Why do Solatube sun tunnels deliver brighter light than other systems?

Since I tried to explain the difference in the amount of light you get from different types of tube, quite a number of people have expressed not just surprise, but a lot of interest in this aspect of Solatube sun pipes. So I thought I would bring these various thoughts together in a single blog.

When comparing light pipes or sun tunnels, the choice of reflective tubing used is one of the most significant factors.

So, what’s the difference between a 98% reflective sun tunnel and a 99.7% reflective Solatube? The answer is “a lot more than you might think”.

Now, it doesn’t sound like a big difference does it – 98% or 99.7% reflective? However, it makes a MASSIVE difference in sun tube systems, and here why:

  • 98% reflective: Each time light bounces down the tube it loses 2% of its energy, or light. Over just 10 bounces that equates to a 20% loss of light.
  • 99.7% reflective: Each time light bounces down the tube it loses just 0.3% of its energy, or light. Over 10 bounces that equates to a tiny 3% loss of light.

Over longer tube runs that difference becomes even greater – with 20 bounces you lose over 30% of the light with the less reflective tubing and just 6% with Solatube. Now that’s a very big difference when you’re trying to light up a room.

It’s physics, not magic!

The reflectivity of the tubing in a Solatube sun pipe is one of the most significant factors that determines how much light a system delivers in to your home. And the longer the length of the sun tunnel the greater the impact of the reflectivity. Essentially the longer the sun tunnel, the less light you get. And that’s just down to basic physics:

  • Each time light bounces down a Solatube sun pipe it uses up some of its energy; and that ‘energy’ is light.
  • The more reflective the Solatube material, the more light gets bounced down the tube and in to your home.
  • The less reflective the sun tunnel material, the less daylight will be delivered in to your room.

So don’t get confused in to thinking that a really short tube won’t allow much light to be piped in side. The opposite is actually true and the shorter your Solatube is, the more light will be piped in to your home. In fact, this gives you a win-win situation; not only does a shorter Solatube deliver MORE light, it is also cheaper (longer tube lengths clearly cost more than shorter ones). You therefore get MORE light for LESS money!

Higher % reflectivity = more light

We’ve therefore established that the more reflective the Solatube is (or the higher percentage reflectivity) the more light you’ll receive down your sun tunnel. So, what are the choices in reflective material? In terms of sun tunnel systems you only really need to be aware of the following options:

  • At the top of the range is 99.7% reflective Solatube – the worlds’ most reflective material. There’s nothing more reflective available in terms of Solatubes.
  • Next you drop down to 98% reflective sun tunnels, used by practically all copycat systems out there. And the reason they use this is because it’s cheaper.
  • Anything less than 98% reflective is generally just not worth it and few manufacturers offer this, but beware the flexible tube…

Flexible tubes just don’t deliver much light

Unfortunately, there are still a number of companies that try to sell you a system that uses a flexible tube and this is the least reflective option of all. Essentially the inside of the tube is like scrunched up tin foil and so, rather than reflecting the light down the tube, the light is bounced around in thousands of different directions with as much light heading back up the tube as down it.

If there was only one piece of advice that you came away with, having read this blog, it would be “do not get fooled in to using a flexible tube system” as they simply just do not deliver any meaningful amounts of daylight, except over the shortest of tube lengths (less than a couple of feet).

The following graph clarifies the difference that reflectivity makes when choosing your Solatube sun pipe.

So, 99.7% reflective Solatubes deliver a lot more light than 98% reflective sun tunnels

This means you can install a smaller size Solatube, or fewer Solatubes, in order to get the same amount of light as you would from larger sun tunnels.

I hope that the above clarifies matters with regard to tube reflectivity and in particular why, what appears to be a small difference in percentage terms adds up to a BIG difference in the amount of light delivered in to a room.

I hope all the above helps and If you are interested in bringing natural light into your home, why not contact us at info@solatubescotland.co.uk; 07778 283 427 to find out whether a Solatube sun pipe can help you. Typically, a fully installed system might cost anywhere between £900 – £1,200; that’s supplied, professionally installed and includes the VAT.

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