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Lighting In the LibraryA Student Energy Audit

Lighting In the LibraryA Student Energy Audit

. . OFFICE OF ENERGY EFFICIENCY

AND RENEWABLEENERGY

OFFICE OF BUILDING TECHNOLOGY,

STATE AND COMMUNITY PROGRAMS

Table of Contents

Description Page

Introduction

Overview and goals of the current and planned school energy audit activities ....................................................................................... 1

Background information on school energy issues .................................................................................................................................... 1

National science and mathematics content standards and benchmarks ................................................................................................. 2

Assessment discussion ............................................................................................................................................................................. 3

Rubric ........................................................................................................................................................................................................ 4

Getting Ready for the Lighting in the Library Activity ................................................................................................................................ 5

Lighting in the Library ActivityStudent Pages

Suggested Activity for class period one:

Lighting in the library activity background and example material .................................................................................student pages 1-2

Data gathering and observation math problem worksheet ................................................................................................ student page 3

What is the current situation math problem worksheet ....................................................................................................... student page 4

Suggested Activity for class period two:

Determine the feasibility of installing energy-efficient lighting .......................................................................................... student pages 5

Light output and cost data for several energy-efficient lamps ............................................................................................. student page 6

Plan new approach math problem worksheets ................................................................................................................. student pages 7

Compare your new approach with your current situation .................................................................................................. student pages 8

What’s the bottom line math problem worksheet ................................................................................................................. student page 9

Summary of variables used in the calculations worksheet ................................................................................................ student page 10

AppendixTransparency Masters

High School Energy Inventory: Lighting Technology Primer

All About Energy Primer

Glossary

Lighting In The LibraryA Student Energy Audit

Overview / School Energy Audit:The U.S. Department of Energy’s vision for Energy Smart Schools is to “form a nationalpartnership to cut energy bills in schools and reinvest the savings in educating the nation’smost valuable resource….our children”. The plan is to invest in “books not BTUs”. Someschools have taken the energy savings dollars and reinvested the funds into local educa-tion priorities. By reducing energy use, our schools could spend approximately $1.5 billionmore on books, computers, and teachers each year by the year 2010. That amounts toalmost $30 for each student, 40 million new textbooks, or 30,000 new teachers. In thisactivity, your students learn science and mathematical concepts in a hands-on, minds-onway. They become empowered to research their school environment and make recommen-dations for changes. They begin by focusing on the energy saving and pollution preventingopportunities that can be achieved by changing the light bulbs in your school library. Theyconclude their work by extending these findings to the opportunities in the entire school andpreparing a presentation for the school board.

LevelGrades 8-12

SubjectMathematics

Goals of the High SchoolEnergy Audit

• Provide students with tools andinformation they need to effec-tively monitor energy use withintheir school building

• Identify ways to save their schoolsmoney by using energy wisely

• Understand that the informationthat they learn may be used tohelp improve the environment

• Create in students and teachersan appreciation and passion forusing energy efficiently andwisely

• Assist schools in using theirschool buildings as workinglaboratories for learning aboutenergy

• Encourage schools to considermanaging or retrofitting theirbuildings so that energy is usedas efficiently and wisely aspossible

• Link between energy use likelighting and electricity produc-tions at power plant to CO2

emissions at smokestack toGreenhouse gas/global warming

IntroductionWe spend most of our time in buildings—homes, schools, offices, and stores. Butmost people hardly notice details about thebuildings, such as how they are designed,how they are built, and how well they aremaintained. The details have a strongeffect on how comfortable a building is andhow much it costs to operate.

An “energy-efficient” building is morecomfortable than a wasteful building. Itneeds less fuel for heat and less electricityfor cooling. A building that is badlydesigned and poorly maintained wastesmoney. This is because the buildingcomponents are trying to heat and air-con-dition the outdoors as well as the indoors.

In a 1995 report, School Facilities: Condi-tion of America’s Schools, the GeneralAccounting Office (GAO) estimated that thecost of bringing the Nation’s 110,000 K-12schools into good overall conditions was$112 billion.

The report revealed:• 28,100 schools serving 15 million

students have less-than-adequateheating, ventilation, and air-conditioningsystems

• 23,100 schools serving 12 millionstudents have less-than-adequateplumbing

• 21,100 schools serving 12 millionstudents have less-than-adequate roofs

The National Center for EducationStatistics projects that elementary andsecondary enrollments will swell from 52.2million in 1997 to 54.4 million in 2006. Soas our nation grapples with modernizingolder schools we will also need to build anadditional 6,000 new schools to accommo-

date growing student enrollment over thenext decade. We must take advantage ofthis building boom to introduce energyefficiency in the design, construction andoperation of our nation’s next generation ofschool buildings.

With the backlog for repairs and continuedoperation of older, inefficient, and oftenpolluting equipment and school buses, ourschools are wasting large amounts ofenergy and valuable taxpayer dollars thatcould be used to teach students. Ournation’s schools spend over $6 billion ayear on energy. Significant opportunitiesexist to lower energy bills with equipmentupgrades and the use of widely availableenergy-efficient technologies such asenergy-efficient lights, motors, energymanagement systems and alternativelyfueled school buses.

As an added benefit, these improvementscan result in better lighting conditions,better indoor and outdoor air quality, andbetter controlled classroom temperature –all of which can improve the productivityand general well-being of students andteachers.

Impact of InadequateSchool Facilities onStudent LearningBusinesses have spent millions of dollarson understanding the link between workenvironment and productivity. Yet, wegenerally view schools as separate publicinstitutions the same way we view correc-tional facilities. Current research has linkedstudent achievement and behavior to thephysical building conditions and over-crowding.

Teachers� Guide 1

OFFICE OF ENERGY EFFICIENCY AND RENEWABLE ENERGYBUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMS

High School Energy Auditand Teachers� Guide

Energy Smart Schools

High School Energy Audit

The High School Energy Audit

Guide is a tool for you to use with

your students to take an active role

in making changes in the school

environment. Contact your

administration and find out if your

school is on the school construc-

tion or retrofit schedule for your

school district. If it is, an opportu-

nity exists for your students to

complete the energy audit and

make a formal presentation to the

school board and administration

on their energy saving recommen-

dations. The audit is designed to

use the library, and eventually the

whole building as a working and

living laboratory for the students to

learn about energy efficiency and

renewable energy. The U.S.

Department of Energy will make

additional school energy audit

activities available before the end

of the school year for those who

would like to extend this project

into a more comprehensive audit.

For the most update activities and

information, please continue to

check the following web page

address: http:ww.eren.doe.gov/

buildings/earthday/.

Earth Day Teachers� Guide 2

Decaying environmental conditions suchas peeling paint, crumbling plaster,nonfunctioning toilets, poor lighting,inadequate ventilation, and inoperativeheating and cooling systems can affect thelearning as well as the health and themorale of staff and students. A school yearis approximately 180 days. This is alot oftime to spend in an atmosphere that is notconducive to learning or teaching.

National Science andMathematics ContentStandards and Benchmarksfor Science LiteracyThe content and associated activities arechallenging and rigorous for high schoolstudents. The standards and benchmarksthat are covered in these activities arenoted in the individual teacher guides. Thestandards that are covered in the HighSchool Energy Audit are as follows:

National Science EducationStandardsPHYSICAL SCIENCEContent Standard AScience as InquiryAs a result of their activities in grades9-12, all students should develop:• Abilities necessary to do scientific inquiry• Understandings about scientific inquiry

Content Standard BAs a result of their activities in grades 9-12,all students should develop an under-standing of:• Conservation of energy and increase of

disorder• Interactions of energy and matter

SCIENCE IN PERSONAL AND SOCIALPERSPECTIVESContent Standard FAs a result of activities in grades 9-12, allstudents should develop understanding of:• Natural resources• Environmental quality• Science and technology in local,

national, and global challenges

Benchmarks for Science LiteracyBenchmark 4 –The Physical Setting4B – The Earth - Students will understandphysical concepts and principles as energy,gravitation, conservation, and radiation.

Benchmark 5 –The Living Environment5E – Flow of Matter and Energy - Studentswill understand the conservation of matterwith the flow of energy in living systems.

Benchmark 8 –The Designed World8C – Energy Sources and Use - Studentscan examine the consequences of theworld’s dependence on fossil fuels,explore a wide range of alternative energyresources and technologies, and considertrade-offs in each. They can proposepolicies for conserving and managingenergy resources.

National Math StandardsStandard 1: Mathematics asProblem SolvingIn grades 9-12, the mathematics curricu-lum should include the refinement andextension of methods of mathematicalproblem solving so that all students can:• use, with increasing confidence,

problem-solving approaches toinvestigate and understandmathematical content;

• apply integrated mathematical problem-solving strategies to solve problemsfrom within and outside mathematics;

• recognize and formulate problemsfrom situations within and outsidemathematics;

• apply the process of mathematical mod-eling to real-world problem situations

Standard 2: Mathematics asCommunicationIn grades 9-12, the mathematics curricu-lum should include the continued devel-opment of language and symbolism tocommunicate mathematical ideas so thatall students can:• reflect upon and clarify their thinking

about mathematical ideas andrelationships;




• formulate mathematical definitions andexpress generalizations discoveredthrough investigations;

• express mathematical ideas orally andin writing;

• read written presentations of mathemat-ics with understanding;

• ask clarifying and extending questionsrelated to mathematics they have reador heard about;

• appreciate the economy, power, andelegance of mathematical notation andits role in the development of math-ematical ideas.

Standard 3: Mathematics asReasoningIn grades 9-12, the mathematics curricu-lum should include numerous and variedexperiences that reinforce and extendlogical reasoning skills so that all studentscan:• make and test conjectures;• formulate counterexamples;• follow logical arguments;• construct simple valid arguments;

and so that, in addition, college-intendingstudents can:• construct proofs for mathematical

assertions, including indirect proofs andproofs by mathematical induction.

Standard 5: AlgebraIn grades 9-12, the mathematics curricu-lum should include the continued study ofalgebraic concepts and methods so that allstudents can:• represent situations that involve variable

quantities with expression, equations,inequalities, and matrices;

• use tables and graphs as tools tointerpret expressions, equations, andinequalities;

• operate on expressions and matrices,and solve equations and inequalities;

• appreciate the power of mathematicalabstractions and symbolism—and so that, in addition, college-intending students can:

• use matrices to solve linear systems;• demonstrate technical facility with

algebraic transformations, includingtechniques based on the theory ofequations.

Standard 6: FunctionsIn grades 9-12, the mathematics curricu-lum should include the continued study offunctions so that all students can:• model real-world phenomena with a

variety of functions;• represent and analyze relationships

using tables, verbal rules, equations,and graphs;

• translate among tabular, symbolic, andgraphical representations of functions;

• recognize that a variety of problemsituations can be modeled by the sametype of function;

• analyze the effects of parameterchanges on the graphs of functions;and so that, in addition, college-intending students can understandoperations on, and the generalproperties and behavior of, classesof functions.

Standard 10: StatisticsIn grades 9-12, the mathematics curricu-lum should include the continued study ofdata analysis and statistics so that allstudents can:• construct and draw inferences from

charts, tables, and graphs that summa-rize data from real-world situations;

• use curve fitting to predict from data;• understand and apply measures of

central tendency, variability, andcorrelation;

• understand sampling and recognize itsrole in statistical claims;

• design a statistical experiment to studya problem, conduct the experiment, andinterpret and communicate the out-comes;

• analyze the effects of data transforma-tions on measures of central tendencyand variability; and so that, in addition,college-intending students can:

• transform data to aid in data interpreta-tion and prediction;

• test hypotheses using appropriatestatistics.

Assessment/RubricAn assessment is just one methodof evaluating each student’s graspof the major concepts presented in

the activities. Teachers areencouraged to use the assess-

ments as-is or to develop their ownassessments that meets the

individual needs of the students.The assessments are used at the

end of each activity. However,these assessments are provided asguidelines for the teacher to use indeveloping appropriate measure-

ment packages. Many assessmenttechniques are available, including

multiple-choice, short-answer,discussion, or open-ended ques-tions; structured or open-endedinterviews; homework; projects;

journals; essays; dramatizations;and class presentations. Among

these techniques are thoseappropriate for students working in

whole-class settings, in smallgroups, or individually. The modeof assessment can be written, oral,or computer oriented. Please use

these ideas and add or deleteaccording to your needs. The tasksin this audit usually involve open-ended, problem-solving activities

but some will require recall ofcontent knowledge.

Included with the assessment is astandard, generic rubric. The rubric

is established as guideline forperformance. It is also a useful

form of self-evaluation because itlets the student know what is

expected for high quality work.




Student RubricCreditsThe National Renewable EnergyLaboratory would like to give creditto the following agencies forsupplying information that used toprepare the High School EnergyAudit :

National Energy Education Devel-opment (NEED) Project withtechnical assistance from Dr. LoriMarsh of Virginia Tech

U.S. Department of EnergyAtlanta Regional Support OfficeAtlanta Student Audit ProgramPrepared by Gregory Guess of theKentucky Natural Resources andEnvironmental Protection Cabinet,Division of Energy

Ken Baker of the Idaho Departmentof Water Resources,Energy DivisionEnermodal Engineering, Inc.John Heiland Grand ConnectionsPacific NorthwestNational LaboratoryIdaho Commercial BuildingEnergy Code Users Guide

U.S. Department of EnergyMaking Cents of Your EnergyDollar: A Guide to IdentifyingEnergy and Cost Saving Opportu-nities in Institutional Buildings,Volume 1 - Energy Audit

U.S. Department of Housing andUrban DevelopmentIn the Bank or Up the Chimney?A Dollars and Cents Guideto Energy-Saving HomeImprovements

Carol WilsonSavings Through EnergyManagement (STEM) Program

Energetics, IncorporatedGraphic design and editing


E xceeds M eets M eets S o m e D oes N o t M eet E xpectations E xpectations E xp ectatio ns E xpectation s

P oints E arned 6 4 2 0

Calculations of the activities and observations that were conducted

Calcula tions are complete, include clear writing, re levant examples, and contain very few

Calcula tions are complete, written clearly and have few errors

Calcula tions are incom plete, unclear, or contain seve ral errors

No calcula tions of activities are included

Data show ing potential sources of energy savings

Data is well done and includes useful information. Graphs and symbols are used

Data complete and includes a useful graph

Data is not clear or incomplete

No data is supplied

Description of how the team will validate the findings

Multiple validation techniques are used that produce accurate and conclusive

Validation techniques are effective and produce conclusive results

Efforts are made to validate the information but is incomplete, irrelevant, or

There is no validation o f the find ings

Explanation of the potential relevance or importance of the findings

The relevance is clearly articula ted and the explanation makes a compelling statemen t

The relevance of the find ings is clearly articulated

The explanation or relevance is illogical or fa ils to communicate c learly

No explana tion or relevance is offered

Use of the internet to research relevant information concerning building components and energy

Demonstrates the ability to research a topic w ithout assistance using several tools

Demonstrates the ability to research a topic w ithout assistance

Research topics with m in imal assis tance

Does not demonstrate the ability to research a topic

Cooperative group behavior

Team worked in a consistently positive mode; clear evidence of shared work and responsibility

Team worked mostly in a positive mode; effort made to include all mem bers

Team members requ ired careful monitoring; presentation component

Team members d id not work as a team

Presentation delivery Clear evidence of participation in some form by every team member; all parts well p lanned; strong portrayal of the teams specia l

Evidence of participation by the majority of the team; good planning and execution; special interest o f the team is evident

Participation by only 1 or 2 mem bers; little ev idence of group planning; special interest of team is not clearly presented

No participation by the team to p repare a presentation

Technology based presentation

Final project is enhanced through use of technology

Final project is partially technology based

Final project not technology based

No final project completed

errors


suggestions

,

results

Real life Math and Science Activities provided by U.S. Department of Energy�s Office of Energy Efficiency and Renewable Energy; Office of Building Technology, State and Community Programs

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GlossaryAnnual Energy Index. The ratio of thetotal annual energy consumption of abuilding or plant in millions of Btu divided bythe total building area in thousands of squarefeet. The AEI is computed in thousands ofBtu per square foot of building per annum asa way of characterizing energy usage in thebuilding.

Air Changes per Hour. A measure ofhow rapidly air is replaced in a room over aperiod of time, usually referring to thatreplaced by outside air.

Air Conditioning. The process of treatingair to meet the requirements of the condi-tioned space by controlling simultaneouslyits temperature, humidity, cleanliness anddistribution.

Air Conditioners. Systems that controlthe temperature and humidity of air usingelectricity to power fans and pumps calledcompressors. Air conditioners use arefrigeration cycle to extract heat from indoorair and expel the heat outside.

Air Handler. Mechanical ventilationsystems contained inside large sheet metalboxes. Air handlers have fans inside thatsupply air to rooms through ducts con-nected to them. Air handlers recirculate airinside buildings and provide fresh air fromoutside. They usually contain coils of coppertubing with hot or cold water inside thetubing. When fans blow air across the tubescontaining hot water, heat is transferred tothe air blown through the ducts for heating.When fans blow air across the tubescontaining cold water, heat is removed fromthe air blown through the ducts for cooling.

Air Infiltration. The process by whichoutdoor air leaks into a building by naturalforces (pressure driven) through cracks inwalls and around doors and windows.

Ballast. Devices for starting and controllingthe electricity used by a lamp. Ballasts alsoprotect electrical circuits in lighting systems.A ballast typically consumes 10 percent to20 percent of the total energy used by a lightfixture and lamp.

Boilers. Heating systems that burn naturalgas, oil, coal, or sometimes wood or wastepaper as fuel to heat water or producesteam. The heated water or steam is thencirculated in pipes to devices calledradiators and convectors. Radiators are made

of a series of large iron grids or coils, whileconvectors are usually made of networks ofnon-iron metal tubes with steel finssurrounding the tubes. Hot water or steamcan be circulated in a boiler system bypressure and gravity, but pumps are typicallyused to control the circulation moreefficiently. Boilers sometimes also providehot water for showers, cleaning, or otheruses in schools.

British Thermal Unit (Btu). The amountof energy required to raise one pound ofwater one degree Fahrenheit.

British Units. A unit of measure of energyand other scientific phenomena based onthe British Engineering System. For example,temperature is measured in degreesFahrenheit in British units.

Caulking. A flexible material made of latexor silicone rubber used to seal up cracks in awall or between window frames and doorframes and walls. Caulking reduces theinfiltration of outside air into a building andmakes it more energy efficient and reducesmaintenance due to wear from rain, sun, andother weather related stress on a building.

Celsius or Centigrade. The SI tempera-ture scale on which the freezing point ofwater is zero degrees and the boiling pointis 100 degrees at sea level.

Chillers. Refrigeration machines used insome schools to provide cool air. They usea refrigeration cycle that extracts heat fromwater and rejects it to outdoor water. Chillersproduce cold water that is fed through coilsof copper tubing contained in air handlers.Air handlers contain fans that blow air acrossthe copper tubes containing cold water. Thiscools the air, which is then delivered torooms through ducts.

Controls. Devices, usually consisting ofelectronic components, used for regulatingmachines; for example, a thermostat is acontrol that regulates the heating andcooling equipment in a building.

Cooling Load. Calculated on a monthly,yearly or seasonal basis by multiplying theoverall thermal transmittance (U-value) of abuilding (in Btu per hour per degree F persquare foot) times total building surface areatimes 24 hours/day times the number ofcooling degree days per time perioddesired.

Degree Days, Cooling. A method ofestimating the cost of cooling a residentialhome based on the local climate, and isusually expressed in the average number foran entire year. The degree day value for anygiven day is the difference between themean daily temperature and 65 F when thetemperature is greater than 65 F. The total forthe year is the sum of the average daily valuefor 365 days a year.

Degree Days, Heating. A method ofestimating the cost of heating a residentialhome based on local climate. Like coolingdegree days, heating degree days are usuallyexpressed in an average number for a year.The degree day value for any given day is thedifference between 65ºF and the mean dailytemperature when the temperature is lessthan 65 F. Degree days are a measure of theseverity of the heating season and aredirectly proportional to fuel consumption.

Ducts. An enclosed tube or channel,usually made of sheet metal or flexibleplastic, for delivering air to rooms in abuilding. Supply ducts bring treated air fromair handlers, consisting of warm air in thewinter to warm the rooms and cool air in thesummer for air conditioning. Old ducts thatlie in unconditioned areas of a building oftenleak significant quantities of air and can resultin large energy losses in a building.

Efficiency. The ratio of the energy usedfor a desirable purpose, such as heating orlighting, compared with the total energyinput, usually expressed in percent.

Electricity, or Electric Energy. A basicform of energy measure as kilowatt-hours(kWh). For conversion, one kWh ofelectricity is 3413 Btu�s. Electricity isgenerated in electric power plants, most ofwhich burn fossil fuels to produce heat,which is converted to electricity in agenerator. The process is not 100%efficient, and it takes, on average, about11,600 Btu of heat energy from fossil fuels togenerate 1 kWh of electricity.

Envelope, or Building Envelope. Theexternal surfaces of a building, including aswalls, doors, windows,roof and floors in contact with the ground.

Fahrenheit: The temperature scale in�English� units used in the United States andEngland on which the freezing point of


water is 32 degrees and the boiling point ofwater is 212 degrees at sea level.

Foot-candle. A unit of measure of theintensity of light. A foot-candle is a lumen oflight distributed over a 1-square-foot (0.09-square-meter) area.

Fossil Fuels. Fuels consisting of coal, oil,natural gas, propane, and those derivedfrom petroleum such as gasoline that arederived from prehistoric plants having been�fossilized� by remaining for eons underpressure underground. These fuels arecalled hydrocarbons because the hydrogenand carbon in the fuels combines withoxygen in the air to release heat energy.

Global Warming: Possible acceleratedincrease in the Earth�s temperature causedby excess production of greenhouse gasesdue, in large part, to the depletion offorests, air pollution from automobiles,making electricity via fossil fuels and burningfossils fuels for other needs.

Greenhouse Effect: The trapping of thesun�s heat. In houses and cars it can becaused by glass. In the Earth�s atmosphere itis a naturally occurring phenomenonresulting from the interaction of sunlight withgreenhouse gases (such as CO2 and CFCs).This interaction helps maintain the delicatebalance of temperature and breathable airnecessary for life as we know it.

Heat Capacity (rcp) per unit volume of air.As used in this document, heat capacity isthe amount of heat energy it takes toincrease the temperature of one cubic footof air by one degree Fahrenheit.

Heat Pumps. Energy-efficient heating andcooling systems that use the refrigerationcycle to move heat from one source (air,water, or the Earth) to another.

Heat Transfer. The movement of heatenergy always flowing in the direction fromhotter to colder through materials such aswalls or windows in a building. The flow ofheat energy is usually measured in terms ofBtu/h, and is equal to the area times thetemperature difference divided by thethermal resistance (R-value).

Heating, Venti lat ing, and Air-Condi-tioning (HVAC). Systems that provideheating, ventilation and/or air-conditioningwithin with buildings.

Humidity. The amount of water vapor inthe air, and usually expressed in terms ofpercent relative humidity. This figurerepresents the amount of moisture the airactually contains divided by the total amountof moisture that it is physically possible forthe air to hold at a particular temperature. Inother words, at 100% relative humiditycondensation will occur, and if outdoors, itwill start raining.

Insulation. Material used to increase theresistance to heat flow. In buildings, threetypes of insulations are most common: battsusually made from fiberglass that fit betweenwall studs or roof joists; loose-fill usuallymade from shredded newspaper (treatedcellulose) that is blow into wall cavities orattics; and rigid foam boards usually madefrom petrochemicals (polyisocyanurate) thatare nailed into walls, under roofs, or justbelow outside wall coverings like siding orsheathing.

Kilowatt (kW). A unit of electric powerequal to one thousand watts.

Kilowatt Hour (kWh). A unit of electricenergy equal to one thousand watts over aperiod of one hour.

Lamp. A generic term for a non-naturalsource of light. In fluorescent fixtures, lampsalso refer to the part of the glass tubes thatlight up when electricity is turned on.

Lumen. An SI unit of light output from asource such as a lamp or light fixture.Commonly, the efficacy of electrical lightingis gauged by the number of �lumens perwatt� of light output per unit of electricpower input listed on the lamp manufactur-ers� label.

Occupied Hours. The time when abuilding such as a school is normallyoccupied with people working or attendingclasses.

Power. The time rate of doing work, whichin SI units is measured in Watts, and in Britishunits, is measured in British thermal units perhour (Btu/h). In the United States, we usuallyrefer to electric power in terms of Watts andheat flow in terms of Btu/h.

Simple Payback Period. The length oftime required for an investment to pay foritself in energy savings.

SI Units. Units of measuring energy andother scientific phenomena based on theInternational System (or SI for SystmeInternationale d�Unites). For example,temperature is measured in degrees Celsiusin SI units.

Therm. A unit of gas fuel containing100,000 Btu�s. Most natural gas bills arecharged according to the number of thermsconsumed.

Thermal Resistance (R-value). A termused to measure an insulating material�sresistance to the flow of heat, and usuallymeasured in units of square feet x hour xdegrees F per Btu. Thermal resistance is thereciprocal of thermal conductance (U-value).R-values can be added together to obtain anoverall value for an insulated wall or ceiling.

Thermostats. Heating and coolingsystems� controls that monitor the tempera-tures of buildings and allow temperatures tobe maintained or changed automatically ormanually.

U-value (Thermal Transmittance): Overallcoefficient of heat expressed in British unitsas Btu�s per square foot per hour per degreeF. The lower the U-value, the less heat istransferred. Numerically, it is equivalent to thereciprocal of the sum of the thermalresistance of materials measured in their R-values.

Unoccupied Hours. The time when acommercial, industrial, or institutionalbuilding is normally empty of people, exceptmaintenance people such as janitors.

Ventilation. Air supplied to buildings fromoutdoors plus air recirculated from indoorsthat has been filtered and treated by heating,cooling, and/or air handling equipment.

Watt. An SI unit of measurement for power.In the United States, a watt almost alwaysrefers to electric power, and is equal to theamount of power (energy per second)supplied when one ampere of electriccurrent flows at a potential difference of onevolt. For conversion to British units, 1,000watts equals 3,413 Btu�s.

Weatherstripping. Materials such asmetal, plastic, or felt strips designed to sealspaces between windows and doorframesto prevent infiltration of outside air into abuilding.

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Glossary

OverviewThe purpose of the Lighting in the Library Activity is to calculate the electricity used toprovide lighting in the school library and determine the feasibility of saving energy andmoney by using energy efficient lighting fixtures.

Your students will assume the role of an energy auditor assigned the task of assessing thecurrent situation and making a recommendation for energy-efficient improvements. Thisactivitity requires a trip to the library, an examination of the school’s energy bill, and a basicunderstanding of algebraic concepts as a problem solving strategy.

LevelGrades 8 - 12

SubjectMathematics, Economics

Concepts• Efficiency: getting a desired

outcome lighting with the leasteffort and cost

• Energy-efficient lighting fixtures• Energy conservation• Cost of electricity

Applicable National StandardsNational Math Standards:• Standard 1: Mathematics as

Problem Solving• Standard 2: Mathematics as

Communication• Standard 3: Mathematics as

Reasoning• Standard 5: Algebra• Standard 6: Functions

Skills• Addition, subtraction, multiplica-

tion, and division• Compiling lighting energy and

cost data• Drawing a plan of the library• Critical thinking• Problem solving• Creating and giving presenta-

tions

ObjectiveCalculate the feasibility of replacingolder, less efficient lighting in thelibrary with new fixtures that aremore efficient and cost less tooperate.

(continued next page)

Getting ReadyThe exercise is designed in two parts. Thefirst part consists of determining the energyconsumption, operating costs, and amountof “greenhouse gases” resulting from theexisting lighting fixtures. The second partentails determining the economic feasibil-ity of retrofitting the existing fixtures withthree types of energy-efficient lights.

Two primers have been prepared to helpyou and your students ramp up yourenergy, environment, and lighting knowl-edge relatively quickly (see appendix). Inaddition, helpful hints and some examplesspecific to each step have also beenprovided. Before class, use the All AboutEnergy Primer or download a copy of thesecondary energy infobook located at:www.aep.com/environmental/renewables/solar/powerPie/pdf/second.pdf/). Eachstudent in the class should have a copy ofthe following:• All About Energy Primer or Infobook• student pages 1-10• Lighting technology primer• glossary

Choosing the Room in theSchool for the ExerciseThe exercise is designed for the schoollibrary; however it will work for almost anyroom in the school. If the school library isnot available, choose a different commonroom, preferably one with different kinds oflight fixtures with different on/off schedules.Ask the librarian or custodian to help thestudents determine the on/off schedule forthe lights in the library. For example, thereis typically one schedule for when school isin session and another for when it is out ofsession.

Additional Exercises forAdvanced StudentsAsk the students to see if there are anyrooms in the area to be studied wherelights are left on for long periods of timeand are not occupied. Advanced studentsmight determine the feasibility of installingmotion detectors for those rooms as anextra credit exercise. Motion detectors willautomatically turn lights on and off. Costsof motion sensors could be determined bycalling a local electrical wholesale houseand calculating labor at 1/2 hour per switchat a cost of $50 to $75 per hour for anelectrician’s time. The savings accrue fromthe number of hours the lights can beturned off. The payback period for theinvestment in motion detectors can becalculated in the same way as the Lightingin the Library exercise.

BackgroundLighting typically accounts for 15 percent ofthe total energy bill of educational institu-tions nationwide. The majority of buildingsbuilt before the 1970s have highlevels of illumination according to thedesign standards of the time. Most useolder fluorescent fixtures with four tubes,the standard fixture used in schools andoffice buildings for many years. As a result,most schools spend too much on lightingbills.

Since the late 1980s, many modernfluorescent fixtures have come equippedwith the more efficient T8 lamp operated byan electronic ballast. Depending on thetask being performed, there are situationswhere the old four light fixture can becoverted to a two light fixture and stillprovide the required amount of light. Theelectronic ballasts were developed tooperate fluorescent tubes more efficiently

Teachers� Guide 5

Lighting in the Library



Energy Smart Schools Teachers� Guide 6

and consume less energy when the lightsare on. Older, standard ballasts consumeup to 20 percent of the total amount ofelectricity required to operate the lamp.Therefore, a 1.2 multiplier was added tothe last equation in Step 5.

Light fixtures in this exercise are typical ofthose installed in schools built from the1950s to the 1980s. During this period, thestandard light fixture was the 4-tubefluorescent located in the ceiling. Incan-descent lighting remains the standardfixture for task lighting. The majority of exitsigns use incandescent bulbs. As studentswill see in this exercise, these fixtures canoften be replaced with newer, more efficienttypes of lighting that cost much less tooperate.

At the same time, there are a large varietyof light fixtures in schools used across thecountry. Some schools have been designedto use natural lighting so effectively incommon rooms, such as the library, that itwill be extremely difficult to reduce theirlighting bills. The best way to tell if there isan opportunity to improve the lightingefficiency of a room is to calculate the“lighting index” for the room as done inSteps 9, 14, and 19. If the index is above1.3 (W/ft2), there is likely an opportunity toeconomically reduce lighting energyconsumption in the library. If the index isbelow 1.3, it will be more difficult to do sowithin a 3-year payback period but thereare still many opportunities for savings andenhancing the visual environment thatwarrant serious consideration. Retrofittingthe lighting system in older buildings,especially in institutional buildings that areilluminated above the current lightingdesign levels, has proven to be one of themost cost-effective energy conservationmeasures. The savings from lightingretrofits depend on the amount of time thelights are used during the year. For lightsthat are on a large percentage of the time,simple payback on the cost of replacingthem is from one to three years.

(continued)Materials• Pencil, paper, and a ruler• Tape measure• One copy per student of the

Student Guide Primers:• Energy Primer or Infobook• High School Energy

Inventory: LightingTechnology Overview

• Student pages 1-10• Glossary

TimeTwo 55-minute classroom periods.

Doing the ActivityIdeally, the students would read theprimers first (perhaps as homework thenight before beginning the activity),and then complete the exercises insubsequent classes. Steps 1-9 shouldbe completed in the first class period.Steps 10-22 can be completed as acombination of in-class time andhomework. When the students aredone, they will have enough materialto prepare a presentation for theschool board about their energy-efficient proposal.


Lighting In the LibraryLighting In the LibraryStudent WorksheetsStudent Worksheets

. . OFFICE OF ENERGY EFFICIENCY

AND RENEWABLEENERGY

OFFICE OF BUILDING TECHNOLOGY,

STATE AND COMMUNITY PROGRAMS


Lighting in the LibraryThe purpose of this exercise is to determine the amount ofelectricity used to provide lighting to the school library.During the course of these activities you will need to imaginethat you are an energy auditor who needs to make recommen-dations to the school administration concerning the feasibilityof saving energy and money by using energy-efficient lighting.To complete this task, an energy auditor would need to obtainthe values of several variables about the location, the currentsituation, energy-efficient replacement options, and anevaluation of their impacts on the bottom line. This exerciseis divided into several steps to help you determine the value ofthe variables necessary to evaluate the energy consumption, itscost and the resulting greenhouse gas from the lights in yourlibrary. We will use the following problem solving applicationstrategy to achieve this objective:

HELPFUL HINTS:This section will provide you with examples and addtionalbackground which may be useful in completing Part 1.

Why is a sketch important to an energy auditor?

A sketch of the library is required that identifies the locationsof the lighting fixtures. The sketch helps the energy auditor orengineer make sure the list of lights is complete, and thus theycan accurately calculate energy savings. Furthermore, asketch is essential for workers hired to make changes to thelighting equipment to be able to identify exactly where thisequipment is located. On the sketch, list the type of lightfixture with its electricity (power) rating, measured in Watts.

How do I draw a sketch to scale of my library andcalculate the area?

Use the sketch paper on page 3 or use a ruler and a blanksheet of paper and draw the largest outline on the piece ofpaper that will fit within the margins. For example, if theroom is 40 feet by 25 feet in size, use a quarter inch scale onthe drawing: 0.25 inch on the drawing represents 1 foot of thelibrary. In this case, the measurements of the drawing on thepage will be 10 inches by 6.25 inches. Note the scale on thesketch, in this case: 0.25 inches = 1 foot, so you can interpretwhat you draw at a later date. Draw an arrow facing north soyou’ll be able to tell which wall is which when you look at thesketch again. The area of a rectangular room is its length timesits width.

How do I find out how much my school paysfor electricity?

In order to calculate savings from energy efficiency, it is firstnecessary to calculate how much the school is paying forenergy. Electricity costs used for savings calculations arebased on the average cost of electricity for the school. Thisnumber can be obtained from the school administration bychecking the utility bill and equation four.

How do I determine the number of Watts of electric powerthe light bulbs in my library use?

The power consumption of different types of lighting can bedetermined by inspecting the lamps and ballasts in thefixtures. If it is impossible to inspect the fixtures themselves,try to determine the wattage of the lamps by asking the personresponsible for changing them, such as the custodian. If this isnot possible, assume the following watt ratings for the lightbulbs below:

n Incandescent lights use lamps that you can examine todetermine the rating (e.g. 100 Watts).

1 . E n erg y u se2 . C ost3 . A ir P o llu tio n

UN DERSTAN DG e ne ra l b ac kgro u n d & C u rre n t S itu a tion

SO LVEC o m pa re thecu rre n t s itua tio nw ith yo ur p la n

PLANA be tte r a p p roa c h

LO O K B ACKE va lua te th e im p a c to f y ou r p ro po sa l

n UNDERSTAND the current situation

n PLAN a new approach

n SOLVE equations to compare the current light designwith your new plan

n LOOK BACK and compare the bottom lineimpact of your plan

Part 1 requires a visit to the library to understand yourcurrent situation. There, you will take an inventory of all ofthe lights in the room, estimate the schedule the lights are onand off, and using that information, calculate how much itcosts to light the library for a year. You’ll also estimate theamount of carbon dioxide (greenhouse gas) that is generatedto make the electricity for these lights. While you workthrough the calculations, note the answers on the Variable Keyon page10 . This will help you keep track of your answers,and assist you in making accurate bottom line conclusionsduring the final look back steps.

� Student Page 1

• Energy Use• Cost• Greenhouse Gas


n Incandescent exit signs require power only for the lamp;assume they use 40-Watt bulbs.

n Fluorescent lights use either the old standard, 40-WattF40 lamps or the newer 34 watt energy saver lamps. Theballast regulates current and voltage to ensure properoperation of the fluorescent lamps. All ballasts use acertain amount of energy while operating fluorescentlamps. This energy is called ballast loss and must beincluded in the calculation. A standard ballast consumes20 percent of the total power of the fixture. The totalpower required to operate a fluorescent fixture is thewattage of the tube multiplied by the number of tubestimes 20 percent (in other words, times 1.2). See examplebelow. To help you remember to include the ballast lossinside the fluorescent fixture in your calculations, we havewritten this 1.2 multiplier in the last equation containedin step 5.

Example:

If a fluorescent fixture has four standard tubes, at 40Watts each plus the ballast, the entire fixture is rated at:

School VacationDuring school vacations, the library is open on weekdays from9 a.m. to 3 p.m. This equals six hours a day for five days aweek totaling 30 hours a week. If your school has eight weeksoff during the summer, a three-week winter break, a week offfor spring break, and a week off for holidays, vacationsaccount for 13 weeks a year. The calculated “on times” formost of the lights in this case would be as follows:

where:w = hours per week that the lights are on when

school is inis inis inis inis in sessionx = weeks school isisisisis ininininin sessiony = hours per week lights are on when school

is not inis not inis not inis not inis not in sessionz = weeks during year when school is notis notis notis notis not ininininin

session

You would complete the equation as follows

w = 60 x = 39 y =30 z = 13(60 x 39) + (30 x13) = BB=2730

What is a lighting efficiency index?

Energy engineers often use a lighting efficiency index such asthe one below. When the index is higher than that for similarrooms or buildings, engineers can identify in advance wherepotential energy savings can be achieved. If the index isgreater than 1.3 Watts/ft2, it indicates that there are probablyopportunities for savings. The index is calculated by dividingthe total watts consumed by the area. This index is recorded aswatts /ft2 . The equations in steps 9, 14, and 19 will help yousee where you are and where you could be in relation to thisstandard.

How do I determine the number of hours per week thatthe lights are on in the library?

The estimated schedule for each fixture is best determined byinterviewing people who work in the library, such as thelibrarians or the custodian. This information combined withthe equation in step 3 will help you determine the answer tothis important variable.

Example:

School SessionsFor the purposes of illustrating how such a schedule mightwork, take a hypothetical school library where the lights areon from 7 a.m. to 7 p.m., Monday through Friday. Duringschool sessions, the lights are on 12 hours a day for five daysa week totaling 60 hours a week.

(4 x 40) x 1.2 = 192 W (4 x 40) x 1.2 = 192 W (4 x 40) x 1.2 = 192 W (4 x 40) x 1.2 = 192 W (4 x 40) x 1.2 = 192 Watts Fatts Fatts Fatts Fatts Fixtureixtureixtureixtureixture

(((((wwwww xxxxx xxxxx) + () + () + () + () + (yyyyy xxxxx zzzzz) = B) = B) = B) = B) = B

If the lighting index, (Watts / ft2) is greater than 1.3,there are probably opportunities for energy savings.

0 1.3 w/f 2 3

� Student P � Student P � Student P � Student P � Student Page 2age 2age 2age 2age 2


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Data gathering and observationINSTRUCTIONS: In order to get to the bottom line, the energy auditor must get generalinformation about the specific location. The answers to the first four steps will help youcomplete the calculations necessary to understand your current situation, plan a betterapproach, solve issues concerning your new approach, and finally, look back at thedifference you can make with energy efficiency. To begin, follow the directions for eachstep. Consult the background information as needed.

Measure the dimensions of thelibrary floor and sketch it to scalebelow. Be sure to write thelength and width on the sketch.Then draw the location andcorrect number of the incandes-cent light bulbs, fluorescent tubelight bulbs, and incandescentexit sign light bulbs that you see.

Ask the people that work in thelibrary how many hours per daythe lights are on when school isin session and when school isnot in session. Use this informa-tion and the key below todetermine the total hours thelights are used in the library.Write your answer in the variablekey next to B on page 10.

Calculate the area (length xwidth) of the library and writeyour answer in the variable keynext to A on page 10.

A=

(w x x) + (y x z) = B B=

where:w= hours per week that the lights are on

when school is in sessionx = weeks school is in sessiony = hours per week lights are on when school

is not in sessionz = weeks during year when school

is not in session

Use the equation below tocalculate the average cost yourschool pays per kilowatt-hour.Write your answer in the variablekey next to C on page10.

Total monthly energy bill in $ = CTotal kilowatt-hours from monthly bill

• E nergy U s e• C ost• A ir P o llu tion

� Student Page 3

C=



Instructions: Energy au-ditors must learn the value ofseveral variables about thecurrent room in order toconvince administrators thatenergy efficiency is a goodidea. Steps 5-9 will help you

find the value of the following variables about the light bulbs inyour library: the number of watts (D); the number of kilowatt-hours (E); annual electricity cost (F); the carbon dioxide green-house gas created by the electricity produced (G); and thecurrent lighting index (H). To begin, follow the directions belowand complete the equations. Don�t forget to transfer your an-swers to the variable key on page 10.

In Column 2, write the number oflight bulbs you counted for eachtype listed in column one.Complete each equation. Then,add the answers in column 4and enter this new watt total inanswer block D and on page10.

Number of incandescentlight bulbs with 40 watts




Number of exit signs with 40watt Incandescent light bulbs




Number offluorescent light tubes

Refer to steps 4 and 6 for thevalue of the variables in theequation below. Then do themath to determine the currentannual cost of operating thelights in your library. Write youranswer in the variable key next toF on page10.

E x C = F F=

The amount of carbon dioxidegreenhouse gas generated duringelectricity production rangesfrom 1.4lbs. to 2.8 lbs. perkilowatt-hour, depending onwhether or not the electricity isproduced from coal, nuclearpower, or hydropower (see

greenhouse gas article in the energy and environmentprimer). Use the equation below to estimate the amountof greenhouse gas created when the electricity is made topower the lights in your library. Write your answer in thevariable key next to G on page10.

E x 2 = G G=

Use the following equation tocalculate an overall lighting indexfor the library. This index is theWatts consumed per squarefoot. Write your answer in thevariable key next to H on page10.

D = H H=A

Use the total watts you calcu-lated in step 5 (D) and the totalhours the lights are used in a yearfrom step 2 (B) in the equationbelow to figure out how manykilowatt-hours are consumed bythe lights in your library. Writeyour answer in the variable keynext to E on page 10.

D x B = E E=

x 40 watts =

x 60 watts =

x 75 watts =

x 100 watts =

x 40 watts =

x 60 watts =

x 75 watts =

x 100 watts =

x 40 watts x 1.2=


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What is the Current Situation?

1000

Column 1 Column 2 Column 3 Column 4

D =

� Student Page 4

(or 34)



Summary of Abbreviations○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

Used in the CalculationsA area of a room measured in square feetBtu British thermal unitsft2 square feeth hourkW kilowattkWh kilowatt-hourlm lumenL length of a classroom wallmmBtu million British thermal units (Btu)W width of a classroomwk weeksyr year$ U.S. dollarsx multiplication (also *)+ addition- subtraction/ division (also “per,” as in dollars per

year; e.g. $ / yr)

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Summary of Variables Used in the Calculations

A = Area (Length times width) of library =

B = Total hours lights used in a year =

C = Average cost per kilowatt-hour =

D = Total watts consumed by your library lights =

E = Kilowatt-hours consumed by your library lights =

F = Annual cost of operating your library lights =

=

H =Current lighting index for your library =

with your new plan =

new library lighting plan =

library lighting plan =

your new library lighting plan =

M = Lighting index with your new library lighting plan =



Q= Greenhouse gas prevented in a year =

lights you propose =

=

T = Initial cost of the (LED) exit signs (chart 1) =

U =Number of (LED) exit signs you propose =

ballast fluorescent tubes =

tubes you propose changing =

Y = payback for your plan (years) =

• E ne rgy U s e• C ost• A ir P o llu tion

G = Estimated amount of carbon dioxide (CO2)greenhouse gas generated during electricityproduction

K =Annual cost of electrity with your new

I = Total watts consumed by your library lights

J = Kilowatt-hours consumed with your

L = Amount of carbon dioxide (CO2) greenhouse gaswith

N = Energy saved in a year with your new

P = the money saved in a year with your new

R = Initial cost of the compact

S =Number compact fluorescent

V =Initial cost of the T-8 electronic

W=Number electronic ballast T-8 fluorescent

� Student Page 10

• Energy Use

• Cost

• Greenhouse Gas


Determine the Feasibilityof Installing Energy Efficient Lighting

In this part of the exercise, youwill plan a new approach tolighting your school library.This new plan will use lessenergy, cost less, and result inless greenhouse gas. Your planwill also include bottom linecalculations and decisionfactors such as: identifying thecosts and payback for buyingand installing new lighting

equipment and making a determination about whether or notthe new, more efficient lighting will provide sufficient illumina-tion to the library.

Background Information

The feasibility of replacing existing lighting with moreefficient lighting depends on the cost of replacement versusthe savings. The per year savings depend on the type oflighting and the number of hours per year the lights are on.Three types of efficient lighting will be examined here:

• replacing incandescent bulbs with compact fluorescentlamps

• replacing incandescent exit signs with those lit by lightemitting diodes (LED)

• replacing the existing F40 lamps and 34 watt energysaver fluorescent fixtures with T8 lamps andelectronic ballasts

Similar efficiencies can be obtained from exit signs using lightemitting diodes (LED), also used in the display areas on acalculator. LEDs are very long lasting and require very littlepower. For this reason, they work very well in applicationssuch as exit signs that must stay on all the time.

Replace F40 lamps and 34 watt energy saver lamps withT8 lamps and electronic ballasts (retrofit)

Replacing the existing 40w or 34w fluorescent lamps with themore efficient T8 lamp that is operated by an electronicballast will provide excellent energy savings and also producea superior quality of lighting which is important in a libraryenvironment. It is important that the existing fixtures be wellcleaned before the new lighting is installed. Fixtures get dirtywith age and are rarely cleaned. Up to 40% of a fixture’sefficiency can be lost to dirt, so it is critical that all fixturesare well cleaned when being retrofitted. Replacing the old F40lamps with the new efficient T8 lamps can save as much as40% of the energy while providing equivalent or superiorlevels of illumination and a much better quality of lighting.

New fluorescent fixtures with energy-saver tubes, reflective louvers,and electronic ballasts provide almost as much light as the old,

4-tube fixtures while using less than half the electricity.

Replacing incandescent bulbs with compactfluorescent lampsThe savings result from increased efficiency: getting morelight with less electricity. The efficiency of these fixtures canbe measured in terms of lumens per Watt (lm / Watt), and thehigher the lumens per Watt rating, the more efficient they are.Generally, fluorescent lamps are much more efficient thanincandescent bulbs, producing as much as four times morelight (and less heat) with the same electricity input. Forexample, a 27-Watt compact fluorescent lamp provides 1800lumens, while a 100-Watt incandescent bulb produces 1750lumens. The CFL produces almost four times the lumens perWatt of the incandescent bulb.

Replacing incandescent exit signs with those lit by lightemitting diodes (LED)

• E nergy U se• C ost• A ir Po llu tion

� Student Page 5

Compact fluorescent lamps (CFL)can replace incandescent lamps inmany applications. Although theCFLs cost more initially, they lastmuch longer and cost one fourth asmuch to operate. They are mosteffective in areas where the lights are

on for long periods.



Chart 1.

Light Output for Several Types of Energy-Efficient LampsLamp Type Cost Lamp Watts Lumens Lumens

*replace Life (h) per Watt

Replace incandescent bulbs withcompact fluorescent lamps

Compact fluorescent lamp (CFL) $14 10,000 27 1800 67

Standard incandescent bulb $.50 1,000 100 1750 17.5

Replace F40 or 34 watt energy saver tubes withwith T8 lamps and electronic ballasts

F40 or 34 watt fluorescent lamp $ 5 per tube 20,000 192 11,960 62

T8 lamp and electronic ballast $ 8.75 22,000+ 106 10,620

Replace incandescent exit signs with LED exit signsIncandescent exit signs 1,000 40 �

LED exit signs $ 90 20,000 2 �

* Cost to replace fixtures in an existing building is higher than to install them in a new building because of higher labor costs toremove and replace fixtures. For example, costs for LED exit signs themselves are as low as $10. The estimates in this chartinclude labor costs and may vary by 30% or more, depending on location.

PAY BACKWhile commercial establishments require a 3-year payback or less for investing in lighting, schools and institutional facilities willgenerally accept a much longer payback period ranging up to six years. Some of the reasons these longer payback periods areacceptable include:

• The savings will continue many years after the initial investment is recovered since most schools are intended to be in use for50 years or more

• Educators are concerned both with immediate savings from a new system and lighting quality

Occasionally, the first cost of a new, efficient system will require a simple return of investment that exceeds 5 years; however, thelong-term benefits actually prove that the new, more efficient system with the higher first cost is the better investment. Steps 18-22 will provide you with first hand information about the economics for your school.

� Student Page 6

per tube


I=

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Plan a New ApproachInstructions: When energy auditors plan a new approach to lighting the library, theyconsider many factors, including when and how to use daylight, time controls on somelights and which energy-efficient light bulbs will deliver the same or better light but use lessenergy. In this activity we will concentrate on three common energy-efficient light replace-ment options. They are compact fluorescent lights, LED exit signs, T8 Fluorescents. In steps10-14 you will recommend energy-efficient light bulb replacements, and then work to find theanswer to the following variables about your new plan: the number of watts (I); the numberof kilowatt-hours (J); its annual electricity cost (K); the carbon dioxide greenhouse gascreated by the electricity produced (L); and the new lighting index (M). To begin, followthe directions to write and solve the equations below. Then complete the calculations andtransfer the value of these variables to your key on page10.

Refer to your library sketch and theequations you completed in step5 to determine the number ofinefficient light bulbs you couldreplace with the energy-efficientoptions you read about on yourbackground sheet. Complete the

equations below. Then add up the answers to each equationand write this total in the variable key next to I on page 10.

_________________ X 27 watts = ____________Number of incandescentlight bulbs replacedby compact fluorescent lights

__________________ X 2 watts = ____________Number of exit signs withincandescent lightbulbs replaced LED exit signs

__________________ X 34 watts = ____________Number of fluorescent light tubesyou can replace with T8

Refer to steps 4 and 11 for thevalue of the variables in theequation below. Then do the mathto determine the current annualcost of operating the lights in yourlibrary. Write your answer in thevariable key next to K on page10.

J x C = K K=

The amount of carbondioxide greenhouse gas generatedduring electricity productionranges from 1.4lbs. to 2.8 lbs. perkilowatt-hour (depending onwhether or not the electricity isproduced from coal, nuclearpower, or hydropower). Use the

equation below to estimate the amount of carbon dioxidegreenhouse gas created when the electricity is made to powerthe lights in your library with your new approach. Write youranswer in the variable key next to L on page10.

J x 2 = L L=

Use the following equationto calculate an overall lighting indexfor the library. This index is thewatts consumed per square feet.Write your answer in the variablekey next to M on page 10.

I = M M=

Use the total watts you calcu-lated in step 10 (I) and the totalhours the lights are used in ayear from step 2 (B) in theequation below to figure out howmany kilowatt-hours are con-sumed by the new approach youplanned. Write your answer in

the variable key next to J on page10.

I x B = J J=


� Student Page 7

A1000



Instructions: Finally,the energy auditor mustcompare the currentapproach and the newplan. If you have nottransfered the values of thevariables you calculatedfrom the previous pagesonto the variable key onpage 10, go back and do itnow. Then write theequations with the valuesconcerning your schoollibrary and do the math.

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Calculate the energy savingsbetween the current lights inyour library and the new lightsyou recommended in your plan.

N= E - J = N

Where N = the energy savedin a year

Calculate the energy cost savingsbetween the current lights inyour library and the new lightsyou recommended.

P= F -K = P

Where P = the money savedin a year

Calculate the greenhouse gasemissions prevented by replacingyour current lights in your libraryand the new lights you recom-mended.

Q= G - L = Q

Where Q = lbs. of carbondioxide prevented in a year

This exercise is designed to helpyou identify the paybackpossible from your proposedlighting changes. Simple pay-back is defined as the initial costdivided by the first-year dollar

savings. To determine the simple payback that would occur ifyour school adopted your proposed lighting changes,use the equation below. Note: Financial decision-makersusually use a 3-year payback.

(R x S) + (T x U) + (V x W) = ____________= yP year

payback

Where:P= the money saved in a yearR= Initial cost of the compact fluorescent lights

(See Chart 1, page 6)S =Number compact fluorescent lights you proposeT= Initial cost of the (LED) exit signsU =Number of (LED) you proposeV =Initial cost of the electronic ballast T-8 fluorescent tubesW=Number electronic ballast T-8 fluorescent tubes you propose

Now compare the indexbetween your current situation,your proposed new lighting planand the 1.3 w/ft 2 standard usedby auditors to determine theprobability of energy savings.Plot the values for H and Mbelow.


0 1.3 w/f 2 3

� Student Page 8

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Compare Your New Approach with the Current Situation• Energy Use• Cost• Greenhouse Gas


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What�s The Bottom Line?Instructions: Use your variable key on page10 to fill in the chart below. Then considerproposing that the school accept your plan for a more energy-efficient, cost-effective,environmentally friendly library. Use the table in step 20 and the results of your work in steps21-22 in your proposal.

If you get the total square footage of your school and complete the equations below you will have a good idea about the impact you can make on your school.

Energy Cost

Current lights in theLibrary (variables E,F,G)

Proposed new plan forthe lights in your library(variables J,K,L)

Savings from yourproposal (variablesN,P,Q)

NA


� Student Page 9

estimated energy saved by applying your planto the whole school

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What difference can this make in your school?

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Make an Energy Smart Schools presentation.

x sq. footage of school =

PA

estimated money saved by applying your planto the whole schoolx sq. footage of school =

QA

estimated CO2 greenhouse gas prevented by applyingyour plan to the whole schoolx sq. footage of school =

Discuss your idea and findings with your classmates and teachers and make one combinedproposal to your school board and administration team. Research the Energy Smart Schoolsprogram offered by the U.S. Department of Energy (www.eren.doe.gov/energysmartschools)and include the many benefits of this program and your findings from this activity as support formaking your school or library more energy-efficient.


Greenhouse Gas

Unit Pre and Post Test1 The energy in fossil fuels such as coal is

stored as...

a chemical energyb electrical energyc thermal energyd nuclear energy

2 Which energy source provides the nation withthe most energy?

a coalb natural gasc petroleumd electricity

3 Which residential task uses the most energy?

a lightingb heating waterc heating roomsd cooling rooms

4 Most energy conversions produce...

a lightb heatc motiond sound

5 The major use of coal in the U.S. is to...

a fuel trainsb heat homes and buildingsc make chemicalsd generate electricity

6 What percentage of the energy we use comesfrom renewable energy sources?

a 4 percentb 8 percentc 16 percentd 25 percent

7 Compared to incandescent light bulbs, fluores-cent bulbs...

a use more energyb use less energyc use the same amount of energy

8 Which fuel provides most of the energy to commercialbuildings?

a electricityb natural gasc coald petroleum

9 Which sector of the economy consumes the mostenergy?

a transportationb commercialc industriald residential

10 Which greenhouse gas is considered the most signifi-cant to global climate change?

a sulfur dioxideb methanec ozoned carbon dioxide

11 Electricity is measured in...

a amperesb voltsc kilowatt-hoursd current

12 Natural gas is transported mainly by...

a bargeb tankerc pipelined truck

13 The average cost of a kilowatt-hour of electricity in theU.S. is...

a 8 centsb 25 centsc 1 dollard 5 dollars

14 Natural gas is measured by...

a volumeb weightc heat contentd flammability

What Is Energy?Energy does things for us. It moves cars along the road and boatson the water. It bakes a cake in the oven and keeps ice frozen inthe freezer. It plays our favorite songs and lights our homes atnight so we can read a good book.

Energy is defined as the ability to do work––to cause change-- andthat work can be divided into five main tasks:

1. Energy gives us light.

2. Energy gives us heat.

3. Energy makes things move.

4. Energy makes things grow.

5. Energy makes technology work.

Forms of EnergyEnergy takes many different forms. It can light our homes or heatthem. There are six forms of energy.

Mechan i ca lMechanical energy puts something in motion. It moves cars andlifts elevators. It pulls, pushes, twists, turns, and throws. A ma-chine uses mechanical energy to do work and so do our bodies!We can throw a ball or move a pencil across a piece of paper.Sound is the energy of moving air molecules!

Kinetic energy is a kind of mechanical energy. It is theenergy of a moving object. A moving car has kinetic energy.A stalled car does not; however, if it’s poised at the top of ahill, it may have potential energy.

Potential energy is the energy an object has because of itsposition. Potential energy is resting or waiting energy. Aspring is a good example of potential energy. Energy can bestored in the spring by stretching or compressing it. Thesum of an object’s kinetic and potential energy is the object’smechanical energy.

R a d i a n tRadiant energy is commonly called light energy. But light en-ergy is only one kind of radiant energy. All waves emit energy.Radio and television waves are other types of radiant energy. Soare gamma rays and x-rays. Light waves do work by wiggling thereceptors in back of our eyes.

All About EnergyChemica lChemical energy is the energy stored in food, wood, coal, petro-leum, and other fuels. During photosynthesis, sunlight gives plantsthe energy they need to build complex chemical compounds.When these compounds are broken, the stored chemical energyis released in the form of heat or light.

What happens to a wood log in a fireplace? Burning the woodbreaks up the compounds, releasing the stored chemical energyin the forms of thermal and radiant energy.

Electr icalElectrical energy is a special kind of kinetic energy––the energyof moving electrons. Everything in the world is made up of tinyparticles called atoms. Atoms are made up of even tinier particlescalled electrons, protons, and neutrons.

Electricity is produced when something upsets the balancing forcebetween the electrons and protons in atoms and the electronsmove from one atom to another. We can use electricity to performwork like lighting a bulb, heating a cooking element on a stove, ormoving a motor.

T h e r m a lThermal energy, or heat energy, is also a special kind of kineticenergy. It is the energy of moving or vibrating molecules. Thefaster the molecules move, the hotter an object becomes and themore thermal energy it possesses.

Thermal energy can do work for us or it can be the result of doingwork. Do this. Rub your hands together quickly. What do youfeel? You feel heat. When two objects slide against each otherthey produce friction heat.

Nuc learNuclear energy is energy locked in the nucleus of the atom. It isthe force that binds the nucleus of the atom together. The energycan be released when atoms are combined or split apart.

Nuclear power plants split atoms of uranium in a process calledfission. The sun combines atoms of hydrogen to produce heliumin a process called fusion. In both fission and fusion, mass isconverted into energy, according to Einstein’s Theory, E + mc2.

Conservation of EnergyYour parents may tell you to conserve energy by turning off the lights. But, toscientists, conservation of energy means something else. The law of conservationof energy says energy is neither created nor destroyed.

Energy cannot be created or destroyed, but it can be transformed. That’s reallywhat we mean when we say we use energy. We change one form of energy intoanother. A car engine burns gasoline, converting its chemical energy into heatand mechanical energy that makes the car move. Wind mills change the kineticenergy of the wind into electrical energy. Solar cells change radiant energy intoelectrical energy.

Energy can change form, but the total quantity of energy in the universe remainsthe same. The only exception to this law is when mass is converted into energyduring nuclear fusion and fission.

Energy EfficiencyEnergy efficiency is how much useful energy you can get out of a system. In theory,a 100 percent energy-efficient machine would change all the energy put in it intouseful work. Converting one form of energy into another form always involves aloss of usable energy, usually in the form of heat. In fact, most energy transforma-tions are not very efficient.

The human body is no exception. Your body is like a machine, and the fuel for your“machine” is food. Food gives us the energy to move, breathe, and think. But yourbody isn’t very efficient at converting food into useful work. Your body is less thanfive percent efficient most of the time, and rarely better than 15 percent efficient.The rest of the energy is lost as heat. You can really feel the heat when you exercise!

An incandescent light bulb isn’t efficient either. A light bulb converts ten percent of the electrical energy into light and the rest (90percent) is converted into thermal energy (heat). That’s why a light bulb is so hot to the touch.

Most electric power plants are about 35 percent efficient. It takes three units of fuel to make one unit of electricity. Most of the otherenergy is lost as waste heat. The heat dissipates into the environment where we can no longer use it as a practical source of energy.

Energy UseImagine how much energy you use every day. You wake up to anelectric alarm clock. You take a shower with water warmed by ahot water heater. You listen to music on the radio as you dress. Youcatch the bus to school. And that’s just some of the energy you useto get you through the first part of your day!

Every day, the average American uses about as much energy as isstored in seven gallons of gasoline. That’s every person, every day.Over a course of one year, the sum of this energy is roughly equalto 2,500 gallons of oil. Energy use is sometimes called energyconsumption.

Who Uses Energy?The U.S. Department of Energy uses three categories to classifyenergy users: residential and commercial; industrial; and trans-portation. These users are sometimes called sectors of the economy.

Residential & CommercialResidences are people’s homes. Commerce includes office build-ings, hospitals, stores, restaurants, and schools. Residential andcommercial are lumped together because homes and businessesuse energy for much the same reasons—heating, air conditioning,water heating, lighting, and operating appliances.

The residential and commercial sector of the economy consumedabout 34 quads of energy in 1997 (the residential sector consumedmore than two-thirds of this energy.)

I ndus t r ia lThe industrial sector includes manufacturing, construction, min-ing, farming, fishing, and forestry. This sector consumed 35 quadsof energy in 1997—more energy than the residential and com-mercial sector.

Transpo r ta t i onThe transportation sector refers to energy use by cars, buses, trucks,trains, ships, and airplanes. In 1997, the United States used largeamounts of energy for transportation, more than 24 quads. About95 percent was supplied by petroleum products like gasoline, die-sel fuel and jet fuel.

Energy Use and PricesIn 1973, when Americans faced their first oil price shock,people didn’t know how the country would react. How wouldAmericans adjust to skyrocketing energy prices? How wouldmanufacturers and industries respond? We didn’t know theanswers.

Now we know that Americans tend to use less energy whenenergy prices are high. We have the statistics to prove it.

When energy prices increased sharply in 1973, energy usedropped, creating a gap between actual energy use and howmuch the experts had thought Americans would be using.

The same thing happened when energy prices shot up againin 1979 and 1980—people used less energy. In 1985 whenprices started to drop, energy use began to increase.

We don’t want to simplify energy demand too much. Theprice of energy is not the only factor in the equation. Otherfactors that affect how much energy we use include the public’sconcern for the environment and new technologies that canimprove the efficiency and performance of automobiles andappliances.

Most energy savings in recent years have come from improvedtechnologies in industry, vehicles, and appliances. Withoutthese energy conservation and efficiency technologies, wewould be using much more energy today.

In 2000 and 2001 deregulation of power utilites and years ofpopulation increases without the building of new power plants,caused an energy crisis in California. Energy prices tripled inthe state in one year. power companies could not keep up withenergy demand. This added to the problem as power providersbegan to go bankrupt, leading to rolling blackouts and further price increases.

MEASURINGenergy“You can’t compare apples and oranges,” the old saying goes.And that holds true for energy sources. Just think. We buygasoline in gallons, wood in cords, and natural gas in cubic feet.How can we compare them?

With British thermal units, that’s how. The heat energy con-tained in gasoline, wood, or other energy sources can be mea-sured by British thermal units or Btu’s.

One Btu is the heat energy needed to raise the temperatureof one pound of water one degree Fahrenheit. A single Btu isquite small. A wooden kitchen match, if allowed to burn com-pletely, would give off one Btu of energy. One ounce of gaso-line contains almost 1,000 Btu’s of energy. Every day the aver-age American uses roughly 889,000 Btu’s.

We use the quad to measure very large quantities of energy. Aquad is equal to one quadrillion (1,000,000,000,000,000) Btu’s.The United States uses about one quad of energy every 3.9days. In 1997, Americans consumed 94.2 quads of energy, anall-time high.

HOMES & COMMERCE

36%

INDUST RY

38%

T RANSPORTAT ION

26%

SOURCE: ENERGY INFORMAT ION ADMINIST RAT ION

mkuhn

Modern Energy Use

Sources of EnergyPeople have always used energy to do work for them. Thousands ofyears ago, cave men burned wood to heat their homes. Later peopleused the wind to sail ships. A hundred years ago, people used fallingwater to make electricity.

Today people are using more energy than ever before and our livesare undoubtedly better for it. We live longer, healthier lives. We cantravel the world, or at least see it on television.

Before the 1970s, Americans didn’t think about energy very much.It was just there. Things changed in 1973. The Organization forPetroleum Exporting Countries, better known as OPEC, placed anembargo on the United States and other countries.

The embargo meant they would not sell their oil to those countries.Suddenly, our supply of oil from the Middle East disappeared. Theprice of oil in the U.S. rose very quickly. Long lines formed at gasstations as people waited to fill their tanks with the amber-coloredliquid they hadn’t thought much about before.

Petroleum is just one of the many different sources of energy we useto do work for us. It is our major transportation fuel. We use coal anduranium to produce most of our electricity, and natural gas to heatour homes and cook our food.

There are ten major energy sources that we use in the United Statestoday, and we classify those sources into two broad groups—renew-able and nonrenewable.

N o n r e n e w a b l e sNonrenewable energy sources are the kind we use most in theUnited States. Coal, petroleum, natural gas, propane, and ura-nium are the major nonrenewable energy sources. They areused to make electricity, to heat our homes, to move our cars,and to manufacture all sorts of products from aspirin to CDs.

These energy sources are called nonrenewable because theycannot be replaced in a short period of time. Petroleum, forexample, was formed millions of years ago from the remains ofancient sea life, so we can’t make more petroleum in a shorttime. The supply of nonrenewable sources will become morelimited in the future.

R e n e w a b l e sRenewable energy sources include biomass, geothermal en-ergy, hydropower, solar energy and wind energy. They are calledrenewable energy sources because they can be replenished bynature in a relatively short period of time. Day after day, thesun shines, the wind blows, and the rivers flow. We mainly userenewable energy sources to make electricity.

Speaking of electricity, is it a renewable or nonrenewable sourceof energy? The answer is neither.

Electricity is different from the other energy sources because itis a secondary source of energy. That means we have to useanother energy source to make it. In the United States, coal isthe number one fuel for generating electricity.

BIOMASSrenewable energy source

Used for heating, electricity, transportation

GEOTHERMALrenewable energy source

Used for heating, electricity

HYDROPOWERrenewable energy source

Used for electricity

SOLARrenewable energy source

Used for heating, electricity

WINDrenewable energy source


COALnonrenewable energy source

Used for electricity, manufacturing

NATURAL GASnonrenewable energy source

Used for heating, industrial production

URANIUMnonrenewable energy source


PETROLEUMnonrenewable energy source

Used for transportation, manufacturing

PROPANEnonrenewable energy source

Used for heating, transportation

ENERGYsourcesModern Consumption

2 . 9 %

0 . 4 %

4 . 1 %

0 . 1 5 %

0 . 0 5 %

2 2 . 7 %

2 3 . 1 %

7 . 1 %

3 7 . 7 %

1 . 7 %

* Consumption of Other Energy Sources 0.1%

Energy Consumption

The residential and commercial sectors–homes and buildings–consume 36 percent of the energy used in the United Statestoday. We use that energy to heat and cool our homes and build-ings, to light them, and to operate appliances and office ma-chines.

In the last 25 years, Americans have significantly reduced theamount of energy we use to perform these tasks, mostly throughtechnological improvements in the systems we use, as well asin the manufacturing processes to make those systems.

Heating & CoolingThe ability to maintain desired temperatures is one of the mostimportant accomplishments of modern technology. Our ov-ens, freezers, and homes can be kept at any temperature wechoose, a luxury that wasn’t possible 100 years ago.

Keeping our living and working spaces at comfortable tempera-tures provides a healthier environment, and uses a lot of en-ergy. Half of the average home’s energy consumption is for heat-ing and cooling rooms.

The three fuels used most often for heating are natural gas,electricity, and heating oil. Today, more than half of the nation’shomes are heated by natural gas, a trend that will continue, atleast in the near future. Natural gas is the heating fuel of choicefor most consumers in the United States. It is a clean-burning,inexpensive fuel.

Most natural gas furnaces in the 1970s and 1980s were about 60percent efficient - they converted 60 percent of the energy inthe natural gas into usable heat. Many of these furnaces are stillin use today, since they can last 20 or more years with propermaintenance.

New furnaces manufactrured today can reach efficiency rat-ings of 98 percent, since they are designed to capture heat thatused to be lost up the chimney. These furnaces are more com-plex and costly, but they save significant amounts of energy.

The payback period for a new high-efficiency furnace is be-tween four and five years, resulting in considerable savingsover the life of the furnace.

Electricity is the second leading source of energy for home heat-ing and provides almost all of the energy used for air condition-ing. The efficiency of air conditioners and heat pumps has in-creased more than 50 percent in the last 25 years.

In 1973, air conditioners and heat pumps had an average Sea-sonal Energy Efficiency Rating, or SEER, of 7.0. Today, the aver-age unit has a SEER of 10.7, and units are available with SEERratings as high as 18.

These high-rated units are more expensive to buy, but their paybackperiod is only three to five years. Payback period is the amount oftime a consumer must use a system before beginning to benefitfrom the energy savings, because of the higher initial investmentcost.

Heating oil is the third leading fuel for home heating, and is widelyused in northeastern states. In 1973, the average home used 1,294gallons of oil a year. Today, that figure is 833 gallons, a 35 percentdecrease.

This decrease in consumption is a result of improvements in oilfurnaces. Not only do today’s burners operate more efficiently, theyalso burn more cleanly. According to the Environmental Protec-tion Agency, new oil furnaces operate as cleanly as natural gas andpropane burners.

A new technology under development would use PV cells to con-vert the bright, white oil burner flame into electricity.

Cost ManagementThe three most important things a consumer can do to reduce heat-ing and cooling costs are:

M a i n t e n a n c eMaintaining equipment in good working order is essential toreducing energy costs. Systems should be serviced annuallyby a certified technician, and filters should be cleaned orreplaced frequently by the homeowner.

Programmable ThermostatsProgrammable thermostats raise and lower the temperatureautomatically, adjusting for time of day and season. They alsoprevent people from adjusting the temperature They can lowerenergy usage appreciably.

Caulking & WeatherstrippingPreventing the exchange of inside air with outside air is veryimportant. Weatherstripping and caulking around doors andwindows can significantly reduce air leakage. Keeping win-dows and doors closed when systems are operating is also anecessity.

Residential/Commercial SectorSpace

H e a t i ng3 2 %

Ligh t ing2 8 %

SpaceCool ing

1 6 %

O t h e r1 5 %

Food Storage

Water Heating

5 %

4 %

COMMERCIAL ENERGY USE

Building DesignThe placement, design, and construction materials used can affectthe energy efficiency of homes and buildings. Making optimumuse of the light and heat from the sun is becoming more prevalent,especially in commercial buildings.

Many new buildings are situated with maximum exposure to thesun, incorporating large, south-facing windows to capture the en-ergy in winter, and overhangs to shade the windows from the sunin summer. Windows are also strategically placed around the build-ings to make use of natural light, reducing the need for artificiallighting during the day. Using materials that can absorb and storeheat can also contribute to the energy efficiency of buildings.

For existing houses and buildings, there are many ways to in-crease efficiency. Adding insulation and replacing windows anddoors with energy-efficient ones can significantly reduce energycosts. Adding insulated blinds, and using them wisely, can alsoresult in savings. Even planting trees to provide shade in summerand allow light in during the winter can make a difference.

L i g h t i n gLighting is essential to a modern society. Lights have revolution-ized the way we live, work, and play. Today, about five percent ofthe energy used in the nation is for lighting our homes, build-ings, and streets.

Lighting accounts for about 10 percent of the average home’senergy bill but, for stores, schools, and businesses, the figure ismuch higher. On average, the commercial sector uses about 28percent of its energy consumption for lighting.

New systems on the market combine high efficiency water heat-ers and furnaces into one unit to share heating responsibilities.Combination systems can produce a 90 percent efficiency rating.

In the future, expect to see water heaters that utilize heat frominside the building that is usually pumped outside as waste heat.Systems will collect the waste heat and direct it into the waterheater, resulting in efficiency ratings three times those of conven-tional water heaters.

The temperature on most water heaters is set much higher thannecessary. Lowering the temperature setting can result in signifi-cant energy savings. Limiting the amount of hot water usage withlow-flow faucets and conservation behaviors also contributes tolower energy bills.

Energy Efficiency RatingsWe use many appliances every day. Some use less than 10 centsworth of electricity a year, while others use much more. Have younoticed that those appliances that produce or remove heat re-quire the most energy?

In 1990, Congress passed the National Appliance Energy Conser-vation Act, which requires appliances to meet strict energy effi-ciency standards. All appliances must display a yellow label whichtells how much energy the appliance uses.

When purchasing any appliance, consumers should define theirneeds and pay attention to the Energy Efficiency Rating (EER)included on the yellow label of every appliance. The EER allowsconsumers to compare not just purchase price, but operating costas well, to determine which appliance is the best investment.Usually, more energy efficient appliances cost more to buy, butresult in significant energy savings over the life of the appliance.Buying the cheapest appliance is rarely a bargain in the long run.

In the next few years, consumers will have the choice of manysmart appliances that incorporate computer chip technology tooperate more efficiently, accurately, and effectively.

Most homes still use the traditional incandescent bulbs inventedby Thomas Edison. These bulbs only convert about ten percentof the electricity they use to produce light; the other 90 percent isconverted into heat. With new technologies, such as better fila-ment designs and gas mixtures, these bulbs are still more effi-cient than they used to be. In 1879, the average bulb producedonly 1.4 lumens per watt, compared to about 17 lumens per watttoday. By adding halogen gases, this efficiency can be increasedto 20 lumens per watt.

Most commercial buildings have converted to fluorescent light-ing, which costs more to install, but uses much less energy toproduce the same amount of light. Buildings can lower their long-term lighting costs by as much as 50 percent with fluorescentsystems.

Heating WaterIn residential buildings, heating water uses more energy thanany other task, except for heating and cooling. In commercialbuildings, such as schools, heating water consumes about fourpercent of total energy consumption. Most water heaters use natu-ral gas or electricity as fuel.

Water heaters today are much more energy efficient than earliermodels. Many now have timers that can be set to the times whenhot water is needed, so that energy is not used 24 hours a day.

Electr ic i ty6 9 %

N a t u r a lG a s

2 2 %

P e t r o l e u m7 %

O t h e r 2%

FUELS USED BYCOMMERCIAL BUILDINGS

ElectricityThe Nature of ElectricityElectricity is a little different from the other sources of energythat we talk about. Unlike coal, petroleum, or solar energy, elec-tricity is a secondary source of energy. That means we must useother sources of energy to make electricity. It also means wecan’t classify electricity as renewable or nonrenewable. Theenergy source we use to make electricity may be renewable ornonrenewable, but the electricity is neither.

Making ElectricityAlmost all electricity made in the United States is generated bylarge, central power plants. These plants usually use coal, ura-nium, natural gas, or other energy sources to produce heat en-ergy which superheats water into steam. The very high pressureof the steam turns the blades of a turbine.

The blades are connected to a generator which houses a largemagnet surrounded by a coiled copper wire. The blades spin themagnet rapidly, rotating the magnet inside the coil and produc-ing an electric current.

The steam, which is still very hot, goes to a condenser where it iscooled into water by passing it through pipes circulating over alarge body of water or cooling tower. The water then returns tothe boiler to be used again.

Moving ElectricityWe are using more and more electricity every year. It is consid-ered an efficient energy carrier––it can transport energy effi-ciently from one place to another. Electricity can be produced ata power plant and moved long distances before it is used.

Let’s follow the path of electricity from power plant to a lightbulb in your school.

First, the electricity is generated at the power plant. Next, it goesby wire to a transformer that “steps up” the voltage. A trans-former steps up the voltage of electricity from the 2,300 to 22,000volts produced by a generator to as much as 765,000 volts (345,000volts is typical). Power companies step up the voltage becauseless electricity is lost along the lines when the voltage is high.

The electricity is then sent on a nationwide network of transmis-sion lines made of aluminum. Transmission lines are the hugetower lines you may see when you’re on a highway. The lines areinterconnected, so should one line fail, another will take overthe load.

Step-down transformers located at substations along the linesreduce the voltage to 12,000 volts. Substations are small build-ings or fenced-in yards containing switches, transformers, andother electrical equipment.

Electricity is then carried over distribution lines which bringelectricity to your school. Distribution lines may either be over-head or underground. The overhead distribution lines are theelectric lines that you see along streets.

Before electricity enters your school, the voltage is reduced againat another transformer, usually a large gray can mounted on anelectric pole. This transformer reduces the electricity to the 120volts that are needed to run the light bulb in your school.

Electricity enters your house through a three-wire cable. The“live wires” are then brought from the circuit breaker or fuse boxto power outlets and wall switches in your home. An electricmeter measures how much electricity you use so the utility com-pany can bill you.

The time it takes for electricity to travel through these steps—from power plant to the light bulb in your home—is a tiny frac-tion of one second.

Demand-Side ManagementDemand-side management is all the things a utility companydoes to affect how much people use electricity and when. It’sone way electric companies manage those peak-load periods.

We can reduce the quantity of electricity we use by using betterconservation measures and by using more efficient electricalappliances and equipment.

What’s the difference between conservation and efficiency?Conserving electricity is like turning off the water in the showerwhile you shampoo your hair. Using electricity more efficientlyis like installing a better shower head to decrease water flow.

Demand-side management can also affect the timing of elec-trical demand. Some utility companies give rebates to custom-ers who allow the utility company to turn off their hot waterheaters (via radio transmitters) during extreme peak demandperiods, which occur perhaps 12 times a year. One East Coastpower company gives participating customers a $4 per monthrebate.

Economics of ElectricityHow much does electricity cost? The answer depends on thecost to generate the power (50%), the cost of transmission (20%)and local distribution (30%).The average cost of electricity is8.5 cents per kWh for residential customers. A major key tocost is the fuel used to generate electricity. For example, elec-tricity produced from natural gas costs more than electricityproduced from coal or nuclear power.

Another consideration is how much it costs to build a powerplant. A plant may be very expensive to construct, but the costof the fuel can make it competitive to other plants, or viceversa. For example, nuclear plants are very expensive to build,but their fuel—uranium—is very cheap. Coal-fired plants, onthe other hand, are much less expensive to build than nuclearplants, but their fuel—coal—is more expensive.

Power to the PeopleEveryone knows how important electricity is to our lives. All ittakes is a power failure to remind us how much we depend on it.Life would be very different without electricity—no more instantlight from flicking a switch; no more television; no more refrigera-tors; or stereos; or video games; or hundreds of other convenienceswe take for granted. We depend on it, business depends on it, andindustry depends on it. You could almost say the American economyruns on electricity.

Reliability is the capability of a utility company to provideelectricity to its customers 100 percent of the time. A reliableelectric service is without blackouts or brownouts.

To ensure uninterrupted electric service, laws require mostutility companies to have 15 to 20 percent more capacitythan they need to meet peak demands. This means a utilitycompany whose peak load is 12,000 MW, would need tohave about 14,000 MW of installed electrical capacity. Thishelps ensure there will be enough electricity to go aroundeven if equipment were to break down on a hot summerafternoon.

Capacity is the total quantity of electricity a utility companyhas on-line and ready to deliver when people need it. A largeutility company may operate several power plants to gener-ate electricity for its customers. A utility company that hasseven 1,000-MW (megawatt) plants, eight 500-MW plants,and 30 100-MW plants has a total capacity of 14,000 MW.

Base-load power is the electricity generated by utility com-panies around-the-clock, using the most inexpensive energysources—usually coal, nuclear, and hydropower. Base-loadpower stations usually run at full or near capacity.

When many people want electricity at the same time, thereis a peak demand. Power companies must be ready for peakdemands so there is enough power for everyone. During theday’s peak, between 12:00 noon and 6:00 p.m., additionalgenerating equipment has to be used to meet increased de-mand. This equipment is more expensive to operate. Thesepeak load generators run on natural gas, diesel or hydro andcan be running in seconds. The more this equipment is used,the higher our utility bills. By managing the use of electricityduring peak hours, we can help keep costs down.

The use of power pools is another way electric companiesmake their systems more reliable. Power pools link electricutilities together so they can share power as needed.

A power failure in one system can be covered by a neighbor-ing power company until the problem is corrected. There arenine regional power pool networks in North America. Thekey is to share power rather than lose it.

The reliability of U.S. electric service is excellent, usually betterthan 99 percent. In some countries, electric power may go out sev-eral times a day. Power outages in the United States are usuallycaused by such random occurrences as lightning, a tree limb fallingon electric wires, or a car hitting a utility pole.

When figuring costs, a plant’s efficiency must be considered. Intheory, a 100 percent energy-efficient machine would change allthe energy put into the machine into useful work, not wasting asingle unit of energy. But converting a primary energy source intoelectricity involves a loss of usable energy, usually in the form ofheat. In general, it takes three units of fuel to produce one unit ofelectricity.

In 1900, electric power plants were only four percent efficient.That means they wasted 96 percent of the fuel used to generateelectricity. Today’s power plants are over eight times more effi-cient with efficiency ratings around 35 percent. Still, this means65 percent of the initial heat energy used to make electricity islost. (You can see this waste heat in the great clouds of steam pour-ing out of giant cooling towers on newer power plants.) A moderncoal plant burns about 8,000 tons of coal each day, and about two-thirds of this is lost when the heat energy in coal is converted intoelectrical energy.

But that’s not all. About two percent of the electricity generated ata power plant must be used to run equipment. And then, even afterthe electricity is sent over electrical lines, another 10 percent ofthe electrical energy is lost in transmission. Of course, consumerspay for all the electricity generated whether “lost” or not.

The cost of electricity is affected by what time of day it is used.During a hot summer afternoon from noon to 6 p.m., there isa peak of usage when air-conditioners are working harder tokeep buildings cool. Electric companies charge their indus-trial and commercial customers more for electricity duringthese peak load periods because they must turn to more ex-pensive ways to generate power.

D e r e g u l a t i o nSince the 1930s, most electric utilities in the United Stateshave operated under state and federal regulations in a definedgeographical area. Only one utility provides service to anyone area. People and businesses can not choose their electric-ity provider. In return, the utilities have to provide service toevery consumer, regardless of the profitability.

Under this model, utilities generate the power, transmit it tothe point of use, meter it, bill the customer, and provide infor-mation on efficiency and safety. The price is regulated by thestate. As a result, the price of a kilowatt-hour of electricity toresidential customers varies widely among the states and utili-ties, from a high of 16 cents to a low of four cents. The price forlarge industrial users varies, too.

Three kinds of power plants produce most of the elec-tricity in the United States: fossil fuel; nuclear; andhydropower. There are also wind, geothermal, trash-to-energy, and solar power plants, but they generateless than 3% of the electricity produced in the U.S..

MAKING electricityFossil Fuel Power PlantsFossil fuel plants burn coal, natural gas, or oil. These plants use the energyin fossil fuels to superheat water into steam, which drives a turbine gen-erator. Fossil fuel plants are sometimes called thermal power plants be-cause they use heat energy to make electricity. Coal is the fossil fuel ofchoice for most electric companies, producing 52.5 percent of the elec-tricity. Natural gas plants produce 14.1 percent. Petroleum produces lessthan three percent of the electricity in the U.S.

Nuclear Power PlantsNuclear plants produce electricity much as fossil fuel plants do except thatthe furnace is called a reactor and the fuel is uranium. In a nuclear plant, areactor splits uranium atoms into smaller parts, producing heat energy.The heat energy superheats water into steam and the high pressure steamdrives a turbine generator. Like fossil fuel plants, nuclear power plants arecalled thermal power plants because they use heat energy to make elec-tricity. Nuclear energy produces 17.8 percent of the electricity in the U.S.

Hydropower PlantsHydro (water) power plants use the force of falling water to generateelectricity. Hydropower is the cheapest way to produce electricity in thiscountry, but there are few places where new dams can be built. Hydro-power is called a renewable energy source because it is renewed continu-ously by rainfall. Hydropower produces 10.2 percent of the electricity inthe United States.

SOURCE: ENERGY INFORMATION ADMINISTRATION

U.S. ELECTRICITY PRODUCTION

Uranium

Coal

OtherGeothermal,Wind & Solar

NaturalGas

Hydropower

Petroleum

Biomass

52.5 %

17.8 %

14.1 %

10.2 %

2.7 %

1.7 %

1.0 %

The types of generating plants, the cost of fuel, taxes, and envi-ronmental regulations are some of the factors contributing tothe price variations.

In the 1970s, the energy business changed dramatically in theaftermath of the Arab Oil Embargo, the advent of nuclear power,and stricter environmental regulations. Independent powerproducers and co-generators began making a major impact onthe industry. Large consumers began demanding more choicein providers.

In 1992, Congress passed the Energy Policy Act to encouragethe development of a competitive electric market with openaccess to transmission facilities. It also reduced the require-ments for new non-utility generators and independent powerproducers. The Federal Energy Regulatory Commission (FERC)began changing their rules to encourage competition at thewholesale level. Utilities and private producers could, for thefirst time, market electricity across state lines to other utilities.

Some state regulators are encouraging broker systems to pro-vide a clearinghouse for low-cost electricity from under-uti-lized facilities. This power is sold to other utilities that need it,resulting in lower costs to both the buyer and seller. This whole-sale marketing has already brought prices down in some areas.

Many states are now considering whether competition in theelectric power industry is a good thing for their consumers.This competition can take many forms, including allowing largeconsumers to choose their provider and allowing smaller con-sumers to join together to buy power.

Eventually, individual consumers may have the option of choos-ing their electric utility, much like people can now choose theirlong-distance telephone carrier.

Their local utility would distribute the power to the consumer.Some experts say this could lower electric bills, but don’t expectto see this happening on a large scale in the next few years.

It will take the industry and the states several years to decide ifresidential competition is a good thing and figure out how toimplement the changes.

Future DemandHome computers, answering machines, FAX machines, micro-wave ovens, and video games have invaded our homes and theyare demanding electricity! New electronic devices are part of thereason why Americans are using more electricity every year.

The U. S. Department of Energy predicts the nation will need toincrease its current generating capacity of 780,000 megawatts bya third in the next 20 years.

Some parts of the nation have experienced power shortages inthe last few years. Some utilities resorted to rolling blackouts—planned power outages to one neighborhood at a time—duringthe 1995 blizzard. New England utility companies warn residentsevery summer to expect brownouts (decreases in power levels)whenever sweltering weather looms over the region.

Conserving electricity and using it more efficiently help, but ex-perts say we will need more power plants. That’s where the chal-lenge begins. Should we use coal, natural gas, or nuclear power togenerate electricity?

Can we produce more electricity from renewable energy sourcessuch as wind or solar? And where should we build new powerplants? No one wants a power plant in his backyard, but every-one wants the benefits of electricity.

Experts predict we will need 205 thousand more megawatts ofgenerating capacity by the year 2010. Demand for electricity doesnot seem to be coming to an end.

We must make machines and appliances that use electricity muchmore energy efficient, or we will have to build the equivalent of350 coal plants by the year 2010 to meet that demand.

Which energy sources will provide this additional electricity?Most new power generation will come from natural gas. Naturalgas is a relatively clean fuel and is abundant in the United States.

New natural gas combined-cycle turbines use the waste heat theygenerate to turn a second turbine. Using this waste heat increasesefficiency to 50 or 60 percent, instead of the 35 percent efficiencyof conventional power plants.

Power is the rate (time) of doing work. A watt is ameasure of the electric power an appliance uses. Ap-pliances require a certain number of watts to workcorrectly. All light bulbs are rated by watts, (60, 75, 100watts) as well as appliances (such as a 1500-watthairdryer).

A kilowatt is 1,000 watts. A kilowatt-hour (kWh) is theamount of electricity used in one hour at a rate of 1,000watts. Think of adding water to a pool. In this analogy, akilowatt is the rate, or how fast water is added to thepool; and a kilowatt-hour is the amount, or how muchwater is added to the pool.

MEASURING electricityJust as we buy gasoline in gallons or wood in cords, we buy electricity inkilowatt-hours. Utility companies charge us for the kilowatt-hours weuse during a month. If an average family of four uses 750 kilowatt-hoursin one month, and a utility company charges 10 cents per kilowatt-hour,the family will receive a bill for $75. (750 x $0.10 = $75)

Power companies use megawatts and gigawatts to measure hugeamounts of electrical power. Power plant capacity is measured in mega-watts. One megawatt (MW) is equal to one million watts or one thou-sand kilowatts. Gigawatts are often used to measure the electrical en-ergy produced in an entire state or in all the United States. One giga-watt is equal to one billion watts, one million kilowatts, or one thousandmegawatts.

The Greenhouse EffectEarth’s AtmosphereOur earth is surrounded by a blanket of gases called the atmo-sphere. Without this blanket, our earth would be so cold thatalmost nothing could live. It would be a frozen planet. Our atmo-sphere keeps us alive and warm.

The atmosphere is made up of many different gases. Most of theatmosphere (99 percent) is oxygen and nitrogen. The other onepercent is a mixture of greenhouse gases. These greenhouse gasesare mostly water vapor, mixed with carbon dioxide, methane,CFCs, ozone, and nitrous oxide.

Carbon dioxide is the gas we produce when we breathe and whenwe burn wood and fossil fuels. Methane is the main gas in naturalgas. It is also produced when plants and animlas decay. The othergreenhouse gases (ozone, CFCs and nitrous oxide) are producedby burning fuels and in other ways.

Sunlight and the AtmosphereRays of sunlight (radiant energy) shine down on the earth everyday. Some of these rays bounce off molecules in the atmosphereand are reflected back into space. Some rays are absorbed by mol-ecules in the atmosphere.

THE GREENHOUSE EFFECT

About half of the sunlight passes through the atmosphereand reaches the earth. When the sunlight hits the earth,most of it turns into heat (thermal energy). The earth ab-sorbs some of this heat. The rest flows back out toward theatmosphere. This keeps the earth from getting too warm.

When this heat reaches the atmosphere, it stops. It can’tpass through the atmosphere like sunlight. Most of the heatenergy becomes trapped and flows back to the earth. Weusually think it’s the sunlight itself that warms the earth,but actually it’s the heat energy produced when the sunlightis absorbed by the earth and air that gives us most of ourwarmth.

The Greenhouse EffectWe call this trapping of heat the greenhouse effect. A green-house is a building made of clear glass or plastic. In coldweather, we can grow plants in a greenhouse.

The glass lets the sunlight in. The sunlight turns into heatwhen it hits objects inside. The heat becomes trapped. Thelight energy can pass through the glass; the heat energy can-not .

SUN

EARTH

Radiant energy (white arrows) from the sun travels through space and shines on the earth. Someradiant energy is reflected back into space by the atmosphere. Some radiant energy is absorbed by theatmosphere and turns into heat energy.

Half of the radiant energypasses through the atmosphereand reaches the earth, where itturns into heat (black arrows).

Some of this heat energy is ab-sorbed by the earth.

Most of the heat energy flowsback into the air where it istrapped by the atmosphere.

Very little heat energy passesthrough the atmosphere andescapes into space.

The trapped heat energy flowsback toward the earth.

Another continuing dispute is the issue of emissions trading.Europeans want strict limits on trading to force countries tomake domestic cuts. Unlimited emissions trading would al-low rich countries––like the United States––to have higherdomestic emissions in return for investing in clean technolo-gies in developing countries.

Greenhouse GasesWhat is in the atmosphere that lets light through, but traps heat?It’s the greenhouse gases, mostly carbon dioxide and methane.These gases are very good at absorbing heat energy and sendingit back to earth.

In the last 50 years, the amount of some greenhouse gases––especially carbon dioxide and methane––has increased dramati-cally. We produce carbon dioxide when we breathe and whenwe burn wood and fossil fuels: coal, petroleum, natural gas, andpropane.

Some methane escapes from coal mines and oil wells. Some isproduced when plants and garbage decay. Some animals alsoproduce methane gas. One cow can give off enough methane ina year to fill a hot air balloon!

Global Climate ChangeScientists around the world believe these greenhouse gases aretrapping more heat in the atmosphere as their levels increase.They believe this trapped heat has begun to change the averagetemperature of the earth. They call this phenomenon globalwarming .

Many long–term studies indicate that the average temperatureof the earth has been slowly rising in the last few decades. Infact, the last decade has seen two of the hottest years on record.

Scientists predict that if the temperature of the earth rises just afew degrees Fahrenheit, it will cause major changes in the world’sclimate. They predict there will be more flooding in some placesand periods of drought in others. They think the level of theoceans will rise as the ice at the North and South Poles melts,causing low-lying coastal areas to disappear. They also predictmore erratic weather––causing stronger storms and hurricanes.

Some scientists don’t believe the world’s temperature will rise asmuch as the predictions indicate. They think it is too soon totell if there will be long-term changes in the global climate. Theythink slight warming could prove beneficial, producing longergrowing seasons for crops, warmer nights, and milder winters.

Countries all over the world are concerned about the threat ofglobal warming. They believe we need to act now to lower theamount of carbon dioxide we put into the atmosphere. Theybelieve we should decrease the amount of fossil fuels that weburn.

Greenhouse gases makeup less than one percentof the atmosphere.

Greenhouse gases aremore than 97 percentwater vapor.

> 1%< 97%

> 3%

EARTH’S ATMOSPHERE

Carbon Dioxide, Methane,CFCs, and Other Gases

EART H’SAT MOSPHERE

NIT ROGEN

OXYGEN

GREENHOUSE GASEWater Vapor

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