Feature, Retail

ILP tackles ‘confusion’ over maintenance factors

John Savory of Edge Lighting measuring the light output of LED luminaires in a Waitrose store. The ILP has now published a guide, Guidance Note: GN11, to outline the latest industry thinking for maintenance factors for LED lighting and high intensity discharge variants.

THE INSTITUTION of Lighting Professionals is attempting to address widespread ‘confusion’ in the industry over the determination of maintenance factors with LED luminaires.

The publication of GN11/20 is intended to give advice to lighting managers, engineers, designers and equipment specifiers to enable information from manufacturers or suppliers to be understood in a consistent manner.

Maintenance factors were introduced as a way of calculating the light output of an installation taking into account the degradation due to dirt and dust on the diffusers,

and the loss of lumen output of the light source, especially a fluorescent tube.

All of this needed to be brought together in a single figure, and thus Maintenance Factor (MF) was created. Formulae were created, factor values were agreed and tables were produced.

The introduction of solid-state light sources however, has caused some uncertainty regarding how their deterioration in light output, due to ageing and environmental factors, should be determined.

The ILP has now published a guide, Guidance Note: GN11, to outline the latest industry thinking for LED lighting and high intensity discharge variants.

The publication of GN11/20 is intended to give advice to lighting managers, engineers, designers and equipment specifiers to enable information from manufacturers or suppliers to be understood in a consistent manner.

The document reviews the latest British, European and International Standards, using this as the basis for its recommendations to help eliminate confusion by demonstrating the development of a simpler, more consistent methodology, that takes into account the differing parameters of LED light sources compared with high intensity discharge lamps.

It says that the methodology in BS PD ISO/CIE TS 22012: 2019 is the best practice approach for calculation of maintenance factors for LED luminaires.

The guidance in BS EN 62717 and BS EN 62722 is not suitable for the calculation of maintenance factors for any luminaires.

Download the guidance HERE.