“So it is important that when automation occurs, people understand why it is happening, and intuitive controls that allow them to return to their preferred state or modify certain aspects of their environment are critical to maintaining occupant confidence in building systems,” he recommends. “If people understand that an automated shade is deploying to maintain conditions of comfort in their space, yet they can still act to modify it within some boundary condition, they will have a better relationship to the technology.”

Along these lines, Fragali says it is important to determine the building owner’s daily needs and expectations of their individual shading system. “Location and exposure are essential to consider when selecting the ideal materials and finishes, as well as educating your client on the required maintenance for each individual material selected,” she says.

Controls generally allow for varying degrees of user override and are also designed to capture systems back into automatic after a period of time to ensure that solar control of the building is maintained. User override can be achieved through switches and can interface with other systems, such as the building management system/building automation system (BMS/BAS) or audio visual (AV) system.

In the United States, the BACnet protocol is generally used for integration with the BMS/BAS, although other communication protocols can be used as well. BACnet over IP is the predominant BMS/BAS integration method. The head end of the shading control system is connected to the building IP network. This allows two-way communication, with the BMS/BAS being able to obtain information about the status of the shading devices as well as providing commands to move the shading systems as appropriate, for example if there is a fire alarm.

It is also possible to customize the control system to meet the specific requirements of a project. For example, the design team can specify when and to what extent the shading system will be deployed. In addition, operations at deployment and overrides are site-configurable components of a wel-engineered control system. Overrides are particularly important in terms of setting priorities for the various lighting, AV, fire protection, and other systems that may be integrated with the shading control system. A proper control system that is automated and comissioned correctly requires little end-user override and makes shading operations much less noticeable.

Control systems can allow for a wide range of methods of integration, including a BMS/BAS interface, as noted, an RS 232/485 AV interface, or an interface with other systems by means of contact closures.

On the topic of aesthetics for the interface, there is generally standard artwork for the switches, but this can be customized on larger projects.

Enhanced end-user interaction can include a custom switch to allow both the shading systems and operable windows to be controlled from the same interface. Switches can also incorporate status LEDs.

Conclusion

In summary, properly controlled exterior shading systems are a key strategy for optimizing the benefits of daylighting, controlling solar heat gain, and mitigating glare. While there are a number of options, architects and designers regard fabric zip systems, venetian blinds, and rack arm systems as effective shading solutions in achieving these requirements.

“We find that all three systems are easily maintained and can be customized to fix any project needs. They offer a wide range of colors and finishes for any design we wish to achieve, making them well suited for any project,” reports Fragali.

In conclusion, she emphasizes the effectiveness of exterior over interior systems. “Unlike interior shading systems, exterior examples maximize the amount of ambient light into the building while preventing any direct sun penetration, which is essential to the design of any project.”

EXTERIOR VENETIAN BLINDS CONTRIBUTE TO NET-ZERO GOALS FOR MIXED-USE SAN DIEGO PROJECT

Photo: Nick Merrick, Hall + Merrick

BNIM’s LEED Platinum net-zero design for Makers Quarter Block D in San Diego features an exterior venetian blind system linked to an automated sun-tracking system so that it is automatically deployed and tilted to prevent direct sun penetration.

Makers Quarter is a five-block development in downtown San Diego that aims to provide a creative environment for entrepreneurs and artists. At the heart of the development is Block D, a six-story collaborative office hub, designed by BNIM, with retail and hospitality outlets at street level and offices above.

Helping the architect achieve its LEED Platinum and net-zero goals, the design uses a variety of techniques, including two active shading systems that facilitate natural daylighting while providing flexibility for building tenants to control their own workspaces.

One of these strategies is an exterior venetian blind system. The blinds are installed on the south and west elevations and incorporate perforated, flexible, 80-millimeter slats. The blinds are linked to an automated sun-tracking system so that they are automatically deployed and tilted to prevent direct sun penetration, while allowing as much natural daylight into the building as possible. The systems are retracted when there is no sun on the facade. The system also allows manual control so that tenants can override the automated system for periods of time during the day. Analysis of the building’s performance demonstrates that the exterior venetian blind system allows the building to outperform the baseline energy goal by 66 percent.

RACK ARM SOLUTION IN SOHO

Photo courtesy of Draper, Inc.

An exterior-mounted rack arm system is integrated with the skylight structure and delivers balanced daylighting for a duplex apartment in the middle of SoHo, Manhattan, New York.

The owners of a top-floor duplex apartment in the middle of SoHo, Manhattan, New York, had a significant solar issue with a living room that opened onto a rooftop terrace. The room had west-facing glazing as well as an inclined skylight. Despite using interior shading systems, the skylight allowed substantial solar gains into the space, which meant that the room was effectively unusable during the summer months.

A number of shading options were considered before a decision was made to go with an exterior-mounted rack arm system. The system was designed to integrate with the skylight structure and incorporated 3-inch extruded aluminum louvers. Each of the three sections of the skylight had a radio frequency motor, programed to operate together from a handheld remote.

The shading system has proved to be very effective, allowing the room to be used throughout the year. In the winter months, the louvers are generally left in the open position to allow the solar gains inside to reduce heating requirements.

END NOTES

¹“Study: Natural Light Is the Best Medicine for the Office.” 31 January 2018. Web. 20 July 2020.

²Meister, Jeanne C. “The #1 Office Perk? Natural Light.” Future Workplace. 3 September 2018. Web. 20 July 2020.

³Ander, Gregg D. “Daylighting.” World Building Design Guide. 15 September 2016. Web. 20 July 2020.

⁴Malmquist, Derek. “A Glaring Issue: The Negative Implications of Glare in the Workplace.” 12 May 2016. Web. 20 July 2020.