1. Introduction to Problem Analysis & Estimation
CLEI 150A, Fall 2014

2. What defines a sustainability "problem?"
Sometimes called "wicked"
Difficult to define
Seems intractable
Multicausal
Unforseen consequences
No obvious solution
Socially complex
Behavioral change
Interdisciplinary
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3. Need, Design & Product don't always (often) coincide--and sometimes the "need" is an artificial or created one
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4. How do we go about analyzing a problem or question?
What is it we want to know?
A technical feature or issue
Public policy issue or program
Behavior or practice
Why do we seek an answer & what is the character of the answer?
Purely informational or didactic reasons
To estimate problem magnitude
Input into problem framing
What do we want to know?
Quantity? How much energy used per house?
A stock? How much energy is available?
A flow? How much energy is required per unit of time?
Reasons for or causes of behavior?

5. We always begin with a set of preconceived notions, which need to be revealed for their effect on problem framing
The answer you get is usually a result of how a problem is framed
What embedded assumptions do we make about the problem?
How does this affect how we understand and analyze a problem?
Consider mobility
Do we assume individualized mobility?
Do we assume instant supply?
Do we design only around the car?
Do we believe that only prices matter?

6. Problem: How many piano tuners in Chicago
Problem: How many piano tuners in Chicago? Calculate an order of magnitude estimate
What is an “order of magnitude” & why is this a useful estimate?
What do you need to know or estimate to answer the question?
The question has two parts:
How many people in Chicago?
How many households in Chicago?
How many households have pianos?
How long does it takes to tune a piano?
How many pianos can/will one person tune in a year?
Answer: Divide number of pianos in Chicago by number of pianos one person tunes in a year

7. Another problem: how much water do you use daily?
What do you need to know?
For what do you use water?
Drinking; Washing; Cooking; Cleaning; Services; Embedded water in food
How much water does each activity consume?
How often do you engage in each activity?
Estimate each one to arrive at your estimated water "footprint"
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8. Using dimensional analysis
It is critical to be precise about input and output units
If you end up with strange units, your answer is probably incorrect
In what units is the answer you seek?
In what units are the inputs into your probem?
The input units must cancel out to give correct output units
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9. Calculate annual consumption of gasoline by cars in the U.S.
Total number of cars =
persons ÷ persons/car = cars
Total miles per year =
miles/year-car x cars = miles/year
Total gasoline consumed =
miles/year ÷ miles/gallon =
gallons/year
Variable or quantity
Unit of measurement
number of gallons consumed per year
gallons/year
U.S. population
persons
# persons per car
persons/car
# miles driven per year per car
miles/year-car
total number of miles per year
miles/year
avg. miles per gal.
miles/gallon
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11. Group exercise: For the following problem, please determine what you need to know, but don't try to solve it
Problem: Chuck Zillionaire wants to either build or refurbish a house that will not require any external sources of energy. He wants a big space (10,000 sq. ft.), but does not know whether it will cheaper to start from scratch or find a suitable existing residence or building and rehabilitate it. And he has a budget, but wants to know which option will cost less.
Your task is to decide what kinds of quantities and variables you would need to know in order to estimate an answer, and to do a dimensional analysis whose final units are in dollars.
Now: Take the problem home and fill in as many of the blanks as you can.
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