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Flexible-duct Sun Tunnel Systems

If you are in the market for a Tubular Daylight System (TDS) there are two different types to consider; rigid or flexible. Flexible solar tubes are cheaper to buy, while rigid systems are  much more efficient. Naturally, we feel that rigid solar tubes are better as that is the type of product we sell, but what are the facts?

Rigid systems like our own Solarspot ® systems feature a fixed tunnel lined with a highly reflective material to reflect light from the sky down into your home. Flexible systems consist of an air-conditioning style duct lined with foil which is fairly ineffective. The BRE (Building Research Establishment) have previously tested flexible solar tubes and shown that the highest efficiency they could return was 6% if the tube was vertical and pulled taut – not a situation likely to occur in most homes. When they compared this with a rigid sun tunnel system featuring a reflectivity of more than 99% (our own Vegalux material has a reflectivity of 99.7%) they found that the rigid system outperformed the flexible one around 10 times over.

This all means that while the individual flexible duct sun tunnels may be cheaper to buy, as you will need 10 of them to achieve the same levels of light as a rigid system, it works out much more expensive. As both systems cost much the same to install, you would need to pay as much as ten times the installation costs for the flexible systems (or settle for much dimmer results).


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