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Tubular Skylights

Add natural lighting to rooms through a small tube rather than a large roof window.

A tubular skylight gathers sunlight from a leak proof dome, bounces it down a light reflective tube to a lens cover that diffuses the sunlight throughout the room.

Many homeowners enjoy the natural lighting that skylights provide. However, skylights often do not distribute light evenly, are a significant source of energy loss, and can cause UV damage to carpets and furniture. Tubular skylights, on the other hand, use the sun for lighting interiors without the drawbacks associated with conventional skylights. They are generally easier to install than typical skylights and, from the home's interior, resemble conventional lighting fixtures.

Tubular skylights have a roof-mounted light collector typically consisting of an acrylic lens set in a metal frame. Most have a reflective sun scoop in the rooftop assembly that directs sunlight into a metal or plastic tube which has a highly reflective interior coating. The reflective tube guides the sunlight to a diffuser lens, mounted on the interior ceiling surface, that spreads light evenly throughout the room. The shape of the scoop is generally parabolic to reflect sunlight into the home regardless of the sun's angle in the sky.

Some tubular skylights have integrated electrical lights so the fixture can provide light both day and night and some have integrated baffles to regulate the amount of incoming sunlight.

The performance of tubular skylights varies widely between brands. Tests performed at the Alberta Research Council indicated that one 13-inch tubular skylight had equivalent light output of up to one 700-watt incandescent bulb in December and one 1,200-watt bulb in June.


Affordability

Some of these systems cost less than conventional lighting systems, and most cost much less than a conventional skylight.

Energy Efficiency

By utilizing the light from the sun during the day, considerable energy savings can be realized by not using electric lights. Energy savings attributed to tubular skylights will depend on the application.

Quality and Durability

Because tubular skylights fit between rafters or other structural elements and are lightweight, there typically does not need to be any modifications to a structure. Their simple design, complete with self-flashing kits, leads to their longevity.


Easy

Tubular skylights can be ordered directly from manufacturers and distributors. Like traditional skylights, tubular skylights are only effective in the living area directly under the attic or roof, so, in multi-story homes, tubular skylights can light only the top floor. Installing in some rooms may require a long reflective tube to connect the rooftop collector and the diffuser. As the length of the reflective tube increases, its effectiveness in transmitting light decreases. Additionally, tubular skylights do not provide a view like traditional skylights and windows.


The retail price of a tubular skylight ranges from about $150 for small basic models to more than $600 for larger, deluxe models. The installed cost can be lower than conventional skylights because additional framing is not needed for installing in new homes, and fewer framing alterations are needed in existing homes.


When compared with conventional skylights, there will be less energy loss (and, hence, energy cost) associated with the use of tubular skylights. Reduction in electric lighting needs, however, will be similar.


Section R308.6 of the 2003 International Residential Code covers skylights and sloped glazing.


Bruce Davis Construction: Washington Square, La Plata, Maryland


Installation is usually simpler than standard skylights and uses only common hand tools. In most installations, a hole the diameter of the reflective tubing is cut in the roof sheathing and interior ceiling. The self-flashing collector is mounted on the roof and the reflective tubing attaches to the collector and extends to the interior wall surface. The diffuser mounts to the end of the reflective tubing. The narrow diameter of the tube (between 10 and 21 inches) allows the reflective tubing to pass between roof rafters or trusses. The fixture's light weight allows it to be mounted on the existing roof and interior ceiling with no additional support. Manufacturers generally claim that their product can be installed in less than two or three hours.

For full effectiveness, tubular skylights should be mounted on areas of a roof that receive direct sunlight for large portions of the day (e.g., unshaded areas or the south slope of a roof). Tubular skylights are typically mounted on pitched roofs above attic space, but are also suitable for low-slope roofs.


Many manufacturers offer 10 year warranties, and some offer lifetime warranties.


Unlike traditional skylights, tubular skylights transmit indirect, diffuse sunlight that reduces potential UV ray damage to carpets and furniture. They also distribute light more evenly throughout a room (no harsh direct sunlight enters the room). Because the rooftop solar collector has a small surface area and because of the airspace between the collector and the diffuser, building heat loss in the winter and heat gain in summer are minimized. Their small size also minimizes their impact on the home's appearance.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.