To calculate the quantity of lighting sources to purchase, it is important to consider not only the watts, but especially the lumens generated.
A good power LED product is now capable of achieving an efficiency of at least 60 Lumens per Watt and, in some cases, can even reach close to 90-100 lumens.
The luminous power, or luminous flux, is simply the total amount of lumens produced by a lamp. To calculate the illuminance expressed in lux per square meter, you must divide the luminous flux (total lumens produced by one or more lighting fixtures) by the surface area of the environment to be illuminated.

For example, to illuminate an office, approximately 300-400 lumens per square meter are recommended. If your office is 100 square meters, you will need approximately 30,000-40,000 lumens of luminous power.

 

 

Illuminance = 30,000 /100 = 300 lumens per square meter.

For a correct installation, it is necessary to know the beam angle of each light source. The beam angle allows us to determine the lux that the light source can generate on a surface depending on the installation distance.

 

 

THE RECOMMENDED VALUES PER SQUARE METER (1m²) ARE THE FOLLOWING:

 

RESIDENTIAL LIGHTING: (lux = lumens per square meter)

 

- Passage Area: 50 – 150 lux
- Reading Area: 200 – 500 lux
- Kitchen: 200 – 500 lux
- Bathroom: 100-150 lux
- Bathroom (mirror): 400 lux
- Bedrooms: 50-150 lux

 

 

 

COMMERCIAL LIGHTING:

 

- General Offices: 300 – 400 lux
- Design Offices, Technical Activities: 400 – 500 lux

 

 

 

INDUSTRIAL LIGHTING:

 

- Generic Warehouses: 150 lux
- Warehouses with specific activities (e.g. welding): 300 lux

 

 

Example:   For a 4x4 m bedroom   (therefore residential bedroom lighting 50-150 lux per square meter)

 

4x4 = 16 m² ; 16m2 x approximately 100 lux = 1600 recommended lumens, although of course some people prefer more light while others prefer less.

 

At this point, you should choose lighting capable of generating around 1600 lumens. For example, if your bedroom has only one light point, you can simply choose a 16W LED lamp, which on average should generate around 1600 lumens. If instead you have a lamp with 2 light points, two 8W LED bulbs will be enough (8x2=16W), thus generating approximately the same desired 1600 lumens.