beasley, PE, F.ASCE

Building façades are often constructed with materials of variable strength that are constantly exposed to weather and attached with hundreds or thousands of concealed connections that cannot be easily inspected or maintained. These materials and connections, which may have been installed with minimal supervision due to difficult access, are often suspended over busy sidewalks with the expectation they will last forever—or at least for the building’s economic life. Continue reading

Expanding the Glass Canvas with Digital Printing

Photo courtesy Dip-Tech Digital Printing Technologies Ltd.

Photos courtesy Dip-Tech Digital Printing Technologies Ltd.

by Brian R. Savage, CPA

Previously, when architects wanted to add printed design elements to the glass skin of a building, they were limited to one- or two-color silk-screening or digital prints with difficult, organic-based inks. Now, ceramic-based inks have transformed digital imaging, resulting in a more controllable process with durable, long-lasting, hues.

The current generation of digital printers gives designers the opportunity to turn what was just the functional façade of a building into a decorative canvas. They also provide a way to optimize design, color, and solar performance for many types of façades. For example, curtain walls can have an image applied across the entire elevation while stone veneer can be replaced with a printed replica that can reduce cost and weight. Printing on punched openings can add a nice contrast to the other façade materials used in the building design.

Digital printing basics
There are various digital printing processes available for the architectural glass market. The two main differences within these digital printing techniques are the types of ink used and how the printer transfers the ink onto the glass substrate. This article focuses mainly on inkjet-style printers using drop-on-demand technology.

Designs previously impossible to accomplish are now within reach by using digital printing technology. At the AFIMall City in Moscow, the design goal was to bring the Russian forest into the city.

Designs previously impossible to accomplish are now within reach by using digital printing technology. At the AFIMall City in Moscow, the design goal was to bring the Russian forest into the city.

These printers employ a programmable print head that travels back and forth just above the substrate where the image is being applied. Each color of ink has its own grouping of nozzles on the print head that is individually activated and drops ink onto the glass substrate in the proper location—hence the name ‘drop-on-demand.’ The printers are usually located in a glass fabrication facility; the use of a clean room is recommended to reduce the chance of airborne particles contaminating the print.

Digital printing processes generally rely on organic ultraviolet (UV)-cured, inorganic ceramic inks that are fired to the glass during the heat-treating process, or specialized inks for printing on interlayers.

The cost for each of these printing types varies depending on the project’s size or complexity of the glass make-ups, but they are generally competitive with one another. UV-cured printing is suitable for interior applications, but has a limited use on exterior façades as the ink degrades over time.

Ceramic ink printing is useful in both exterior and interior applications, and can be employed in multiple types of make-ups. Printed interlayers must be used in laminated make-ups and may be subject to stretching and distortion during the fabrication process, but remain lightfast over extended periods.

In the past, the physical properties of ceramic frit—including the corrosive effect it had on the size of print heads and particles within the frit—made them difficult to print with an inkjet printer. Those drawbacks have been addressed and ceramic ink is now practical for use with a digital printer. Ceramic frit and ceramic ink are composed of microscopic particles of glass, pigments, and a liquid carrier. The liquid portion is dried and then fired so all that remains fused to the glass are the glass particles and pigments.

Digital printing’s flexibility means it can be used monolithically, or included in laminated and insulating glass units (IGUs). It can also be employed in combination with interlayers and have solar control coatings applied directly over the digital print, resulting in improved solar performance. Digitally printed glass can be used in numerous building areas, including:

  • exterior façades;
  • interior dividing walls;
  • signage; and
  • office walls.

The versatility and resolution capability of ceramic ink means various types of images can be printed, including photorealistic images, text, variable graphics, and patterns. Additionally, textures similar to wood grain, granite, and marble can be produced with excellent results. Both the transparency and opacity of the print are controllable. (These types of prints will be referred to as ‘images’ throughout this article.)

Digitally printed glass can be maintained in the same manner as other ceramic frit-coated glass. As a general rule, if it harms the glass, it harms the print. The recommended cleaning procedure includes using a conventional window-washing solution or mild soap and water in conjunction with a nylon bristle bush where needed. Razor blades, putty knives, and metal parts of glazing tools can scratch the printed surface, so care must be taken with their use. However, in most applications, it will be permanently protected in an insulating or laminated unit.

Drop-on-demand digital mixing deposits ink onto the glass to form the final color.  Photos courtesy Brian R. Savage

Drop-on-demand digital mixing deposits ink onto the glass to form the final color. Photos courtesy Brian R. Savage

By applying a frequency modulation (FM) screen effect (left) or amplitude modulation (AM) screen effect (right) to an image, a designer has the ability to adjust a façades solar performance, light transmittance, and privacy controls.

By applying a frequency modulation (FM) screen effect (left) or amplitude modulation (AM) screen effect (right) to an image, a designer has the ability to adjust a façades solar performance, light transmittance, and privacy controls.

Comparison to other glass enhancements
In the past, when there was a desire to add a visual design element to a building’s façade or interior, architects have largely been limited to a narrow range of products, including silk-screened designs and various interlayer systems. Each product has its advantages and disadvantages.

Silk-screening is usually the most cost-effective when there is a desire for only one or two colors, a repeating pattern is used, or there are many units to be silk-screened. However, the actual screen used in the silk-screening process can be cost-prohibitive, and is limited in the number of prints it can produce before reaching the end of its useful life.

Printed and colored interlayers can be useful when solid hues are required, but since they must be bonded between two pieces of glass, they can only be used in make-ups with a laminated component.

Digital printing helps remove some of these barriers, but may not be the ideal solution in all instances. It should be thought of as a complement to other technologies, including silk-screening and interlayers, and not necessarily as a replacement. If there is a desire for multiple colors within a design, a complex design is used, or an image is stretched across multiple units of the elevation, digital printing may be ideal.

Textures such as granite can be reproduced to potentially reduce cost and weight on the façade of a building. This digital granite can also be used in areas such as backsplashes.

Textures such as granite can be reproduced to potentially reduce cost and weight on the façade of a building. This digital granite can also be used in areas such as backsplashes.

Graduated dots and lines are easily produced with digital printing. Multiple colors on the same lite of glass can be added to enhance the design.

Graduated dots and lines are easily produced with digital printing. Multiple colors on the same lite of glass can be added to enhance the design.

 

 

 

 

 

 

 

 

 

 

 

Characteristics of ceramic ink
The inks used in digital printing are similar to the frit used in the silk-screening process. Both are ceramic-based, and perform and behave almost identically. The main difference is inks are produced with smaller particles of glass to allow them to flow through the print head onto the glass substrate. The inks also contain inorganic pigments, which help them to be as color-stable as ceramic frit over the printed image’s life.

The inks used in North America are free of heavy metals like cadmium or lead. Even with that limitation, a wide gamut of colors can be achieved by mixing base ink colors into final printed colors. There are two methods of color mixing—premixing and digital mixing during printing.

The first type is useful when there are only a few colors involved, or when a smooth color appearance is required for a project such as interior signage. Digital mixing is essentially the same concept as an inkjet printer.

With digital mixing, distinct variations in colors are achieved by placing drops of individual colors next to each other. Looking closely at a television screen offers the same effect—the screen is generally made up of blue, green, and red pixels; the three colors appear individually from a close distance, but combine to form the final image when viewed from farther away. This same concept occurs with digital mix. Blue and red drops of ink placed next to each other appear individually when examined up close, but combine to form purple when seen at a distance.

The inks are also able to be applied by the printer at varying thicknesses to achieve design results such as solar control or desired color variations. For example, blue ink tends to be more translucent than other colors, so a print with more blue may allow additional light transmission to the building’s interior during the day. A predominantly blue design may also let out more light at night as viewed from the exterior. If the intent is to limit the transfer of light, the various colors can be applied at different thicknesses to balance the amount of light transferred. However, the reverse is also true. If the intent is to create a façade that essentially glows with a stained glass effect from the interior or exterior, the image can be adjusted to achieve the desired effect.

Comparison of ceramic-based inks and organic-based inks
Ceramic-based inks and organic-based inks have advantages and limitations. Ceramic-based inks are durable and remain fused to the glass for a long-lasting print. Colorfast over long periods, they are resistant to scratches and abrasions. However, there are limitations on the achievable colors due to the restrictions on the use of heavy metals in production of ceramic ink. Ceramic ink standards for durability, expansion fit, and gloss falls under ASTM C1048, Standard Specification for Heat-strengthened and Fully Tempered Flat Glass.

On the other hand, organic-based inks tend to have a much wider color palette than ceramic-based, but are not as durable. Organic inks are not very colorfast, which limits their use to mostly interior applications. Organic-based inks cure at a lower temperature (i.e. 170 C [338 F]) than ceramic-based based inks (i.e. 600 to 670 C [1112 to 1238 F]), resulting in a potentially lower use of energy during fabrication.

Multiple font sizes, colors, and densities can be easily produced with digital printing.

Multiple font sizes, colors, and densities can be easily produced with digital printing.

The print head drops ink onto the glass as it moves back and forth just above the glass surface.

The print head drops ink onto the glass as it moves back and forth just above the glass surface.

The digital print process
The actual digital printing procedure can be separated into two distinct, but dependent, processes—electronic design file manipulation, and printing the image on the glass substrate.

The electronic design files can be produced in various formats. Both raster and vector-based images are acceptable in this process. The key attribute is the files must be high-resolution; the larger the actual printed image, the larger the file required. Since each project’s requirements are different, the meaning of ‘high-resolution’ varies. The proper preparation of image files is one of the most critical steps in the process. The printed glass quality can only be as good as the file used to generate the print.

Due to the thinner viscosity of the ceramic inks, a balance must be achieved regarding image resolution. Thinner viscosity allows for higher resolutions than may be possible with other ceramic-based media. However, care must be taken when the ink is applied at thicker opacities, as it may start to run together and blur the printed image.

The files can be individually designed for each unit to be produced, or the entire elevation can be designed as one file, allowing software to then tile the image across a façade. Such computer programs, which are usually proprietary and specific to each printer’s manufacturer, can also adjust the image for the inclusion of items such as mullions and holes for point-supported glass so the image flows seamlessly from one pane to the next. Finally, the software rips the image into color layer files for each of the base ink hues to be printed. For instance, a purple image might be ripped into a blue and red layer. Depending on the images’ complexity, there may be multiple layers of the same color.

These different color layer files are then sent to the printer where the image is interpreted and ink is deposited onto the glass substrate. Once the lite of glass has the image printed on it, the glass is sent through a tack oven to dry the ink. Newer-generation printers are now able to dry the ink as the image is being printed. At this point in the process, the ink has a matte finish and has not permanently adhered to the glass substrate.

The printed image is sent from the tack oven through a heat-treating oven where it is heat-treated, tempered, or even bent, according to the specification. The ink is fired at temperatures of 600 to 670 C (1112 to 1238 F), depending on the oven’s setup. It is only after this step when the image is permanently fired to the glass and the ink takes on a glossy finish. From here, the printed glass can be directed to other processes, including coating application, laminating, and insulating lines. If it is to be used in interior applications, it might even be left in monolithic form.

Otherwise-plain façades can be upgraded with relatively lightweight and cost-effective digital printing. [CREDIT] Photo courtesy Dip-Tech Digital Printing Technologies Ltd.

Otherwise-plain façades can be upgraded with relatively lightweight and cost-effective digital printing. Photo courtesy Dip-Tech Digital Printing Technologies Ltd.

The proprietary software adjusts the image to correctly print across multiple lites of glass.

The proprietary software adjusts the image to correctly print across multiple lites of glass.

Benefits and limitations
Benefits of the digital printing process include cost savings, design flexibility, and repeatability. The cost savings over silk-screening occur when numerous screens are required relative to the final number of units needed to be produced. There are also no storage costs with digital printing (something associated with screens) because files are kept electronically.

Design flexibility is achieved by allowing for custom images consisting of multiple colors. Micro-lines, micro-dots, and dual images add to the flexibility offered by digital printing. Dual images consist of an image viewed from one side of the glass with a different one seen from the other side—even though both images are printed on the same surface of glass. Finally, stored design files mean replacements and reproductions can be produced years later with dependable results.

There are also limitations to the digital printing process that must be taken into consideration to determine whether digital printing is the appropriate choice. Calculating performance data across the façade can be challenging.

As mentioned, the various colors of ink can transmit light and solar energy at different levels. For example, a large-scale print project involving multiple colors combined with a custom image across a façade allows light and solar energy to enter the building in various levels, even within the same pane of glass. As a result, performance data can be difficult to calculate. However, minimal performance levels can be gauged because performance characteristics, coating applied to the digital print or glass substrate, and other enhancements are already known.

Matching the color of the final printed image to the designer’s vision can also be challenging. The amount of light being transmitted and reflected during a sunny versus cloudy day, or afternoon versus night, affects the way the image is perceived.

Additionally, applying a coating over the print may mute the vibrancy of the colors. The choice of substrate can also cause the colors to appear different than the design. For example, regular clear glass may impart a green hue to the image, while a low-iron glass substrate helps subdue this ‘green-shift’ effect. All these issues must be taken into account when designing an image using digital printing.

Data courtesy Viracon

Data courtesy Viracon

Finally, to control the level of light and solar energy entering the building’s interior, a silk-screened-type pattern can be applied on the glass. For example, a white dot pattern with 50 percent coverage on a 25-mm (1-in.) clear IGU can reduce the light transmission by 38 percent and lower the solar heat gain coefficient (SHGC) by 30 percent (Figure 1).

This reduction occurs by blocking the light and solar energy from entering the building at the outboard lite of glass. At the same time, designers may add more of an aesthetic element to the façade than the single color of dots or lines that silk-screening usually provides.

Digital printing expands on the ability to incorporate solar, light, and privacy control to an electronic design file before printing an image. One of the methods involves applying a computer-aided design (CAD) file, normally used to produce an actual screen for the silk-screening process, to the image to be printed. For example, a CAD file with 40 percent coverage of holes that might have previously been printed in white ceramic frit can now be applied to an electronic design file and printed in multiple colors and without the need to purchase screens.

Some additional methods include converting the image to patterns of dots in halftone processes known as amplitude modulation (AM) screening and frequency modulation (FM) screening. AM screening converts the image to dots that are the same distance from center-of-dot to center-of-dot, but the individual dot size can vary.

FM screening, also known as ‘stochastic screening,’ is characterized by the size of the printed dots remaining constant. However, the distance between the dots is visually random to create the various densities of the image within the print.

When combined with a low-emissivity (low-e) coating, digital printing can add an attractive and functional element to a façade. [CREDIT] Photo courtesy Brian R. Savage

When combined with a low-emissivity (low-e) coating, digital printing can add an attractive and functional element to a façade. Photos courtesy Brian R. Savage

Digital printing can help optimize project design, color, and solar performance.

Digital printing can help optimize project design, color, and solar performance.

Conclusion
There is a constant demand for new and diverse ways for designers to leave their mark on a building’s façade. Digital printing has emerged as a versatile and colorful addition to the supply of products helping define this vision. Not only can multiple colors and design concepts be added with relative ease, but many performance aspects within the façade design of solar control and privacy can also be fine-tuned through both hardware and software features available to digital printing.

Digital printing is versatile enough to be used in interior and exterior applications, can be specified in combination with other glass products, and has the durability of ceramic frit applications used for years in architectural design.

Brian R. Savage, CPA, is a product manager at Viracon Inc. He has worked in the construction industry for 10 years and has led the launch of numerous new products at Viracon. Savage can be contacted by e-mail at bsavage@viracon.com.