1. How important is lighting output or efficacy?
A common question is “What is the equivalent lumen output in LED compared to our existing light fitting?”
This question is difficult to answer simply, as output is just one factor to consider. Light distribution and uniformity are just as important, and this is where LED has a distinct advantage. Whether it is for maximum productivity in the workshop or being able to see a ball on a hocky field at night, it really is about selecting products that are fit for purpose.
Another important consideration is around ‘Efficacy’ – or lumens per watt. A higher efficacy may be desired to increase power saving, for example 150 lumens per watt rather than 85, but it can diminish the overall luminaire life, based on the specified Temperature Ambience (Ta) Rating.
Higher efficacy means raw LED’s are driven harder and run hotter. Be mindful of this and ask your lighting provider the question about Ta Ratings for the light fittings recommended and any implications this might have.
2. IP (Ingress Protection) Rating
This can be a tricky one as it comes down to the best rated option to suit the specific installation location. See the below table to cross reference best fit for purpose to protect yourself and equipment from flying particle objects (dust) and moisture. This is represented as a two-digit code, for example an interior office light might have an IP20, while a light specified for a workshop environment might be IP65, or for underwater, IP68.
It is important to suggest to your supplier what IP Rating you wish to achieve before making a commitment.
Image credit: geotecsolar.com
3. CRI (Colour Rendering Index). What does it mean, and does it apply for my installation?
The CRI value is helpful for predicting how accurate the colour spectrum range (RGB) is from a LED Light Source. The acronym initials stand for Red, Green and Blue and the broad array of colours available from these three additive primary colours. It is typically used for display of images in electronic systems, such as televisions and computers, as well as traditional photography.
It is represented as a number between 0 and 100 and the closer to a CRI of 100 – the more colour is produced, and objects will appear more vibrant.
If there is a low CRI (≤70) rating of a luminaire, you will miss the vibrance of colour of a surface (or product) you are trying to illuminate. This might be perfectly fine if colour vibrance is not overly important for your application, and you can benefit from lower upfront costs.
See the below examples of CRI vs reflectance/absorption vibrancy.
Image 1. Reflectance/Absorption = Vibrance of desired surface illuminance.
4. Performance and lifespan
Apart from energy efficiency, another main advantage of a LED luminaire is a lifespan of around 50,000+ hours, and if run for 10 hours a day, this equates to 13.7 years. Compared to the old incandescent bulb with a life of as little as 1000 hours, there really is no comparison as to age. This makes LED conversion well worth the investment, and a lower maintenance option.
The difference between LED and High Intensity Discharge (HID) lighting, is that performance over the lifespan of the lamp is more consistent (see Image 3). This also needs to be considered with the Ta (Temperature Ambiance) rating, which might impact on LED lifespans depending on installation conditions.
5. How can I make sure I choose the best LED options to suit my facility?
Lighting is a complex area and deciphering which of the many options are right for your project can be difficult.
It is a good idea to ask your lighting supplier to provide a ‘mock up’ lighting design that demonstrates the best possible solution based on your specific requirements and the unique characteristics of your facility.
This should demonstrate light positioning and distribution maps, appropriate ratings and any other standards or considerations you might need to factor into your decision.
Ben White is Lighting Designer and Business Development Manager at Earthtrack.
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