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

What is Energy?What is Energy?

Anything that has the ability to do work

Measuring Energy Measuring Energy

Calorie The heat required to raise the temperature of one gram of water one degree Celsius

Reading Food LabelsReading Food Labels

Ask students to bring in their favorite food

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 ____?

Touch Measure of Energy Touch Measure of Energy EfficiencyEfficiency

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

Light Bulb EfficiencyLight Bulb Efficiency

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

Building Energy UseBuilding Energy Use

Daily Electricity UseDaily Electricity Use

Weekly Electricity UseWeekly Electricity Use

Annual Electricity UseAnnual Electricity Use

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?

Energy Used to MoveEnergy Used to Move

Track how far you go each week by type of vehicle

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

ComparisonsComparisons