While comparing different types of luminaires, manufacturers and design performances, one should consider technical and design parameters as well as evaluate results of implementing each specific type of luminaire. It is also necessary to assess the outcomes of implementing the precise type of fixtures. For example, compare the light efficiency in a small office, warehouse and shopping center, illuminated by A36 or A66 LED luminaires and fluorescent office lamps. All calculations are based on actual value of luminous flux and the consumed power of luminaires.
Office space of 24 m2
Space size is 6x4m, ceiling height - 3m. It is illuminated by 5 A66 LED luminaires. Considering that it is an office space, energy calculations were made per 250 working days per year, 8-hour working days. Location of light fixtures and interior outfitting is shown in pictures below.
Calculation data of illumination, made in DIALux program package and based on space parameters and luminaire specifications, are listed in the table:
| Fluorescent lamp | A66 LED luminaire | |
| Number of luminaires, pcs. | 5 | 5 |
| Luminous flux of one luminaire, lm | 2950 | 3300 |
| Total luminous flux, lm | 14750 | 16500 |
| Average illumination of surface, lux | 358 | 410 |
| Power consumption of 1 luminaire, W | 72 | 23 |
| Power consumption of 5 luminaires, kW | 0.36 | 0.12 |
| Consumed power per year, kW*h | 720 | 240 |
In this example, the average illumination of space by LED luminaires is higher by 13% compared to fluorescent lamps at the same conditions . Therefore, under equal quantity of luminaires, illumination level of workspaces increases and energy savings are 480 kW*h per year (66.7%).
Warehouse of 112 m2
Space size is 8x14m, ceiling height - 3.8m. It is illuminated by 18 luminaires. Considering that it is a warehouse and it is usually connected with office work time, energy calculations were also made per 250 working days per year, 8-hour working days. Location of light fixtures and interior outfitting is shown in pictures below.
Calculation data of illumination, made in DIALux program package and based on space parameters and luminaire specifications are listed in table:
| Fluorescent lamp | A36 LED luminaire | |
| Number of luminaires, pcs. | 18 | 18 |
| Luminous flux of one luminaire, lm | 2950 | 3300 |
| Total luminous flux, lm | 53100 | 59400 |
| Average illumination of surface, lux | 224 | 250 |
| Power consumption of 1 luminaire, W | 72 | 23 |
| Power consumption of 18 luminaires, kW | 1.3 | 0.43 |
| Consumed power per year, kW*h | 2600 | 860 |
In this example, the average illumination of space by LED luminaires is higher by 11% compared to fluorescent lamps at the same conditions. Therefore, under an equal quantity of luminaires, illumination level of workspaces increases and energy savings are 1740 kW*h per year (66.7%).
24-hour retail space of 420 m2
Space size is 14x30m, ceiling height - 4m. It is illuminated by 100 luminaires. Considering that it is a 24-hour retail space, energy calculations were made per 365 working days per year, 24-hour working days. Location of light fixtures and interior outfitting is shown in pictures below..
Calculation data of illumination, made in DIALux program package and based on space parameters and luminaire specifications, are listed in table:
| Fluorescent lamp | A36 LED luminaire | |
| Number of luminaires, pcs. | 100 | 100 |
| Luminous flux of one luminaire, lm | 2950 | 3300 |
| Total luminous flux, lm | 295000 | 330000 |
| Average illumination of surface, lux | 490 | 550 |
| Power consumption of 1 luminaire, W | 72 | 23 |
| Power consumption of 100 luminaires, kW | 7.2 | 2.4 |
| Consumed power per year, kW*h | 63072 | 21024 |
In this example the average illumination of space by LED luminaires is higher by 11% compared to fluorescent lamps at the same conditions. Therefore, under an equal quantity of luminaires, illumination level of workspaces increases and energy savings are 42048 kW*h per year (66.7%).
Thus, proceeding from the above example, equipment and maintenance expences were calculated for space, requiring the installation of 100 luminaires. Cost schedule for 3 years based on equipment and maintenance expences for 100 LED luminaries and the same quantity of fluorescent lamps is shown in the picture below.
The calculation is based on electrical energy rate - 0.15 EUR per 1kW*h. A comparison is made with fluorescent lamps 72W.
The payback period for an area with a 24-hour working day is around 1 month, while annual savings are 6 438 EUR.
The payback period for an area with a 8-hour working day is around 3 months, while annual savings are 2 146 EUR.
Proceeding from these examples, we can conclude that an equal number of fluorescent lamps, A36 and A66 LED luminaires assure a significant increase of illumination level above work surfaces as well as energy savings up to 60%.
