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More on Energy Conservation

More on Energy Conservation. Lecture #16 HNRT 228 Spring 2016 Energy and the Environment. Overview of Material. Energy Conservation Space Heating Thermal Insulation Air Infiltration Lighting Appliances Some considerations of agriculture and industry. iClicker Question.

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More on Energy Conservation

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  1. More on Energy Conservation Lecture #16 HNRT 228 Spring 2016 Energy and the Environment

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

  3. 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 • D Depends on power plant output

  4. 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 • D Depends on power plant output

  5. iClicker Question • Which type of washing machine conserves the most energy and water? • A Top loader • B Front loader

  6. iClicker Question • Which type of washing machine conserves the most energy and water? • A Top loader • B Front loader

  7. iClicker Question Turning off your computer will harm it. A True B False

  8. iClicker Question Turning off your computer will harm it. A True B False

  9. iClicker Question Leaving your heat on is more efficient than turning it down because you need so much energy to heat the house back up. A True B False

  10. iClicker Question Leaving your heat on is more efficient than turning it down because you need so much energy to heat the house back up. A True B False

  11. iClicker Question • Which unit is used to measure insulation of walls? • A Q-value • B R-value • C S-value • D T-value • E U-value

  12. iClicker Question • Which unit is used to measure insulation of walls? • A Q-value • B R-value • C S-value • D T-value • E U-value

  13. iClicker Question • Which unit is used to measure insulation of windows? • A Q-value • B R-value • C S-value • D T-value • E U-value

  14. iClicker Question • Which unit is used to measure insulation of windows? • A Q-value • B R-value • C S-value • D T-value • E U-value

  15. iClicker Question • Which of the following will conserve more energy. • A A wall with R-value 12 • B A wall with R-value 14 • C A wall with R-value 16 • D A wall with R-value 18 • E A wall with R-value 20

  16. iClicker Question • Which of the following will conserve more energy. • A A wall with R-value 12 • B A wall with R-value 14 • C A wall with R-value 16 • D A wall with R-value 18 • E A wall with R-value 20

  17. iClicker Question • Which of the following will conserve more energy. • A A window with U-value 0.12 • B A window with U-value 0.14 • C A window with U-value 0.16 • D A window with U-value 0.18 • E A window with U-value 0.20

  18. iClicker Question • Which of the following will conserve more energy. • A A window with U-value 0.12 • B A window with U-value 0.14 • C A window with U-value 0.16 • D A window with U-value 0.18 • E A window with U-value 0.20

  19. National Average Home Energy Costs

  20. 70 'F 30 F Furnace Why do we need Heating?

  21. Typical Heat losses- Conventional House

  22. iClicker Question • Energy transfer by electromagnetic waves is • A Radiation • B Convection • C Conduction

  23. iClicker Question • Energy transfer by electromagnetic waves is • A Radiation • B Convection • C Conduction

  24. iClicker Question • Energy transfer by the bulk motion, or large scale motion of molecules in gas or liquid form from one location to another is • A Radiation • B Convection • C Conduction

  25. iClicker Question • Energy transfer by the bulk motion, or large scale motion of molecules in gas or liquid form from one location to another is • A Radiation • B Convection • C Conduction

  26. iClicker Question • Energy transfer by contact of molecule with another molecule is one way to define • A Radiation • B Convection • C Conduction

  27. iClicker Question • Energy transfer by contact of molecule with another molecule is one way to define • A Radiation • B Convection • C Conduction

  28. Conduction Energy is conducted down the rod as the vibrations of one molecule are passed to the next, but there is no movement of bulk material

  29. Convection Energy is carried by the bulk motion of the fluid

  30. Radiation Energy is carried by electromagnetic waves. No medium is required

  31. Degree Days • Index of fuel consumption indicating how many degrees the mean temperature fell below 65 degrees for the day • Heating degree days (HDD) are used to estimate the amount of energy required for residential space heating during the cool season. • Cooling degree days (CDD) are used to estimate the amount of air conditioning usage during the warm season

  32. How do we calculate HDD? • HDD = Tbase - Ta • if Ta is less than Tbase • HDD = 0 • if Ta is greater or equal to Tbase • Where: Tbase = temperature base, usually 65 F Ta = average temperature, Ta = (Tmax + Tmin) / 2

  33. Heating Degree Days • Calculate the number of degree days accumulated in one day in which the average outside temperature is 17ºF. Degree days = 1 day ( 65 – Tout) = 1 (65-17) = 48 degree days

  34. Heating Degree Days in a Heating Season • Calculate the degree days accumulated during a 150-day heating season if the average outside temperature is 17ºF Solution: Heating Season Degree days = 150 days ( 65 – Tout) = 150 (65-17) = 7,200 degree days

  35. Degree Days for the Heating Season For Virginia data see http://cdo.ncdc.noaa.gov/climatenormals/clim81/VAnorm.pdf Sterling, VA 5237

  36. Significance of HDD • Mrs. Young is moving from Anchorage, Alaska (HDD =10,780) to State college, PA (HDD = 6,000). Assuming the cost of energy per million Btu is the same at both places, by what percentage her heating costs will change? Solution HDD in Anchorage, Alaska = 10,780 HDD in State College PA = 6,000 Difference = 10,780 - 6,000 = 4,780 Saving in heating fuel costs are

  37. Home Energy Saver Online • http://homeenergysaver.lbl.gov/

  38. Home Heating Costs in State College, PA Average House Energy Efficient House Total $1,891 Total $1,019

  39. Home Heating Costs • Related to amount of insulation, material that resists the flow of heat • Insulation is rated in terms of thermal resistance, called R-value, which indicates the resistance to heat flow. The higher the R-value, the greater the insulating effectiveness. The R-value of thermal insulation depends on the type of material, its thickness, and density. • R-30 better than R-11

  40. Places to Insulate • Attic is usually the easiest ad most cost effective place to add insulation • Floors above unheated basements should be insulated • Heated basements should be insulated around the foundaton

  41. R-values for Building Materials

  42. Thickness of various materials for R-22

  43. R-Value for a Composite Wall

  44. Home Heating Energy • Heat loss depends on • Surface Area (size) • Temperature Difference • Property of the wall ( R value) Outside 30¨F Inside 65¨F Q (Btus) 1 A (area) x Temperature Diff (Ti – To) = t (time, h) R

  45. Q Q t t Heat Loss Tcold Thot Heat Loss = Id Q/t is in Btu/h Area in ft2 Tin-Tout in °F Then the thermal resistance is R-value. The units of R-value are

  46. Wall loss rate in BTUs per hour • For a 10 ft by 10 ft room with an 8 ft ceiling, with all surfaces insulated to R19 as recommended by the U.S. Department of Energy, with inside temperature 68°F and outside temperature 28°F:

  47. Calculation per Day • Heat loss per day = (674 BTU/hr)(24 hr) = 16,168 BTU • Note that this is just through the wall • The loss through the floor and ceiling is a separate calculation, and usually involves different R-values

  48. Calculate loss per "degree day" • If the conditions of case II prevailed all day, you would require 40 degree-days of heating, and therefore require 40 degree-days x 404 BTU/degree day = 16168 BTU to keep the inside temperature constant. • This is the loss per day with a one degree difference between inside and outside temperature.

  49. Heat Loss for Entire Heating Season. • The typical heating requirement for a Pittsburgh heating season, September to May, is 5960 degree-days (a long-term average). Heat loss = Q/t = 404 Btu/degree day x 5960 degree days = 2.4 Million Btus

  50. Economics of Adding Insulation • Years to Payback  =       C(i) x R(1) x R(2) x E-------------------------------------  C(e) x [R(2) - R(1)] x HDD x 24 • C(i)  =  Cost of insulation in $/square feet • C(e)  =  Cost of energy, expressed in $/Btu • E  =  Efficiency of the heating system • R(1)  =  Initial R-value of section • R(2)  =  Final R-value of section • R(2) - R(1) =  R-value of additional insulation being considered • HDD  =  Heating degree days/year • 24  =  Multiplier used to convert heating degree days to heating hours (24 hours/day).

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