Tube Skylights

Tubular Skylight for Daylighting

Daylighting is made possible using tubular skylights.  Tubular skylight is an often applied misnomer for Tubular Daylighting Device.  Tubular skylights can be thought of as “active” or “amplifying” skylights, allowing light to enter buildings through the roof, but with a unique, complex difference.

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How Tubular Skylights Are Different From Traditional Skylights

Traditional skylights are passive windows which allow light to pass through the glass like any other window.  A tubular skylight also allows light to pass through the roof and into interior areas, but the similarities end there.  Tubular skylights are segmented into several individual optical components.  

 

Light Capture and Collection Segment

A well-designed tube skylight efficiently captures sunlight from many entry angles.  The collector captures sunlight and redirects the light downwards towards the second segment of the tube skylight.  The collector, being the point of light entry, is a critical component in tubular skylights.  

Solar Collector Configurations

There are many variations on the solar collector design.  Many collector designs will implement a reflector to increase either the quantity and/or quality of the light which is collected.  Collector and reflector design and implementation can be very advanced or complex in some designs, with some tubular skylights using patented or proprietary configurations. There are several popular solar collector styles, with many collectors varying in overall size, silhouette, and profile.

  • Dome shape
  • Diamond shape
  • Oval shape
  • Vertical orientation

 

Other Tubular Skylight Collector Factors (add glazing)

Using a tubular skylight to efficiently and effectively capture sunlight can be a sensitive process to perfect.  Common measurements used to determine the performance of a tubular skylight are as follows:

  • How well it captures light entering from low angles such as during early morning and late afternoon, or times of year when the sun is positioned close to the horizon.
  • How much light is captured during less than optimal lighting conditions, such as cloudy or foggy days.
  • The color and quality of the light emitted into daylighted areas.  One of a tubular skylight’s goals is to retain the original lighting color as closely as possible.  Lesser performing skylight’s may produce a light which has a strange or unnatural color which is considered undesirable.

 

Skylight Tube Segment

The tubular section of the tube skylight utilizes highly reflective, specialized optical materials to transmit light through the tube.  Light reflects off of these mirror-like materials several times as it travels through the tube.  

 

Pure Light Transfer

The light tube may be mistakenly thought of as a light amplifier, but the role of the transfer section is actually to transfer light unaffected and as purely as possible while minimizing the loss of light.  A key design element of the tube transfer section is not only how well it retains the brightness of light, but also how well it retains the true color of the light it is transferring.  Color Rendering Index is a measurement of how accurately colors are displayed under light.  A design goal in tubular skylights is to achieve a favorable color rendering index (CRI).

Some tubular skylight designs may be able to efficiently run transfer tubes up to 25 feet long or more, allowing tube based skylights to be implemented into a wide range of buildings and applications.  Aside from using different reflective materials on the interior, the skylight’s actual tube may use either a rigid design or flexible design.  In general, a rigid tube system is more expensive but is also more efficient, transmits higher quality light, and is considered to be preferable to a flexible system.

 

Skylight Delivery Segment

The third primary component in a tubular skylight is its light diffuser which feeds light from the tube transfer area into interior areas.  There are three primary types of light diffusers, but the large majority of tubular skylights utilize a prismatic lens to redirect light in many directions, illuminating interior spaces in the process.

 

Light Diffuser Types

  • Opal Diffuser:  An Opal light diffuser contains microparticles within the diffuser material which scatter light particles.  The scattering process emits a softer, less sharp light, which makes it a less optimal selection in daylighting applications.
  • Gaussian Diffuser:  The Guassian style diffuser uses a finely textured surface which is similar to a sandblasted texture.  This texture in the diffuser surface redirects light in many directions.
  • Prismatic Diffuser:  The Prismatic diffuser typically utilizes pyramidal ridges to refract
    (or redirect) light in many directions.

 

More Information on Tubular Skylights

Tubular Skylights employ a range of scientific lighting principles and specialized optical materials to harness daylight.  Daylighting is a sensitive process.  There are many tubular skylight products available, most are based off of similar optical concepts, but each product differs according to its design, quality of materials, and implementation of optical concepts.

Do you have more questions about tubular skylights and the daylighting process?  Please Contact Us with additional questions.