LED technology now offers a viable energy-efficient lighting solution in many commercial applications, says Graham White.

With energy costs continuing to rise, organisations of every size are under pressure to make energy savings. In the indoor environment, lighting is a major consumer of energy, accounting for around 18% of global electricity use. However, lighting is also an area where significant savings can be made relatively easily – and without diminishing the quality of the working environment.

Regulation

This potential for energy savings is emphasised in the relevant parts of the Scottish Building Regulations, with Section 6.5 now requiring a minimum efficacy of 55 luminaire lumens per circuit watt for occupied spaces in commercial lighting schemes, averaged over the whole building.

The effect of Section 6.5 is to encourage the use of high-efficiency light sources, efficient control gear – i.e. high frequency – and more efficient optical design. In addition, Section 6.5 aims to stimulate the uptake of lighting controls by allowing a controls factor of up to 0.85 to achieve the 55Llm/cW figure.

LED technology – the opportunity

In terms of energy efficiency, the progress of LED lighting in recent years has been nothing short of phenomenal. Not long ago, LED technology was confined to use in specific areas such as decorative, ambient and emergency lighting, but today it offers a viable low-energy alternative to fluorescent and halogen lamps in many commercial lighting applications.

Quality LED luminaires which incorporate effective thermal management and accurate drive-current control will maintain more than 70% of their initial light output for at least 50,000 hours – equivalent to 10 years’ commercial use. This compares to 12,000 hours for fluorescents and 5000 hours for halogen lamps.

A long virtually maintenance-free life not only makes LED fittings ideal for applications where lamp replacement would be difficult or disruptive but also significantly reduces the labour and equipment costs associated with routine lighting maintenance. In the healthcare sector, for example, many premises operate 24/7, so the long life of LED luminaires helps to minimise any disturbance to users as there is no need for relamping.

Another significant advantage of LED technology is its ability to operate at very low temperatures. As the operation of fluorescent lighting can be problematic below freezing point, cold stores in the food-service industry have traditionally been illuminated by high-intensity discharge (HID) lighting – the 400W metal-halide luminaire being a typical choice. Now, however, LED luminaires are widely preferred – as well as being able to operate at temperatures down to -30degC, LEDs achieve high light output with low power consumption, creating significant energy savings when used in place of a 400W metal-halide luminaire.

With so many benefits to offer, there is little doubt that LED technology will dominate the future of commercial lighting. Although the capital cost of LED lighting is still generally higher than for conventional lighting technologies, it is important to see beyond the initial outlay and examine the whole-life costs of a lighting scheme, encompassing not only energy usage but also maintenance and
end-of-life costs.

Other energy-saving approaches

Where LED lighting is not appropriate, there are still significant energy savings to be made through the use of more established technologies such as T5 fluorescent or compact fluorescent lamps. Energy-efficient luminaires continue to be developed for these light sources, with enhanced efficiency and downward light output ratio (DLOR), Products are now being developed with integral lighting controls in the form of a high-level PIR detector and a built-in photocell for daylight harvesting.

Lighting controls save energy and money

Whichever type of luminaire is chosen, the use of lighting controls will generate substantial additional energy savings. Simple occupancy detection – where a PIR sensor switches the lighting on while people are present and off again shortly after they leave – can cut energy consumption by 20-40%. In the 5m area next to windows, further energy savings of 50-70% can be produced by using photocells to adjust luminaire output according to the amount of daylight available.

With electricity costs set to remain high for the foreseeable future, now could be a good time to encourage end users to invest in the latest low-energy lighting technologies.