Efficient LED sources are changing the way that we see high-bay lighting in warehouses and distribution centres, but there are some important factors that can't be ignored. There are the obvious considerations, of course. Energy efficiency and running costs will always be high on the list of priorities, and maintenance of high level equipment is usually a logistical nightmare whenever it comes around. An LED solution seems to make sense, but there are extra-special challenges when it comes to warehouse lighting.
Get the layout correct
This may sound an obvious thing, but installation work doesn’t always happen with racking systems already in place. Luminaires that end up on top of shelves are next to useless. Make sure you know where the racking is meant to be before letting the electricians loose on the installation.
Poorly arranged lighting installations waste energy, badly reduce illuminance levels by delivering light to the wrong place and make maintenance an unnecessarily expensive and time-consuming procedure. This doesn’t only apply to LED installations, of course, but you may find that the light distribution from an LED high-bay luminaire is less forgiving than the type of HID sources that we’ve been used to.
Check the optics of the LED system
There is a new generation of high-bay lighting that depends on the use of optical systems to deliver its light pattern. If you’ve decided to make use of the benefits that optics offer, make sure that you’re installing the right version. It’s easy to get light onto the floor, but the operatives need a good wash of light on the vertical face of the racking. That’s one of the big improvements that LED sources have brought to high bay lighting.
Whereas ‘traditional’ high-bay luminaires typically used elliptical HID lamps in spun aluminium reflectors that delivered a wide cone of light, the form factor for the LED high-bay luminaires varies from a high output central module within a reflector, replicating the old HID versions, to styles of linear array that have a definite asymmetrical distribution that suits washing of vertical surfaces.
Avoid glare to fork-lift truck drivers
LED arrays do not work like conventional HID sources. The point intensity of each LED chip can make glare a serious problem if operatives are obliged to look upwards into the luminaire face. This is a typical problem for fork-lift drivers when they need to stack products at the higher levels of racking.
There is a necessary trade-off between luminaire efficacy and visual comfort. An LED high-bay luminaire may report excellent luminous efficacy but may rely on poor optical control to achieve that figure. A good optical system will take into account the needs of those working under the luminaire and may sacrifice a degree of efficiency in doing so.
You don’t need light all the time
There will be times when 100% working illumination isn’t needed. LED installations should be efficient in any event, but that’s no reason not to exploit the technical characteristics of the source. Whereas HID dimming was never really a working option, LEDs can be dimmed very easily
Use localised presence detectors to help reduce energy consumption when no work is going on in specific bays. And save more energy if you have rooflights by linking the lighting to daylight control.
Know what’s happening at all times
Unless you have some kind of monitoring software, you won’t have an idea of how efficiently the installation is performing. Link a robust lighting control strategy with reporting software that gives you all the feedback to inform you on how well the installation is working.
We’re more used to seeing this kind of automatic testing and reporting with emergency lighting. But having a full-time analysis of a lighting installation that’s operating at height and over long periods can bring all kind of benefits when it comes to preventative maintenance.
And know what happens next
Warehouses can be 24/7 operations and that means a life-term for the LED array of around 50,000 hours is less than seven years. Make sure that the specified equipment can be re-fitted with a new LED array and driver when that day comes.
Whole-life assessments of LED installations should come with a statement of the manufacturer’s intentions when the internal components need to be replaced. This is a relatively new area for manufacturers. There has been so much emphasis on the longevity of the LED that its taken some time for the hard truth of the matter to be discussed. LEDs are not for ever but the luminaire housings can be.