Electricity Saving Tips For Homes And Offices

How much lighting is good lighting for a room?

By on June 28, 2018

Good lighting enhances the beauty of a room. Some people take good care of lighting while furnishing a room and some just put a tube-light or a bulb here and there to just light up a room. But have you ever thought how much lighting is good lighting for a room? Have you ever analyzed if you have less light or more light in a room, or are you wasting electricity by putting extra lights? With this article we just want to provide some guidelines to setting up lighting in room, so that you do not waste electricity but light up your room appropriately as per the needs.

Lumens is for brightness not watts

In past we had always compared brightness of a light by comparing wattage of the bulbs. But after using CFLs we realized that same amount of light can be achieved through lesser wattage. So is watt a good representation of brightness? No. The actual technical term for brightness is Lumens. More the lumens, brighter the light is. The number of lumens is different for different bulbs and some of the branded lights do have this information, but most bulbs available in out country do not have this information. But below are some guidelines for comparison:

For Bulbs:

Incandescent Watts

CFL Watts

LED Watts

Lumens (Brightness)

40

8 – 12

4 – 5

450

60

13 – 18

6 – 8

890

75 – 100

18 – 22

9 – 13

1210

100

23 – 30

16 – 20

1750

150

30 – 55

25 – 28

2780

(Source: http://eartheasy.com/blog/2011/08/led-bulbs-are-ready-to-light-your-home-7-tips-you-should-know/)

For Tubelights:

Type

Lumens (Brightness)

T12 40W 4ft

2800

T8 36 W 4ft

2700

T5 28W 4ft

2750

T5 14W 2ft

1275

(Source: http://www.lrc.rpi.edu/programs/nlpip/lightingAnswers/lat5/pc1a.asp)

The above numbers give us a good representation of how different kinds of lights/bulbs compare with each other.Infographic12

How much light is required for your room?

Amount of lighting required for a room depends on the size of the room and the purpose of the room. Intricate tasks require more lighting and just moving around the room requires much less light. The amount of light required in an area is defined as “LUX” level that is equal to lumens/area (lm/m2). Below table gives a good idea of LUX level for various tasks:

Activity

Illumination

(lux, lumen/m2)

Public areas with dark surroundings

20 – 50

Simple orientation for short visits

50 – 100

Working areas where visual tasks are only occasionally performed

100 – 150

Warehouses, Homes, Theaters, Archives

150

Easy Office Work, Classes

250

Normal Office Work, PC Work, Study Library

500

(More details available at: http://www.engineeringtoolbox.com/light-level-rooms-d_708.html)

So if you have a room that is 10 ft x 10 ft (which is 9.29 m2) and you want to do easy office work in the room, then the amount of light required in the room is 250 x 9.29 which is about 2400 lumens. 1 single tube light or about 2 75-80 Watt bulbs can achieve this.

If you have a small area of a square meter and you use it for pc work, then a 12-watt CFL is good for it.

Task based lighting can be done in a room accordingly.

When do you waste electricity?

When you use more lumens in a room than required then you are wasting electricity for extra lighting. There are multiple cases when this happens:

  1. More lights are put in a room than desired.
  2. Lights are hidden on concealed. Many a times this is done with false ceilings to decorate the room.
  3. At times there is some obstruction for the lights and extra lights have to be put to accommodate for the less light.

If you want to save electricity, make sure that any of the above is not happening.

Does brightness of bulb remain same through out its life?

No. It decreases with time for most types of bulbs. Lights become less bright as they age. LEDs are known to have similar levels of light through out their life and in fact they have long lives. Typical life of:

Type

Life

Incandescent Bulb

750-1000 hours

CFL

6000-10000 hours

Tube-lights

7000-24000 hours

LEDs

25000-50000 hours

The range above is for an average quality bulb to a good quality bulb.

(Source: http://www.energysavers.gov/your_home/lighting_daylighting/index.cfm/mytopic=12030

and

http://en.wikipedia.org/wiki/Compact_fluorescent_lamp)

What is color temperature and how does that impact room lighting?

When we go to the market we see many light options in multiple shades of yellow and white/blue. Yellow lights are warm lights and are good for bringing out warm color in the room. They enhance yellow, oranges and browns. This makes them ideal to create a warm and cozy feeling in the room. White lights are cool lights and are closer to daylight. They are good for reading, computer work, kitchen, arts and crafts, etc. In some branded lights the color is represented using temperature. And confusingly, higher Kelvin temperatures (3600–5500 K) are what we consider cool and lower color temperatures (2700–3000 K) are considered warm. Image below shows different shades of lights available in the market and the appropriate use for the sameLight Temp

(Source: http://www.energystar.gov/index.cfm?c=cfls.pr_cfls_color)

So if electricity saving is a priority for you, next time when you are buying a bulb or a tube-light don’t just consider saving watts, but also consider saving lumens.

Some good LED Lights on Amazon

About the Author:
Abhishek Jain is an Alumnus of IIT Bombay with almost 10 years of experience in corporate before starting Bijli Bachao in 2012. His passion for solving problems moved him towards Energy Sector and he is keen to learn about customer behavior towards Energy and find ways to influence the same towards Sustainability. .

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