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 Activity
Student 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
|
Appendix
Transparency Masters
High School Energy Inventory: Lighting Technology Primer
All About Energy Primer
Glossary
Overview / School Energy Audit:
The U. S. Department of Energy's vision for Energy Smart Schools is to "form a national partnership to cut energy bills in schools and reinvest the savings in educating the nation's most valuable resource.... our children". The plan is to invest in "books not BTUs". Some schools 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 billion more on books, computers, and teachers each year by the year 2010. That amounts to almost $30 for each student, 40 million new textbooks, or 30,000 new teachers. In this activity, your students learn science and mathematical concepts in a hands-on, minds-on way. They become empowered to research their school environment and make recommen-dations for changes. They begin by focusing on the energy saving and pollution preventing opportunities that can be achieved by changing the light bulbs in your school library. They conclude their work by extending these findings to the opportunities in the entire school and preparing a presentation for the school board.
Level
Grades 8-12
Subject
Mathematics
Goals of the High School Energy Audit
Introduction
We spend most of our time in buildings,
homes, schools, offices, and stores. But most people hardly notice details about
the buildings, such as how they are designed, how they are built, and how well
they are maintained. The details have a strong effect on how comfortable a building
is and how much it costs to operate.
An "energy-efficient" building is
more comfortable than a wasteful building. It needs less fuel for heat and less
electricity for cooling. A building that is badly designed and poorly maintained
wastes money. This is because the building components are trying to heat and
air-con-dition the outdoors as well as the indoors.
In a 1995 report, School Facilities:
Condition of America's Schools, the General Accounting Office (GAO) estimated
that the cost of bringing the Nation's 110,000 K-12 schools into good overall
conditions was $112 billion.
The report revealed:
The National Center for Education
Statistics projects that elementary and secondary enrollments will swell from
52.2 million in 1997 to 54.4 million in 2006. So as our nation grapples with
modernizing older schools we will also need to build an additional 6,000 new
schools to accommodate growing student enrollment over the next decade. We must
take advantage of this building boom to introduce energy efficiency in the design,
construction and operation of our nation's next generation of school buildings.
With the backlog for repairs and
continued operation of older, inefficient, and often polluting equipment and
school buses, our schools are wasting large amounts of energy and valuable taxpayer
dollars that could be used to teach students. Our nation's schools spend over
$6 billion a year on energy. Significant opportunities exist to lower energy
bills with equipment upgrades and the use of widely available energy-efficient
technologies such as energy-efficient lights, motors, energy management systems
and alternatively fueled school buses.
As an added benefit, these improvements
can result in better lighting conditions, better indoor and outdoor air quality,
and better controlled classroom temperature all of which can improve the productivity
and general well-being of students and teachers.
Impact of Inadequate
School Facilities on
Student Learning
Businesses have spent millions of dollars on understanding the link between work environment and productivity. Yet, we generally view schools as separate public institutions the same way we view correctional facilities. Current research has linked student achievement and behavior to the physical building conditions and over-crowding.
High School Energy Audit and Teachers’
Guide
Energy Smart Schools 3
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 opportunity 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://www.eren.doe.gov/buildings/earthday/.
Decaying environmental conditions
such as peeling paint, crumbling plaster, nonfunctioning toilets, poor lighting,
inadequate ventilation, and inoperative heating and cooling systems can affect
the learning as well as the health and the morale of staff and students. A school
year is approximately 180 days. This is alot of time to spend in an atmosphere
that is not conducive to learning or teaching.
National
Science and Mathematics Content
Standards
and Benchmarks for Science Literacy
The content and associated activities are challenging and rigorous for high
school students. The standards and benchmarks that are covered in these activities
are noted in the individual teacher guides. The standards that are covered in
the High School Energy Audit are as follows:
National Science
Education Standards
PHYSICAL SCIENCE
Content Standard A
Science as Inquiry
As a result of their activities in grades
9-12, all students should develop:
Content Standard B
As a result of their activities in grades 9-12,
all students should develop an under-standing
of:
SCIENCE IN PERSONAL AND SOCIAL
PERSPECTIVES
Content Standard F
As a result of activities in grades 9-12, all
students should develop understanding of:
Benchmarks for
Science Literacy
Benchmark 4
The Physical Setting
4B The Earth -Students will understand physical concepts and principles
as energy, gravitation, conservation, and radiation.
Benchmark 5
The Living Environment
5E Flow of Matter and Energy -Students will understand the conservation
of matter with the flow of energy in living systems.
Benchmark 8
The Designed World
8C Energy Sources and Use -Students
can examine the consequences of the
world's dependence on fossil fuels,
explore a wide range of alternative energy
resources and technologies, and consider
trade-offs in each. They can propose
policies for conserving and managing
energy resources.
National Math Standards
Standard 1: Mathematics as Problem Solving
In grades 9-12, the mathematics curriculum should include the refinement and
extension of methods of mathematical problem solving so that all students can:
Standard 2: Mathematics as Communication
In grades 9-12, the mathematics curricu-lum should include the continued devel-opment of language and symbolism to communicate mathematical ideas so that all students can:
Standard 3: Mathematics as Reasoning
In grades 9-12, the mathematics curricu-lum = should include numerous and varied = experiences that reinforce and extend logical reasoning skills so that all students can:
and so that, in addition, college-intending students can:
Standard 5: Algebra
In grades 9-12, the mathematics curriculum
should include the continued study of
algebraic concepts and methods so that all
students can:
Standard 6: Functions
In grades 9-12, the mathematics curricu-lum
should include the continued study of
functions so that all students can:
Standard 10: Statistics
In grades 9-12, the mathematics curriculum
should include the continued study of
data analysis and statistics so that all
students can:
Assessment/Rubric
An assessment is just one method of evaluating each student's grasp of the major concepts presented in the activities. Teachers are encouraged to use the assess-ments as-is or to develop their own assessments that meets the individual needs of the students. The assessments are used at the end of each activity. However, these assessments are provided as guidelines for the teacher to use in developing appropriate measure-ment packages. Many assessment techniques are available, including multiple-choice, short-answer, discussion, or open-ended ques-tions; structured or open-ended interviews; homework; projects; journals; essays; dramatizations; and class presentations. Among these techniques are those appropriate for students working in whole-class settings, in small groups, or individually. The mode of assessment can be written, oral, or computer oriented. Please use these ideas and add or delete according to your needs. The tasks in this audit usually involve open-ended, problem-solving activities but some will require recall of content knowledge.
Included with the assessment is a standard, generic rubric. The rubric is established as guideline for performance. It is also a useful form of self-evaluation because it lets the student know what is expected for high quality work.
Credits
The National Renewable Energy Laboratory would like to give credit to the following agencies for supplying information that used to prepare the High School Energy Audit:
National Energy Education Devel-opment
(NEED) Project with
technical assistance from Dr. Lori
Marsh of Virginia Tech
U. S. Department of Energy
Atlanta Regional Support Office
Atlanta Student Audit Program
Prepared by Gregory Guess of the
Kentucky Natural Resources and
Environmental Protection Cabinet,
Division of Energy
Ken Baker of the Idaho Department
of Water Resources,
Energy Division
Enermodal Engineering, Inc.
John Heiland Grand Connections
Pacific Northwest
National Laboratory
Idaho Commercial Building
Energy Code Users Guide
U. S. Department of Energy
Making Cents of Your Energy
Dollar: A Guide to Identifying
Energy and Cost Saving Opportu-nities
in Institutional Buildings,
Volume 1 -Energy Audit
U. S. Department of Housing and
Urban Development
In the Bank or Up the Chimney?
A Dollars and Cents Guide
to Energy-Saving Home
Improvements
Carol Wilson
Savings Through Energy
Management (STEM) Program
Energetics, Incorporated
Graphic design and editing
Student
Rubric
|
Exceeds Expections |
Meets Expections |
Meets
Some Expections |
Does
Not Meet Expections |
|
| Points Earned |
6
|
4
|
2
|
0
|
| Calculations of the activities and observations that were conducted | Calculations are complete, include clear writing, relevant examples, and contain very few errors | Calculations are complete, written clearly and have few errors | Calculations are incomplete, unclear, or contain several errors | No calculations of activities are included |
| Data showing 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 of the findings |
| Explanation of the potential relevance or importance of the findings | The relevance is clearly articulated and the explanation makes a compelling statement | The relevance of the findings is clearly articulated | The explanation or relevance is illogical or fails to communicate clearly | No explanation or relevance is offered |
| Use of the internet to research relevant information concerning building components and energy | Demonstrates the ability to research a topic without assistance using several tools | Demonstrates the ability to research a topic without assistance | Research topics with minimal assistance | 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 mo stly in a positive mode; effort made to include all members | Team members required careful monitoring; presentation component | Team members did not work as a team |
| Presentation delivery |
Clear evidence of participation in some form by every team member; all parts well planned; strong portrayal of the teams special "suggestions" |
Evidence of participation by the majority of the team; good planning and execution; special interest of the team is evident | Participation by only 1 or 2 members; little evidence of group planning; special interest of team is not clearly presented | No participation by the team to prepare a presentation |
| Technology based presentation | Final project is
enhanced through use of technology |
Final project is partially technology | Final project not technology based | No final project completed |
Overview
The purpose of the Lighting in the
Library Activity is to calculate the electricity used to provide lighting in
the school library and determine the feasibility of saving energy and money
by using energy efficient lighting fixtures.
Your students will assume the role of an energy auditor assigned the task of
assessing the current situation and making a recommendation for energy-efficient
improvements. This activitity requires a trip to the library, an examination
of the school's energy bill, and a basic understanding of algebraic concepts
as a problem solving strategy.
Level
Grades 8 -12
Subject
Mathematics, Economics
Concepts
Applicable National Standards
National Math Standards:
Skills
Objective
Calculate the feasibility of replacing older, less efficient lighting in the
library with new fixtures that are more efficient and cost less to operate
Materials
Student Guide Primers:
All About Energy
High School Energy Inventory: Lighting Technology Overview
Student pages 1-10
Glossary
Time
Two 55-minute classroom periods.
Getting Ready
The exercise is designed in two parts.
The first part consists of determining the energy consumption, operating costs,
and amount of "greenhouse gases" resulting from the existing lighting fixtures.
The second part entails determining the economic feasibil-ity of retrofitting
the existing fixtures with three types of energy-efficient lights.
Two primers have been prepared to help you and your students ramp up your energy, environment, and lighting knowl-edge relatively quickly (see appendix). In addition, helpful hints and some examples specific to each step have also been provided. Before meeting as a class about this subject, download a copy of the energy and environment primer located on the web page (www. eren. doe. gov/ buildings/ earthday/) chalkboard. Each student in the class should have a copy of the following:
Choosing the Room in the School for the Exercise
The exercise is designed for the school library; however it will work for almost any room in the school. If the school library is not available, choose a different common room, preferably one with different kinds of light fixtures with different on / off schedules. Ask the librarian or custodian to help the students determine the on/ off schedule for the lights in the library. For example, there is typically one schedule for when school is in session and another for when it is out of session.
Additional Exercises for Advanced Students
Ask the students to see if there are any rooms in the area to be studied where lights are left on for long periods of time and are not occupied. Advanced students might determine the feasibility of installing motion detectors for those rooms as an extra credit exercise. Motion detectors will automatically turn lights on and off. Costs of motion sensors could be determined by calling a local electrical wholesale house and calculating labor at 1/ 2 hour per switch at a cost of $50 to $75 per hour for an electrician's time. The savings accrue from the number of hours the lights can be turned off. The payback period for the investment in motion detectors can be calculated in the same way as the Lighting in the Library exercise.
Background
Lighting typically accounts for 15
percent of the total energy bill of educational institu-tions nationwide. The
majority of buildings were built before the 1970s and have high levels of illumination
according to the design standards at the time. Most use older fluorescent fixtures
with four tubes, the standard fixture used in schools and office buildings for
many years. As a result, most schools spend too much on lighting bills.
Since the late 1980s, many modern
fluorescent fixtures have come equipped with the more efficient T8 lamp operated
by an electronic ballast. Depending on the task being performed, there are situations
where the old four light fixture can be coverted to a two light fixture and
still provide the required amount of light. The electronic ballasts were developed
to operate fluorescent tubes more efficiently Energy Smart Schools Earth Day
Teachers’ Guide 6 and consume less energy when the lights are on. Older, standard
ballasts consume up to 20 percent of the total amount of electricity required
to operate the lamp. Therefore, a 1.2 multiplier was added to the last equation
in Step 5.
Light fixtures in this exercise
are typical of those installed in schools built from the 1950s to the 1980s.
During this period, the standard light fixture was the 4-tube fluorescent located
in the ceiling. Incan-descent lighting remains the standard fixture for task
lighting. The majority of exit signs use incandescent bulbs. As students will
see in this exercise, these fixtures can often be replaced with newer, more
efficient types of lighting that cost much less to operate.
At the same time, there are a large
variety of light fixtures in schools used across the country. Some schools have
been designed to use natural lighting so effectively in common rooms, such as
the library, that it will be extremely difficult to reduce their lighting bills.
The best way to tell if there is an opportunity to improve the lighting efficiency
of a room is to calculate the "lighting index" for the room as done in Steps
9,14, and 19. If the index is above 1.3 (W/ ft 2 ), there is likely an opportunity
to economically reduce lighting energy consumption in the library. If the index
is below 1.3, it will be more difficult to do so within a 3-year payback period
but there are still many opportunities for savings and enhancing the visual
environment that warrant serious consideration. Retrofitting the lighting system
in older buildings, especially in institutional buildings that are above the
current lighting design levels, has proven to be one of the most cost-effective
energy conservation measures. The savings from lighting retrofits depend on
the amount of time the lights are used during the year. For lights that are
on a large percentage of the time, simple payback on the cost of replacing them
is from one to three years.
Doing the Activity
Ideally, the students
would read the primers first (perhaps as homework the night before beginning
the activity), and then complete the exercises in subsequent classes. Steps
1-9 should be completed in the first class period. Steps 10-22 can be completed
as a combination of in-class time and homework. When the students are done,
they will have enough material to prepare a presentation for the school board
about their energy-efficient proposal.
Lighting in the Library
The purpose of this exercise is to determine the amount of
electricity used to provide lighting to the school library.
During the course of these activities you will need to imagine
that you are an energy auditor who needs to make recommendations
to the school administration concerning the feasibility
of saving energy and money by using energy-efficient lighting.
To complete this task, an energy auditor would need to obtain
the values of several variables about the location, the current
situation, energy-efficient replacement options, and an
evaluation of their impacts on the bottom line. This exercise
is divided into several steps to help you determine the value of
the variables necessary to evaluate the energy consumption, its
cost and the resulting greenhouse gas from the lights in your
library. We will use the following problem solving application
strategy to achieve this objective:
Part 1 requires a visit to the library to understand your current situation. There, you will take an inventory of all of the lights in the room, estimate the schedule the lights are on and off, and using that information, calculate how much it costs to light the library for a year. You'll also estimate the amount of carbon dioxide (greenhouse gas) that is generated to make the electricity for these lights. While you work through the calculations, note the answers on the Variable Key on page10 . This will help you keep track of your answers, and assist you in making accurate bottom line conclusions during the final look back steps.
HELPFUL HINTS:
This section will provide you with examples and addtional background 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 locations of the lighting
fixtures. The sketch helps the energy auditor or engineer make sure the list
of lights is complete, and thus they can accurately calculate energy savings.
Furthermore, a sketch is essential for workers hired to make changes to the
lighting equipment to be able to identify exactly where this equipment is located.
On the sketch, list the type of light fixture with its electricity (power) rating,
measured in Watts.
How do I draw a sketch to scale of my library and calculate the area?
Use the sketch paper on page 3 or use a ruler and a blank sheet of paper and draw the largest outline on the piece of paper that will fit within the margins. For example, if the room is 40 feet by 25 feet in size, use a quarter inch scale on the drawing: 0.25 inch on the drawing represents 1 foot of the library. In this case, the measurements of the drawing on the page will be 10 inches by 6.25 inches. Note the scale on the sketch, in this case: 0.25 inches = 1 foot, so you can interpret what you draw at a later date. Draw an arrow facing north so you'll be able to tell which wall is which when you look at the sketch again. The area of a rectangular room is its length times its width.
How do I find out how much my school pays for electricity?
In order to calculate savings from energy efficiency, it is first necessary to calculate how much the school is paying for energy. Electricity costs used for savings calculations are based on the average cost of electricity for the school. This number can be obtained from the school administration by checking the utility bill and equation four.
How do I determine the number of Watts of electric power the light bulbs in my library use?
The power consumption of different
types of lighting can be determined by inspecting the lamps and ballasts in
the fixtures. If it is impossible to inspect the fixtures themselves, try to
determine the wattage of the lamps by asking the person responsible for changing
them, such as the custodian. If this is not possible, assume the following watt
ratings for the light bulbs below:
Example:
If a fluorescent fixture has four standard tubes, at 40 Watts each plus
the ballast, the entire fixture is rated at:
|
(4 x 40)
x 1.2 = 192 Watts Fixture
|
How do I determine the number
of hours per week that the lights are on in the library?
The estimated schedule for each fixture is best determined by interviewing people
who work in the library, such as the librarians or the custodian. This information
combined with the equation in step 3 will help you determine the answer to this
important variable.
Example:
For the purposes of illustrating how such a schedule might work, take a hypothetical school library where the lights are on from 7 a.m. to 7 p.m., Monday through Friday. During school sessions, the lights are on 12 hours a day for five days a week totaling 60 hours a week.
School Vacation
During school vacations, the library is open on weekdays from 9 a. m. to
3 p. m. This equals six hours a day for five days a week totaling 30 hours a
week. If your school has eight weeks off during the summer, a three-week winter
break, a week off for spring break, and a week off for holidays, vacations account
for 13 weeks a year. The calculated "on times" for most of the lights in this
case would be as follows:
|
(W x
X) + (Y x Z) = B
|
where:
w = hours per week that the lights are on when school is in session
x = weeks school is in session
y = hours per week lights are on when school is not in session
z = weeks during year when school is not session
You would complete the equation as follows
w = 60 x = 39 y =30 z = 13
(60 x 39) + (30 x13) = B
B=2730
What is a lighting efficiency index?
Energy engineers often use a lighting efficiency index such as the one below.
When the index is higher than that for similar rooms or buildings, engineers
can identify in advance where potential energy savings can be achieved. If the
index is greater than 1.3 Watts/ ft 2 , it indicates that there are probably
opportunities for savings. The index is calculated by dividing the total watts
consumed by the area. This index is recorded as watts /ft 2 . The equations
in steps 9, 14, and 19 will help you see where you are and where you could be
in relation to this standard.
Data gathering and observation
INSTRUCTIONS: In order to get to the bottom line, the energy auditor must
get general
information about the specific location. The answers to the first four steps
will help you
complete the calculations necessary to understand your current situation, plan
a better
approach, solve issues concerning your new approach, and finally, look back
at the
difference you can make with energy efficiency. To begin, follow the directions
for each
step. Consult the background information as needed.
STEP 1
Measure the dimensions of the library floor and sketch it to scale. Be sure to write the length and width on the sketch. Then draw the location and correct number of the incandes cent light bulbs, fluorescent tube light bulbs, and incandescent exit sign light bulbs that you see.
STEP 2
Calculate the area (length x width)
of the library and write your answer in the variable key next to A on page 10.
| A= |
STEP 3
Ask the people that work in the library how many hours per day the lights are on when school is in session and when school is not in session. Use this informa tion and the key below to determine the total hours the lights are used in the library. Write your answer in the variable key next to B on page 10.
(W x X) + (Y x Z) =B
B=
where:
w= hours per week that the lights are on when school is in
session
x = weeks school is in session
y = hours per week lights are on when school is not in
session
z = weeks during year when school is not in session
STEP 4
calculate the average cost your school pays per kilowatt-hour. Write your answer in the variable key next to C on page10.
| Total monthly energy bill
in $
= C ___________________________ Total kilowatt-hours from monthly bill |
| C= |
What is the Current
Situation?
Instructions: Energy au-ditors must learn the value of several variables
about the current room in order to convince administrators that energy efficiency
is a good idea. Steps 5-9 will help you find the value of the following variables
about the light bulbs in your 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
the current lighting index (H). To begin, follow the directions below and complete
the equations. Don’t forget to transfer your an swers to the variable key on
page 10.
STEP 5
In Column 2, write the number
of light bulbs you counted for each type listed in column one. Complete each
equation. Then, add the answers in column 4 and enter this new watt total in
answer block D and on page10.
|
Column 1
|
Column 2
|
Column 3
|
Column 4
|
|
Number of incandescent |
x 40 watts = |
||
|
Number of incandescent |
x 60 watts
=
|
||
|
Number of incandescent |
x 75 watts
=
|
||
|
Number of incandescent |
x 100 watts = |
||
|
Number of exit signs with
40 |
x 40 watts
=
|
||
|
Number of exit signs with
60 |
x 60 watts = |
||
|
Number of exit signs with
75 |
x 75 watts
=
|
||
|
Number of exit signs with
100 |
x 100 watts
=
|
||
|
Number of |
x 40 watts
x 1.2=
(or 34) |
||
|
D=
|
STEP 6
Use the total watts you calcu lated in step 5 (D) and the total hours the lights are used in a year from step 2 (B) in the equation below to figure out how many kilowatt-hours are consumed by the lights in your library. Write your answer in the variable key next to E on page 10.
|
D x B = E
_________ 1000 |
E =
|
STEP 7
Refer to steps 4 and 6 for the value
of the variables in the equation below. Then do the math to determine the current
annual cost of operating the lights in your library. Write your answer in the
variable key next to F on page10.
|
E x C = F
|
F =
|
STEP 8
The amount of carbon dioxide greenhouse
gas generated during electricity production ranges from 1.4lbs. to 2.8 lbs.
per kilowatt-hour, depending on whether or not the electricity is produced from
coal, nuclear power, or hydropower (see greenhouse gas article in the energy
and environment primer). Use the equation below to estimate the amount of greenhouse
gas created when the electricity is made to power the lights in your library.
Write your answer in the variable key next to G on page10.
|
E x 2= G
|
G =
|
STEP 9
Use the following equation to calculate an overall lighting index for the library. This index is the Watts consumed per square foot. Write your answer in the variable key next to H on page10.
|
D
____ A |
= H
|
H =
|
Determine the Feasibility of Installing Energy Efficient
Lighting
In this part of the exercise, you will plan a new approach to lighting your school library. This new plan will use less energy, cost less, and result in less greenhouse gas. Your plan will also include bottom line calculations and decision factors such as: identifying the costs and payback for buying and installing new lighting equipment and making a determination about whether or not the new, more efficient lighting will provide sufficient illumination to the library.
Background Information
The feasibility of replacing existing lighting with more efficient lighting depends on the cost of replacement versus the savings. The per year savings depend on the type of lighting 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 fluorescent lamps
The savings result from increased efficiency: getting more light with less electricity. The efficiency of these fixtures can be measured in terms of lumens per Watt (lm / Watt), and the higher the lumens per Watt rating, the more efficient they are. Generally, fluorescent lamps are much more efficient than incandescent bulbs, producing as much as four times more light (and less heat) with the same electricity input. For example, a 27-Watt compact fluorescent lamp provides 1800 lumens, while a 100-Watt incandescent bulb produces 1750 lumens. The CFL produces almost four times the lumens per Watt of the incandescent bulb.
Replacing incandescent exit signs with those lit by light emitting diodes (LED)
Similar efficiencies can be obtained from exit signs using light emitting diodes (LED), also used in the display areas on a calculator. LEDs are very long lasting and require very little power. For this reason, they work very well in applications such as exit signs that must stay on all the time.
Replace F40 lamps and
34 watt energy saver lamps with
T8 lamps and electronic ballasts (retrofit)
Replacing the existing 40w or 34w fluorescent lamps with the more efficient T8 lamp that is operated by an electronic ballast will provide excellent energy savings and also produce a superior quality of lighting which is important in a library environment. It is important that the existing fixtures be well cleaned before the new lighting is installed. Fixtures get dirty with age and are rarely cleaned. Up to 40% of a fixture's efficiency can be lost to dirt, so it is critical that all fixtures are well cleaned when being retrofitted. Replacing the old F40 lamps with the new efficient T8 lamps can save as much as 40% of the energy while providing equivalent or superior levels 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.
Chart 1
Light Output for Several Types of Energy-Efficient
Lamps
| Lamp Type |
Cost
*replace |
Lamp
Life (h) |
Watts
|
Lumens
|
Lumens
per Watt |
| Replace incandescent bulbs with compact fluorescent lamps |
|||||
| Compact fluorescent lamp (CFL) Standard incandescent bulb Replace F40 or 34 watt energy saver tubes with T8 lamps and eledronic ballasts |
$14
$.50 |
10,000
1,000 |
27
100 |
1800
1750 |
67
17.5 |
| F 40 or 34 fluorescent lamp T 8 lamp and electronic ballast Repalce incoandescent exit signs with LED exit signs |
$5 per tube
$8.75 per tube |
20,000
22,000+ |
192
106 |
11,960
10620 |
62
|
| Incandescent exit signs LED exit signs |
$90 |
1,000
20,000 |
40
20 |
-
- |
* Cost to replace fixtures in an
existing building is higher than to install them in a new building because of
higher labor costs to
remove and replace fixtures. For example, costs for LED exit signs themselves
are as low as $10. The estimates in this chart
include labor costs and may vary by 30% or more, depending on location.
PAY BACK
While commercial establishments require a 3-year payback or less for investing
in lighting, schools and institutional facilities will generally accept a much
longer payback period ranging up to six years. Some of the reasons these longer
payback periods are acceptable include:
Occasionally, the first cost of a new, efficient system will require a simple return of investment that exceeds 5 years; however, the long-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.
Plan a New Approach
Instructions: When energy auditors plan a new approach to lighting the
library, they consider many factors, including when and how to use daylight,
time controls on some lights and which energy-efficient light bulbs will deliver
the same or better light but use less energy. 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 steps 10-14 you will
recommend energy-efficient light bulb replacements, and then work to find the
answer to the following variables about your new plan: the number of watts (I);
the number of kilowatt-hours (J); its annual electricity cost (K);
the carbon dioxide greenhouse gas created by the electricity produced (L);
and the new lighting index (M). To begin, follow the directions to write
and solve the equations below. Then complete the calculations and transfer the
value of these variables to your key on page10.
STEP 10
Refer to your library sketch and the
equations you completed in step 5 to determine the number of inefficient light
bulbs you could replace with the energy-efficient options you read about on
your background sheet. Complete the equations below. Then add up the answers
to each equation and write this total in the variable key next to I on page
10.
|
_________________ |
X 27 watts
|
= ____________
|
|
Number of incandescent
light bulbs replaced by compact fluorescent lights |
||
|
__________________ |
X 2 watts
|
= ____________
|
|
Number of exit
signs with
incandescent light bulbs replaced LED exit signs |
||
|
__________________ |
X 34 watts
|
= ____________
|
|
Number of
fluorescent light
tubes you can replace with T8 |
STEP 11
Use the total watts you calcu lated
in step 10 (I) and the total hours the lights are used in a year from
step 2 (B) in the equation below to figure out how many kilowatt-hours
are con sumed by the new approach you planned. Write your answer in the variable
key next to J on page10.
|
I x B
___________ =J 1000 |
J =
|
STEP 12
Refer
to steps 4 and 11 for the value of the variables in the equation below. Then
do the math to determine the current annual cost of operating the lights in
your library. Write your answer in the variable ket next to K on page
10.
|
J x C = K
|
K =
|
|
J x 2 = L
|
L =
|
Compare Your New Approach with the Current Situation
Instructions: Finally, the energy auditor must
compare the current
approach and the new
plan. If you have not
transfered the values of the
variables you calculated
from the previous pages
onto the variable key on
page 10, go back and do it
now. Then write the
equations with the values
concerning your school
library and do the math.
STEP 15
Calculate the energy savings
between the current lights in
your library and the new lights
you recommended in your plan.
|
N =
|
E - J = N
|
Where N = the energy saved in a year
STEP
16
Calculate the energy cost savings
between the current lights in
your library and the new lights
you recommended.
|
P =
|
F - K = P
|
Where P = the money saved in a year
STEP
17
Calculate the greenhouse gas
emissions prevented by replacing
your current lights in your library
and the new lights you recom
mended.
|
Q =
|
G - L = Q
|
Where Q = lbs. of carbon dioxide prevented in a year
STEP
18
This exercise is designed to help you identify the payback possible from your
proposed lighting changes. Simple pay back is defined as the initial cost divided
by the first-year dollar savings. To determine the simple payback that would
occur if your school adopted your proposed lighting changes, use the equation
below. Note: Financial decision-makers usually use a 3-year payback.
|
|
= ____________= |
Y year
payback |
Where:
P= the money saved in a year
R= Initial cost of the compact fluorescent lights (See Chart 1, page
6)
S =Number compact fluorescent lights you propose
T= Initial cost of the (LED) exit signs
U =Number of (LED) you propose
V =Initial cost of the electronic ballast T-8 fluorescent tubes
W=Number electronic ballast T-8 fluorescent tubes you propose
STEP 19
Now compare the index between your current situation, your proposed new lighting
plan and the 1.3 w/ft 2 standard used by auditors to determine the probability
of energy savings.
What’s The Bottom Line?
Instructions: Use your variable key on page10 to fill in the chart below.
Then consider proposing 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 steps 21-22 in your proposal.
STEP 20
|
Energy
|
Cost
|
Greenhouse Gas
|
|
| Current lights in
the Library (variables E,F,G) |
|||
| Proposed new plan
for the lights in your library (variables J,K,L) |
|||
|
Savings from your |
What difference can this make in your school?
STEP 21
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.
|
N
___ A |
x sq. footage of school =
|
estimated energy saved by applying your plan to the whole school |
|
P
___ A |
x sq. footage of school =
|
estimated energy saved by applying your plan to the whole school |
|
Q
___ A |
x sq. footage of school =
|
estimated CO2 greenhouse gas prevented by applying your plan to the whole school |
Make
an Energy Smart Schools presentation.
STEP 22
Discuss your idea and findings with your classmates and teachers and make one
combined proposal to your school board and administration team. Research the
Energy Smart Schools program 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 for making your school or library more energy-efficient.
Summary of Variables Used in the Calculations
A = Area (Length times width) of library |
M = Lighting index with your new library lighting plan | |||
B = Total hours lights used in a year |
N = Energy saved in a year with your new library lighting plan | |||
C = Average cost per kilowatt-hour |
P = the money saved in a year with your new library lighting plan | |||
D = Total watts consumed by your library lights |
<
Q = Greenhouse gas prevented in a year | |||
E = Kilowatt-hours consumed by your library lights |
R = Initial cost of the compact lights you propase | |||
F = Annual cost of operating your library lights |
S = Number compact fluorescent | |||
| G= Estimated amount of carbon dioxide (CO2) greenhouse gas generated during electricity production | T = Initial cost of the (LED) exit signs (chart 1) | |||
H = Current lighting index for your library |
U = Number of (LED) exit signs you propose | |||
I = Total watts consumed by you library lights with your new plan |
V = Initial cost of the T-8 fluorescent tubes you propose changing | |||
J = Kilowatt-hours consumed with your new library lighting plan |
Y = payback for your plan ( years) | |||
K = Annual cost of electrity with your new library lighting plan |
||||
L = Amount of carbon dioxide (CO2) greenhouse gas with your new library lighting plan |
Summary of Variables Used in the Calculations
| A | area of a room measured in square feet |
| Btu | British thermal units |
| ft2 | square feet |
| h | hour |
| kW | kilowatt |
| kWh | kilowatt-hour |
| lrn | lumen |
| L | length of a classroom wall |
| mmBtu | million British thermal units (Btu) |
| W | width of a classroom |
| wk | weeks |
| yr | year |
| $ | U.S. dollars |
| x | multiplication (also*) |
| + | addition |
| - | subtraction |
| / | division (also "per," as in dollars per year; e.g.$ / yr |
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
The amount and quality of light around us affects our health, safety, comfort,
and productivity. Our country spends more than $37 billion each year on electricity
for lighting, but technologies developed during the past 10 years can help us
cut lighting costs by 30% to 60% while enhancing lighting quality and reducing
environmental impacts. In a typical indoor lighting system, 50 percent or more
of the energy supplied to the lamp can be wasted by obsolete equipment, poor
maintenance, or inefficient use.
Lighting Principles
and Terms
Some basic lighting terms are:
Lamp: a lighting industry term for an electric light bulb, tube, or other
lighting device.
Illumination: the distribution
of light on a horizontal surface. Illumination is measured in footcandles.
Lumen: a measurement of light
output from a lamp (often called a bulb or tube). All lamps are rated in lumens.
For example, a 100-watt incandescent lamp produces about 1750 lumens.
Footcandle: a lumen of light
distributed over a 1-square-foot (0.09-square-meter) area.
Ideal Illumination: the minimum
number of footcandles necessary to perform a task comfortably and proficiently
without eyestrain. The Illuminating Engineering Society says that illumination
of 30 to 50 footcandles is adequate for most home, office, and school work.
Efficacy: the ratio of light
output from a lamp to the electric power it consumes. Efficacy is measured in
lumens per watt (LPW).
Glare: excessive brightness
from a direct light source. Types of glare include direct glare, reflected glare,
and veiling reflections. Direct glare results from strong light from windows
or bright. Reflected glare is caused by strong light from windows or lamps that
is reflected off a shiny surface. Veiling reflection is a special type of reflected
glare that can obscure contrasts and reduce task clarity. Veiling reflections
occur when light is reflected from a work surface, a printed page or a computer
screen.
Light Quality: a measurement
of how well people in a lighted can see to do visual tasks and how visually
comfortable they feel in that space. Light quality is important to energy efficiency
because spaces with higher quality lighting need less illumination. High-quality
lighting is fairly uniform in brightness and has no glare.
Relamping: replacing an existing
lamp and/ or fixture to save
energy.
Types of Lighting
The four basic types of lighting are incandescent, fluorescent, high-intensity
discharge, and low-pressure sodium.
Incandescent lighting is
the most common type of lighting used in homes. Basic types of incandescent
lights are standard household, tungsten halogen, and reflector lamps.
A standard incandescent lamp uses
electric current to heat a tiny coil of tungsten wire inside a glass bulb to
produce light. Compared with other types of lighting, Standard incandescent
lamps, also known as the "A-type light bulb," have the shortest lives and convert
most of the electricity used to power them into heat rather than light.
Tungsten halogen lamps are more energy-efficient than standard incandescent lamps. They have a gas filling and an inner coating that reflect heat. Together, the filling and coating recycle heat to keep the filament hot with less electricity. These lamps are much more expensive than standard incandescents and are primarily used in commercial applica-tions: theater, store, and outdoor lighting systems. (Household incandescent lamps are the least expensive to buy, but they are the most expensive to operate.)
Fluorescent lighting is used primarily in commercial, institu-tional,
and residential indoor lighting systems. Fluorescent lights are about 3 to 4
times as efficient as incandescent lighting and last about 10 times longer.
A fluorescent tube produces light when electric current is conducted through
mercury and inert (chemically unreactive) gases. Fluorescent lamps operate most
efficiently when they are used for several hours at a time.
Fluorescent lights require the use of devices called ballasts for starting and
circuit protection. Ballasts control the electricity used by the lamp, and they
typically consume 10 percent to 20 percent of the total energy used by light
fixtures and lamps. One way to increase the energy savings of fluorescent lights
replacing their ballasts.
Tube fluorescent lamps are the second most popular lamps after standard incandescent.
The two most common types of fluorescent tubes are 40-watt, 4-foot (1.2-meter)
lamps and 75-watt, 8-foot (2.4-meter) lamps. Tubular fluorescent fixtures and
lamps are preferred for lighting in large indoor areas because their low brightness
creates less direct glare than do incandescent bulbs. ( In fluorescent
tubes, a very small amount of mercury mixes with inert gases to conduct the
electrical current. This allows the phosphor coating on the glass tube to emit
light.)
Compact fluorescent lamps are the most significant lighting advance in
recent years. They combine the efficiency of fluorescent lighting with the convenience
and popularity of incandescent fixtures. Compact fluorescent lamps can replace
incandescent lamps that are roughly 3 to 4 times their wattage, which can save
up to 75% of the initial lighting energy. Although they usually cost 10 to 20
times more than compa-rable incandescent bulbs, compact fluorescent lamps last
10 to 15 times as long. The energy saving and long life of compact fluorescent
lamps make them one of the best energy efficiency investments available. Early
versions of compact fluorescent lamps introduced in the 1980s were bulky, heavy,
and too big for many incandescent fixtures. However, newer models with less
heavy electronic ballasts are only slightly larger than the incandescent lamps
they replace. Some types of compact fluorescents include a ballast and a lamp
in a single disposable unit. Other types feature separate ballasts that can
handle about five lamp replacements before they wear out. ( Compact
fluorescent lamps come in a variety of sizes and shapes including (a) twin-tube
integral (b and c) triple-tube integral, (d) integral model with casing that
reduces glare, (e) modular circline and ballast, and (f) modular quad-tube and
ballast. They can be installed in regular incandescent fixtures, and they consume
less than one-third as much electricity as incandescent lamps do.)
High-intensity discharge lighting is used in outdoor lighting applications
such as large indoor arenas. These lamps use an electric arc to produce very
bright light. High-intensity discharge lamps can save 75% to 90% of lighting
energy when they replace incandes-cent lamps and fixtures. They provide the
highest efficacy and longest service life any lighting type. Like fluorescent
lamps, high-intensity dis-charge lamps use ballasts. They take a few seconds
to produce light when first turned on because the ballast needs time to establish
the electric arc to produce light.
The three most common types of high-intensity discharge lamps are mercury vapor,
metal halide, and high-pressure sodium. Metal halide lamps are similar in construction
and appearance to mercury vapor lamps, but they use metal halide gases (along
with mercury gas) in the lamp. Adding metal halide gases inside the lamp produces
greater light output, more lumens per watt, and better color than mercury vapor
lamps. Metal halide lamps are used to light large indoor areas such as gymnasiums,
sports arenas, and anywhere that color rendering is important.
High-pressure sodium lighting is becoming the most common type of outdoor lighting.
High-pressure sodium lamps are very efficient (90 to 150 lumens per watt). Their
efficiency is exceeded only by low-pressure sodium lighting. High-pressure sodium
lamps are also reliable and have long service lives, and they produce a warm
white color. (In a high-intensity discharge lamp, electricity arcs between
two electrodes, creating an intensely bright light. Mercury, sodium, or metal
halide gases act as the conductor.)
Low-Pressure Sodium lamps are used where the color of light is not important,
such as in outdoor security land highway lighting applications. Low-pressure
sodium lamps work somewhat like fluorescent lamps. They are the most efficient
form of artificial lighting available, have the longest service life, and maintain
their light output better than any other type of lamp. A wide selection of low-pressure
sodium lamps exists, and they vary in their construction, efficiency, color
characteristics, and lamp life. Low-pressure sodium lamps produce colors as
tones of yellow or gray.
Replacing Lamps and
Fixtures
When relamping (substituting one lamp for another to save energy), a decision
can be made to increase or decrease the level of illumination. When relamping
a large space, the new lamps should first be tested in a small area to ensure
adequate illumination, occupant satisfaction, and compatibility of the new lamp
with the old fixture.
Matching replacement lamps to existing fixtures and ballasts can be tricky,
especially with older fixtures. Buying new fixtures made for new lamps produces
greater energy savings, reliability, and longevity compared to relamping alone.
Relamping Incandescent
Fixtures
Much is now known about fixture design. Many indoor fixtures waste energy by
trapping a significant amount of light inside the fixture, while many outdoor
fixtures tend to disperse much of the light they produce beyond an intended
area.
New incandescent fixtures are designed
to "push" all the light they produce out into the room. Advances in indoor fixture
design include brighter reflectors and better reflecting geometry.
Many incandescent lamps are mismatched
to their tasks. Some have high wattages which result in unnecessarily high illumi-nation
and energy waste. This can be corrected by using lamps with smaller wattages.
Standard incandescent lamps can often be replaced with improved lamps. And,
for energy savings of 60% to 75%, many incandescent lamps can be replaced with
compact fluorescent lamps.
Standard incandescent lamps can be replace with compact fluorescent lamps in spaces where light is needed for long periods of time. New compact fluorescent lamp fixtures have built-in electronic ballasts and polished metal reflectors which improve light output and energy savings.
Relamping Fluorescent
Fixtures
Although fluorescent lamps are generally energy efficient, there are new, more
efficient fluorescent lamps that use better electrodes and coatings to produce
about the same lumen
output at a lower wattage. Common
40-watt and 75-watt lamps can be replaced with energy-saving lamps of 34 watts
and 60 watts, respectively. Energy-saving lamps for less-common fluorescent
fixtures are also available.
If the ballasts in fluorescent fixtures need to be replaced, improved electromagnetic ballasts and electronic ballasts can be used to raise the efficiency of the fixture 12 percent to 30 percent. Improved electromagnetic ballasts reduce energy loss, fixture temperature, and system wattage. Because they operate at cooler temperatures, they last longer than standard electromagnetic ballasts.
Electronic ballasts operate at a very high frequency that eliminates flickering and noise. They are even more efficient than improved electromagnetic ballasts. Some electronic ballasts even allow use of dimmer switches, which are usually not recommended with most fluorescent lamps.
Improving Lighting
Controls
Lighting controls are devices for turning lights on and off or for dimming them.
The simplest type is a standard snap switch. Other controls are photocells,
timers, occupancy sensors, and dimmer switches.
Standard snap switches, located in numerous convenient areas, are made to turn
off lights in unused areas. Photocells turn lights on and off in response to
changes in natural light levels. For example, photocells turn outdoor lights
on at dusk and off at dawn. Advanced photocells gradually raise and lower fluorescent
light levels with changing levels of daylight.
Mechanical or electronic timers use clock settings to automati-cally turn on
and off indoor or outdoor lights for security, safety, and tasks such as janitorial
work. Crank timers limit lights to short durations where the need for light
is brief.
Occupancy sensors detect motion to activate lights when a person is in the area
and then turn off the lights after the person has left. They are popular for
areas that are not regularly used and offer security advantages over continuous
lighting: when lights suddenly come on, they startle intruders and alert residents
and neighbors to motion in the area.
Dimmer switches reduce the wattage and output of incandes-cent and fluorescent
lamps. Dimmers also increase the service life of incandescent lamps significantly.
However, dimming incandescent lamps reduces their lumen output more than their
wattage. This makes incandescent lamps less efficient as they are dimmed. Dimming
fluorescent lamps requires special dimming ballasts and lamp holders, but does
not reduce their efficiency.
Daylighting
Daylighting means using sunlight for indoor lighting. Modern buildings designed
for daylighting typically use 40% to 60% less electricity for lighting needs
than do conventional buildings.
Sunlight is free and can be easily used to daylight a building. However, using
sunlight without causing glare and without overheating a building can be difficult.
Glare can be avoided with the use of window sills, walls, louvers, reflective
blinds, and other devices to reflect light deep into the building. Windows and
skylights can be located away from the direct rays of the sun to avoid overheating.
For example, placing skylights on the north slope of a roof rather than on the
southern may reduce unwanted heat transfer. Windows are also available with
selective coatings that transmit visible light from the sun while blocking heat
transfer.
Lighting Maintenance
Maintenance of light fixtures is vital to lighting efficiency. Light levels
decrease over time because of aging lamps and dirt on fixtures, lamps, and room
surfaces. To-gether, these factors can reduce illumination by 50% or more, <
while lights continue drawing full power. The following basic maintenance activities
can help prevent this:
Clean fixtures, lamps, and lenses every 6 to 24 months by wiping off the dust.
However, never clean an incandescent bulb while it is turned on. The water's
cooling effect will shatter the hot bulb.
Replace lenses if they appear yellow.
Clean or repaint small rooms every year and larger rooms every 2 to 3 years.
Dirt collects on room surfaces, which reduces the amount of light they reflect.
Consider relamping entire rooms or systems at one time. Common lamps, especially
incandescent and fluorescent lamps, lose 20 percent to 30 percent of their light
output over time. Many lighting experts recommend replacing all the lamps in
a lighting system at once. This saves labor, keeps illumination high, and avoids
overworking any ballasts with dying lamps.
Conclusion
Saving lighting energy requires either reducing electricity consumed by lights
or reducing the length of time the lights are turned on. This can be accomplished
by:
Lighting Facts
A 100-Watt incandescent lamp typically lasts for about 750
hours, while a 28-Watt compact fluorescent lamp lasts for
about 10,000 hours (13.3 times as long). At an average
electricity cost of $0.08 per kWh, the cost of operating 13.3
incandescent lamps over 10,000 hours is $80. The cost of
operating a single 28-Watt compact fluorescent lamp over
10,000 hours at $0.08 per kWh is $22.40. Assuming a cost of
$1.00 for each 100-Watt incandescent lamp, the total life-cycle
cost (product cost plus electricity cost) of using 13.33
incandescent lamps for 10,000 hours is $93.33. Assuming a
cost of $20.00 for one 28-Watt compact fluorescent lamp, the
life-cycle cost of using 1 compact fluorescent lamp is $42.40.
Replacing one 100-Watt incandescent lamp with a 28-Watt with compact fluorescent lamp can:
| 1 The energy in fossil fuels
such as coal is stored as... a chemical energy b electrical energy c thermal energy d nuclear energy |
8 Which fuel provides most
of the energy to commercial buildings? a electricity b natural gas c coal d petroleum |
| 2 Which energy source provides
the nation with the most energy? a coal b natural gas c petroleum d electricity |
9 Which sector of the economy
consumes the most energy? a transportation b commercial c industrial d residential |
| 3 Which residential task uses the most energy |