A building of 750 m2 area is illuminated by 100 units of traditional T8 fluorescent office light fittings. Each fitting gives off around 2300 lumens so 2300 / 7.5 = 306 lumens per m2 of floor area.
Note:- Lux levels will vary with factors such as the colours and reflectivity of the fixtures and fittings of the office, the age of the fluorescent tubes, the cleanliness or otherwise of the reflectors and ambient light coming from other sources.
Each unit has 4 T8 fluorescent tubes of 18 watts with 2 watts power consumption for the ballast so
84 watts x 100 = 8,400 watts = 8.4 kW lighting power consumption in the building.
Lighting Refurbishment Options
Option 1 Traditional Recessed Fluorescent fitting High frequency T5 – modest savings of around 16 watts per fitting and higher light output per fitting, but in no way comparable to LED.
68 watts x 100 = 6,800 watts = 6.8 kW lighting power consumption in the building.
With brighter light in the building – fitting light output not stated but higher than T8.
Around 19% power saving
LED panel lights give an even light and fit flush with a suspended ceiling making cleaning as simple as a wipe over with a damp cloth. LED lighting is directional so a very high proportion of light makes it out of the fitting – especially for back lit panels where the LEDs directly shine in the required direction.
It should be noted that whilst the main saving with LED lighting is usually electricity, that reduced frequency of maintenance can bring significant extra savings and improve safety by reducing work at height.
Option 2 Side lit LED panel lights - 30 watts, 3,600 lumens output so can either fit the same amount of fittings with 56% brighter light, or fit around 65 panels for the same light output.
30 watts x 100 = 3,000 watts 3 kW (56% brighter)* 64% saving
30 watts x 65 = 1,950 watts 1.95 kW (same brightness) 77% saving
*(Based on the Integral Performance + panel range)
Option 3 High efficiency backlit panels – 23 watts, 3,500 lumen output
23 watts x 100 = 2,300 watts 2.3 kW (52% brighter)** 72% saving
23 watts x 67 = 1,540 watts 1.54 kW (same brightness) 81% saving
**(Based on the Integral Compact High Performance + range)
Option 4 State of the art High Performance Variable Wattage 9 to 32 watt, 1,600 to 5,600 lumens
32 watts x 62 = 1,984 watts (50% brighter)*** 76% saving
32 watts x 45 = 1,440 watts (slightly brighter) 82% saving
*** (Based on Integral High Performance Variable Wattage)
This ignores further savings available by dimming the lights when the sun comes out, or any savings from using presence sensors in corridors and stairwells.
Impact on EPC Rating
Converting a building from T8 fluorescent lighting to high efficiency LED lighting will often improve the building's EPC rating by at least one band, and may make the difference re compliance with the Minimum Energy Efficiency Standard for marketing the building for rent or sale.
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