We’re back following our appraisal two weeks ago of some key benefits of using and specifying LED light fittings with particular focus on downlights.

The LED revolution is gaining momentum with a recent development by Audi cars who have won the race to successfully create a car with all LED headlamps, opening the door to mass production for LED integration to all their cars. So having previously looked at the potential benefits, can these developments be embraced by interior designers and specifiers of interior applications?

Let’s simplify the decision making process and cut through some of the jargon in choosing an LED downlight:

How powerful: Measured as lumens. Lumens reveals the measurement of how much light is actually emitted by the fitting. For instance we often see a specification of 3 × 1W, However this is misleading as we do not know from this statement the power or effectiveness (lumens/watt) of the LED unit.

How effective: The LEDs efficiency in producing light is measured in lumens per watt. How well it ability to deliver this light level to how much power is being used to make the LED function. There will be a cost for this ‘efficiency’ as a high output LED can reduce its effective lifespan if the fitting is running at a higher level of power to achieve the desired intensity of light. We have to note the transformer size, typically 350mA or the higher and often more costly 700mA.

Colour Temperature: The figure given describes the colour of white light the fitting will try and deliver. We will discuss this in more depth another time, However you need to know that 2700K is a warm white moving up to 6500K which is a near daylight effect, with 4000K as a neutral white. To head for a colour similar to the standard a low voltage halogen we should be aiming for 2700K to 3000K.

Colour Binning: A strange term that is an attempt by manufacturers to put colours of light given by an LED into a cluster or bin, may be to warn us of imminent dissapointment! LED technologists are busy resolving this issue but until now if you compare three different 3000K (warm white) LED’s they can all have a visually different colour. The Bin tells us into which group we can expect the visible light to fall.

Colour Rendering: This CRI value is one of the main indicators on how accurately the light will reflect the true colour of the object it is illuminating. A CRI of 100 being perfect down to zero. Some manufacturers are claiming an excellent CRI 97.

Driver: The power pack that runs the LED, very often 350mA or 700 mA.

So how do we use all that and arrive at a (quick) answer? Back again soon with our recommendations and explain how came to that decision.