Frequently asked questions 

How can you tell if a tubular daylighting product meets UK building regulations? 

Look for a recognised UK accreditation... 

The United Kingdom Accreditation Service (UKAS) is the sole national accreditation body recognised by government to assess, against internationally agreed standards, organisations that provide certification, testing, inspection and calibration services. The BBA (British Board of Agrément) holds a unique combination of UKAS accreditations within the construction industry; it is an independent non-profit distributing organisation, whose ambition is to provide reassurance to the construction industry that manufacturers’ products, systems and procedures are ‘fit for purpose’.  
 
A BBA-certified product, such as Solatube Daylighting Systems, means that product has passed a series of comprehensive assessments – including laboratory tests, on-site evaluations, quality management checks and inspections of production. Products that receive Agrément Certificates are recognised by building control, government departments, architects, specifiers and industry insurers. BBA certification a mark of quality, safety and reliability that provides reassurance of the product’s fitness-for-purpose. 

...failing that, check the dome material is polycarbonate and not acrylic 

In the UK, the regulations regarding fire spread at roof level are very specific and differ from those in most other countries, including those in continental Europe. Polycarbonate and acrylic react differently to fire and the UK building regulations categorize each material according to their rating; in the event of a fire, polycarbonate, rated a Tp(a) material, does not sustain a flame and will self-extinguish. Acrylic, on the other hand, does not self-extinguish and continues to burn — even if it becomes separated from the roof dome. Solatube's BBA Certificate confirms our polycarbonate dome meets the UK building regulation requirements. 
 

Why should I worry about building regulations? 

Building regulations set standards for the design and construction of buildings to ensure the safety and health for people in or about those buildings. According to the government's Planning Portal, the owner of the property is ultimately responsible for complying with the relevant building regulations. For these reasons, and for the obvious reason that most of us would want to use only safe, compliant products in our homes, it is important to be able to identify if a product is compliant. 
 
"I would always look for a BBA-certified product. It tells me straight away that the product complies, no question." 
Advice from Building Control Officer to one of our customers in Bedfordshire 
 
Some recently-introduced products are imported from countries where building regulations differ or are less stringent than those in the UK. If you are not sure about a product's compliance to UK regulations, ask the supplier to clarify - after all, it is your home and your safety that is at stake. 
 

What should I look for when comparing product performance? 

Check light output measurements are taken over a period of time - not just at one point in the day 

We believe it is better to have an even, comfortable level light throughout the day than a short burst of bright light at midday with dismal levels of light delivery when the sun is low in the sky. Solatube Daylighting Systems have been designed to deliver more uniform, comfortable levels of daylight throughout the day. We do this by using the patented lenses in our dome to ensure that the maximum low level light is captured, but also that bright, midday sun is controlled too. The result is even light delivery all day long, all year long. 

Check you are comparing products of the same size 

It may sound obvious, but comparisons that don't compare same sized systems have to rely on 'calculated' results rather than real life measurements and from our own experience we know this to be unreliable. We were once asked by a prospective commercial client to measure how much light would be transferred over a very long tube length (around 17 metres) from one end of the tube to the other. So we commissioned the BRE (Building Research Establishment) to test it for us. The result was of great surprise to them — not least in significant amount of light transferred from one end of the tube to the other, but the fact that the result was not what they had predicted it would be according to their pre-test 'calculated' results. 

Are the systems double glazed - and if so where? 

Solatube Daylighting Systems are double glazed at ceiling level. This is important because it means the heated or cooled air in your room stays in your room and is not lost 'up the tube'. In a system that is double glazed at roof level, your precious heated (or cooled) air disappears up the tube, usually into the unheated (or uncooled) roof void — very inefficient! 

Are they really the same as Solatube? 

Check out the quality! Solatube invented the tubular daylighting device in the late 1980s and today is the world's leading supplier of daylighting systems in over 90 countries worldwide. As market leader, a key factor in the success of Solatube Daylighting Systems is its quality. From roof dome to ceiling diffuser, every component is manufactured to the highest quality and fully tested, resulting in a superior system that is unrivalled in its performance. Each year our manufacturing processes are audited by the British Board of Agrement to ensure our quality levels are maintained.  
 
Check claims made are like for like products. We have observed suppliers who compare different sized products, or compare their acrylic-domed product to the polycarbonate Solatube domed product and suggest that the two products are comparable. The BBA have confirmed to us that an acrylic domed product has certain restrictions as to its placement on a UK roof whereas the polycarbonate Tp(a) Solatube dome does not; a supplier that does not point out the difference may be unaware of the regulations or are being evasive about their product's compliance and usage. Either way they are best avoided. 

What about thermal performance? 

The Brighten Up Series has been tested by the Gronmij Technical Laboratories to have a u-value of 1.3W/m²K. We also offer an upgrade kit to allow you to further insulate your Solatube Daylighting System up to 0.5W/m²K u-value for the 160 DS and 0.7W/m²K for the 290 DS. 

Can severe weather or other impacts damage the Solatube roof dome? 

Both the acrylic and polycarbonate roof domes are fully impact tested and proven to be completely fit-for-purpose for all weather conditions. A correctly installed Solatube roof dome will not disappear in a high wind, nor allow water ingress during wet weather. The systems are designed to support an imposed snow load of 1.1 kN. 
 
But not all systems on the market are as high quality and robust … 
 
The left hand image below shows a competitor product that has suffered considerable damage following a hail storm. This Italian-manufactured product, which is available in the UK, has a vacuum formed acrylic dome. Vacuum-forming uses sheet material that is then stretched over a mould. This process produces thinner - and thus weaker - areas of the dome wall, thus rendering the dome susceptible to damage – especially during cold weather when the material becomes more brittle. 
 
To avoid potential damage we strongly recommend injection moulded domes that use a material over 3mm thick throughout. 
Cracked vacuum formed roof dome
Vacuum formed 
Injection moulded roof dome
Injection moulded  

How well is a Solatube insulated? 

With a U-value of 1.3 Wm²K, Solatube Daylighting Systems have excellent thermal and acoustic insulating qualities - this is better than many double-glazed windows. For even greater thermal/acoustic insulation up to 0.5 Wm²K please see our award-winning Energy Care Optima enhancement upgrade. 

What does 99.7% reflective actually mean? 

A 99.7% reflective material means that only 0.3% of energy (light) is lost each time light bounces inside the tube material — with 99.7% of the remaining light continuing on. So if the light bounces down the tube 20 times to get from one end to the other, a huge 94.17% of the original light is transferred with Solatube's Spectralight Infinity tube material. 
 
Solatube uses only rigid tubing in its daylighting systems. It is now widely recognised that flexible tube systems are very inefficient in transferring light, however it is important to understand that rigid tube materials can also vary considerably in their levels of light transmittance. A seemingly small difference in the reflectivity level can result in a significant loss of light delivered into the room below. For example, a 98% reflective material would result in only 66.76% of the light being transferred after 20 bounces. 
 
99.7% reflective vs 98% reflective comparison
 
With Solatube's 99.7% Spectralight Infinity tube material over 94% of light is delivered after 20 bounces 
With a 98% reflective tube material, less than 67% of light is delivered after 20 bounces 

How does flexible tube material compare? 

Daylighting systems with flexible tubes simply do not perform well. Flexible tube by its very nature is not a reliable means of transferring light; light entering a flexible tube will not necessarily continue to bounce on a downward path, but will scatter randomly in all directions (including upwards) as it bounces off the concertinaed surface of the tube. Such systems are usually of poor quality and light output from flexible tube products is vastly inferior to that of a rigid tube system, indeed we are often asked to replace them with our system. 
 
Independent test results have shown that Solatube's Spectralight Infinity tube material will deliver 10 times more daylight than a flexible tunnel sun tube. 
 
In the image below, one high quality Solatube Daylighting System replaces two flexible duct systems. Read more in our blog post. 
Solatube vs Flexible daylighting system comparison
 

How long (or short) can the tube be? 

Ideally, the shorter – and straighter – the tube the better the level of light transfer. Subject to application, we recommend a maximum effective tube length of up to 6 metres for the 160 DS (250mm diameter) and 9 metres for the 290 DS (350mm diameter). For a residential installation into a pitched roof, the tube would typically be around 1.5-2.0m long and for a flat roof or vaulted ceiling installation with no extension tubes the tube distance can be as little as 150mm. 

Will I gain or lose heat through the tube? 

Cool Tube Technology is the proprietary material used in Solatube tubing that filters out heat-infused infrared rays to minimize solar heat gain. Furthermore, they are double-glazed at ceiling level to prevent precious heated (or cooled) air escaping from the room below. Some other systems are double-glazed only at roof level which effectively means your heated or cooled air can be lost through the tube as it passes through the roof void. 
 

What's the longest Solatube daylighting system in the UK? 

The longest Solatube in the UK is an amazing 24 metres long! Several of these commercial Solatube Daylighting Systems were installed in a government building in South Wales to deliver daylight into internal rooms. We understand the longest system in the world is currently a Solatube Daylighting System installed in Italy which exceeds 26 metres in length. This system illuminates a dental practice in Milan — something to smile about! 

Why is it important that ceiling fittings are double-glazed at ceiling level? 

A daylighting system that is double-glazed at ceiling level means the thermal barrier is between your room and the roof void, thus your (expensive) heated or cooled air remains in the room below. If the double-glazed point is further up the tube, say at roof level, your precious heated or cooled air will disappear up the tube into the roof void. 

Are the glass ceiling fixtures and ceiling diffusers interchangeable with each other? 

Yes. If your system has the current 'twist fit' mechanism, you can use any of our glass ceiling fixtures in its place. For earlier systems, it may also be possible to upgrade to the latest ceiling fittings by replacing the lower section of your Solatube too - please contact us if you would like any further information. 

Can I reduce the amount of light delivered through the Solatube ceiling fitting? 

Solatube Daylighting Systems do deliver significant amounts of daylight and we are often asked if it is possible to soften or reduce the amount of light delivered. The answer is yes; by inserting one of our special lenses it is possible to soften, colour or reduce the light coming into your room. Alternatively, we offer a manual or Electric Daylight Dimmer for rooms such as bedrooms or presentation rooms. For details of these options please see our Accessories page. 
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