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As sustainability continues leading the charge in most building projects today, daylighting, occupant comfort, indoor air quality (IAQ), privacy, durability, and low maintenance play a prominent role.
Photo courtesy of Pellini
Easy to clean and operate, durable blinds between the glass (BBG)—like this aesthetic design for Madrid’s Centro de Arte di Alcobendas—are a great choice for glare-free daylighting.
While particular building materials, products and systems may offer one or two of these important features, few directly address all of them.
With daylighting playing a major role in building designs, architects are constantly challenged with designing shading systems for these openings to optimally promote natural light while minimizing glare, hot spots, and solar heat gain.
For many commercial facilities, particularly schools and health-care settings, blinds between the glass (BBG) are a compelling option.
“BBG solutions are often appropriate when the owner is looking to lower their carbon footprint with a sustainable, low-maintenance facade,” states Alexander Cox, business development manager, West Coast, Permasteelisa North America Corp., San Francisco. “Key attributes of these systems are high occupant comfort resulting in a higher ‘comfort net-lettable area,’ an abundance of managed daylight without glare, lower cooling energy and lighting costs, and an excellent acoustic performance.”
And unlike other internal blinds and shading systems that collect dust and dirt, require frequent cleaning and maintenance, and take up a larger footprint in the doorway, integrated blinds—hermetically inside the panes of glass—are a clean, easy-to-operate, seamless, and maintenance-free solution.
Taking a closer look at today’s building owner needs and relevant research, just how important are healthy, naturally lit, comfortable buildings?
Prominent Studies
“Owners on all our projects are keenly aware of the importance of thermal control, light control, maintenance, and privacy in their projects,” asserts Moshe Levi, project architect, Spector Amisar Architects, Tel Aviv, Israel.
“User comfort and privacy are high priority,” agrees Maribel Martinez-Wyatt, junior interior designer, HGA Architects, Sacramento, “especially in emergency department or waiting rooms where end users are spending longer lengths of time.”
She also stresses the importance of patient rooms having control over thermal comfort and glare. “By providing control, users can modify their spaces to best accommodate them,” she adds.
In a similar vein, Nico Kienzl, DDes, LEED Fellow, ASHRAE HBDP, director, Atelier Ten, New York, relates, “In general, we see expectations for workplaces increasing with the adoption of WELL [Building Standard] and increased realization of the value of high-performance workspaces that have access to daylight but need to balance visual and thermal comfort.”
In fact, Marc Zobec, technical director, Permasteelisa Group, Vittorio Veneto, Italy, sees current research addressing the relationship between occupant comfort and productivity, which he anticipates will significantly change the way buildings respond to occupant needs.
Along these lines, he sees systems like BBGs as an effective way to address occupant comfort. “Shifting the blind away from the interior of the building and toward the cavity is not only a more effective configuration with regards to the control of solar irradiation and heat gains but also thermal discomfort due to thermal asymmetry from either excessively hot or cold surfaces relative to the indoor conditions.” Zobec explains.
Looking at some statistics, Dodge Data & Analytics’ “The Drive Toward Healthier Buildings 2016” report reveals nearly three quarters of U.S. architects saying that the health impacts of buildings are influencing their design decisions and two-thirds stating that health considerations affect how they design and construct buildings.
Photo: Courtesy of Pellini SpA/Jomar Bragança
An integrated blind design, as shown here at the Tancredo Neves Administrative City building in Minas Gerais, Brazil, optimizes solar control and thermal comfort by positioning the blinds in between the cavity.
Furthermore, out of the 373 architects surveyed in the Dodge report, 89 percent believe that daylight has a high impact on health, and 69 percent of owners and interior designers agree. In addition, 72 percent of architects, 67 percent of interior designers, and 58 percent of contractors link wide accessibility to outdoor views with emotional/mental health.
Meanwhile, Professor Monika Frontczak, Technical University of Denmark, in her “Human comfort and self-estimated performance in relation to indoor environmental parameters and building features” Ph.D. thesis lists sunlight, temperature, and air quality among the most frequently used words building occupants use to describe comfort.
In addition, she states, “In office buildings, it was shown that occupants’ satisfaction was affected not only by indoor environmental parameters (thermal, visual, acoustic environment, and air quality) but also by workspace and building features, such as the view, control over the indoor environment, and amount of privacy.”
Interestingly enough, a survey of close to 500 occupants in a LEED Platinum office building in Charlotte, North Carolina, by researchers from the University of North Carolina and Kansas State University actually found that the visual qualities proffered by natural light and a nice view created an elevated perception of a thermally comfortable environment.
That said, a pair of well-known Heschong Mahone studies originally created a significant buzz around the benefits of daylighting in reporting that call center workers in daylit spaces with views of nature processed calls 6–12 percent faster and performed 10–25 percent better on mental function and memory tests. The second study revealed a 20–26 percent faster learning rate in schools with optimal daylight.
Taking these statistics to heart, today’s green building rating systems as well as codes and standards are requiring higher levels of daylighting in buildings.
For example, in the state of New York, Daniel Donovan AIA, LEED AP BD+C, associate principal, Ashley McGraw Architects, Syracuse, New York, explains that the code requires the window in a classroom to be 50 percent of the length of the exterior wall of that room, which can be a sizable amount of glazing. Consequently, Ashley McGraw likes to specify BBGs, configured strategically so that they can give classroom occupants more control over both daylight and privacy.
In another seminal study back in the 1980s, Roger Ulrich, Ph.D., EDAC, currently professor of architecture at the Center for Healthcare Building Research at Chalmers University of Technology in Sweden, reported an 8.5 percent reduction in hospital stays in rooms with views of nature. And another compelling study by researchers from the University of Pittsburgh and Carnegie Mellon University found a 22 percent decrease in the need for pain medication for patients with sunlit hospital rooms.
Adding to the mix of sound research contributing to the notion that daylight and views directly affects well-being and productivity, a study by Judith Heerwagen, Ph.D., who is currently working for the U.S. General Services Administration’s Office of Federal High-Performance Green Buildings, finds that workers showed reduced signs of stress and levels of frustration, increased patience, and overall satisfaction when they have views to nature through windows. In one of her studies, she states, “Positive moods turn out to be critical for a wide range of outcomes...including job satisfaction, work involvement, motivation, organizational attachment, and lowered absenteeism.”
More recently, Manchester’s University of Salford Holistic Evidence and Design (HEAD) project conducted a detailed “Clever Classrooms” survey of 153 classrooms and found that good light, temperature, and air quality created a 16 percent variation in learning progress over the course of a year for the 3,766 pupils included in the study.
As sustainability continues leading the charge in most building projects today, daylighting, occupant comfort, indoor air quality (IAQ), privacy, durability, and low maintenance play a prominent role.
Photo courtesy of Pellini
Easy to clean and operate, durable blinds between the glass (BBG)—like this aesthetic design for Madrid’s Centro de Arte di Alcobendas—are a great choice for glare-free daylighting.
While particular building materials, products and systems may offer one or two of these important features, few directly address all of them.
With daylighting playing a major role in building designs, architects are constantly challenged with designing shading systems for these openings to optimally promote natural light while minimizing glare, hot spots, and solar heat gain.
For many commercial facilities, particularly schools and health-care settings, blinds between the glass (BBG) are a compelling option.
“BBG solutions are often appropriate when the owner is looking to lower their carbon footprint with a sustainable, low-maintenance facade,” states Alexander Cox, business development manager, West Coast, Permasteelisa North America Corp., San Francisco. “Key attributes of these systems are high occupant comfort resulting in a higher ‘comfort net-lettable area,’ an abundance of managed daylight without glare, lower cooling energy and lighting costs, and an excellent acoustic performance.”
And unlike other internal blinds and shading systems that collect dust and dirt, require frequent cleaning and maintenance, and take up a larger footprint in the doorway, integrated blinds—hermetically inside the panes of glass—are a clean, easy-to-operate, seamless, and maintenance-free solution.
Taking a closer look at today’s building owner needs and relevant research, just how important are healthy, naturally lit, comfortable buildings?
Prominent Studies
“Owners on all our projects are keenly aware of the importance of thermal control, light control, maintenance, and privacy in their projects,” asserts Moshe Levi, project architect, Spector Amisar Architects, Tel Aviv, Israel.
“User comfort and privacy are high priority,” agrees Maribel Martinez-Wyatt, junior interior designer, HGA Architects, Sacramento, “especially in emergency department or waiting rooms where end users are spending longer lengths of time.”
She also stresses the importance of patient rooms having control over thermal comfort and glare. “By providing control, users can modify their spaces to best accommodate them,” she adds.
In a similar vein, Nico Kienzl, DDes, LEED Fellow, ASHRAE HBDP, director, Atelier Ten, New York, relates, “In general, we see expectations for workplaces increasing with the adoption of WELL [Building Standard] and increased realization of the value of high-performance workspaces that have access to daylight but need to balance visual and thermal comfort.”
In fact, Marc Zobec, technical director, Permasteelisa Group, Vittorio Veneto, Italy, sees current research addressing the relationship between occupant comfort and productivity, which he anticipates will significantly change the way buildings respond to occupant needs.
Along these lines, he sees systems like BBGs as an effective way to address occupant comfort. “Shifting the blind away from the interior of the building and toward the cavity is not only a more effective configuration with regards to the control of solar irradiation and heat gains but also thermal discomfort due to thermal asymmetry from either excessively hot or cold surfaces relative to the indoor conditions.” Zobec explains.
Looking at some statistics, Dodge Data & Analytics’ “The Drive Toward Healthier Buildings 2016” report reveals nearly three quarters of U.S. architects saying that the health impacts of buildings are influencing their design decisions and two-thirds stating that health considerations affect how they design and construct buildings.
Photo: Courtesy of Pellini SpA/Jomar Bragança
An integrated blind design, as shown here at the Tancredo Neves Administrative City building in Minas Gerais, Brazil, optimizes solar control and thermal comfort by positioning the blinds in between the cavity.
Furthermore, out of the 373 architects surveyed in the Dodge report, 89 percent believe that daylight has a high impact on health, and 69 percent of owners and interior designers agree. In addition, 72 percent of architects, 67 percent of interior designers, and 58 percent of contractors link wide accessibility to outdoor views with emotional/mental health.
Meanwhile, Professor Monika Frontczak, Technical University of Denmark, in her “Human comfort and self-estimated performance in relation to indoor environmental parameters and building features” Ph.D. thesis lists sunlight, temperature, and air quality among the most frequently used words building occupants use to describe comfort.
In addition, she states, “In office buildings, it was shown that occupants’ satisfaction was affected not only by indoor environmental parameters (thermal, visual, acoustic environment, and air quality) but also by workspace and building features, such as the view, control over the indoor environment, and amount of privacy.”
Interestingly enough, a survey of close to 500 occupants in a LEED Platinum office building in Charlotte, North Carolina, by researchers from the University of North Carolina and Kansas State University actually found that the visual qualities proffered by natural light and a nice view created an elevated perception of a thermally comfortable environment.
That said, a pair of well-known Heschong Mahone studies originally created a significant buzz around the benefits of daylighting in reporting that call center workers in daylit spaces with views of nature processed calls 6–12 percent faster and performed 10–25 percent better on mental function and memory tests. The second study revealed a 20–26 percent faster learning rate in schools with optimal daylight.
Taking these statistics to heart, today’s green building rating systems as well as codes and standards are requiring higher levels of daylighting in buildings.
For example, in the state of New York, Daniel Donovan AIA, LEED AP BD+C, associate principal, Ashley McGraw Architects, Syracuse, New York, explains that the code requires the window in a classroom to be 50 percent of the length of the exterior wall of that room, which can be a sizable amount of glazing. Consequently, Ashley McGraw likes to specify BBGs, configured strategically so that they can give classroom occupants more control over both daylight and privacy.
In another seminal study back in the 1980s, Roger Ulrich, Ph.D., EDAC, currently professor of architecture at the Center for Healthcare Building Research at Chalmers University of Technology in Sweden, reported an 8.5 percent reduction in hospital stays in rooms with views of nature. And another compelling study by researchers from the University of Pittsburgh and Carnegie Mellon University found a 22 percent decrease in the need for pain medication for patients with sunlit hospital rooms.
Adding to the mix of sound research contributing to the notion that daylight and views directly affects well-being and productivity, a study by Judith Heerwagen, Ph.D., who is currently working for the U.S. General Services Administration’s Office of Federal High-Performance Green Buildings, finds that workers showed reduced signs of stress and levels of frustration, increased patience, and overall satisfaction when they have views to nature through windows. In one of her studies, she states, “Positive moods turn out to be critical for a wide range of outcomes...including job satisfaction, work involvement, motivation, organizational attachment, and lowered absenteeism.”
More recently, Manchester’s University of Salford Holistic Evidence and Design (HEAD) project conducted a detailed “Clever Classrooms” survey of 153 classrooms and found that good light, temperature, and air quality created a 16 percent variation in learning progress over the course of a year for the 3,766 pupils included in the study.
Shading Selection
Essentially, the importance of natural light and views is well established, but it is also well known that simply increasing large amounts of glazing on building facades is not necessarily a thermally efficient strategy, nor one that delivers comfortable levels of lighting, not to mention the issue of glare.
“A good work environment that provides sufficient natural daylight and clear transparent views can in turn be a drawback due to glare,” Zobec explains. “This presents a technical design paradox that requires a design balance of daylighting, glare and natural views.”
In fact, HEAD’s report acknowledges that glare has become exacerbated with growth of interactive whiteboards and computer projection in classrooms.
While the study endorses high levels of natural light via large windows, in order to mitigate glare, easy-to-use blinds that don’t cause excessive noise or air flow issues are recommended.
Photo courtesy of Spector-Amisor Architects
Blinds in between the glass deliver easy-to-operate, glare-free daylighting solutions.
In this context, Donovan explains that natural light and clean air, which have been linked to enhanced academic performance, are two factors that BBGs can directly impact.
With conventional blinds, building owners and users must deal with pull cords getting tangled, blinds falling out of line when the door is closed with too much force, and the constant issue of dust gathering on the blinds, the latter of which can jeopardize good IAQ.
This issue is particularly significant amongst office workers, patients in health-care settings, and children in schools with asthma or respiratory health issues, as pollutants and poor IAQ can trigger irritation and inflammation of the lungs.
Just how widespread is this issue? The Centers for Disease Control and Prevention reports that one in 13 people have asthma, amounting to more than 26 million Americans. Among those are 6 million children under the age of 18, with asthma attacks registering as the top reason for missed school days.
A related issue created by dust and pollutants contributing to poor IAQ is the increased possibility of infections in health-care settings. In fact, bacteria is responsible for about 90 percent of hospital-acquired infections (HAI). Particularly in cases where patients are after surgery and their immune systems are low, Healthline reports that HAIs, on average, lead to an additional 6.5 days spent in the hospital and make it five times more likely that patients will be readmitted.
To minimize the risk, health-care professionals recommend a number of strategies, including cleaning surfaces properly, with recommended frequency.
As noted, blinds in between the glass completely eliminate this issue of cleaning dust-gathering blinds and is therefore a common choice in health-care applications.
A case in point is the Hadassah Medical Center’s Davidson Hospital Tower in Jerusalem, Israel, where Spector-Amisor specified BBG in patient rooms and operating suites throughout the 14-story tower, with four additional floors below ground. In particular, the doors to the operating and isolation rooms are shaded with the integrated blinds, enabling staff to observe inside without violating the sterile environment, explains Levi.
Running the Numbers
While daylighting, low maintenance, and IAQ are key factors for building owners, the trump card is always going to be the bottom line.
Building a strong case for sustainable design, the aptly named World Green Building Council’s (WGBC) “Business Case for Green Building” strategically links these issues to economic gain.
“A properly specified palette of sustainable materials and building systems would provide financial benefit in the long term through less-frequent replacement cycles and decreased cleaning and maintenance requirements, as well as benefits linked to healthier indoor environments due to lower toxicity and emissions,” states the report.
Moreover, the document emphasizes the importance of investing in a company’s greatest assets: its employees. Consider the fact that staff salaries and benefits make up a significant 85 percent of total workplace costs, as compared to 10 percent on rent and less than 1 percent on energy, according to the Canada Green Building Council.
Consequently, “research suggests that by making even small improvements to factors such as productivity, health, and well-being, businesses can experience greater financial benefit than they would from more efficient resource use in building operations,” asserts the report.
Furthermore, the WGBC reports a shift in corporate mindsets from ‘how much will green building cost my business’ to ‘how much will not investing in green building cost my business?’
While quality products like BBG may have a somewhat larger upfront cost, the full life-cycle analysis, considering low maintenance, IAQ, daylighting, occupant well-being, and productivity, far outweighs the initial investment.
“Employee productivity and attrition rates can be directly linked to comfort, and the costs of replacing and training employees far outstrips the upfront construction costs for a BBG system,” confirms Cox.
In a similar vein, Bradley Cardoso, principal architect, Hobbs Brook Management, Waltham, in a Building Operating Management article, “Product Selection: Top Facility Managers Reveal Best Practices,” says, “The up-front product purchase price is only a fraction of the overall cost. It is important to understand a product’s potential maintenance issues as ongoing repairs or premature replacement can far outweigh upfront costs.”
BBG Options
Overall, when comparing BBGs to conventional blinds, Donovan points out that the latter are susceptible to damage, prone to collecting dust, and have limited aesthetic appeal. Donovan is impressed with the benefits of BBG systems, namely better IAQ, reduced maintenance, and durability.
Conventional blinds are known to become brittle and break over time, thereby requiring replacement as frequently as every four years. On the contrary, BBGs have the potential to last as long as the windows themselves.
“Accessible controls were a high priority,” Martinez-Wyat adds. “Other non-BBG shading options fall short on accessible controls. With BBGs, even when blinds are randomly drawn, the facade has a more uniform look as the system always covers the full height of each window lite.”
Based on application and user preference, operational systems include the following:
Cord-operated external magnetic device. Two coupled rotational magnetic devices operate the system. One set of magnets is located inside the blind head rail within the cavity, and the other is applied to the external glass surface. This way the integrity of the insulating glass is preserved. A cord loop is used to raise and lower the blinds, and in venetian models, tilting. Electric operation is also available by replacing the external magnetic device with an external motor.
Photo courtesy of Pellini SpA
Two rotational magnetic devices, one inside the cavity and one on the external glass surface, operate this integrated blinds system.
Motorized battery-operated with solar panel. The motorized raising/lowering and tilting functions via a battery-operated swipe control device that is magnetically attached to the window frame or glass surface. The battery module can be recharged through a micro-USB connector or by electricity, and some manufacturers offer an external solar panel.
Manual operation by sliding magnetic handle.
Manual knob control. This tilt-only venetian blind is operated by an external knob. The specially designed corner key containing the rotational magnet is connected to the external knob by a flexible drive cable located within the glazing cavity of the window frame. Because the only visible control is the external knob fixed to the window frame, this fully frees up the glass surface and makes it easy to clean. Another manual knob control system utilizes two gears located in the top and bottom corner keys of the blind, connected to each other by means of a shaft that is completely concealed inside the spacer bar. The system works well for windowsill applications such as structural facades, as the control device located at the bottom of the blind is more easily accessible and within reach.
Internal motor control. For this system, a brushless motor is incorporated within the head rail. In place of brushes, which are subject to wear and tear, the motor operates by means of a magnetic field. In the absence of electromagnetic interference, the system operates at an extremely low noise level. The brushless technology also enables the blinds to be integrated with the most complex building management system networks and managed via mobile devices.
External brushless motor. The system can be easily applied to frontal magnetic transmission systems and retrofitted to existing cord-operated systems. It allows venetian blinds to be raised/lowered or tilted. Pleated and roller blinds can be raised or lowered.
Evaluating the Marketplace
When selecting a BBG manufacturer to partner with, a number of important factors typically go into this decision. Specifiers will want to look at durability, ease of use, thermal performance, integration with high-performance glazing, color and style selections, manufacturer support, and lead times.
“In our opinion, performance and manufacturer support are the two most important,” Levi asserts. “We are employing BBG as a key element in the building envelope system, and as such, it must stand the test of time, exposed to the elements while subjected to constant use. This being the case, it is best to deal only with firms who have deep knowledge of these systems and a proven track record implementing the technology in the field.”
“While we would never select a product that did not provide the desired functionality or aesthetics, in our experience, the top product lines in the marketplace offer a wide variety of options that have addressed all of our needs,” he adds.
Also, emphasizing the importance of selecting experienced manufacturers, Martinez-Wyatt explains, “I would highly recommend a full-sized mockup of the system as well as utilizing a reputable company with warranties and manufacturer support in place in the event of failure.”
Another plus is working with manufacturers who integrate the blind system with a window product. This way, building teams only have to deal with one supplier and can receive a warranty for the full system.
Many BBG systems are manufactured overseas, which significantly increases lead times. However, by working with companies with domestic manufacturing plants, this can significantly impact project schedules and tight deadlines.
Popular Applications
With hygiene, daylighting, and privacy topping the list of design features sought by health-care projects, BBG can be a great fit.
Pointing out the fact the conventional interior shading fabrics can’t easily be wiped clean or laundered, Levi is a fan of BBG for these applications.
For the Jerusalem Hadassah Davidson Tower project, Spector-Amisor felt that the other non-BBG options did not offer the same level of cleanliness for the patients. Furthermore, the architects were concerned that exposed external shades would be more susceptible to breakage and vandalism.
Photo: Courtesy of Pellini SpA/Tom Kohn
Photo courtesy of Spector-Amisor Architects
Enhanced hygiene, privacy, visual comfort, and low maintenance were the main factors leading Spector-Amisor Architects to specify BBG for the Hadassah Medical Center’s Davidson Hospital Tower in Jerusalem, Israel.
Another advantage proffered by BBGs at the Davidson Tower was the fact that they served the dual purpose of lending privacy both during daylight hours and at night.
“During the day, people do not see into the building as the windows appear black due to the combination of bright sunlight outside, window tinting, and lower light levels on the building interior. As such, the role of the blinds in the day is primarily to control solar glare and modulate light levels,” Levi explains. “However, at night, when people can see into the light rooms from the dark outside, the blinds are used to achieve privacy.”
In addition to the patient rooms, offices, and lounges, BBGs were also designed for areas such as the intensive care units, operating rooms, and staff workspaces.
“In the ICU units, they allow monitoring or vision for staff between patient rooms; in the doors to the operating and isolation rooms, they allow staff to observe inside without violating the sterile environment; and in nurse or doctor workspaces, they provide the staff with the flexibility of choosing a more private work environment or one in which they had greater visual control of their surroundings,” relates Levi.
The architect selected tilt-only blinds with a knob which is connected to the blinds by a steel cable and mounted on the structural aluminum profile, as opposed to a sliding magnet or electronic operation. For this particular application, the owner didn’t want any parts that could be removed or lost. The electronic option would have been too costly for this large tower.
Meanwhile, at a hospital in New Haven, Connecticut, Atelier Ten chose a fixed integrated blind system in the clerestory windows of the curtain wall.
“The fixed blinds redirect daylight into the space and prevent direct beam radiation to entering the space to protect sensitive workspaces/equipment,” explains Kienzl. “Important aspects were the fact that they were proven products, had low/no maintenance requirements and met aesthetic requirements of the architects.”
For an emergency room expansion in Roseville, California, HGA specified integral blinds in response to the owner’s goal of privacy, infection control, and low maintenance.
“By using a BBG product, the intention was to eliminate the need for a privacy curtain as well,” relates Martinez-Wyatt.
Another requirement was manual control and the ability to control blinds from both sides of the system. “Final selection was a wheel control system because it met ADA guidelines,” she adds.
In addition to health care, another prevalent application for BBG systems is K–12 and higher-education facilities where IAQ, daylighting, durability, and low maintenance are essentially required.
Overall, John Gladden, AIA, educational designer, Fanning Howey, Columbus, Ohio, points out that BBG products keep blinds out of the way of everyday activities by students and teachers and make life simpler for maintenance staff. “They can clean windows or adjust blinds without fear of damaging the product,” he explains. “In fact, the Ohio Facility Construction Commission’s school design guidelines suggest BBG for all K–12 school design projects.”
Furthermore, he says these systems give schools the freedom to control lighting levels without fear of damaging blinds. “Being able to adjust blinds is particularly important at the elementary school level, where the classroom is a students’ primary home, and different lighting levels are important for different activities. At the high school level, specialized spaces like science labs also require the flexibility of BBG products,” he adds.
Because the blinds are encased in glass, their surfaces don’t collect dust, mold, bacteria, etc., and this contributes to keeping the indoor air clean, explains Donovan. “That’s important when you consider the number of kids with asthma and other respiratory conditions or allergies,” he says.
“In terms of durability, since the blades are out of reach, they are protected from damage,” he continues. “With traditional louver systems, the blades are typically metal—and in a high-traffic location like a K–12 school, more often than not, there are a few blades with bends, dings, or creases in them, which impacts the smooth operation of the blind and is unsightly.”
With regards to maintenance, he points out that it’s far more efficient and effective to wipe down glass surfaces than it is to clean individual louvers.
“There are additional benefits to using BBGs in schools. An example: a lower run of BBG units can be closed/drawn for eye-level privacy, while an expanse of BBG units closer to ceiling height can be left open to allow natural light into the space.”
In the higher-education market, Atelier Ten specified the blinds in a punched window configuration at a University in Illinois.
Here, the architect selected manually operated interstitial blinds in operable windows as a tilt-only function for controlling daylight and glare. Thanks to extensive studies to help optimize the envelope, together with the blinds assisting with daylight distribution, overall energy use is 51 percent better than ASHRAE 90.1-1999 for this project.
Though more prevalent in Europe, office buildings are another great fit for integrated blinds.
A great example is the Parallelo headquarters building in Milan, Italy, where 400 glazed BBGs cover the southwest facade of the sprawling three-story, 14,000-square-meter elevated structure.
Photos: Courtesy of Pellini SpA/Daniele Domenicali
A total of 400 BBG units shade and insulate the sprawling Parallelo headquarters building, designed as a 14,000-square-meter elevated structure in Milan, Italy.
The project is one of the city’s first CENED A energy class commercial buildings, which means that it has achieved the highest level of energy efficiency complying with regional standards. With help from 2,500 square meters of photovoltaic rooftop panels and geothermal heat pumps, total energy costs are 26 percent less than those of a similar-sized traditional building.
Key to the design was figuring out how to shade the southwest facade. Mario Cucinella Architects originally considered brise-soleil sun shades in a metallic grid structure fixed to the building at changeable intervals. However, fixed system wouldn’t have allowed sufficient natural light to come inside, in addition to obstructing the view. Furthermore, the design would have required the creation of a structure on the wall to anchor a metal grid and add walkways to be able to periodically maintain the system. Bottom line, this original scheme was technically complicated and cost prohibitive.
The solution was an integrated blinds system in a double-glazed configuration. The panels run as high as 4.2 meters and over the entire facade, including the attic. The blinds can be rotated manually with a magnetic system or electrically via an external motor. This enables the entire system to be fixed or changed without having to touch the windows.
Debunking Stereotypes
Having established the benefits of BBG systems and its ideal applications, it’s important to address some misconceptions about the technology.
For one, there have been concerns about failure rates. While there may be a greater risk with some BBG systems, it is not an issue with higher end systems.
While Jason Thomas, president, Intigral, Walton Hills, Ohio, acknowledges that this is, in fact, an issue with some products in the marketplace, a number of manufacturers have fully addressed this issue with comprehensive testing.
Along these lines, ANSI/WCMA A100.1-2018: American National Standard for Safety of Window Covering requires that blinds are able to withstand 6,500 full raise and lower cycles in a variety of temperature and humidity conditions.
While this is an important baseline standard, it behooves designers and building owners to look for products that well exceed this standard. In fact, it is possible to find BBG systems capable of completing more than 200,000 full raise and lower cycles.
Another BBG misconception is assuming that all systems have condensation issues.
Case in point, in detailing the system for the Hadassah Medical Center’s Davidson Hospital Tower, Spector-Amisor worked closely with the project’s aluminum consultant and contractor and made sure to place the low-e coating on the glass surface 2 (i.e., the interior side of the outside pane). In addition to reducing the solar heat gain in the cavity between the panes, there have been no condensation problems.
In terms of energy efficiency, some advanced BBG systems incorporate a warm edge spacer bar, which works to insulate the edges of a sealed unit and keep the panes of glass apart. The hermetically sealed design:
- reduces the generation of humidity on the glass perimeter;
- improves the thermal insulation of the profile due to its low thermal conductivity;
- ensures a lower U-value (a measure of heat flow in thermal bridges), halving heat transmission through the perimeter compared to a standard extruded aluminum spacer bar; and
- improves the thermal transmittance value of the window, irrespective of the material used for the frame.
Some integral blind systems are also compatible with triple glazing, further reducing heat loss and rejecting unwanted heat gain and cold.
Another feature, developed in conjunction with European nanotechnology research institutes, is a coated slat which effectively enhances energy efficiencies. The slat is coated with an interference film designed to reflect the most critical solar radiation. Furthermore, the coating creates low emissivity in the slat, thereby affecting the long wave infra-red radiation characteristics.
An additional issue that may cause owners/architects to think twice about choosing BBGs is cost; however, when owners consider the no maintenance, longevity, and low probability of needing to replace the blinds, the longer-term outlook paints a different picture.
“The long-term ROI outweighs the hassle of replacing blinds outside of windows and maintenance associated with them,” confirms Martinez-Wyatt.
“The benefits of BBG systems—reduced maintenance and longer life—more than offset the potential benefits of other products,” agrees Gladden.
Looking Ahead
Looking forward, architects anticipate that the integrated blinds will gain traction, particularly in health-care and K–12 applications.
“This growth will be driven by the desire to achieve green buildings, the increased importance of reducing hospital-acquired infections, and technical improvements to the systems that will increase their life cycle,” states Levi.
Emphasizing the fact that clean environments are worth the added cost in the long run, Martinez-Wyatt also anticipates that BBGs will grow in popularity, especially with its low maintenance requirements.
Overall, Cox believes that sustainable building initiatives, more stringent building codes, smart grids/smart cities with enhanced energy infrastructure and a general global trend to curb carbon emissions will result in more widespread adoption of BBG systems.
