Engineering Design: Seeking Sustainable

Solutions

Objectives

By the end of this unit, students will be able to:

1.Broaden design alternatives by brainstorming sustainable alternatives.

2.Use the sustainable design tables to incorporate sustainability into alternatives analysis.

3. Incorporate sustainability into economic analysis by:

• Conducting life cycle cost analysis• Including environmental benefits in cost-benefit analysis

Engineering Design: Seeking Sustainable Solutions

• Review of sustainability and the engineering design process

• 3 strategies for more sustainable design:

1. Broaden design alternatives

2. Incorporate sustainability into alternatives analysis

3. Incorporate sustainability into economic analysis

Review of Sustainability Concepts

What is Sustainability?

• Meeting society’s present needs without compromising the ability of future generations to meet their own needs. (Brundtland Commission, 1987)

Review of Sustainability Concepts

Triple Bottom Line Solutions

• Good for the environment

• Good for economics

• Good for society

Review of Sustainability Concepts

The 3 Pillars• People

– Fair practices for all people and does not exploit interest of separate parties based on money, status or growth.

• Planet– Management of renewable and non renewable

resources while reducing waste.

• Profit– Financial benefit enjoyed by the majority of society.

Steps in the Engineering Design Process

1. Define the problem– Product or customer requirements, functions and features

2. Brainstorm alternative solutions– Products, structures, or processes

3. Prepare preliminary/conceptual design for each alternative

4. Compare alternatives– Includes establishing criteria and conducting alternatives analysis

– Includes economic analysis

Steps in the Engineering Design Process

5. Choose an alternative

6. Perform detailed design on chosen alternative

7. Build/test, modify as needed

• Real-world example

• At what steps could you consider sustainability?

Considering Sustainability in the Engineering Design Process

1. Define the problem– Product or customer requirements, functions and features

2. Brainstorm alternative solutions– Products, structures, or processes

3. Prepare preliminary/conceptual design for each alternative

Sustainability

Sustainability

Sustainability

SustainabilitySteps in bright green will be considered in this lesson.

Considering Sustainability in the Engineering Design Process

4. Compare alternatives– Includes establishing criteria and conducting alternatives

analysis

– Includes economic analysis

5. Choose an alternative

6. Perform detailed design on chosen alternative

7. Build/test, modify as needed

Sustainability

Sustainability

Sustainability

3 Strategies for More Sustainable Design

1. Broaden design alternatives

2. Incorporate sustainability into alternatives analysis

3. Incorporate sustainability into economic analysis

1. Broaden Design Alternatives

• When brainstorming, consider “out of the box” alternatives that may be more sustainable than ordinary ones.

• Sustainable options may or may not be justified in terms of capital cost or other factors.

– Consideration important– More sustainable alternative may turn out to be superior,

especially if sustainability is considered in alternatives analysis and economics analysis

1. Broaden Design Alternatives

Traditional CE Alternatives

Asphalt Road Concrete Road

1. Broaden Design Alternatives

More Sustainable CE Alternatives

Recycled Asphalt Road

Recycled Asphalt Road with a Bike

Lane

1. Broaden Design Alternatives

Traditional CE Alternatives

Concrete channel with a rectangular cross-section Concrete channel

with a trapezoidal cross-section

1. Broaden Design Alternatives

More Sustainable CE Alternative

1. Broaden Design Alternatives

Traditional CE Alternative

Customary Site Design

1. Broaden Design Alternatives

More Sustainable CE Alternative

Implements Non-Structural Runoff Control

1. Broaden Design Alternatives

Traditional CE Alternatives

1. Broaden Design Alternatives

More Sustainable CE Alternative

1. Broaden Design Alternatives

Traditional ME Alternatives

Gasoline Powered Chevy Malibu

Gasoline Powered Nissan Altima Coupe

1. Broaden Design Alternatives

More Sustainable ME Alternatives

Tesla Electric Car• 220 miles on a charge• 0 to 60 in 3.9 seconds

Smart Fortwo

• 2 passengers

• 3-cylinder engine

• 33 mpg city/41 highway

1. Broaden Design Alternatives

More Sustainable ME Alternatives

Honda FC Hydrogen Car

1. Broaden Design Alternatives

Traditional ME/EE Alternatives

Coal-fired power plant

Natural gas-fired power plant

1. Broaden Design Alternatives

More Sustainable ME/EE Alternatives

Solar power facility Wind farm

1. Broaden Design Alternatives

More Sustainable ME/EE Alternative

Coal-fired plant with carbon capture and sequestration

1. Broaden Design Alternatives

More Sustainable IE Alternative

More Sustainable IE Alternative

Practice Brainstorming Sustainable Design Alternatives

2. Incorporate Sustainability into Alternatives Analysis

Traditional Engineering Design Criteria:

• Function• Cost (capital and operating/maintenance)• Safety• Constructability• Durability• Aesthetic appeal

2. Incorporate Sustainability into Alternatives Analysis

Sustainable Engineering Design Criteria:

The previous list plus:• Impact on people (society)• Impact on the planet (environment)

2. Incorporate Sustainability into Alternatives Analysis

Sustainability Aspects to Consider in Engineering Design

Life Cycle Stage →Sustainability Aspect ↓

1. Materials Acquisition

2. Construc-

tion

3. Use 4. Demolition

a. Material use

b. Energy use

c. Water use

d. Solid waste generation

e. Emissions generation

f. Toxic releases

g. Land impact

2. Incorporate Sustainability into Alternatives Analysis

Sustainable Design Tables

• Handout

• Exercise

3. Incorporate Sustainability into Economic Analysis

Methods of Comparing Alternatives

• Present worth, annual payments, future worth analysis

• Break-even comparisons

• Rate of return (ROR), incremental rate of return (IROR) analysis

• Cost-benefit analysis

Life cycle cost analysis

Quantify environmental benefits

Use a lower discount rate

3. Incorporate Sustainability into Economic Analysis

Life Cycle Cost Analysis

• In choosing among engineering project/product alternatives, consider life cycle costs, or the total cost of ownership over the life of the project/product.

• Also called “cradle to grave" or "womb to tomb" costs.

• Useful in present worth, annual payments, future worth analysis (methods that compare costs of alternatives), and in break-even comparisons if benefits are not included

3. Incorporate Sustainability into Economic Analysis

Life Cycle Cost Analysis

• Phases of project/product life to consider:– Planning – Design – Construction/production– Operations – Maintenance, renewal/rehabilitation – Replacement or disposal

3. Incorporate Sustainability into Economic Analysis

Life Cycle Cost Analysis

• What phases of project/product life cycle are traditionally considered in alternatives analysis?

• Why might using full life cycle cost analysis benefit the environment?

3. Incorporate Sustainability into Economic Analysis

Life Cycle Cost Analysis

Example problem

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

Methods of comparing alternatives that include benefits:

• Rate of return (ROR), incremental rate of return (IROR) analysis

• Cost-benefit analysis

In evaluating benefits, be sure to quantify environmental benefits so they are not excluded.

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

• Suppose that a city is doing a cost-benefit analysis for how to use a piece of land. Two alternatives include:

1. Allowing a developer to construct a shopping mall, and

2. The “do nothing” alternative – leave the land as a forest.

• How would you quantify the costs associated with each alternative?

• How would you quantify the benefits associated with each alternative?

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

• Quantifying environmental benefits is typically difficult, so environmental benefits historically have often been left out.

Ways to quantify environmental benefits:• Surrogate markets• Surveys

– Willingness to pay to visit a park– Willingness to pay to use an HOV lane–

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

Ways to quantify environmental benefits:

• Health benefits

– Air pollution caused by an industry may cause people to miss work. A dollar value can be assigned to missed work using salaries. Installing an air pollution control device would have a quantifiable health benefit of fewer people missing work.

– Health care costs attributable to air quality

–

• Other

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

• Cost-benefit analysis: Used to choose among engineering project/product alternatives

• For each project alternative, calculate the ratio of benefits to costs, with all benefits and costs adjusted for the time value of money (typically everything is adjusted to present).

• Choose the option with the highest benefit-cost ratio or net benefit

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

• PVB (present value of benefits)

• PVC (present value of costs)

• BCR (benefit cost ratio) = PVB / PVC

• Net benefit = PVB - PVC

3. Incorporate Sustainability into Economic Analysis

Quantify Environmental Benefits

Example problem – Cost-benefit analysis

3. Incorporate Sustainability into Economic Analysis

Use a Lower Discount Rate

• Another way to consider sustainability in all types of economic analysis: use a lower discount rate

• A high discount rate implies a very low value on the welfare of future generations

Summary