Household Energy Conservation and Efficiency

Evaluating energy consumption is the first step engineers must take when trying to reduce energy consumption. This step is part of the "understand the problem" and "gather information" steps in the problem solving spiral.

After this lesson, students should be able to:

• Calculate energy use and analyze how changing behaviors and appliances affects energy use.
• Conduct an experiment and make comparisons based on experimental evidence.

The use of electricity in the home was addressed in the graphing activity of lesson 1. Many of the concepts covered here were introduced (superficially) in that lesson. The general concepts of this lesson include:

1. Energy conservation can be defined as the protection, preservation, management, or restoration of our energy resources.
2. Conservation is one of the ways we can reduce energy use, thus reducing the amount of pollutants put into our atmosphere from the burning of fossil fuels and reducing the negative effects resulting from the combustion of these fuels.
3. Conservation methods include modifications to our daily behaviors to reduce energy consumption (for example, turning off lights).
4. Efficiency can be achieved by choosing energy-efficient products. These products still provide work, light or heat, but do so with less energy consumption than less-efficient products.

• The U.S. EPA and U.S. Doe have a rating system to label energy efficient products and appliances. See EnergyStar at https://www.energystar.gov/
• Changing light bulbs to CFLs is one way to increase the efficiency of light bulb use. As shown in the light bulb options information provided below, many engineering advances in lighting systems have occurred recently. Learn about Energy Star light bulbs at https://www.energystar.gov/products/learn-about-led-lighting

Light Bulb Options

75W incandescent equivalent bulbs

Compact fluorescent light bulbs (CFLs)

See photo and product description at EarthEasy's website: http://eartheasy.com/live_energyeff_lighting.htm

• Wattage: 18 W (76% energy savings)
• Lasts: 8,000 hours
• Cost: $22 per pack
• Requires special bulb recycling to collect and contain mercury

Cold cathode fluorescents (CCFLs)

18 watts = 75 watt incandescent equivalent

See photo and product description at: https://www.jacksonelectricsupply.com/BF40U20205_19B_p/bf40u20205-19b.htm

• Wattage: 18 W (76% energy savings)
• Lasts: 25,000 hours
• Low energy costs; less mercury then CFLs

Light Emitting Diode (LED)

The 5 Watt LED light:

• is efficient and cost effective
• is the most powerful direct replacement bulb
• fits standard sockets

See photo and product description at EarthTechProducts at: http://www.earthtechproducts.com/energy-saving-led-light-bulbs.html

• Wattage: 5 W (93% energy savings)
• Cost: $60
• No mercury; expensive

How are your unit projects going? Have you come up with some good ideas about how you might reduce your energy consumption? In this lesson, we will explore more closely how we use energy in our homes and identify some ideas for conserving energy or using it more efficiently. Recall these terms:

• Conservation – not using consumer energy products (for example, turning lights off, walking instead of driving)
• Efficiency – benefiting from the value of using energy (for example, still being mobile), but consuming much less energy to meet same goal (for example, using an automobile with high miles per gallon)

Household electricity use in the U.S.CopyrightCopyright (data) US Department of Energy's Energy Information Agency

We use energy in our lives everyday. Our homes use energy in many ways. Home heating/cooling systems are the largest consumer of energy in most U.S. households. Heating water is also a large energy consumer. Refer to the three associated activities: Watt Meters to Measure Energy Consumption, Household Energy Audit, and Light vs. Heat Bulbs to illustrate the energy used from various electrical devices and household appliances using various approaches over a 3 day lesson plan. 

Another large energy consumer category is electric lighting and appliances. (Refer to data in the Excel graphing activity, lesson 1, for specific information.) Our homes are filled with appliances that use electrical energy to work for us. Toasters, microwave ovens, televisions and computers are examples of the appliances we use everyday. We compare electrical energy use in units called watt-hours or kilowatt-hours. Lighting accounts for 20-25% of all the electricity used in the U.S. On average, a household uses 5-10% of its energy for lighting. A commercial industry on the other hand consumes 20-30% of its energy in lighting alone; 50% or more of the energy used is wasted by obsolete equipment, inadequate maintenance, or inefficient use.

Consumer demand for appliances that turn on quickly and LED lights that stay on all the time creates a constant "stand by" power requirement that can be very substantial. This power is sometimes called "leaking electricity." Unplugging these appliances is the only way to reduce the stand by power load. (Show some examples on computer, TV, other appliances that might be in the classroom.)

Energy savings for lighting will require either reduction in use or more efficient usage. New technologies have provided significant reductions in the power needed for lighting.

Worksheet & Homework: Assign students the Light Bulbs Activity Worksheet and Homework. The homework may be redundant if a thorough home energy audit is also done.

Homework & Activity Sheets: Assign students the home energy audit homework/activity sheets.

Energy Star. Compact Fluorescent Light Bulbs, U.S. EPA and U.S. Department of Energy. Accessed December 30, 2008. https://www.energystar.gov/index.cfm?c=cfls.pr_cfls

This lesson was originally published by the Clarkson University K-12 Project Based Learning Partnership Program and may be accessed at http://internal.clarkson.edu/highschool/k12/project/energysystems.html.