Step 3: Distance between LEDs and diffusor foil
Consider the distance between the LEDs. If they are closely placed (low pitch), they will appear less visible and a diffusor with lower haze level could be used. But also, the distance between the LEDs and the diffusor foil plays a role for the appearance of the luminaire. The closer the LEDs are placed to the diffusor, the more visible they will appear, but this can be prevented by adding an effective diffusor.
Step 4: Avoid light traps
Make sure light is not send in traps where it is wasted, decreasing the efficiency of the luminaire. Use reflectors to exploit the light in full and avoid unnecessary gaps inside the luminaire where the rays can escape. Even small reflector parts can make a huge difference.
Step 5: Design for later retrofit
As a rule of thumb, a lamp has a lifespan of 20 years, but this is only a small step within a fast-turning product lifecycle. Thus, from a sustainability point of view, it makes sense to design a luminaire that is either viable for later retrofitting to extend product life or for upcycling the materials. For luminaires, this can be done by using easy-to-change light sources, and optical lighting components and batteries that are replaceable.
Step 6: Choose quality electronics
Electronics are beyond our scope, but from a sustainability point of view, we know from experience that it’s important to choose quality LEDs, drivers and power supplies that enable longer product life cycles. Electronical parts are heavy power consumers, and it’s important to prevent them from superheating as their efficiency and lifespan decrease at higher temperatures.
 According to Working Paper about the consequences of requirements to environmental-friendly design of light sources from the EU Commission, October 2019.