bringing energy into the classroom robert k. kaufmann boston university august 11, 2014
TRANSCRIPT
Bringing Energy Into the ClassroomBringing Energy Into the Classroom
Robert K. Kaufmann
Boston University
August 11, 2014
http://www.bu.edu/cees/people/faculty/kaufmann/index.html
Bringing Energy Into the Bringing Energy Into the ClassroomClassroom
- Understanding energy- Touch measures of energy efficiency- Building energy use- A home energy audit- How much energy do I use directly
Measuring Energy Measuring Energy
Calorie The heat required to raise the temperature of one gram of water one degree Celsius
Human Body Temperature
‘Normal’ body temperature 37oCActive Range 36oC - 38oCStability Range 34oC - 41oCCritical thermal maximum 43oCCritical thermal minimum 28oC
So LetSo Let’’s Do a Simple Calculations Do a Simple Calculation
How much do you weigh? ________(kilograms)What is normal room temperature? ____ (degrees Celsius)What percentage of your body is water ______ (percentage 60M 55F)How many calories are needed to maintain each gram of your body __?How many calories do you need to eat ____?
Law of Conservation
Matter is neither created nor destroyed in a physical or chemical transformation
Second Law of Thermodynamics
In all energy conversion processes, energy loses its ability to do work and is degraded in quality
Energy In Equals Energy OutEnergy In Equals Energy Out
Energy In Work out
Waste Energy (Heat)
Machine
Efficiency = Work out/Energy in
Energy Flows in Light BulbsEnergy Flows in Light Bulbs
Electricity In Light
Waste Energy (Heat)
Light Bulb
Efficiency = Work out/Energy in
LightbulbsLightbulbs
Incadescent bulbIncadescent bulb
Compact FlourescentCompact Flourescent
Halogen bulbHalogen bulb
What Kind of Bulb to Buy?What Kind of Bulb to Buy?
How much does the bulb cost?How much does electricity cost?How long does the bulb last?How often is the bulb on?What is the interest rate?
A Calculation?A Calculation?
dollars/megalumen-hour=( initial-dollars+watts-consumed*dollars-per-kilowatt-hour*thousand-hours-lifetime) ( average-lumens * thousand-hours-lifetime / 1000 )
60-watt incandescent bulb, 800 lumens, 1,000 hours lifetime, $1.00 initial cost:
( $1.00 + 60 * $0.10 * 1 ) / ( 800 * 1 / 1000 ) = ( $1.00 + $6.00 ) / 0.8 = $8.75 / megalumen-hour
15-watt CFL bulb, 800 lumens (680 average), 6,000 hours lifetime, $5.00 initial cost:
( $5.00 + 15 * $0.10 * 6 ) / ( 680 * 6 / 1000 ) = ( $5.00 + $9.00 ) / 4.08 = $3.43 / megalumen-hour
Personal Energy AuditPersonal Energy Audit
- How much energy do you use to move around?- How much energy do you use to heat your house ?- How much energy do you use to cool your house?
Home Energy AuditHome Energy Audit
Obtain Information- Electric Company (monthly bills)- Gas Company (monthly bills)- Oil Company (monthly bills)- - Weather Data (daily temperature)- Size of home (square meters)
Weather DataWeather Data
Heating Degree Days = 65oF – Outside TemperatureCooling Degree Days = Outside Temperature – 65oF
Measuring Energy UseMeasuring Energy Use
Heating Degree Days or Cooling Degree Days per MonthHeating Degree Days or Cooling Degree Days per Month
Ene
rgy
Use
per
Mon
thE
nerg
y U
se p
er M
onth
Slope = Slope = Energy UseEnergy Use HDDHDD