The objective of this project was to install the 3M architectural daylighting system with multiple sunlight collectors into an existing Department of Defense (DoD) facility to effectively reduce energy consumption and enhance the lighting quality and work environment. The 3M architectural daylighting system allows for active sunlight tracking, collection, and concentration bringing more light into the building, penetrating light deeper into the core or below grade, and allowing multiple discreet light extraction points. The project planned to build a full-scale operational daylight harvesting system suitable for use at the site at Fort Bliss, Texas, after testing and validation. Unfortunately, a number of difficulties arose that halted the complete testing of the system, requiring it to be dismantled.
The 3M architectural daylighting system was comprised of the following components:
- Sunlight Collector/Concentrator - located on the roof
- Distribution System - to bring the light to the location intended
- Light Extraction System - room lighting (to include LED for artificial light)
Optical components within the sunlight collector direct sunlight through small openings on the roof or exterior walls, into the light ducts. Within the ceiling cavities, electric light fixtures are replaced with specially designed dual-function light ducts that transport and distribute sunlight deep within the building. These light ducts can dually operate as efficient electric fixtures, and they are controlled automatically to supplement the daylight when necessary.
The project completed installation of the architectural daylighting system at Fort Bliss, but the 3M™ Sunlight Delivery System did not complete final calibrations and final testing. Based on elements needed to make the system operational, development costs were too great to proceed with the project. Difficulties included:
- Unreliable tracking performance. Alignment is critical to the performance of this system. The tracking method included a feedback loop, which fine tuned alignment based on sensors within the collector. This loop was problematic due to software issues with the controller and physical changes in the optical path due to heat and dust.
- Poor hyperbolic reflector alignment and performance. This design depended on concentrated sunlight interacting with a hyperbolic reflector in order to deliver light long distances. Because of unanticipated heat build-up and concentrated sun energy, the team was not able to adequately protect the hyperbolic reflector from degradation (“tarnishing effect”). This greatly reduced the coupling of light into the ducts.
- Poor collector environmental protection. In this environment, the project continually battled issues related to blowing sand. The clear polycarbonate domes scratched almost immediately, though improved once a coating was applied. The collectors also collected a lot of dust internally, which necessitated frequent cleaning. A sealing system was never identified, which could ensure a clean optical path.
- Too much dependence on remote support. Facilities management at Fort Bliss was not in a position to support the technical and mechanical requirements needed to keep the system operational. Given that the project never hit operational state, the team believed that continued monitoring and maintenance of the system would have been required even if successfully deployed. Tasks such as realignment of mirrors, replacing domes, cleaning equipment, updating tracking software, monitoring fail-safes, troubleshooting malfunctions, execution of system software, report generation, and similar activities were beyond the job duties of personnel at the site. 3M was not in a position to provide long-term continuing support, and the facility wanted as near a turn-key system as possible.
Overall, system performance was not what was expected. The effect from the intensity of the sun on the hyperbola was greater than expected. 3M tried three different solutions to reduce this effect, but all were unreasonable to develop. The technology still needs improvement, and the output was not as anticipated.
The 3M architectural daylighting system actively tracks, captures, and transports the sun’s natural, full visible spectrum daylight into the interior space of a building where natural lighting is limited. By harvesting free and abundant light from the sun, the system has the potential to provide a more sustainable, energy efficient lighting solution resulting in reduced energy demand during high cost, on peak hours. The 3M™ Sunlight Delivery System utilized a hybrid lighting solution option that incorporated additional artificial lighting and controls allowing for consistent light levels in overcast and night time situations. Use of a system like this has been shown to improve employee productivity, health, and morale and can also help contribute to green and sustainable building certifications across multiple credit categories.
This ESTCP project resulted in a full-scale operational model that was designed, installed, and tested at Fort Bliss. Results indicate that more development effort is needed in order to improve system reliability and performance. Implementation issues encountered as part of the project are described under the Demonstration Results section above.