# How To Choose The Right Lamp For Your Homes

By mandy, 9th Feb 2011 | Follow this author | RSS Feed
Posted in Wikinut>Guides>Money Saving Tips

Find out how you can save money just by choosing the lamps you have at home. People have been searching for ways to save at home and spend money wisely but usually fail to take a look at this one area.

## 1) Know what the illumination level requirement for the room is.

Illumination is the amount of light, evaluated according to its capacity to produce visual stimulation. Illumination requirements at home are usually below 30 footcandles or 323 lux. Room illumination level requirements are dependent on the room type and the usual tasks performed in it.

## 2) Identify the tasks that will be performed in the room.

Dining and conversation areas need illumination levels of 3-5 footcandles only while kitchens and sewing rooms require around 50 footcandles. That means, you do not need to put the same number of lamps in critical areas and in areas where visual requirements are minimal.

Assuming most of the lamps you use at home are already Compact Fluorescent Lamps (CFLs) because you know it is one of the ways you can save on your electricity bills, there are still options for you to choose from. Online and offline lighting manufacturers, distributors and sellers usually have data for the different lamps they sell. By browsing through their catalogues, you will see the lumen output and the wattage of a particular lamp series. Say, you need to light a dining room of 1000 square foot area using a 13-watt, Twin Tube Compact Fluorescent with a lumen output of 900 lumens, Four lamps will be sufficient to give you an illumination level of 3-5 footcandles.

illumination/lamp= lumen output of one lamp/room area = 900/(1000 sq. ft) = 0.9 footcandle

illumination (using four lamps) = 4x0.9 = 3.6 footcandles

total lamp wattage = 13 x 4 = 52 watts

The calculation presented is only a simple analysis and general calculation that can be understood by any layman. Factors like how the room is going to be maintained and the fact that lamps depreciate with time is not considered.

If you use an 18-watt of the Twin Tube Compact Fluorescent mentioned above that has a lumen output of 1150 you will only need three lamps but the total wattage here is 54 while in the previous, only 52.

illumination/lamp= lumen output of one lamp/room area = 1150/(1000 sq. ft) = 1.15 footcandles

illumination (using four lamps) = 3x1.15 = 3.45 footcandles

total lamp wattage = 18 x 3 = 54 watts

You will find an initial difference in the lamp cost since lamp cost will be directly proportional to the wattage. Based on retail price, using the 18-watt lamp would cost 3 x \$5.95 = \$17.85, while using the 13-watt would initially cost 4 x \$5.87 = \$ 23.48. The four 13-watt lamps will cost \$5.63 more than the three 18-watt lamps.

Let us recall our options: We let option A => using four 13-W lamps and option B => using three 13-W lamps. Option A costs \$ 23.48 while option B costs 3 \$17.85. Option B, though cheaper by \$5.63, is 2W higher in terms of kilowatt consumption. Let’s say the lamps will operate for six hours per day and 30 days per month;

kWhr = (2/1000) x 6 hrs. = 0.012 (per day)
kWhr = 0.012 x 30 = 0.36 (per month) => the kWhr difference in using option B

## 5) Know how much the lamp consumption will cost you in the long run.

Assuming the lamps will have a lifespan of two years and the cost per kWhr is \$ 0.19, we can calculate the cost difference in terms of power consumption.

Cost of the 2-W difference: \$ 0.19 x 0.36 = \$0.0684 (per month)
Cost of the 2-W difference: \$ 0.0684 x 24 = \$1.6400 (after two years)

The above calculation shows that option B is not only cheaper initially but throughout the estimated life. Even if we maximize the life of the lamp to five years, option B is still going to be cheaper. Choosing lower rated lamps do not necessarily translate to savings. We need some knowledge as to our choices and we need to think a little bit more than what we normally do.

### Meet the author

mandy
I'm a registered electrical engineer by profession, teaching at a university. I have varied interests and I write to express and help others.