Integrative Design

It is common to look for energy savings in isolation. However, this approach can obscure opportunities where one efficiency affects another part of the system.

Pipe example

• Larger pipes decrease fluid friction but cost more as the diameter increases.
• In isolation, you balance the pipe capital cost against the extra energy for the pump to overcome the friction.
• If you take an integrative approach, spending more on larger pipes can result in a smaller, cheaper pump.

Insulation example

• Thicker insulation decreases thermal energy loss for the same temperature difference.
• In isolation, you balance the insulation cost against the heating energy saved.
• If you take an integrative approach, spending more on insulation can result in a smaller, cheaper heater or air conditioning system.

Downstream versus Upstream

Because of the efficiency losses in power generation and delivery, the most important place to save energy is downstream.

Insulation Optimization

Assume that insulation cost is proportional to the thickness, since doubling the thickness doubles the material.

q = UA \Delta T

The U-value is given by the material conductivity divided by the thickness, so the power is inversely proportional to the thickness.

q \propto 1/t