CHAPTER III - Building Inventory
In the previous chapter you started to develop a method for tracking energy use. In this and the following chapter you will begin to develop a precise listing of energy using features in your buildings and your options for saving energy.
There are three fundamental systems associated with understanding energy use in buildings:
(1) energized systems, (2) non-energized systems and (3) human systems.Energized systems
are those which consume energy directly and include heating, ventilation, cooling, humidification, dehumidification, lighting, water heating, waste handling, cooking, and equipment such as kilns, shop equipment, televisions, and computers.Non-energized Systems
do not consume energy directly but affect the amount of energy which an energized system must expend to get its job done. Typical non-energized systems include walls, windows, floors, roof, ceiling, and doors. Other factors influencing energy use are landscaping and siting.|
An example of these can be made with a car. If you are cold you can start the engine and either run the heater or roll up the windows. Can you identify the energized and non-energized components?
Start the engine and run the heater (circle one) E NE
|
Human systems
are persons who affect when and in what quantity energy is consumed. These persons include students like yourself, teachers, staff and visitors. When your mother yelled at you, "Close the door, we can't heat up the whole outdoors" she was trying to influence a component of the human system (YOU) in her energy use environment. Your mother realized that an open door wastes energy, and she knew the energy has a cost, because she paid the heating bill.You can see that energy use depends on the equipment you are using, it's efficiency and reliability, and on behavior. Whether we use energy wisely or wastefully depends on the choices we make. For example, it does not make much sense to change to higher efficiency lighting and then leave the lights on all the time. The savings are canceled by an increase in usage. Buildings don’t use energy, people do.
Project and Exercises
A. Measure and record the characteristics and equipment in your school that account for its energy use.
Tools
1. Blueprint of your school
2. Ruler, tape measure, clip board and pad
Steps
1. Confirm the blueprints - At a time that is not disruptive to classes, confirm that the blueprints accurately reflect the current school facilities. Note any changes that have taken place. Have walls been moved? Are the rooms still used for the original purpose or is a classroom now a weightroom or a lounge a classroom? Note any changes and unusual energy using equipment such as a kiln. At this stage a lot of detail is not needed. Major energy using equipment such as lighting and the kitchen will be looked at in greater detail later. If you do not have blueprints, now is a good time to create a floor plan of the school that you can use as a reference for your energy management program. Note different heating/cooling zones and where the controls are located.
2. From the floor plan determine the heated square footage of the school.
B. Use your results above with the energy use information you determined in chapter II to determine the BTUs and dollars per square foot/year.
Calculate BTU per Square Foot
(1) Total # BTU used for the year: ___________ BTU
(2) Total square feet of heated space in your school: ________________ft2
(3) Divide (1)/(2) to get BTU/square foot _______________________ BTU/ft2
(4) Divide #3 by 1000 to get kBTU/square foot/year _______________
Calculate $ per Square Foot
(1) Total Energy $ spent for the year _________________ $
(2) Total square feet of conditioned space in your school _____________________ ft2
(3) Divide (1)/(2) to get Dollars $/square foot ________________________Dollar/ft2
Energy Utilization Index (EUI)
Energy auditors use a measure called Energy Utilization Index or Energy Use Index, "EUI" to enable comparisons between different buildings and energy types. EUI is calculated by converting all energy used in a building to a common unit, BTUs, and then dividing it by the square footage of the heated/cooled space in the building.
The Energy Use Index (EUI) is the most common means of expressing the total energy consumption for each building . The EUI is usually expressed in BTUs/Square Foot-Year and can be used to compare energy consumption relative to similar building types or to track consumption from year to year in the same building. Sometimes EUI is given as thousands of BTU/square foot-year. This alternate definition will be used in the following example from the Portland Schools. The average for Portland Public Schools is 70 (seventy thousand Btu per square foot of conditioned space per year) with a low of 35 and a high of 120. Place your school on the scale below: How did your school do? (See item B.4 at the bottom of the previous page)EUI for Three Portland Public Schools
L_______________________________X_________________________________H
35 x x x 70 120
Lincoln (52.17) Roosevelt (70.23) Grant (78.96)
| Do a field investigation: Science investigators often identify "outliers" or standouts in their research. In a toxicology study, close observation of the mice who survived a sublethal dose is looking at standouts. Why did these mice live while the others died? Or looking at why some people get cancer when exposed to carcinogens and others do not. You can look at energy outliers too. In Portland, for example, Franklin High School had the highest energy use index (EUI) and Jefferson High School had the lowest (EUI). WHY? Consider taking a field trip to schools in your district that have very high or low EUIs to see if you can identify what the differences are in terms of location, construction, and operation. You should be able to get energy use data from the Energy Coordinator in your school district. Find out who this person is and think about doing some interviews. How about people who should know why there are differences. School custodians? Administrators? Keep record of your notes. |
The Energy Utilization Index (EUI) provides information similar to "average gas mileage" of your car. Cars with a low average gas mileage burn a lot of gas per mile; those with a high average gas mileage burn less gas per mile. These data allow energy managers to construct a base year. Normally the base year is the observed EUI before an energy program is started. Alternatively, the base year can be the average energy use per square foot of the last three years. Changes in energy use can then be seen over time. Obtaining accurate values for the data used in your audit such as square feet of conditioned space and careful selection of the base year is critical. Other factors such as climate and size of the student population may be of importance.
EUI and Base Years What do energy statistics look like? How do the numbers help us to make decisions? The table below shows monthly energy use EUI statistics for March, 1993 for the Portland Public School District. The base year used for the District is June 1989 to May 1990 or energy use that was prior to a retrofit. Depending on your school district, these data may or may not be available. However, with monthly energy bills you can establish your own base year and create a table similar to this one. Example: Monthly Energy Use Statistics - March, 1993 Portland Public Schools
|
Facility |
Monthly Consumption(mmBtu) |
Monthly Cost |
EUI Type |
EUI |
EPI |
|
Franklin |
1,975 |
$10,969 |
1 |
85.76 |
102.87 |
|
Wilson |
2,724 |
$14, 545 |
1 |
84.01 |
90.01 |
|
Grant |
2,456 |
$12,824 |
1 |
78.96 |
95.23 |
|
Voc. Vill. |
553 |
$3,144 |
1 |
78.85 |
113.39 |
|
Roosevelt |
2,235 |
$12,267 |
1 |
70.65 |
103.87 |
|
Benson |
3,349 |
$19,117 |
1 |
70.23 |
78.36 |
|
Marshall |
1,814 |
$12,215 |
1 |
69.28 |
127.28 |
|
Madison |
2,488 |
$12,334 |
1 |
67.03 |
146.88 |
|
Cleveland |
1,850 |
$12,041 |
1 |
65.69 |
90.71 |
|
Jefferson |
2,446 |
$13,958 |
1 |
65.22 |
117.95 |
|
Lincoln |
1,333 |
$8,553 |
1 |
52.17 |
91.98 |
EUI types:
1 - kBtu/sq ft/yr EUI-Energy utilization Index EUI-Energy utilization Index
EPI - Energy Performance Index. Comparison to last year energy use =100. Wilson is using about 10% less energy than last year; Madison about 47% more.
Does it make most sense to compare buildings based on energy used per square foot? Would energy used per student, or energy used per square foot -hour of operation be better measures on which to base comparisons? What do you think?