What is Solarspot® tubing made from?
All Solarspot® systems incorporate Vegalux® 99.7% reflective tubing – anodised aluminium sheets laminated with 3m Daylighting DF2000MA film, the most reflective tubing material in the world – to guarantee optimum light transmittance. In addition, the systems are designed to maintain the maximum available tube diameter within their designated sizes. For example, a Solarspot® 250mm system maintains its diameter throughout the whole system compared to other systems that taper – thus losing valuable energy. This is one reason why a Solarspot® will deliver significantly more light than any other 250mm systems at a distance of around 5m.
How much brighter is the Solarspot compared to other leading sun tube systems like the Solatube?
Compared to other quality rigid tube systems, the Solarspot is considerably bright. For example, in independent testing at the BRE the D-38 was proven to be around 70% brighter than the Solatube 290DS. Compare the D-38 with a flexible system like the Velux Sun Tunnel and the amount of light from the Solarspot will be around 15 times greater.
Why is the Solarspot so much brighter than the Solatube when they both have the same reflective value, 99.7%?
It’s true that both systems have the same reflective value but that’s where the comparison ends. There are two factors that give the Solarspot a brightness advantage of around 70%, on like for like category sizes; the dome and the tube widths.
Taking the latter first, Solarspot systems are slightly wider than Solatube’s so the extra volume of the tube allows more light to be transferred. For example, the Solarspot D-25 is 250mm at the ceiling with the vast majority of the tube system being 265mm. On the other hand, the Solatube 160DS (who knows what DS actually means) is 250mm at the top but the majority of the system is only 237mm wide. Less tube diameter means less efficiency, but also less material so more profit for the manufacturer.
However, the big difference is at the dome. Solatube will tell you that there dome restricts over-powering midday sun (in the UK – are you kidding) whereas the truth is that it restricts all over-head light, on sunny or cloudy days, cutting out around 50% of all available light. And if you fit the LightTracker Reflector you’ll be cutting out even more light which is why a lot of their installers actually take this out before fitting the dome.
Does the Solarspot have a highest performance guarantee like the Solatube does?
Unlike manufactures that publish meaningless guarantees*, that are impossible to make a claim against, our claims of performance are endorsed by independent testing from the BRE (Building Research Establishment). The figures for brightness that we quote don’t come from our marketing department, they are scientifically assessed and calculated by the BRE, and that is how we are able to make these claims.
If you read our website you’ll notice that we are not shy about referencing our unit’s performance against that of much larger companies products. We can only do that if the information we quote is correct, and that is why use the UK’s highest authority to do our testing.
*The Solatube Highest Performance Guarantee requires customers to pay for a certified testing authority to take light readings of the Solatube unit on four specified days throughout the year, every hour on the hours during daylight periods (that’s over a 17 hour period in June) and then submit the results for them to review. If they find that you have a case they will refund the price of your Solatube system, but not the thousands of pounds it will cost you to make the claim in the first place.
Polycarbonate or Acrylic domes?
Actually there are no specific regulations written specifically for tubular daylight systems. Polycarbonate must be used for roof lights if the area of glazing exceeds the ratio of 5:1 on the overall area of the roof. Light tube domes are much smaller than traditional roof windows so don’t even come close to the threshold for this. Even taking the largest Solarspot system (900mm diameter) the recommended ratio would be around 70:1. Even with the highest concentration of roof domes it would be impossible to achieve the required 5:1 that requires Polycarbonate.
Is Acrylic better than Polycarbonate for sun tube domes?
Categorically yes. To start with, acrylic has a better transparency rating that polycarbonate. However, the big difference is the suitability of the two materials for roof domes. Acrylic is extremely stable when exposed to the UV present in daylight, unlike polycarbonate that goes yellow in a surprisingly short time.
Recently tests were carried out by the BRE on behalf of Monodraught (SunPipe) to assess the effects of 4 years of exposure to UV light on Solatube’s and their own domes. In that test the Solatube dome, after 4000 hours of exposure to UV, had lost over 10% efficiency and the polycarbonate was a ‘darker yellow and a part of the surface appeared roughened’.
How important is the reflectivity value of the tube?
Light travels through the system by bouncing off the reflective sides of the tube. As light travels down a tube it loses energy with every bounce. The amount of energy (light) that is lost will be determined by the reflectivity of the surface of the tube. The number of bounces of light will be determined by the length of the tube, the angle of light as it hits the side of the tube and the length of the tube.
For example, a tube with a reflective surface of around 99.7% (specular refectivity of visible light) will lose 0.3% with every bounce. A tube with a 98% (92% specular reflectivity and 6% diffused reflectivity) reflective surface will lose a minimum of 2% per bounce. You then need to consider the number of bounces that the light takes to reach from one end of the tube to the other. If the light bounces 20 times in the tube and loses 2% per bounce it will have lost around 30% of its original strength. If it is only losing 0.3% then it will retain around 94% of the source light for delivery to the room. This example is based on tube systems with similar lengths and diameters.
However, Solarspot systems have a variety of additional design enhancements to increase the overall efficiency of the system. The Solarspot dome ensures that no light is blocked from entering the system. The RIR® Light Funnel not only captures additional light, it changes the angle that the light enters so that it bounces less, and therefore loses less energy. Solarspot systems also maintain their tube diameters so that there is a greater distance between bounces. All of these factors contribute to creating the most efficient tubular daylight system available on the market today.
How long can the tube be?
The simple rule is; the shorter and straighter the tube, the greater the light delivery will be. However, it is possible to duct light along comparatively long distances, particularly if the building can accommodate a wider tube diameter.
Having said that, a Solarspot® D-25 will still deliver worthwhile light levels across distances of up to 8m. Larger systems such as the Solarspot D-38 can deliver effective light levels up to distances of over 11m.
Is there a minimum distance or tube length?
The minimum distance that a tube is likely to be equal to that of the thickness of the roof timbers and depth of the roof, including the turret up stand of the flashing. Solarspot TDS are designed to telescope together to accommodate this and will fit into the any depth of roof.
Can the tube be cut to length?
Yes, it is relatively straight forward to cut Solarspot®extensions to length but rarely is it necessary. Extension tube sections are designed to telescope together for ease of installation so tube length can be adjusted by simply overlapping the tubes as required rather than cutting them.
There is also a wide variety of Solarspot®extensions available; ranging from 200mm to 1200mm, as well as a selection of adjustable angle adaptor extension, so you should be able to specify exactly the distance required.
How do the tube sections connect together?
Solarspot® extension tubes and adjustable angle adapters are designed with a slight taper so that they can be telescoped together. The joints are then held in place with high-quality foil tape, which is also used to seal all of the tube seams. For very long or angled tube lengths, self-tapping screws can be used to fasten the tubes together to give additional strength and stability.
Can I split the light from one dome to light two rooms?
Solarspot® TDSs are designed to use one dome per tube. Splitting the tube would dramatically reduce the light delivery capacity of the system making it problematic and inefficient, and certainly not something we’d recommend, however there are specific applications that this can be done. For example; starting on the roof with a large dome and tube diameter, then splitting into two smaller diameter tube systems.
How do Solarspot® systems compare to tubular skylights that use flexible tubing?
There is no comparison between the light from a Solarspot® rigid TDS and that of even the ‘best’ flexible system. On average a Solarspot® TDS will deliver at around 20 times more light, size-for-size, than a flexible system and if the system has a bend in it (usually why flexible systems are chosen) the difference could be around 50 times more light.
Can I turn the light off?
There will be certain application where you may want to control the amount of light entering a room; a conference room or bedroom are two prime examples. For this situation we have two options to choose from. The first is an electrically controlled damper.
The Solarspot® Solar-Dimmer™ is fitted within the tube and can be controlled via a manual wall-mounted switch, hand-held remote control or BMS.
There is also a manual blind system that simply fits on the ceiling, around the diffuser, and pulled across as required.
Do I need to keep the roof dome clean?
All Solarspot® systems are maintenance free and therefore there is no need to clean the roof dome. The dome design and shape prevents debris build-up using the rain to clean away any dirt or bird droppings.
Does heavy snow effect the performance of a Solarspot® TDS?
Clearly, a covering of snow will temporarily reduce the light output but the dome will be fine. Solarspot® are sold throughout the world, in countries with much higher snow falls than we experience in the UK and so are designed to cope with whatever the weather has in store.
What is the dome made of?
All Solarspot® domes are supplied in anti-shock acrylic and designed not to turn yellow when exposed to sunlight. The dome is virtually unbreakable and has passed stringent international missile impact tests.
Polycarbonate domes can be supplied if required.
Can I fit an electric light into a Solarspot® so that it can be used at night?
Light kits are available for all sizes of Solarspot® systems. These can be installed into the tube to utilise the highly efficient diffuser and minimise ceiling clutter.
We also offer a fully interactive LED solution that can be controlled remotely or via a building management system (BMS) – please contact us for more information.
Will an electric light kit reduce the amount of daylight from Solarspot?
The lamp unit inside the tube is relatively small so any light loss is minimal. The advantage in having just one neat ceiling installation yet having a two-in-one or three-in-one multi-functional