Let's say you use ceiling lamps for the lighting of room, total - 25 units. Each luminaire has 4 units of 18 W T 8 fluorescent lamp with electromagnetic ballasts, so the total - 100 units. Lamps have been used for several years and you need to change the “worn-out” lamps and launchers more and more frequently. We propose to replace all the lamps into the economical T5 14 W fluorescent lamps without changing the luminaire and using the T5 system.

See a comparative table.

Luminaires switch on 12 hours, 6 days per week:

 

Used lighting – T 8 18W fluorescent lamps with electromagnetic ballasts.

Recomended lighting :–T5 14W fluorescent lamps, using T5 system.

One(1) luminaire uses electrical power per hour (further kWh)

0,112 kWh (4x0,028 kWh)

0,056 kWh (4x0,014 kWh)

Working time per day -12 hours – one luminaire (1) uses kWh per day

1,344 kWh (12x0,112 kWh)

0,672 kWh (12x0,056 kWh)

27 working days per month – one luminaire(1) uses  kWh per month.

36,29 kWh (27x1,344 kWh)

18,14 kWh (27x0,672 kWh)

Twenty five (25) luminaires use   kWh per month

907 kWh (25x36,29 kWh)

453 kWh (25x18,14 kWh)

If you don‘t pay excise and VAT for the electrical power - 0,386 LT/kWh, you need to pay per month

350,10 Lt (907x0,386 Lt)

174,86 Lt (453x0,386 Lt)

So you will save per month 175, 24 Lt (350, 10-174,86 Lt), per year – 2102,88 Lt (12 x 175,24 Lt).Lighting renovation investment 1997,00 Lt (100 x 19,97 Lt), is repaid over one year. If the luminaires turn on 24 hours, days per week – is repaid over 5 month and save 4669, 08 Lt per year in addition .

Do you need additional 2102, 88 Lt per year – you will decide.