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Frequently Asked Questions



    What is the maximum tunnel run length for the commercial VELUX SUN TUNNEL skylight?
    For optimal light transfer between the outdoors and the interior space, VELUX recommends 20 feet maximum between the roofline and the ceiling grid. There is no reason other than optimal lighting output that the TCR commercial SUN TUNNEL skylight cannot be installed in applications of 20 feet or more.
    Can skylights help save energy?
    Yes. Artificial lighting is one of the largest sources of energy consumption in commercial and industrial applications. On average, artificial lighting accounts for 40% of the building’s total energy. Utilizing the high visible light transmittance VELUX acrylic skylights has been shown to significantly reduce these energy costs through the benefits of daylighting.
    Don’t skylights create heat? Shouldn’t I select the skylight with the lowest U-value and solar heat gain?
    The energy savings achieved from reducing dependency on electric lighting far exceeds any heat gain or heat loss in the vast majority of applications. Additionally skylights typically provide less heat than electric lighting. This is why you should choose a skylight that has superior visible light transmittance in lieu of selecting a skylight just based on thermal values.

    VELUX acrylic skylights provide extremely high levels of visible light, and are available with thermal breaks and weep systems to maximize energy efficiency making them ideal for all commercial and industrial applications. Installing skylights often pays for itself in two years or less.
    Do skylights create glare?
    VELUX offers skylights that have a 100% haze factor that provide diffused lighting with no glare. High levels of visible light transmittance are maintained, but that light is spread evenly throughout the space.
    Do VELUX acrylic skylights become yellow or deteriorate over time?
    No. VELUX extrudes only high quality acrylic that does not become yellow or brittle over time like competitor’s skylights. In fact we offer a 10 year warranty on acrylic color.
    How can I achieve LEED points with skylights?
    Reference our LEED brochure for detailed information about achieving LEED credits with skylights.
    What is the difference between a CM and a CMA?
    While both are curb mounted skylights, the CMA has a maintenance free design. Its frame is painted neutral gray, and it has a white PVC interior for an esthetically pleasing interior finish.
    Our job requires fall protection; can I still use an acrylic skylight?
    Yes. Because VELUX utilizes high quality acrylic we can offer CAP and CM skylights that are OSHA compliant without special glazings or increased cost. We also offer polycarbonate glazings and fall protection screens where desired.
    Are blinds and controls available in commercial?
    The sunscreening accessory tray can be used with standard size curb mounted commercial skylights to provide access to blinds and controls including the solar blackout blind.
    How is the TCR commercial VELUX SUN TUNNEL™ Skylight sold?

    The TCR commercial VELUX SUN TUNNEL™ Skylight is composed of three “standard” elements:

    • Roofing components (P1, or Q1): Dome, flashing and top elbow
    • Standard ceiling components (P2): Adapter box (round to square transition that fits into a 2x2 ceiling tile), diffuser frame and prismatic diffuser, flexible bottom elbow; an optional round bottom kit is available for spaces with no ceiling.
    • Telescopic rigid tunnel (P3): can be extended to 5 feet
    • In addition, a 24” coupler piece is optionally available for added flexibility in the length of the tunnel run.
    How much interior space will a TCR commercial VELUX SUN TUNNEL skylight illuminate?
    Depending on the length of the run and the orientation (for sloped roofs) as well as the geographical location of the job, it is estimated that a TCR commercial VELUX SUN TUNNEL™ skylight can bring adequate lighting to 150 – 400 square feet.
    Is there a “standard” length with the commercial VELUX SUN TUNNEL skylight?

    The TCR VELUX SUN TUNNEL skylight was designed to be completely modular. The roofing component and the ceiling component should always be “standard” as they are needed on all jobs. The modularity comes from the almost unlimited combinations of extension pieces such as the 5’ telescopic tunnel or the 24” coupler piece.

    All applications from 3' runs to 20' + can be accommodated simply by combining several of the telescopic components or using the 24” coupler. For very short runs, only the roofing component and the ceiling component may be needed. For runs up to 8 feet (from roofline to ceiling tile), a telescopic tunnel is required in addition to the roofing and ceiling components. For longer runs, a combination of telescopic tunnels and couplers may be required. 

    For details on what parts are needed for various run lengths, please contact us.

    What does the commercial VELUX SUN TUNNEL look like from the interior of the building?
    On the inside, the TCR commercial VELUX SUN TUNNEL skylight is designed to fit in standard 2’ x 2’ ceiling tile. The adapter box can also be retrofitted into a hard sheet rock ceiling if necessary. The diffuser is square in shape and prismatic for optimal light diffusion.
    What is the definition of a commercial VELUX SUN TUNNEL skylight, “run”?
    A “run” is the distance between the ceiling and the roofline. VELUX makes recommendations in the Commercial Skylight Catalog (V-USA-1824) as to which components should be used for which runs. These recommendations account for the run as well as the height of the curb and flashing overlap with collar.
    What type of flashing comes with the TCR commercial VELUX SUN TUNNEL skylight?
    The  TCR commercial VELUX SUN TUNNEL skylight  is composed of a curb-cap style flashing to better accommodate the preferred flashing method on commercial roofs. The commercial sun tunnel is simply installed on top of a pressure treated site-built (8” minimum) curb just like any other curb mounted skylight.
    What types of applications are best for the TCR commercial VELUX SUN TUNNEL skylight?
    The TCR commercial VELUX SUN TUNNEL skylight is primarily designed for low-sloped and flat roof applications with a suspended ceiling or hard ceiling in the interior space.