Chapter 7 Energy Conservation

Chapter 7Energy Conservation Lecture #14 PHYS 331/581 Spring 2019 Renewable Energy

iClicker Question • About what percentage of U.S. electricity is derived from nuclear power? • A 10 • B 20 • C 30 • D 40 • E 50

iClicker Question • Which of the following countries has the highest percentage of electricity generated by nuclear power? • A United States • B United Kingdom (Great Britain) • C Japan • D France • E Russia

iClicker Question • Which of the following describes the Roentgen? • A the unit of absorbed dose equivalent. • B the unit of absorbed dose. • C the unit of exposure to ionizing radiation • D all of the above • E none of the above

iClicker Question • Which of the following describes the RAD? • A the unit of absorbed dose equivalent. • B the unit of absorbed dose. • C the unit of exposure to ionizing radiation • D all of the above • E none of the above

iClicker Question • Which of the following describes the REM? • A the unit of absorbed dose equivalent. • B the unit of absorbed dose. • C the unit of exposure to ionizing radiation • D all of the above • E none of the above

iClicker Question • Which statement is true about fusion? • A Fusion is just another name for nuclear fission. • B Fusion and fission are variations of the same nuclear process. • C Fusion is the breakup of heavier chemical elements into lighter chemical elements. • D Fusion is the process of producing heavier chemical elements from lighter chemical elements. • E Fusion is the process of converting energy into matter.

Overview of Chapter • Energy Conservation • Space Heating • Thermal Insulation • Air Infiltration • Lighting • Appliances • Some considerations of agriculture and industry

Adapted from Home Energy Seminar at Tufts University with Professor Anja

Home Energy Seminar Overview • Home Energy - Lights • Home Energy - Appliances • Fridges,Washing machines,AC • Home Energy - A little Physics • Building diagnostics • Insulation vs. Air-tightness • Home Energy - Windows • Home Energy - Heating Systems

N.B. Addressing Energy Conservation Issues May Help Address Other Issues Energy SecurityNational SecurityJob SecurityAir Pollution

Efficiency Thoughts An estimated 94% of materials become waste before a product is even manufactured. Only 6 per cent of materials extracted each year are embodied in durable goods!

Home Energy Seminary Save Money! Protect the Climate! Americans spend more than $160 billion a year to heat, cool, light and live in our homes. Homes use about 21% of the energy we use as a nation. Homes contribute about 17% of our national emissions of greenhouse gases.

Compact Fluorescent Light bulbs (CFLs) More expensive upfront ($1-$12) but they can save $30-$50 over lifetime of bulb. Many different types of CFLs available (including for small fixtures, 3-ways, etc). Last 10 times longer! Watch for available rebates. Some chemical safety issues.

Compact fluorescent bulbs • Take 1-2 min to reach fullest brightness • Are less bright when it is cold • If concerned about brightness, buy higher wattage • Should not flicker after 1-2 seconds

Compact fluorescent bulbs • Are not all of equally good quality • Test out a brand before you invest much in them • Regular CFLs don’t work in dimmable fixtures • Buy a dimmable CFL • Check out www.efi.org for other specialty bulbs

Compact fluorescent bulbs • Have a small amount of mercury: call your locality about proper disposal. • But they still use less mercury than would have been produced at the power plant when you use a regular incandescent bulb

Compact fluorescent bulbs If every household in the US replaced its fixtures with CFLs Possible Savings: 800 million MWh

Energy Hog! Halogen Torchieres Nice light but… Uses 300W – 500W…. (a normal bulb uses 60W) Halogen torchieres are also a fire hazard! Buy a torchiere which uses a CFL

From the New York Times “LED bulbs are a gigantic improvement over incandescent bulbs and even the compact fluorescents, or CFLs, that the world spent several years telling us to buy. LEDs last about 25 times as long as incandescents and three times as long as CFLs; we’re talking maybe 25,000 hours of light. Install one today, and you may not own your house, or even live, long enough to see it burn out. (Actually, LED bulbs generally don’t burn out at all; they just get dimmer.) “You know how hot incandescent bulbs become. That’s because they convert only 5 to 10 percent of your electricity into light; they waste the rest as heat. LED bulbs are far more efficient. They convert 60 percent of their electricity into light, so they consume far less electricity. You pay less, you pollute less. “But wait, there’s more: LED bulbs also turn on to full brightness instantly. They’re dimmable. The light color is wonderful; you can choose whiter or warmer bulbs. They’re rugged, too. It’s hard to break an LED bulb, but if the worst should come to pass, a special coating prevents flying shards. “Yet despite all of these advantages, few people install LED lights. They never get farther than: “$30 for a light bulb? That’s nuts!” Never mind that they will save about $200 in replacement bulbs and electricity over 25 years.”

Appliances Energy Star: www.energystar.gov Look for the energy star label! More than 35 product categories are available with the ENERGY STAR label. Careful! Energy Star appliances are rated by size class. Look for the smallest appliance that fits your needs.

Refrigerator If your refrigerator is more than 8 years old, it makes sense to replace it. The new one will pay for itself in energy savings in about 3-6 years. Again! Energy Star appliances are rated by size class. Look for the smallest refrigerator that fits your needs! Side-by-side are least efficient.

iClicker Question • How many fewer power plants might be needed if every household changed to compact fluorescent lighting? • A About one • B More than one • C More than 100

Washing Machines BAD: Top-loader GOOD: Front-loader 40 to 60% less water 30 to 50% less energy 50 to 70% less detergent

Front –loading Washing Machines Top-loader: 40 gallons of water per load. Front loader: 20 - 25 gallons. You could save as much as 7,000 gallons of water per year! Gentler on clothes. Decreases drying time considerably. Do a better job cleaning clothes. Be modern, get a front-loader! Top-loaders are the technology your grandparents used Only do full loads. Use cold water as often as possible.

Conventional Dryer • 800-1000 kW/year • $80-$120/ year Be old-fashioned - dry your clothes like your grandparents did! Tip: If you do not have time to hang all your clothes, hang the heavy, and thick items: towels, sheets, socks…

Use Fans Instead of AC! Only 10-15% of the energy an AC uses. (Shut the fan off when you leave the room, because it does not actually cool the air but just move it. The exception to this is a window fan to get cool night air from the outside into the house.)

Be cheap! Turn it off! Most electricity is used by things that are on a lot and use a lot of power: Refrigerator (500kWh-1300 kWh per year) Freezer (500kWh-1300 kWh per year) Desktop Computer (300-1000 kWh per year) Lights Don’t forget to turn your heat or AC off /down!

iClicker Question • Which type of washing machine conserves the most energy and water? • A Top loader • B Front loader • C There is no difference

Myth Turning off your computer will harm it. WRONG! This used to be true back when computers had green screens and punched cards……

Myth Leaving your heat on is more efficient than turning it down because you need so much energy to heat the house back up. WRONG! Think about it! It’s as if you’d claim that putting down your suitcase while waiting for the bus uses more energy than holding it up the whole time, because you’d have to pick it up again.

Get a Home Energy Audit A professional will be able to analyze your house and give you advise. You’ll get most out of it, if you are well educated. Prepare well and ask lot’s of questions.

A Little Physics: How Heat Travels: Convection The flow of hot and cold gases This is how heat travels through leaks, cracks and gaps in your house.

Will she be warm enough in the winter? Convection: Air leaks: This is why you wear a wind breaker over your woolen sweater!

Blower-Door Test

What You Can Do: Use weather stripping and caulking. It is cheap and it works. Stay warmSave Money From the simple to the sophisticated, air sealing pays

Conduction Heat exchange between adjacent molecules This is how heat travels through materials. Some materials conduct heat better than others. Insulation slows the movement of heat.

Lower Conduction withInsulation: This is why you wear a woolen sweater in winter and a cotton sweatshirt in the summer

Infra-red Photography

Insulation is rated by: Resistance: R-ValueHigh R-value = high insulation properties You want: High R- Value Windows are rated by: Conductance: U-value Low U-value = high insulation properties You want: Low U- Value

Chapter 7 Energy Conservation