Rooflights
VELUX TWF sun tunnel
Roof-mounted sun tunnels can be installed in all types of roof and wherever roof windows or façade windows cannot be fitted. They bring light into rooms through a specially designed tunnel running from the roof to the ceiling, providing daylight indoors regardless of the season or time of day. They are intended for rooms within the top storey of a building where windows cannot be installed, such as a dressing room, corridor or bathroom.
The TWF sun tunnel is installed where the distance from the ridge, measured along the tunnel's centre line from the top surface of the batten to the ceiling, is between 0,4 m and 2 m.
The sun tunnel's main components are: the roof module; BFX waterproofing that fits tightly around the components to protect against moisture; a highly reflective flexible tunnel with a mirrored coating and 98% reflectivity; a vapour barrier membrane fitted tightly to the sun tunnel structure; and a ceiling element with a glowing-edge effect.
Tunnel rooflights consist of three basic components. The first, on the roof, is polyurethane flashing integrated with a pane in a flat frame measuring 47 x 47 cm. It uses a 4 mm toughened pane with a photoactive, easy-clean, hydrophilic coating that speeds up surface drying. This makes it much easier to keep the rooflight clean and therefore working at full efficiency.
The next component, between the roof and ceiling, is a mirrored light tube. In the TWF model, this is a flexible 2-metre light tube with a diameter of 35 cm (14"). The Miro Silver coating provides light transmission efficiency of up to 98%.
The third element, fitted to the ceiling, is an acrylic insulation kit providing effective thermal insulation. The sun tunnel comes with a matt pane as standard. A frosted or prismatic pane can be ordered as an extra.
Tunnel rooflights provide significant energy gains compared with artificial lighting. The energy obtained from natural light is approximately 9 W per 1000 lumens. For example, if the light output from the rooflight is 2000 lumens, the solar energy supplied is approximately 18 W. The amount of light passing through a tunnel rooflight depends on its construction.
The rooflight can also be fitted with a ZTL electric lighting kit, which provides additional room lighting after dark. The kit can be fitted after the rooflight has been installed. Maximum bulb wattage: 23 W.
Construction
Ut value = 2,2 W/m2K
polyurethane flashing integrated with a pane in a flat frame - roof element dimensions 47 x 47 cm
4 mm toughened pane with an easy-clean coating
tube construction: TWF – flexible 2-metre light tube with a diameter of 35 cm (14")
acrylic insulation kit
ceiling trim in the form of a white ring (standard)
permitted roof pitch from 15° to 60° (profiled roofing materials) and from 35° to 60° (flat roofing materials)
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