The Content Of The Article:

How much light do we need? It depends on the place, our age and our habits. explanations:

Rules for good home lighting

How many lumens for each room

The number of lumens emitted by a lamp is clearly indicated on the packaging (this is the amount of light emitted per second). But to estimate the total number of lamps needed for general lighting, we use the following formula:

total luminous power = (lux) x (part area) x (1 / luminaire efficiency) x (1 / reflection factor)

• The number of lux depends on the room
• The luminaire efficiency is given by the manufacturer. It should normally appear in the luminaire manual (it is usually between 0.7 and 0.8).
• The reflection factor depends on the color of the walls according to whether they are raw plaster (0.85), painted white (0.7), light colored (0.6), light gray (0.5), light wood (0, 4), red brick (0.2) or slate gray (0.1).

Number of lamps needed for a small room with light walls

For example: in a 12 m² white painted room (reflection factor of 0.7), if you want to have 100 lux, you need luminaires with 0.8 efficiency. Demonstration:
Calculation of the total power of light:

In our example, the formula is: 100 x 12 x 1 / 0.7 x 1 / 0.8 =
2,142 lumens

The number of lamps needed according to the type of bulb is:

- With incandescent having a yield of 15 lm / W, it will be necessary to install 143 W.
Three 60 W lamps
- With halogens displaying a yield of 25 lm / W, it will be necessary to install 86 W.
Two 40 W lamps
- With compact fluorescents with a performance of 60 lm / W, it will be necessary to install 36 W.
three 12 W lamps

Amount of light depending on the room to be illuminated

The recommendations of the French Association of Lighting:
The French Association of Lighting (AFE) recommends to respect levels of luminous intensity according to the activity (the unit of measure is the lumen / m², more generally called lux).

PieceGeneral lightingSpot lighting
100 lux100 lux
(on console)
Staircase200 lux300 lux
(on bearings)
Stay200 lux300 lux
(as a reader)
100 lux250 lux
(in front of the dressing room)
300 lux500 lux
(on office)
Cooked300 lux425 lux
(on work plan)
Bathroom300 lux500 lux
(in front of mirror)
Garage100 lux400 lux
(on DIY workbench)

In comparison, a very sunny summer day is around 100,000 lux, while a covered summer day varies from 30,000 to 40,000 lux.