Solatube Uses New Material To Brighten Its Future
A roof-mounted dome collects natural light and directs it down a highly reflective cylinder to a light diffuser in the room ceiling. The diffuser has the appearance of a standard light fixture.
The cylinder tubing can be angled around attic or other obstructions for easy installation . The highly reflective interior material lining of the tubing reflects light all the way down the tube to the diffuser.
Owing to the total reflectance and specular reflectance properties of the material, the maximum amount of light reaches the room interior.
In reviewing the available options for the interior material, Solatube design engineers considered a number of factors, especially specular reflectance, defined as the light emission reflection off the surface as a percentage of the incoming beam. A 30 specular reflectance test was performed by the Solatube engineers, as this angle represents the maximum bend allowable in the recommended installation of these devices.
In addition to the total and specular reflectance tests, Solatube engineers also evaluated the materials under consideration for distinctness of image (DOI), 15 reflected haze (H15), color metrics (CIE "LAB", yellowness index ASTM D1925) and to ASTM standards E308 and E430.
At present, only a few major manufacturers offer laminated lighting sheet material for this mirror-like finish application. After a careful examination of the available vendors, Solatube chose to partner with MSC Laminates and Composites, A Material Sciences Company, and utilize its Specular+ material.
Specular+ is manufactured in two distinct steps. First, a clear, super plastic polyester film undergoes a process known as Magnetron Sputtered Vacuum Deposition (MSVD), in which a layer of pure silver is deposited onto the film. MSVD is currently recognized as the most advanced thin-film metallizing process, offering excellent metal-to-film adhesion.
Next, through a proprietary continuous coil coating process at MSC Laminates and Composites, the film is permanently bonded to coil steel or aluminum, in thicknesses from .015"-.035" and widths up to 48". The process utilizes a thermoset, cross-linked adhesive system which chemically bonds the film to the substrate, creating a film-tearing bond strength substantial enough to eliminate delimination, bend crazing or cracking, forming restrictions and even iridescence.
Specular+ is a component recognized by UL, under File No. E104090 and meets flame spread requirements under UL #1570, #1571 and #1572. MSC Laminates and Composites Inc. is a recognized EPA "Green Lights" Ally company, as their products demonstrate substantial energy saving characteristics.
On the Solatube application, the coil of Specular+ is cut, formed, back-welded and fitted with elbows of a 15 radius, thereby allowing up to a 30 bend maximum in installation. Currently, Solatube units are offered in 10", 14" and 16" diameter models with maximum recommended tube lengths to 15'.
By comparison to a standard 100-watt incandescent bulb which generates 1200 lumens or a 40-watt, 48" fluorescent tube which produces 2300 lumens, these are the relative outputs of Solatube models:
A 10" Solatube compares to a 2'x2' skylight while a 14" or 16" model compares to a 2'x4' skylight.
For more information on this application, please contact: SOLATUBE INTERNATIONAL, INC.
For more information on Specular+ and the entire family of high reflectance materials, please contact: MSC LAMINATES AND COMPOSITES INC.