How much light do I need?

The light or the level of illuminance is the total flux of light on a surface per unit area. The area, often referred to as “the work plane” is the space where the lighting is mostly required for, such as a work space, for example.

Outdoor light levels on a clear day are of 10 000 lux, inside buildings, the offices near the windows are close to 1 000 lux. If you move towards the middle area of the building, we can measure numbers as low as 25 to 50 lux. So, lighting is a necessity for such low levels, but how to measure the levels required?

Depending on the type of activities performed in a specific room, you have different recommended light levels. For example, for normal activities, we are looking at 500 to 1000 lux. And, for work related operations requiring more precision, you can go up to 1500 to 2000 lux.

Here is a quick chart from the engineer tool box1 for recommended levels of illuminance depending on the environment and activities related:

Home areas	Illumination (lux, lumen/m2)

Light reading	300-500
Heavy reading & work spaces	500-1200
Kitchen	300-550
Dining room	200-300
Laundry room	200-550
High detail workshop	1000-2000

Institutional & Office Spaces	Illumination (lux, lumen/m2)

Hallways & stairways	150-300
Storage rooms	100-500
Classrooms	250-550
Offices	300-750
Restrooms	150-300
General exercise in gymnasium	300-400
Basketball in gymnasium	750-1000
Meeting rooms and auditoriums	100-200
Library	300-500
Maintenance room	300
Science labs	300-500
Woodworking shop	300-750
Open space offices	500-750

Activity	Illumination (lux, lumen/m2)

Public areas with dark surroundings	20 - 50
Simple orientation for short visits	50 - 100
Working areas where visual tasks are only occasionally performed	100 - 150
Warehouses, Homes, Theaters, Archives	150
Easy Office Work, Classrooms	250
Normal Office Work, PC Work, Study Library, Groceries, Show Rooms, Laboratories	500
Supermarkets, Mechanical Workshops, Office Landscapes	750
Normal Drawing Work, Detailed Mechanical Workshops, Operation Theaters	1,000
Detailed Drawing Work, Very Detailed Mechanical Works	1500 - 2000
Performance of visual tasks of low contrast and very small size for prolonged periods of time	2000 - 5000
Performance of very prolonged and exacting visual tasks	5000 - 10000
Performance of very special visual tasks of extremely low contrast and small size	10000 - 20000

There are many tools available online to obtain light level recommendations or software using IES files, but your simplest bet is to contact a lighting specialist you trust.

1 http://www.engineeringtoolbox.com/light-level-rooms-d_708.html

September 8, 2017