Impunity wrote:Sir consider 100W incandescent lamp priced at KES. 40
Now consider a Phillip energy saving bulb priced at KES. 280 and giving an equivalent of 100W of luminescence from an incandescent bulb!
I let the bulb shine/wakas for 5 hours per day daily; after how many days will I recoup my investment? As in what is the break even point.
Please explain with figures and give examples to make it sink in.
Thanks.
Mukiha must be busy elsewhere. Let him review my working below when he comes back.
Let us assume you are domestic consumer and your average monthly power bill is KSh. 2,000.00
This bill includes fixed charge of KShs. 120/-. Hence, balance or real cost of power units (Kilowatt hours) is KShs. 2000-120 = 1880/-
The tariff for domestic consumers is structured as follows:
Charge of KShs. 2/- for the first 1-50 units
Charges of KShs 8.10 for the next 51-1500 units
Hence, number of units consumed in an average month can be given by: (1880- (2*50) /8.10) + 50 = 270 units
The average cost per unit is therefore given by KShs. 2000/270= KShs. 7.40
Assume you went ahead to buy the incandescent bulb. The number of units at the end of the month attributable to the bulb is given by:
0.1*5*30=15kwh
Hence this bulb will cost you 15*7.4 = KShs. 104.00 in power bills for one month.
Assuming you alternatively went for equivalent energy saving bulb of 18watts, the number of units consumed at the end of the month attributable to the energy saving bulb is:
.018*5*30 = 2.7kwh
Hence the energy saver will cost you 2.7*7.4 = KShs. 20/- in power bills for one month.
The difference in cost of energy for the two options is Ksh. 104-20 = Ksh. 84/-
The difference in initial purchase cost is Khs. 280-40 = 240/-
Hence, it will take you 240/84 = 2.8 months to recover the additional cost of buying energy saver bulb. But remember the lifespan of energy saving bulbs is many times more that of incandescent bulb.