Velux Sun Tunnel

Without question the best known name in roof lights and windows throughout the world

Unless your're installing on a south-facing roof the Velux is virtually uselss. With systems like the Solarspot; light is captured and redirected into the tube. With the Velux, this light is lost as it simply passes straight over the roof.

Their roof windows are well designed and the product performance is exceptional. If only the same could be said about their sun tunnel. The same manufacturing quality is still there but the light levels they deliver don’t live up to the Velux name.

The Velux Sun Tunnel is available with a flexible or rigid tube. Both systems employ a flat plate of glass on the roof rather than a dome. The advantage of the flat plate is that they are preferred when there is a planning constraint or the customer doesn’t like the idea of a dome from a cosmetic point of view. However, from a light capture point of view, the flat panel approach is pretty much useless.

If the roof unit is placed on a south-facing roof then the performance will be ok at around lunchtime, but first thing in the morning and then after lunch the sun just passes over it the light-levels will drop off massively. And if you have to locate the roof section on a north-facing roof then you can pretty much forget about getting anything other than ‘cold’ north light.

Solarspot vs FlexiMoving on to the tube options, despite what you may have heard, the difference between the flexible and rigid tube is massive. If you compared even the best flexible tube (which is probably the Velux) with even the worst rigid unit then difference will be significant. And the great irony is that the two systems will probably cost you the same to install.

You’ll often see flexible systems advertised for locations where you need to be able to ‘bend’ the tube around an obstacle. This is even more bad advice as any kinks or bends in the tube will just make matters worse. Personally we wouldn’t recommend them and over the years we’ve been asked to replace numerous flexible units for disgruntled customers who have discovered to their cost that they’d wasted their money.

solartube flexible sun tunnels velux
Flexible tubes lose around 95% of the light that could be delivered to the room.

The BRE did some testing of this unit and it’s published on the Solatube website and it shows that the flexible tube is less than 4% efficient. Compare this with a unit like the Solarspot which is 63% for the same specification, you can see why we’re not keen on these – even if they are easy to fit.

Read the summary of the BRE report

As for the rigid Velux Sun Tunnel, it’s not too bad if you can get it relatively straight and it’s on a bright south facing roof but on the basis that the installation will be the same as it would for a more efficient unit then you have to ask if it represents good value.

Velux Pros (Flexible)

  • Cheap and easy to fit

Velux Cons (Flexible)

  • Waste of money

Velux Pros (Rigid)

  • Medium price point
  • Not bad on south-facing roofs over short distances
  • Range of accessories
  • Flat panel is good for listed and conservation protected areas
  • Well-made as you’d expect from Velux

Velux Cons (Rigid)

  • Only 98% reflective tubing – which is not as good as it sounds
  • Average light delivery even on south-facing roofs unless it’s the height of summer
  • Useless on north-facing roofs
  • Difficult to fit with only one bend as supplied
  • There are much better options available