Light Bulbs and Energy Conservation (Orry Klainman)

Title: Light Bulbs and Energy Conservation

Principle(s) Investigated: Light Bulb Energy Efficiency, Energy Conservation, Mechanics of Lightning Technologies

Standards: HS-ESS3-4: Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.

Materials: 2x Light Fixtures

2x 40w Incandescent Bulbs

2x 40w-Equivalent Compact Fluorescent Bulbs

2x 40w-Equivalent LED Bulbs

2x Infrared Thermometers

2x Kill-A-Watt Electricity Usage Monitor

Lux Light Meter Pro iPhone Application

Data Graphic Organizer, Model Handouts, Safety Instructions

Procedure:

1. Secure light fixtures firmly to a table or desk with an edge
2. Plug Kill-A-Watt monitor into electrical socket
3. Plug fixtures into the Kill-A-Watt monitor, set press the "down" button until display reads "watt"
4. Making sure fixture is set to off, screw in 40w incandescent bulb
5. Turn on fixture, note the reading on the Kill-A-Watt monitor, record on the data graphic organizer
6. Aim infrared thermometer at glowing filament in the bulb (being careful to shield eyes), take reading of light bulb in Fahrenheit, record on data graphic organizer
7. Using the light meter application, hold back of phone 1-2 feet away from bulb, take a reading of the light output of the bulb (being careful to shield eyes), record on data graphic organizer
8. Turn off light fixture, wait until bulb is cool to the touch, remove from fixture
9. Screw in compact fluorescent bulb and repeat steps 5-8
10. Screw in LED bulb and repeat steps 5-8
11. Discuss and answer remaining questions on graphic organizer

Student prior knowledge: What are Watts, What are Joules, What is Temperature? What are lumens?

Explanation: The purpose of this experiment is to explore the evolution of lighting technology and how it affects energy efficiency, heat output and light output. As lighting technology has advanced, we have been able to maintain the same amount of light energy output from light bulbs while drastically reducing energy consumption and heat output. In the experiment students will record data from 3 different artificial light sources to compare technologies and gather data that demonstrates these technological differences. The incandescent bulb, being the oldest and least efficient technology requires the highest amount wattage consumption, and produces the most heat per set amount of light energy (measured in lumens). The compact fluorescent, is able to produce the same amount of light energy (lumens) for 1/4 the energy consumption (watts) and less than half the heat output. LED bulbs, being the newest and most efficient technology, is able to produce the same amount of light energy (lumens) at 1/8 the energy consumption (watts) and 1/3 of the heat of an incandescent bulb. Students, who likely do not know about these lighting technologies beforehand, or which are the newest, most efficient etc. will gather data to determine for themselves these differences. The teacher will prompt students to come up with a basic model that explains how different bulbs could possibly produce the same light energy while consuming less electrical energy and producing less heat.

The goal would be students recognizing the principle of energy efficiency. This will then prompt a larger discussion about why energy efficiency is a key aspect of energy conservation and the larger implications for an Environmental Science class. Students will learn how important lighting is to the larger question of conservation given its ubiquity and percentage of all US energy consumption (10%). After the experiment, students will be given handouts with models of the three light bulb technologies, and basic information explaining them, and future lessons can expand on the mechanics and properties of different light bulbs.

If teachers wish to expand on the properties of light bulbs, they can also introduce students to the concept of correlated color temperature (CCT). The color labels on light bulbs are given in degrees Kelvin (2700K, 3000K, 5000K etc.). This is referring to the perceived color of a black body object heated to that temperature. In more practical terms we could relate these color temperatures to the visible hue of stars that burn at different temperatures, which hotter stars giving off a more blue-white color to our eyes, and cooler stars giving off a red-orange color. The light bulb color temperatures correlate to these star temperature scales roughly. So a 5000K bulb would give off a white-blue color, while a 2700K bulb would give off a red-orange color. These effects are created in different ways depending on the bulb technology. Students can be prompted as to what impact color temperature has on human psychology.

Questions & Answers:

1. What role does heat play in energy efficiency and energy conservation?
   1. Hotter spaces require more air conditioning to keep them at temperatures that are comfortable for human habitation. Air conditioning consumes a significant amount of electricity. Given the high number of light fixtures and bulbs in most living spaces, more efficient lighting can have a significant effect on a room's temperature. This can save a household or business on their air conditioning usage and therefore utility bill.
2. What effect does energy efficiency have on light bulb lifespan?
   1. Hotter temperatures cause electronics to run less efficiently overall, shortening product lifespans, including the light bulbs themselves. As designs have allowed for light bulbs that produce the same light output at a cooler temperature, this has the added benefit of putting less strain on the structure of the bulb itself. As a result, more efficient bulbs not only require less electricity, they last significantly longer before burning out. An average LED bulb has an average life span of 25,000 hours compared to 1200 hours from a current day incandescent bulb.
3. Why is energy conservation important beyond simple cost?
   1. In many parts of the United States and the world, energy is produced for homes and businesses by the burning of fossil fuels. These fossil fuels have been scientifically proven to be contributors to global climate change, as well as poor air quality leading to reduction in human life spans. Energy conservation efforts are aimed at reducing the electricity needed for people to conduct their lives, especially in areas where power plants run on fossil fuels.

Applications to Everyday Life:

1. LED technology has led to advancements in the efficiency and quality of displays (such as televisions and computer screens). Current day screens are higher resolution, thinner and also require less energy to run than was possible with previous technologies.
2. Helping students understand energy efficiency (both wattage use and heat output) from lighting can lead them to apply the same principles to all electronic devices in their homes. Replacing appliances and computers, for example, in a home with more energy efficient models will have the same benefits of replacing incandescent bulbs with LEDs.
3. Color temperature in lights can help evoke important emotional states in people depending on the space. Light has an effect on human biology and psychology. Light is tied to wakefulness and mood, as can be seen in studies relating to Seasonal Affective Disorder. In our society, we consider red-orange-yellow-amber tones to be "warm," "cozy," and "inviting." For this reason, most people should be lower color-temperature bulbs (e.g. 2700K, "warm white") in living rooms and bed rooms. In contrast, a hospital benefits from bulb color-temperatures that appear more blue-white, this evokes alertness and makes it easier to see fine detail.

Photographs:

Videos: