Q: What is the LightLouver Daylighting System?

A:

LightLouver is a passive optical side-daylighting device that is positioned inboard ( inside ) of  the “daylight” window which redirects incident sunlight upward and deep into the daylit space while eliminating glare and any direct sunlight penetration onto work surfaces. The result is an ambient source of daylight made accessible to interior spaces that would otherwise be dependent on electric lighting. The heat associated with the redirected daylight stratifies against the ceiling and out of the occupied space, reducing the requirement for mechanical cooling as well. [ Provide link to LightLouver Description Section. ]

Q: Is the LightLouver Daylighting System a Light Shelf?

A:

The LightLouver Daylighting System constitutes a significant improvement over a traditional interior or exterior light shelf. Each reflective slat in a LightLouver unit performs the same function as a light shelf, but with improved performance. By adding specific optical geometry and a highly specular reflective surface to the light shelf concept, a greater percentage of daylight is redirected much deeper inside a building than previously possible by a light shelf while eliminating glare. By miniaturizing the optical design concept into small reflective slats and stacking them into a window treatment, total solar control is achieved, meaning no uncomfortable direct sun glare and reduced solar heat gain. [ Provide link to LightLouver Description Section. ]

Q: Can I use the LightLouver Daylighting System in my building?

A:

The LightLouver Daylighting System can be applied to any window that receives direct sunlight, provided that the bottom edge of the LightLouver unit is at least 7' above finished floor height.  Also, the visible light transmission of the window glazing should generally be above 60 % in new buildings and above 50 % in existing buildings. LightLouver units work best with a highly reflectance ceiling ( 80 % reflectance  minimum ). [ Provide link to Design Information – New and Existing Building Design Guidelines. ]

Q: How much light do LightLouver units provide?

A:

LightLouver Daylighting System provides an annual average illuminance of approximately 20 to 30 foot candles within the daylit zone created. The daylit zone created is 14' deep for each vertical foot of LightLouver unit installed. For example, an application of 2 foot high LightLouver units will create a daylit zone that is approximately 28' deep. [ Provide link to Performance Information – Illumination Distribution and to Design Information – Design Integration Guidelines. ]

Q: Can LightLouver units be used in a retrofit application?

A:

Yes! Because the LightLouver Daylighting System is lighter and easier to install than most other daylighting options, it is the perfect option for daylighting and energy efficiency retrofit projects. [ Provide link to Design Information section – Existing Building Design Integration Guidelines. ]

Q: How much do LightLouver units cost?

A:

The LightLouver Daylighting System costs approximately $2.00 to $2.25 per square foot of  daylit floor area. Or calculated as a function of LightLouver unit area, the cost is approximately $35.00 / sf  (i.e. a 5 ‘ wide x 2' high LightLouver unit would cost approximately $350.) [ Provide link to Performance Information section – Comparative Normalized Cost Information. ]

Q: How are LightLouver units installed?

A:

LightLouver units are mounted on support brackets which are attached to the window frame. The geometry of the brackets is such that the panels cannot be unintentionally dislodged, but can still be pivoted out to 45 degrees to allow easy cleaning of the daylight windows behind the LightLouver unit.

Q: What facades can I apply LightLouver units to?

A:

LightLouver units can be used in windows on east, south, and west-facing facades.  LightLouver units are an excellent choice for east and west facades, where sun angles are low, because of the unique optical design of the LightLouver reflective slats redirects all sunlight above a 5o solar altitude angle upward onto the ceiling. [ Provide link to LightLouver Description ]

Q: Can the LightLouver Daylighting System be used in existing buildings?

A:

Yes. The LightLouver Daylighting System can be used in existing buildings as long as:

• Windows have access to the sun and are not shaded by obstructions such as overhangs, trees, or other buildings.
• Windows are not too darkly tinted. Windows can be tinted, but should not be extremely dark.
• Windows must be tall enough that the bottoms of the LightLouver units are at least 7’ feet above the finished floor.  This is necessary so that sunlight is not reflected directly into building occupant eyes.

A screening tool is available on the web site to determine if an existing building is a good candidate for LightLouver. [ Provide link to Design Information – Existing Building Design Integration Guidelines, and to Existing Buildings Program – Feasibility Checklist. ]

Q: Can LightLouver units be used to solve glare problems in an existing building?

A:

Yes.  LightLouver units are frequently used to solve glare problems caused by windows, clerestory windows or light shelves.

Q: Do LightLouver units increase the heat gain to the building?

A:

No.  In fact, the heat gain to the building is decreased because LightLouver units provide five times as much illumination per watt of heat as most electric lighting systems.

Q: Can LightLouver units be used to solve heat and glare problems on west-facing windows?

A:

Yes.  LightLouver units can be installed above conventional window treatments ( mini-blinds or shades ) to eliminate glare while redirecting sunlight upward onto the ceiling, allowing the electric lights to be turned off.

Q: How hard is it to mount LightLouver units?

A:

LightLouver units are very easy to install, typically taking less then 10 minutes per unit.  Support brackets are attached to the top of the window frame with two self-tapping screws per bracket.; then the horizontal header of the LightLouver unit slips into the brackets and locks into place. [ Provide link to the Installation Manual. ]

Q: What do I have to do to maintain LightLouver units?

A:

To maintain good performance, LightLouver units should be dusted once or twice a year, typically as often as the window behind the LightLouver unit is cleaned.  LightLouver units pivot at the top so that the “daylight” windows behind the units can be cleaned. LightLouver units have been installed in buildings throughout the U.S. since 2001 and cleaning and maintenance of the LightLouver units has not been a problem or a large maintenance cost. [ Provide link to the LightLouver Maintenance Manual. ]