Lecture 11 Conservation

1. Fall 2011 Lecture 11 Conservation

2. Assignments Energy Audit 2Prepare a summary report of the energy usage of your building extracted from the ITRON web site. This should include data from different periods of the year to cover times with heating and air conditioning, and varying building occupancy; an analysis of daytime vs. night time usage (which may be very useful in helping to identify energy savings), and weekday vs. weekend. Length: ~two pages of text plus figures. Upload to ELMS. Due Date: Tonight New Reading Assigment - Chapter 5 Wolfson EXAM – Likely November 1

3. What year was the PC (IBM Personal Computer) Introduced 1970 1975 1980 1982 1984 1986 1990 Page 3

4. Steve Jobs http://www.youtube.com/watch?v=OYecfV3ubP8 Page 4

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6. Production vs. Conservation ANWR

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8. Production vs. Conservation ANWR - total reserves estimated at 5-10 billion barrels of oil US annual oil consumption: 7 billion barrels per year If we increase mileage from 27(current) to 30 mpg, this saves an ANWR every 6-12 yrs…

9. What could go wrong? Page 9

10. http://www.mckinsey.com/clientservice/electricpowernaturalgas/downloads/US_energy_efficiency_full_report.pdfhttp://www.mckinsey.com/clientservice/electricpowernaturalgas/downloads/US_energy_efficiency_full_report.pdf The width of each column represents the amount of efficiency potential (in trillions of BTUs), while the height represents to annualized cost in dollars per million BTUs Page 10

11. McKinsey Study: • By 2020: • invest $520 Billion • save $1200 Billion • reduce US energy by 9 quads Page 11

12. Energy Conservation vs. Conservation of Energy First Law of Thermodynamics Energy is conserved Energy Conservation Reduce usage of energy More efficient production More efficient distribution More efficient products Changing our usage patterns Personal choices “The cleanest power plant is the one never built.”

13. Global Energy Usage - Selected Countries Australia 5700 Bangladesh 161 Brazil 1067 China 1138 France 4518 Germany 4203 Ghana 400 India 512 Japan 4040 Kenya 481 Mexico 1533 Russia 4423 South Africa 2596 US 7794 2003 Energy per capita in kg oil equivalent

14. Why are we such energy hogs? • The US is a large country • Our standard of living is much higher • Oil companies have too much political influence • We don’t care about conservation • We are not hogs - the rest of the world is just catching up.

15. Energy Star rated appliances Page 15

16. Energy Star Joint program of EPA and DoE Started in 1992 certifies products as energy efficient now expanded to buildings > 95% of computer monitors are ES rated 20% heating systems 20% washers/dryers Program has saved ~5% of total US electricity demand in 2006

17. Energy Saved Page 17

18. Standby power • 1 W on for a year is ~3.15x107 Wsec • ~3.15x107 Wsec / 3600 sec/hr = 8750Wh = 8.750kWh • At $0.15/kWh -> $1.31 per year/kWh • http://standby.lbl.gov/summary-chart.html Page 18

19. Lighting - Incandescent vs. Compact Fluorescent

20. Incandescent Spectrum Compact Fluorescent Spectrum Page 20

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22. Incandescent Spectrum HalogenSpectrum Page 22

23. Lighting Light output measured in lumens Amount of visible light per solid angle Lights with equal lumens have equal brightness Maximum possible efficiency = 684 lm/W (all energy converted to visible light) Incandescent bulb : ~ 1700 lm for 100 W Compact Fluorescent Lights (CFL) ~1700 lm for 23W Sold as 100 W equivalent , i.e. same lumen output as 100 W incandescent bulb Typically 4X more efficient!

24. Say goodbye to incandescent bulbs…

25. Do they save me money? • 100 W CFL ~ $3.00 • 100 W Incandescent ~ $0.75 • Calculate payback time • Assume I use light ~ 3 hrs. per day • In one year incandescent consumes 3h X 0.1 kW X 365 = 110 kWh • I pay $ 0.15 /kWh to PEPCO • My cost per year = $16.50 • The CFL only uses 24 W, so cost is (24/100) $16.50 = $3.96 • I save a difference of $12.50/year • I invested $2.25, so it pays back in 2.25/12.5 = .18 years = 2 months!! • Should I replace a working incandescent bulb?

26. What happens to the heat incandescent bulbs produce? • In the summer they add to your air-conditioning bill • it takes ~3 times less energy to remove the heat – • still that adds 30% • In the winter – it adds heat so your electric bill is reduced • normal heating costs about half as much as electric resistance heat so you save about 50% in the winter Page 26

27. A bathroom decision My wife wanted to renovate our bathroom The designer said “what about a heated floor? I wanted to know what it was going to cost to operate Page 27

28. How much was a heated floor going to cost to use? • The floor heater uses 400W (when on) • Using the calculation from above: • At $0.15/kWh -> $1.31 per year/kWh • So this would be about $520/year • But the heater only runs at most 5 hours/day so about 1/5th of the time • So $520-> $100/yr • But I only use it in the winter (say 1/2 of the year) • So now it’s $50/yr • But I only use it when we would be using heat so it adds heat to the house • This is about a factor of 2 less efficient than my heat pump • So now it’s $25/yr Page 28

29. So what did we do? Page 29

30. Fluorescent Lamps Low pressure mercury discharge gives off UV UV hits a fluorescent coating that emits a white light Page 30

31. What about mercury? • CFLs typically have 3-5 mg of Hg (as do all fluorescents) • About 1/3 of all Hg emissions come from coal power plants • According to EPA about 50 tons Hg are emitted each year by coal plants • They generate 2 X 1012 kWh of electricity per year • Coal produces 50 X 109 mg/2X1012 kWh = 2.5 X 10-2 mg/kWh • A 100 W incandescent bulb lasts about 2000 hrs., using a total of 200 kWh of electricity. • If all from coal this would be lead to 5 mg of Hg • Bottom line: mercury is about the same (assuming we do NOT recycle CFLs) Page 31

32. LEDs - Light emitting diodes • Even more efficient than CFLs • Different colors • Now used in traffic lights, car tail lights • Still too expensive for straight replacement The New Year’s ball in Times Square

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34. Stopping Heat Loss at Home http://www.iranalyzers.com/home/ Page 34

35. Insulation Heat transfer: Radiation Convection Conduction

36. Eliminating radiation losses - use layers(Note: infrared doesn’t go through glass) Stefan-Boltzmann Law: Power radiated = A  T4 A  T14 Outside (cold) Inside (warm) A  T24 P1 = A  T14 - T24 ) Double pane window T1 T2 Add intermediate layer: A  T14 A  Ti4 P1 = A  T14 - Ti4 ) = = A  T14 - (1/2)(T14 + T24)) = A (1/2) (T14 - T24) -> 2X less power lost! A  T24 A  Ti4 T1 T2 Ti Balance: T14 + T24 = 2 Ti4 Ti4 =(1/2)(T14 + T24)

37. Convection loss Easy: seal up any cracks, block drafts Problem: If your house is too tightly sealed, may have problems with indoor air quality Average US house - changes air 1 - 1.5X per hour Can be reduced to ~ 0.2X per hour safely But depends on building materials Formaldehyde in FEMA trailers!

38. Conduction loss Use insulation Measured with R value Rate of heat transfer = A T/R R-1 about 1 inch of still air R-values add In MD we should have R-30 in our attics

39. Windows Can be responsible for up to 40% of heat loss Single pane -> double pane ->triple pane As good as R-10

40. UMD's 'WaterShed' Wins Solar Decathlon 2011 Home's Innovative Sustainablity Inspired by the Chesapeake Bay UMD's WaterShed combines energy efficiency and water conservation Click all images for hi-res. COLLEGE PARK, Md. - The University of Maryland's innovative WaterShed House has won the highly competitive U.S. Department of Energy Solar Decathlon 2011. http://newsdesk.umd.edu/engaged/release.cfm?ArticleID=2529 Page 40

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42. LEED Certification • Leadership in Energy & Environmental Design (LEED) • Defines a “Green Building standard” • Points are distributed across in categories such as: • Sustainable Sites, • Water Efficiency, • Energy and Atmosphere, • Materials and Resources, • Indoor Environmental Quality • Rating • Certified - 40 - 49 points • Silver - 50 - 59 points • Gold - 60 - 79 points • Platinum - 80 points and above Page 42

43. First Platinum Re-Developed Building 1225 Connecticut Avenue, N.W., located in the Dupont Circle neighborhood Page 43

44. Passive Solar

45. Passive Solar

46. Home heating - First Law vs. Second Law First Law Efficiency: Energy out/energy in Example: resistive electric heat ~ 100% efficient (1st Law) Heating requires relatively low temperatures (don’t want 500 deg air blowing out of ducts) Need to go from Toutside~ 273 K to Tinside ~ 300 K Wouldn’t we be better off moving heat around, especially since the indoor and outdoor temperatures are not too different? Second Law Efficiency: Energy of absolute best process (Carnot)/(energy in) Tinside /(Tinside-Toutside)=300 K/27k= 11 Now electric heat is 9% efficient (2nd law) : We have lots of room for improvements!

47. My (parents) home is heated with… • Natural gas • Propane • Oil • Electric (resistive) heat • Heat Pump • Solar • I have no clue.

48. Furnaces Oil -popular in New England Natural gas Propane Very efficient (1st Law) >90% Not a lot of room for improvements Home heating

49. Heat Pumps Move heat from outside to inside ( a refrigerator run backwards - cooling the outdoors)

50. Heat Pumps Rated with SEER rating (Seasonal Energy Efficiency rating) SEER = ratio of seasonally averaged cooling power in BTU/h compared to Watts of electricity used (measured when used as air conditioner) e.g. SEER of 16 produces almost 5X more cooling power than it uses in electricity -remember - we are moving heat so we can have a 1st Law efficiency > 1! -Why don’t we all have heat pumps?