Phys 150 Lecture 271Phys 150 Lecture 71 Please sit together in pairs: –Onyema and Jason –Alejandra and Jiayuan –Chris and Erica –Ryan and John W. –John F. and Dian –Walter and Michael –Max and Honglu –Amanda and Matt –Pauline and Lin –Jennifer and Anwen –Alexandra and Mengyue –David and Melissa –Abigael and Erich –Jake and Irfan Phys 150 Lecture 221

Phys 150 Lecture Apr-2011 Phys 150 Lecture 252 Announcements Check your grades on the gradebook and me if there are any problems. Final Exam is Tuesday, May 7, 7:00 PM to 10:00 PM in this room (Loomis 151). Covers Chapters 1-10 and Chapters 6, 25 from MacKay (see the Phys 150 web page). One essay on the final exam will be about energy and alternative energy. The other essay will be on electromagnetic radiation (visible light, IR, X-rays, etc.) and nuclear radiation (alpha, beta, gamma).

Phys 150 Lecture Summer reading Physics for Future Presidents (Richard Muller, the popular book for the layman). Energy for Future Presidents (R. Muller) The Long Thaw (David Archer)

Phys 150 Lecture May-2011 Phys 150 Lecture 274 A typical 1929 house Phys 150 Lecture 274

5 3-May-2011 Phys 150 Lecture 275 i>clicker question When retrofitting a house, what’s the most important step? A.Sealing cracks B.Adding insulation C.Replacing windows Phys 150 Lecture 275

6 3-May-2011 Phys 150 Lecture 276 i>clicker question When retrofitting a house, what’s the most important step? A.Sealing cracks – reduce air infiltration B.Adding insulation C.Replacing windows -Flow of hot or cold air is “convection” Phys 150 Lecture 276

7 Air sealing Attic Basement Phys 150 Lecture 277

8 3-May-2011 Phys 150 Lecture 278 i>clicker question When this 1929 house was built, it had A.No insulation in the walls B.2 inches of wool insulation C.3 inches of fiberglass insulation D.3.5 inches of cellulose insulation Phys 150 Lecture 278

9 3-May-2011 Phys 150 Lecture 279 i>clicker question When this 1929 house was built, it had A.No insulation in the walls B.2 inches of wool insulation C.3 inches of fiberglass insulation D.3.5 inches of cellulose insulation -Original heating system was coal burning furnace -Insulation reduces heat “conduction” (and also aids air sealing) Phys 150 Lecture 279

10 Dense pack cellulose –3.5 inches dense pack cellulose –R = 13 (R = resistance to heat conduction) Phys 150 Lecture 2710

Phys 150 Lecture May-2011 Phys 150 Lecture 2711 i>clicker question When this 1929 house was built, it had A.No insulation in the attic B.2 inches of wool insulation C.3 inches of fiberglass insulation D.3.5 inches of cellulose insulation Phys 150 Lecture 2711

Phys 150 Lecture May-2011 Phys 150 Lecture 2712 i>clicker question When this 1929 house was built, it had A.No insulation in the attic B.2 inches of wool insulation – “rock wool” C.3 inches of fiberglass insulation D.3.5 inches of cellulose insulation -Rock wool is similar to fiberglass Phys 150 Lecture 2712

Phys 150 Lecture 2713 Loose fill cellulose –13 inches loose fill cellulose –R = 49 (R = resistance to heat conduction) Phys 150 Lecture 2713

Phys 150 Lecture 2714Phys 150 Lecture 2714

Phys 150 Lecture May-2011 Phys 150 Lecture 2715 i>clicker question The result of air sealing and adding insulation to the walls and attic of this 1929 house is (gas furnace) A.10% reduction in gas, no reduction in electricity B.20% reduction in gas, no reduction in electricity C.20% reduction in gas, 10% reduction in electricity D.30% reduction in gas, 30% reduction in electricity Phys 150 Lecture 2715

Phys 150 Lecture May-2011 Phys 150 Lecture 2716 i>clicker question The result of air sealing and adding insulation to the walls and attic of this 1929 house is (gas furnace) A.10% reduction in gas, no reduction in electricity B.20% reduction in gas, no reduction in electricity C.20% reduction in gas, 10% reduction in electricity D.30% reduction in gas, 30% reduction in electricity The blower on the gas furnace uses electricity Phys 150 Lecture 2716

Phys 150 Lecture May-2011 Phys 150 Lecture 2717 You can do it too! Home energy audit ($50) –Act on Energy (Ameren Illinois) Central and Southern Illinois –Smart Ideas (Com Ed) Chicago and Northern Illinois Audit is performed by an independent third party (Conservation Services Group) There are financial incentives for many upgrades Phys 150 Lecture 2717

Phys 150 Lecture 2718Phys 150 Lecture 2718 i>clicker question To reduce energy use even further, the best things to add is A.a high-efficiency air conditioner B.a high-efficiency gas furnace C.an air-source heat pump D.a ground-source heat pump (geothermal)

Phys 150 Lecture 2719Phys 150 Lecture 2719 i>clicker question To reduce energy use even further, the best things to add is A.a high-efficiency air conditioner B.a high-efficiency gas furnace C.an air-source heat pump D.a ground-source heat pump (geothermal)

Phys 150 Lecture 2720 Geothermal Heat Pump

Phys 150 Lecture 2721 Geothermal Heat Pump Water Heater Heat Pump Pre-heat tank

Phys 150 Lecture 2722Phys 150 Lecture 2722 i>clicker question To reduce energy use to zero, we need to add A.a residential wind turbine B.a solar water heater C.solar photovoltaic panels D.All of the above

Phys 150 Lecture 2723Phys 150 Lecture 2723 i>clicker question To reduce energy use to zero, we need to add A.a residential wind turbine B.a solar water heater C.solar photovoltaic panels D.All of the above

Phys 150 Lecture 2724 Solar photovoltaic (PV) AC PV panels

Phys 150 Lecture 2725 Solar photovoltaic (PV) Microinverter AC PV panels

Phys 150 Lecture 2726Phys 150 Lecture 2726 i>clicker question Modern well-insulated windows are coated with a material that A.reflects IR radiation B.absorbs IR radiation C.reflects UV radiation D.absorbs UV radiation

Phys 150 Lecture 2727Phys 150 Lecture 2727 i>clicker question Modern well-insulated windows are coated with a material that A.reflects IR radiation – ITO (Indium Tin Oxide) B.absorbs IR radiation C.reflects UV radiation D.absorbs UV radiation – ordinary glass -Windows typically have R ≈ 3 (or U = 1/R ≈ 1/3)

Phys 150 Lecture 2728Phys 150 Lecture 2728 i>clicker question In the winter, if you turn down your thermostat at night (but put it back to normal during the day), you will A.use less energy B.use more energy C.use less energy at night but more during the day, with no net change in energy use D.pay less for energy because natural gas is more expensive at night

Phys 150 Lecture 2729Phys 150 Lecture 2729 i>clicker question In the winter, if you turn down your thermostat at night (but put it back to normal during the day), you will A.use less energy B.use more energy C.use less energy at night but more during the day D.pay less for energy because natural gas is more expensive at night -Heat loss is proportional to temperature difference between inside and outside

Phys 150 Lecture 2730Phys 150 Lecture 2730 i>clicker question Which of these is NOT a unit of energy? A.BTU B.Calorie C.kW D.Joule

Phys 150 Lecture 2731Phys 150 Lecture 2731 i>clicker question Which of these is NOT a unit of energy? A.BTU – beware: furnaces, etc., are rated in BTU – but they really mean BTU/hr B.Calorie C.kW – power (kWh is unit of energy) D.Joule