Advancing the Daylighting Discussion

Explore the scientifically proven advantages of automation in daylight management
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Sponsored by MechoSystems
Jeanette Fitzgerald Pitts
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Automated Daylight Control Systems

As the successful performance of automated shading systems continues to be documented and the impressive results they are able to provide become more widely known, it is no surprise that more options for automated daylight control are popping into the market. Designers can now choose from automated shading systems, automated louvered systems, and automated electrochromic (EC) glazing to provide glare and solar heat gain control.

Automated Louvered Systems

Automated louver systems can be installed on the interior of the building, such as a venetian blind solution, or they can be incorporated onto the building exterior or into an environmental wall, allowing conditioned air and exchange air to run through the outer skin of the building.

Exterior louvered systems have been used for years in Europe, where the solar conditions and cloudy weather are a better fit for the capabilities of a louvered system. They have not been as successful in the United States, where brighter sky conditions and clearer weather patterns can make the louver a less-than-effective daylight filter.

One critical difference between a louvered solution and a shading solution is that louvers essentially combine blades and open space to manage direct sunlight, whereas shading systems use a woven filter to uniformly manage daylight across the window pane. This has two important implications on the interior. When louvers are fully closed, or closed beyond the cutoff angle, it is impossible to see the cityscape or outdoor environment on the other side. Whenever louvered systems are somewhat open, they will allow some degree of completely unfiltered daylight into the space. This creates striations of bright slivers of light next to dark slivers of shadow. This pattern of stark contrast can be visually distracting and may disrupt the balance of illuminance ratios within the field of view. Solar shades create a symmetric and continuous shadow in a space, which is markedly different than the striated shadows caused by a louvered system.

“Exterior louver systems are impressive architectural statement pieces,” explains Jim Ashmore, IES. “They add a truly unique and dynamic element to a building facade, but as a mechanism for glare and solar heat gain control, louvered solutions have some pretty significant limitations. Louvers cannot simultaneously provide a view to the outdoors and protect the interior from direct sun. At any given time, they can either be opened enough to see through or closed enough to block the direct beam radiation.”

Automated Electrochromic Glass System

Electrochromic (EC) glass is electronically tintable glass that can be used for windows, skylights, and curtain walls. What separates EC glass from the standard IGU is the EC coating applied to the inside, or cavity-facing, surface of the exterior pane of glass. The coating itself consists of multiple layers of ceramic material. Applying a low-voltage direct current to the coating causes it to gradually tint, providing an increasingly more effective barrier to light penetration and solar heat gain, while preserving the outdoor views. The effect is also easily reversed, untinting the glass and returning it to its highest transmittance state.

EC glass offers multiple tint options that range from clear to fully tinted. These tint options enable EC glass to tailor the level of light and heat control it provides to best match the conditions of the time of day or support the unique visual needs of the task at hand.

Control can be automated using software that considers sun path and sky conditions or light and BTU sensors mounted on the exterior of the building that cause the glass to tint appropriately in response to environmental conditions. In the presence of direct and intense sunlight, the glass tints to its lowest transmittance level, maximizing the light control at the pane, and then untints automatically when the glare condition has passed to optimize daylight admission.

The technology for EC glass is evolving rapidly, and some manufacturers are offering panels that can tint independent segments within a single pane to offer a solution for challenging solar conditions.

“In my opinion, at this time, electrochromic glazing does not effectively control glare. Solar fabric is better at scattering the glare that can be caused by the orb of the sun. While EC glazing products can offer 1 or 2 percent transmittance values, it is still not dark enough to effectively control the brightness of a direct view of the sun,” explained Loisos. “In terms of managing solar heat gain, high-performance spectrally selective glass can effectively reflect a significant portion of the IR energy responsible for heat gain, and it remains in a perpetually clear state, whereas EC glazing has to get pretty dark to provide the same solar heat gain control, compromising the amount and color of light in the interior space.”

As the capabilities of automated shading systems continue to develop, and the technologies and metrics that can prove how effective these systems are at managing daylight continue to emerge, the design community may experience a paradigm shift, where the disadvantages of manual pull-chain shade control are widely known and accepted and automated shade control becomes synonymous with good daylighting design. Until recently, the cost of manual shades was not able to include the opportunity cost of poor daylight management so manual shades boasted deceptively low costs and provided subpar daylighting performance. Today, designers are able to quantify the impact that automated shading systems can have on a project, and building occupants will be able to bask blissfully in the optimized shade and daylight provided by automated shades.

Jeanette Fitzgerald Pitts has written dozens of continuing education articles for Architectural Record covering a wide range of building products and practices.

“Neolith

MechoSystems is the world's leading designer and manufacturer of manual, motorized, and automated solar-shading systems for the architectural and design communities. The company provides contemporary WindowManagement® solutions for today's design challenges. Products are designed to meet the challenges of sustainability, WindowManagement®, and effective daylighting. To contact representatives and distributors worldwide, visit: www.MechoSystems.com/automation

 

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Originally published in Architectural Record
Originally published in May 2016


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