- AR
Calculating the number of lighting fixtures is an important part of lighting design. The correct calculation can ensure that the room's lighting effect meets the standard while saving energy and reducing usage costs.
The calculation formula for the number of lighting fixtures
N =(Eva × S）/ （Φ xCU× K ）
N refers to the number of LED lamps.
Eva (Illuminance) refers to the luminous flux of visible light received per unit area. In layman's terms, it is how bright it is per square meter. The unit is lux (lx) and 1lx=1lm/㎡
S (Room area): S=length x width
Φ(Lumens) refers to the total luminous flux value of a lamp
CU (The space utilization coefficient ) refers to the percentage of the light beam emitted from the lighting fixture that reaches the floor and work surface. Therefore, it is related to the design of the lighting fixture, the installation height, the room size, the reflectivity, and the lighting rate, which also varies accordingly.
K (Maintenance factor ): refers to the factor multiplied by the decrease in light output capacity and the increase in the use time of the light source as the lighting fixture ages or the reduction of spatial reflection efficiency and illumination due to dust accumulation in the room.
| Room (Place) | Reference plane and its height | Standard illumination value Eva (lx) | UGR | CU | Ra |
| The living room of the residential building (general activities) | 0.75m horizontal plane | 100 | 19 | 0.6 | 85 |
| The living room of the residential building (writing and reading) | 0.75m horizontal plane | 300 should use mixed lighting | 19 | 0.6 | 85 |
| The dining room of the residential building | 0.75m dining table surface | 150 | 19 | 0.4 | 85 |
| General reading room of the library | 0.75m horizontal plane | 300 | 19 | 0.6 | 85 |
| General office of an office building | 0.75m horizontal plane | 300 | 19 | 0.6 | 85 |
| General supermarket business hall | 0.75m horizontal plane | 300 | 19 | 0.4 | 85 |
| Hospital waiting room, registration hall | 0.75m horizontal plane | 200 | 19 | 0.4 | 85 |
| School classroom | Desktop surface | 300 | 19 | 0.6 | 85 |
| School classroom blackboard | Blackboard surface | 500 | 16 | 0.7 | 85 |
| General corridor and flow area of public place | Ground surface | 50 | 22 | 0.4 | 85 |
| Escalator of public place | Ground surface | 50 | 22 | 0.4 | 85 |
| Rough machining of industrial building machinery | 0.75m horizontal plane | 200 | 22 | 0.6 | 85 |
| General machining tolerance of industrial building machinery ≥0.1mm | 0.75m horizontal plane | 300 should add local lighting | 22 | 0.6 | 85 |
| Precision machining tolerance of industrial building machinery <0.1mm | 0.75m horizontal plane | 500 should add local lighting | 19 | 0.6 | 85 |
| Environmental pollution characteristics | Room (Place) | Minimum number of lamp cleanings (times/year) | Maintenance factor value（K） | |
| Indoor | Clean | Bedrooms, offices, restaurants, reading rooms, classrooms, wards, guest rooms, instrument and meter assembly rooms, electronic component assembly rooms, inspection rooms, shops, business halls, etc. | 2 | 0.8 |
| common | Waiting rooms, theaters, machining workshops, mechanical assembly workshops, farmers' markets, gymnasiums, etc. | 2 | 0.7 | |
| Severe pollution | Public kitchen, forging workshop, foundry workshop, cement workshop, etc. | 3 | 0.6 | |
| Outdoor | Awning, platform | 2 | 0.65 | |
