In the course of discussing with many consumers of electricity, it is obvious many assume their electricity costs should be cheap or at most a fixed figure. In this post, I'll be looking to educate consumers who have no energy measuring device about how to calculate their true energy costs.

The easiest way to know or determine what your energy bills are or will be in the coming month is to get information of the unit of energy consumption measured in Wattage (W) or the current passing through the conductor of the appliance and measured in Amperes or Amps for short.

On the most common electrical appliance, the bulb, the unit of energy is mostly represented in Watts and is usually inscribed on the tip of the glass casing of the filament. Bulb come in different Wattage ranging from 8W, 11W, 15W, 26W, 40W, 60W, 85W, 105W and the really bright options used for halogen lighting come in 250W, 300W, 400W, 500W or more.

It hardly matters that a bulb is energy saving or white or yellow, what truly matters is the Wattage consumed when it is in use. In other words, a 105W Energy Saving bulb (ESB) will consume more Watts than a 60W non-energy saving bulb. It is the energy consumed that matters. The ESB are also made to last longer, sometimes lasting up to five to six years. Effectively, the makers envisage that you don't have to spend money replacing your bulbs as regularly as the Non Energy Saving Bulbs thus putting savings back in your pockets.

To be continued....

1. BULB

Energy Consumption of a Bulb

1 bulb 1 Watt of energy consumed for 1 hour for 1 day equals 0.001 kWh of consumption.
1 bulb x 8 Watts x 1 hour x 1 day = 0.008 kWh of consumption.
1 bulb x 26 Watts x 5 hours x 30 days = ~4 kWh of consumption
4 bulbs x 26 Watts x 5 hours x 30 days = ~16 kWh of consumption (assuming the supply to your area is steady)

Recall that you likely have your security lights on all night (~8 hours)

4 bulbs x 40 Watts x 8 hours x 30 days = ~24 kWh of consumption (assuming supply to your area is steady)

In Eko DISCO, this bill of 24 kWh of consumption for your bulbs alone will cost you N24.24 per 1 kWh where you are on the R2SP (Residential Single Phase) tariff. So for using 24 kWh, your bill for your bulbs alone totals to N581.76 exclusive of VAT.

In Ikeja DISCO, this bill of 24 kWh of consumption for your bulbs alone will cost you N21.30 per 1 kWh where you are on the R2SP (Residential Single Phase) tariff. So your bill for using 24 kWh will total to N511.20 exclusive of VAT.

In most cases, many consumers assume using a CFL (Compact Fluorescent) bulb is a good enough reason to reduce your energy bill, however most fail to confirm the Wattage of the bulbs with some using bulbs as high as 85W and wondering why their bills remain sky high. As shown in the image, the standard brightness for a bulb at 1,600 lumens, requires a lot of energy generated depending on the bulb type, so do not erroneously believe that once it is a spiral or CFL ESB, it automatically translates to a cheaper bill.

When buying your bulbs, search for those with lower Wattage, but higher lumens. They will turn out more expensive that the usual bulbs, but will last longer and will result in cheaper bills.

2. FRIDGE

Energy Consumption of a Fridge

The wattage of a regular size fridge differs from manufacturer to manufacturer however the easiest way to know what the Wattage for your fridge is to check any of the following:

1) Owner's manual - check for the Operating Wattage or the current (measured in Amps) as well as the voltage.
2) The rating plate usually found behind, or at the sides of the appliance
3) On the website of the manufacturer.

Where you find the Wattage of the Fridge, it does make it easier to calculate, however where you have two Wattage figures and are unable to determine which is operating and which is starting Wattage, look for the Current (measured in amps) as well as the voltage. To get the Power measured in Wattage:
Amps x Voltage = Wattage

As a rule of thumb, I'll stick to using a general home appliance table for ease of calculations. In this case, I'll be using a regular size Fridge with 400W operating or running Wattage.

1 400W Fridge x 1 hour x 1 day = 0.4 kWh of consumption
1 400W Fridge x 5 hours x 1 day = 2 kWh of consumption
1 400W Fridge x 10 hours x 1 day = 4 kWh of consumption
1 400W Fridge x 10 hours x 30 days = 120 kWh of consumption

EKDISCO = 120 kWh x N24.25 = N2,910 exclusive of VAT

IKEJADISCO = 120 kWh x N21.30 = N2,556 exclusive of VAT

As you'll rightly notice, this consumption assumes there's supply for at least 10 hours a day for 30 days, as such where there's supply for more than 10 hours on certain days, the calculation for such a bill will be applied appropriately and result in a higher bill.



1

I have specifically started this posts with the bulb and the fridge as a good example of how usually overlooked appliances that are left running without much thought irrespective of the time of the day are very likely the culprits that result in a bill at the end of the month even when you spend 10-14 hours out of your apartment (for those who have to leave the house for work between Monday - Friday).

These two ubiquitous appliances are the reasons that come rain or sunshine, so long as you have them at home running or idling, will result in a bill depending on the hours of supply to your area during a monthly billing cycle.

Now, I have not added the accompanying Freezer and will do a post next about it. Where you have a regular size deep freezer (single chest), the size of the fridge should apply. However where you have a double chest or a larger size, then your costs will tend to increase even where you have a thermostat.

Op is the consumption per unit of a fridge the same as that of a chest freezer?

More of this pls

DBriteLitehouse:
More of this pls

Very interesting and insightful write-up,how we over look certain minor items (household) that will spike up our power consumption monthly.
Please will appreciate an in-depth lecture on using wattage of home appliances to determine the type of inverter(KVA),battery and the wattage or KVA of the solar panel required to power a house based on established total appliances wattage.