Case 14541

A Passive Louver-Based Daylighting System


Daylighting system, window louver, energy-efficient windows, passive lighting, building technology


Channeling daylight into the interior of deep-plan buildings.


Daylight is a valuable resource for both energy and human health. However, this resource is often underutilized in buildings due to the difficulty of controlling the changing qualities of daylight. Deep-plan building spaces pose an especially challenging problem because traditional sidelighting strategies are only effective for workplanes adjacent to the façade. Infrequently adjusted shading systems can also limit the availability of daylight.


The system comprises a special window unit installed at the top of the daylight façade along with reflective panels which cover the ceiling from the daylight façade to a distance of approximately 4 m inboard. The system redirects both diffuse skylight and direct sunlight from a wide range of incoming angles into the building space at a shallow upward angle. To mitigate glare concerns, a horizontal array of optically clear rods are placed at the outlet of the louvers. These elements act as cylindrical lenses which spread the light in the azimuth direction, without affecting the light’s elevation angle. To assist the light in penetrating deeply, light that hits the ceiling near the facade is spread-specularly reflected down onto the workplane, rather than being diffusely scattered.

  • Bridge the gap between expensive, maintenance-intensive automated systems and ineffective passive systems that cause glare
  • Simple, static, and maintenance free.

  • Kevin Thuot, (MIT Mechanical Engineering Department)
  • Marilyne Andersen, (MIT Department of Architecture)

Intellectual Property:

US Provisional Application 61/413804 filed on November 15, 2010


Thuot, K. & Andersen, M., 2011. A Novel Louver System for Increasing Daylight Usage in Buildings. In Bodart, M. & Arnaud, E., eds. International Conference on Passive and Low Energy Architecture. Louvain-la-Neuve, 2011.

Cross-Sectional Diagram of the Soralux Daylighting System
Cross-Sectional Diagram of the Soralux Daylighting System

Window Unit Section View (Left) and Plan View (Right)
Window Unit Section View (Left) and Plan View (Right)

Last revised: Aug 24, 2011

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