The Illuminating Engineering Society of North America (IESNA) is the organization in the United States that develops standards of illumination. Chapter 10 of the IESNA Lighting Handbook, 9th Edition, provides a procedure for lighting design that emphasizes both lighting quality and quantity. Although weighing factors such as the worker’s age and the speed or accuracy required for a task are recommended, the light levels required for a workspace generally fall between 20 to 100 footcandles. Basic lighting recommendations for almost any area or activity, along with the procedures for refining them, are listed in the IESNA Lighting Handbook. The Handbook and other lighting reference material are available for purchase at the IESNA website: www.IESNA.com
Tools to Calculate SLX Daylighting System Requirements
Photometric data for the SLX system has been calculated and submitted by Lighting Technology, Inc. an independent laboratory in Denver, CO. Partial results of the tests are shown on the Photometric chart in the Testing section of this catalog. This chart gives the designer average illumination levels for an area given the spacing of the skylights and the height of the ceiling.
Please consider the following when determining the layout of the Daylite SLX units:
- If possible, avoid conflicts with other systems by completing the daylighting layout before specifying other systems for the roof.
- Other sources of daylight such as windows, open doors, and other skylights can reduce the number of Daylite SLX units required to effectively light the building.
- A uniform installation pattern will help to create an even spread of light throughout the daylighted area.
- The Daylite Company recommends that the light shaft be extended below the level of any exposed beams or ductwork.
Pitched Roofs - Care should be taken not to position SLX units in such a way that the roof blocks the sunlight.
Roof Mounted Equipment - SLX skylights should not be placed within 6 feet of the north side of parapets, air conditioning units, or other equipment that would obstruct the sun from the skylight. Such obstructions may significantly affect the performance of the Daylite SLX unit.
Drop Ceilings - The SLX’s 48-inch shaft design allows the internal lensing to integrate into must suspending ceilings. However, the orientation of the SLX roof penetration should coincide with the suspended ceiling grid so that the light shaft will now require any curves or turns to match up with the ceiling grid.
Electric Lighting System - Photo cells and control lighting systems can be used effectively with the Daylite SLX system.
Diffusers - The Daylite Company offers different styles and types of diffusing lenses for use in most buildings.
Clear Enhanced Acrylic Prismatic Lens - This lens is in the shape of an inverted pyramid and is recommended for use in buildings with ceilings greater than or equal to 16-feet in height. This lens transmits 92% of available daylight.
Flat Acrylic Prismatic Lens - Recommended for ceilings less than or equal to 16-feet.
Flat White Acrylic Prismatic Lens - This lens fits neatly between standard “T” bar supports used on many drop ceilings. The milky white acrylic has a softer appearance and reduces transmitted light by 30%. Recommended for ceilings 10 to 16 feet in height.
Light Shading - Some applications may require adjustable lighting for times when a darker environment is desired. This is common in conference rooms or classrooms, which are sometimes used for presenting films or video presentations. The optional shut-off unit should be specified in those types of applications
Safety / Security Grills - Specify a safety or security grill to prevent unauthorized entry through the roof or guard against falls through the skylight opening.
Installation - In most aspects, installation of the SLX system is similar to the other curb-mounted skylights. As stated above, the upper edge of the curb must sit level when attached to the roof. We recommend that the SLX unit be installed by licensed roofers / contractors that have received training from a Daylite factory representative.
The Daylite SLX unit has been independently tested for the following characteristics:
- Uniform Building Code AC-16 Standard for Plastic Skylights.
- ICBO Report #ER-2469.
- Photometric Data.
- Standard Resistance to High Winds up to 90 mph, custom designed for higher winds.
- Dome resistance to Heat - up to 210 degrees F.
- Thermal Cycling - From 180 degrees to -20 degrees F.
- Contact Us for full reports on these tests.
Use of daylighting techniques can be helpful in qualifying a building for Leadership in Energy & Environmental Design (LEED) credits. To qualify for credits under category 4, Indoor Environmental Quality, the LEED program requires a minimum daylight factor of 2% in 75% of all space occupied for critical visual tasks. However, when designing with some skylights, it may become necessary to increase the daylight factor in order to achieve the desired light levels. Due to its ability to channel daylight into buildings, the SLX system may be able to provide the desired level of light while maintaining a lower skylight to floor space ratio. This may be of significant value when considering the heat gain or loss attributed to daylighting.