Annual Power savings

You may have received one of our promotional vouchers with an estimated annual saving.   This is how we calculated the savings.  Also see our new power saving calculator.

Please note some areas will need more or less light depending on the area and personal preference.  For more information on light output please refer to individual bulb technical specifications, and the following article  http://www.ledsunlimited.co.nz/technology-light

The cost of electricity per kilowatt hour (including GST and levies) varies from area to area and as of 28 April 2011 for residential use, this tends to be between range from about 13.5c for the cheaper off peak plans, up to 33.37c for peak usage.    We will use the average of these two figures: 23.4c .    Here is an example on how Contact Energy explains how they determine their costs, other companies are likely to have similar prices: http://www.contactenergy.co.nz/web/findoutabout/chargesexplained?vert=fh

Have a look at your power bill and see for yourself, the rate should be on it.

The kilowatt hour, or kilowatt-hour, (symbol kW·h, kW h or kWh) is a unit of energy equal to 1000 watt hours.   For example, a 100 watt light bulb will use consume 0.1 kilowatts per hour, or in other words it will take 10 hours to consume a kilowatt hour of electricity.

We are assuming the amount of time a bulb is estimated to be turned on is for 2 hours in the morning and 5 hours in the evening, or 7 hours per day.  Over a year of everyday use that comes to  2555 hours per year.

Of course not everyone uses bulbs for 7 Hours, some lights may hardly get used more than 1 or 2 hours average, but think about the bulbs that get left on the most, these are the best candidates for replacing with LED bulbs as they will provide the greatest savings.

Replacing every bulb in your house might be a bit expensive, but replacing a few of the highest usage bulbs is not expensive at all, in-fact it SAVES you money.

I will try and get a nice interactive calculator embedded into this article shortly to make it easier to try your own values.   In the meantime if you wish to try different average hours of use, simply divide each of the "Annual running cost per bulb" by 7, this gives an average of 1 hour a day, multiply this by the number of average hours usage you wish to check.  Then compare them.     You can try different KW/hr pricing following a similar method (e.g. divide the annual cost by 23.4 then multiply by the price you wish to check).
 

E22
The LED E22 draws only 6 watts, we are comparing that to a 60 watt incandescent which has a similar light output.      The LED E22 bulb will take nearly 167 hours to use a kilowatt of power  (1000 divided by 6), whereas an ordinary 60w incandescent will use the same amount of power in 16.7 hours.   To put that in perspective a week is 168 hours, so in other words you could leave the LED E22 bulb on constantly for a week and it would still use nearly a third less power than the regular bulb would in a single day!

So to calculate the savings rate we determine the hourly consumption rate of each bulb, multiply that by 2555 hours per year, multiply that by the cost per kilowatt hour, and then compare them to each other.

Bulb Type Rate of consumption Hours per year (7hr avg per day) KW/hr cost Annual Running Cost per bulb
E22 LED Type 0.006 KW per hour 2555 23.4c $3.59
60w Incandescent 0.06 KW per hour 2555 23.4c $35.87

So based on these figures and assumptions, the E22 LED type will be $32.28 cheaper to run annually, which almost saves you the initial cost of the bulb in the first year!   

When you consider LED bulbs are rated to last considerably longer than incandescent bulbs the savings over the lifespan of JUST ONE bulb could easily reach into HUNDREDS of dollars!


MR16
The 10 LED MR16 bulb in our promotion draws 2.2 watts, we'll compare the power consumption to a 30 watt halogen bulb.   Bear in mind for areas that need light output similar to 50 watt halogens we have a range of more powerful MR16 bulbs available, the annual savings are even more significant with these.  

Bulb Type Rate of consumption Hours per year (7hr avg per day) KW/hr cost Annual Running Cost per bulb
10 LED MR16 0.0022 KW per hour 2555 23.4c $1.32
30w Halogen MR16 0.03 KW per hour 2555 23.4c $17.94

So based on these figures this MR16 LED bulb will be $16.62 cheaper to run annually, virtually saving you the initial cost of the bulb in the first year.

 

G4
The 6 LED G4 bulb in our promotion draws 1.5 watts, we'll compare power consumption with a 20 watt G4 halogen bulb.   Like the MR16 we also have a range of G4 type bulbs to suit different applications.

Bulb Type Rate of consumption Hours per year (7hr avg per day) KW/hr cost Annual Running Cost per bulb
6 LED G4 0.0015 KW per hour 2555 23.4c 89 cents
20w Halogen G4 0.02 KW per hour 2555