The operating principle of an unpowered daylight tube is fairly simple. Firstly, a small-diameter dome harvests daylight at roof level. This light is then transported as much as 20m via a reflective rigid tube, before being diffused as required in a controlled manner at interior room/space level. Increasingly popular in the domestic marketplace, there is some thought that industry might be missing out on the savings in energy and carbon emissions presented by these innovative devices.
Solatube of Australia patented the first tubular daylighting system in 1986 and has since expanded worldwide. Although the application possibilities of Solatube are almost unlimited for both new construction and retrofit projects, there are of course a number of burning questions, not least: how much light can be expected?
“As part of our advice and design service we undertake a project-specific daylight plan to include a light calculation via lighting design/planning software such as DIALux evo and Relux,” explains Steve Brennan, sales manager at Techcomlight, UK distributor for Solatube. “With these software packages we can calculate and visualise the illuminance levels provided by the design throughout the area and assess whether it meets the necessary requirements. Once complete, the plan can be used to provide a clear ROI calculation.
Although many variables exist when calculating payback, based on Techcomlight’s experience of past projects, ROI of between three and 10 years can typically be achieved.
“Natural daylight via Solatube systems and LED lighting is not something that should be compared or seen as competition to one another, as daylight is not available 24 hours a day,” says Brennan. “Solatube systems and energy-efficient LED lighting complement each other to provide a low-energy, 24-hour solution for maximum savings in energy consumption.”
The main influences for any daylight assessment performed by the company are the daylight level required for the nature of work to be undertaken in the area, in conjunction with the type of certification to be achieved, such as the daylight factor (DF) or the BREEAM (Building Research Establishment Environmental Assessment Method; www.is.gd/refudi), LEED (Leadership in Energy and Environmental Design; www.is.gd/zijecu) or WELL certification standards (www.is.gd/owiwor).
Although daylight tubes can replace both skylights and conventional electrical lighting within buildings that are occupied solely during daylight hours, most commercial buildings are also used during the hours of darkness. As a result, systems such as Solatube are typically supplemented by a building’s electrical lighting scheme, which can be automated with sensors to minimise requirements during daytime.
“Smart, energy-efficient LED lighting fixtures can be integrated into Solatube daylighting systems and controlled directly by the building’s light management system, such as DALI,” says Brennan.
Alongside reductions in energy consumption and carbon footprint, further advantages of daylight tubes include non-disruptive installation at external roof level, greater security than skylights, filtration of harmful UV radiation and happier employees.
“When sunlight is allowed to enter a building via a Solatube daylighting system, the occupants tend to be happier, healthier and more productive,” claims Brennan. “Research has shown that daylighting improves productivity, increases employee retention and reduces absenteeism. Systems deliver brilliant, natural light so that facilities can switch off electrical lighting during daytime to enhance the working environment and reduce energy costs.”
The desire for natural daylight within industrial settings is certainly increasing, as recent Techcomlight projects indicate. Waaijenberg Mobility, for instance, is a Netherlands-based manufacturer of customised vehicles for people with reduced mobility. Hundreds of Cantas (two-seat micro-cars) are assembled at the company’s Veenendaal facility every year, which is where the factory hall’s leaking skylights were due for replacement. In total, 16 Solatube systems (53 mm diameter) and Optiview ceiling diffusers were installed.
“Thanks to the right guidance and expertise, the area has been transformed into a perfectly lit room,” says owner Mariska Waaijenberg.
Another recent example can be seen at Segro Park Amsterdam Airport, a new commercial development. The project achieved BREEAM Excellent rating with the inclusion of natural daylight provided by Solatube systems. As Solatube is relatively unobtrusive, minimal roof space was required, which meant there was space for other sustainable resources such as solar panels.
Another specialist in light tube technology is Monodraught. The company’s Sunpipe systems are said to offer sustained 98% reflectance, a 75% reduction in lighting costs and less heat loss in comparison with traditional roof lights. Sunpipe collects daylight using a patented high-impact acrylic dome, passing it through a mirror-finished aluminium tube that reflects and directs the natural daylight to a double-glazed ceiling diffuser.
Among recent takers for this solution is the Klášterec nad Ohří, Czech Republic facility of ZF Electronics. A total of 112 Sunpipe natural lighting systems (1,000 mm diameter) have been installed above a new production area for sensors and switches. Initial feedback from the contractor, Kajima Czech Design & Construction, is positive. Monodraught has been told there is lots of light in the hall during sunny days, making it unnecessary to use electric lighting during such times.
In the UK, Monodraught Sunpipe systems have been specified for the rejuvenation of Battersea Power Station, which will see an entirely new town centre development created in southwest London. Commercial roofing company BriggsAmasco is working closely with Monodraught, which has been tasked with providing a completely bespoke natural lighting solution at the Switch House West area development. In total, 44 bespoke Sunpipe systems will be installed using the old power station’s turbine vent shafts. The systems are 4.5 m long and 1.3 m in diameter. In addition, eight ceiling-level systems will provide a consistent ceiling lighting aesthetic; each one featuring internal LED luminaires. Completion of the Battersea Power Station project is scheduled for autumn 2021.
BOX: A PLACE IN THE SUN
Another unpowered alternative to light tubes is solar lighting, such as the Parans system. With Parans, intelligent modular sensors are placed on the roof where they track the sun during the day. Fibre-optic cables are connected to the collector and lead the natural light up to 100 m down through the building, while retaining a high level of light quality and intensity. Inside the building, the fibre-optic cables terminate in a ceiling-mounted spotlight, or luminaire of any type.
In support of the installation, the Parans system is online 24/7 to provide performance data. Customers can receive information on the amount of sunlight hours in the building, while the service organisation can monitor its level to ensure maximum uptime.
“Parans brings sunlight deep into large buildings where it would not normally penetrate,” says Anders Koritz, CEO of the Sweden-headquartered company. “There are very few solutions available on the market for large buildings where the distance to windows can be considerable. Using Parans, the light emitted by the luminaires is genuine sunlight, with all the wavelengths we are exposed to outdoors.”
Demonstrating its effectiveness, Parans has recently been installed in a road tunnel in the south of the Netherlands.
“The lights are installed near the ends of the tunnel, where they adjust according to light levels outdoors, preventing drivers from being dazzled when leaving the tunnel – or having to gradually adjust their eyes to the darkness upon entry,” says Koritz. “It’s one of the company’s biggest projects to date, worth approximately SEK 18 million [approximately £1.5 million].”