National Grid’s recent publication ‘Future Energy Scenarios’ gives consideration to where energy demands and supplies might come from right up to the year 2050. It is clear from this that, if not managed carefully, demand on electricity could significantly increase to critical proportions. This is partially due to the anticipated increase in the use of Electric Vehicles, encouraged to meet government decarbonisation targets.

From the report we can surmise that energy costs are likely to increase and that high demands may cause capacity overloads and power outages. It seems like now is a good time to consider replacing high consumption conventional lighting with highly efficient LED technology.

Reaping the benefits of LED

Low energy consumption and a reduced need for maintenance means a fast payback of capital expenditure whilst lowering a building’s carbon footprint. Once the new lighting is in place there is no need for regular re-lamping and therefore no disruption to the process or loss of productivity. To give some examples of the potential energy savings with LED:

Racking aisles – replace existing 250W Metal Halide low bay (approx. 14,000 lumens at 265W) with Aerial Industry High Rack (16,500 lumens at 100W). Open area – replace existing 6x80W T5 fluorescent high bay (approx. 31,000 lumens at 480W) with Aerial Twin (33,500 lumens at 279W) The savings are clearly significant, around 60% against Metal Halide and 40% against fluorescent.

So, for 100 replacement 279W luminaires in a 24/7 operation at 10 pence per kWhr, an annual saving of £17,607 could be achieved with a payback within 2 years. And the results will be even better using occupancy and daylight linked lighting controls!

Keeping an eye on quality

Product quality should be considered; look for high quality materials and recognised LED / driver brands with good lifetime and efficacy figures. Good quality LED products are likely to be backed by a 5 year warranty including on-site support.

Desired lighting levels should still be achieved at the end of a given period or maintenance cycle. Lifetime figures are often stated as 50,000 hours but how much have they depreciated in this time? If no other details are published, it can generally be assumed 70% of original output (ie ‘L70’). At Whitecroft we publish lifetime metrics at L70, L80 and L90 enabling a more informed decision and accurate design.

There are different ways to present lighting efficiency. A product appears better if the initial output from the LEDs and nominal wattage are published. This will often be shown as Lumens per Watt (L/W). However the correct method for making comparisons is to use actual lumens (ie. light output after reduction for luminaire efficiency) divided by the total circuit watts. This is known as ‘efficacy’ and is presented as Luminaire Lumens per Circuit Watt (LL/CW). This is the figure to be considered when targeting Enhanced Capital Allowance (ECA) credits.

If retrofit LED lamps are being considered, bear in mind there could be a loss of efficiency as reflectors will have been designed for optimum performance with the original lamps. Although energy savings appear good and lumen outputs appear to match existing, the resulting lighting levels could turn out lower than the original installation. For this reason the Carbon Trust do not include this style of replacement lamp in the Energy Technology List for ECA credits.

Finally, remember the users of the space. Visual comfort is important to ensure operatives can concentrate on their tasks without distraction from high intensity lighting with poor glare control. Opal or prismatic diffusers are ideal for minimising discomfort glare.

Making the switch to LED

Through our large technical sales force and lighting design team, Whitecroft Lighting can help with; scheme evaluation, lighting design, find a suitable electrical contractor and even funding.

We can help building owners reclaim up to 20% tax through the Enhanced Capital Allowance (ECA) scheme for using high efficiency lighting. The minimum criteria for general interior lighting has recently increased to 105 LL/CW, raising the bar and ensuring the top 20% higher performance products meet the criteria.

Iain Wilkie is Product Manager for Industrial and Outdoor Lighting at Whitecroft Lighting Ltd.