Glidevale Sunscoop Systems Frequently Asked Questions

Glidevale Sunscoop Tubular Rooflight systems are used to bring natural daylight into internal rooms and spaces that have no, or insufficient, windows. They consist of a roof-mounted clear polycarbonate dome or skylight connected to a tube with an internal mirrored finish providing optimum specular reflectance. Natural daylight enters the dome or skylight and is reflected down the tube and into the room through a ceiling-mounted diffuser.

Below are some of the more frequently asked questions about tubular rooflight systems.

How do Glidevale Sunscoop tubular rooflights contribute to sustainable building design?

Glidevale Sunscoop tubular rooflights are an effective and efficient means of maximising natural daylight in dark areas, virtually eliminating the need for supplementary electric lighting during the day, especially in corridors. Used to complement artificial lighting, they can considerably reduce the annual energy consumption of any building and therefore CO2 emissions.

What light levels can be achieved?

The light output from the Sunscoop system depends on the external sky conditions and light levels and other influencing factors, such as the length and diameter of the tubing, reflectivity of the tubing and the number of bends in the system. Following extensive testing over two years on Glidevale Sunscoop systems by the SILSOE Research Institute, Glidevale have developed a unique and sophisticated computer programme which can accurately predict the light levels achievable with the Sunscoop system in any given application, compared to standard electric light bulbs.

Is there a limit to the length of tubing?

Obviously the longer the length of tubing the more light loss there would be down the tube. Using a larger diameter system or 98% reflective tubing can help to limit the light loss on longer runs. The Glidevale Sunscoop calculator tool can accurately compare light levels for 95% reflective or 98% reflective systems in 250mm, 350mm or 530mm diameter across the whole range of external light levels.

Is the reflectivity of the tube important?

Yes. The Glidevale Sunscoop system offers a choice of two reflectance levels, SR95 Specular which incorporates a pure aluminium layer and has a total reflectance of 95% and SR98 which incorporates a pure super silver layer and has a total reflectance of 98%. On longer tube lengths and with both elbows at maximum crank SR98 would offer improved light levels over SR95. The calculator tool can be used to demonstrate the difference in light levels in specific applications. Both offer a high level of reflectivity compared to some other systems in the market where reflectivity can be as low as 70%, especially with flexible tubing.

What about bends in the system?

For maximum effectiveness, the tubes should be as straight as possible. However since it is often impractical to site the ceiling diffuser directly below the roof mounted glazing, the tubing system allows an offset by means of two elbows, one at roof level and one at ceiling level. They are adjustable up to 30o from vertical. There should be no other bends or offsets in tubing as monitoring has shown that these will adversely affect performance.

Does it matter where they are sited on the roof?

Where possible the roof-mounted glazing should be located on a south-facing slope to gain the maximum amount of daylight under both direct and diffuse conditions. The light and sun deflector (LSD), if specified, should be orientated to face due south. Other factors which need to be considered are location of the room to be lit and suitable position of the ceiling diffuser, roof space obstruction and proximity of other buildings, trees, etc which may cast shadows at certain times of the day or year.

What is a light and sun deflector?

This unique, optional device is fitted under the roof glazing and intercepts direct sunlight that would otherwise miss the top of the system at both low and high incident angles, reflecting it down the tube. Monitoring has shown that a south-facing LSD can increase the light level at the ceiling diffuser by up to 20% in direct sunlight conditions.

How do I weatherproof the flashing on the roof?

Glidevale, with their 20 years of experience in manufacturing dedicated slate and tile ventilators to suit virtually all roof coverings, offer a range of dedicated roof flashings for different types of pitched and flat roof coverings, all tested for driving rain resistance. Flashings are supplied in a range of standard colours or can be colour matched to specific roof coverings including composite panel and standing seam systems. All flashings are manufactured from fire-retardant ABS giving an AA fire rating to BS476 and can therefore be used on roofs without restriction on number, spacing or position.

How do you clean the glazing unit?

The glazing is self-cleaning and cleaning would not normally be required. Should cleaning be necessary for any reason wipe with warm soapy water only, do not use abrasive materials.

Can you put a light in the system to avoid duplicate fittings or paired lighting?

The Sunscoop system can be supplied with an optional integral electric light fitting (2 on 530mm diameter systems) with a 13Wor 20W low-energy bulb (equivalent to a 65W or 100W conventional lamp). This avoids the need for an additional light fitting for night-time use.

Can you block the light out say for presentations?

Control over the light level entering the room may be required at certain times in conference rooms, lecture theatres, classrooms and hospital wards Glidevale supply an optional motorised light-attenuating damper which can be activated from a wall switch to reduce or entirely block out the light when required.

Can they be used in fire rated floors or ceilings?

In longer Sunscoop systems the tubing may pass through an intermediate floor or ceiling that provides fire separation. As with any ducted system it is important that the tubing does not form a path for fire. Fire protection collars providing up to 120 minutes fire resistance to BS476 are available for all diameters of Sunscoop tubing.

Can they be used in wet rooms or would condensation get into the tubing?

Ceiling diffusers are supplied with closed cell foam seals between the ceiling and the diffuser and between the diffuser and the reflective tubing. As long as the installation instructions are followed and the foam seal is compressed against the surface of the ceiling and tube, water vapour cannot enter the system and therefore condensation would not be a problem.

Does condensation form in the tubing where it passes through the cold loft space?

All exposed tubes and elbows within unheated voids such as loft spaces should be lagged with Glidevale tube insulation, to reduce heat loss and the risk of condensation within the tube.

Are they Part L compliant?

The Building Regulations (England and Wales) Approved Documents L1 and L2 require a u-value of 2.2 W/m2K for all rooflights. Sunscoop tubular rooflights meet this requirement when fitted with either a polycarbonate secondary glazing skin and/or tube insulation in unheated spaces.

Is the product guaranteed?

Glidevale Sunscoop tubular rooflights have been designed and developed under ISO 9001 quality management systems. The Sunscoop glazing is manufactured from 3mm clear UV-stabilised polycarbonate. This has a 10-year warranty (supported by the polycarbonate manufacturer) against loss of impact strength, excessive yellowing and loss of light transmission. The production process has also been assessed by the polycarbonate manufacturer and the warranty has been extended to cover any effects of the forming process. The glazing and flashings have been impact-tested to EN1873 Modular Rooflights and may be deemed to be non-fragile for HSG33 Safety in Roofwork. Tubes and elbows have 25-year product warranty which guarantees that the material will not splinter, yellow, darken, peel off, blister, crack or develop any other surface degradation which could reduce the overall reflectivity, even after prolonged UV exposure

Are the ceiling trims available in colours other than white?

Ceiling trims are supplied in white as standard. They are also available with a brushed aluminium or brass effect finish. Other colours may be possible subject to minimum quantities.

Do you need planning permission for a Glidevale Sunscoop?

Not for the smaller sizes as it is no different to a chimney or flue. If the property is listed or in a conservation area then permission must be obtained. The In-Line or Traditional skylight version is often used in conservation areas as an alternative to the dome.

Back >